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Systematic design and analysis of solar thermal cooling systems in different climates
Abstract
About 1000 solar thermal cooling systems have been installed worldwide, so experience with system sizing and design is limited. To counter the lack of experience and to evaluate the potential of energy and cost efficient solar cooling systems, a systematic system design study has been carried out covering most climatic regions worldwide. For each technology investigated, an energy optimized control strategy was developed which maximizes the primary energy efficiency.
It could be shown that a reduction of nominal chiller power by 30%–40% or more hardly affects the solar cooling fraction for most climates, but significantly increases the machine operating hours and thus improves the economics. Single effect absorption cooling systems easily reach 80% solar cooling fraction for all but very humid climates. Primary energy ratios can be over 3.0 and primary energy savings between 30 and 79%, depending on system design and cooling load data.
The economic analysis shows that solar thermal cooling and heating is more viable in hot climates than in moderate European climates. To achieve payback times of 10 years with today's energy prices, the investment costs have to be reduced by 30–70% depending on the location and dimensioning.
... A typical office building with high internal loading similar to the one used in reference [44] is considered for this study. The air inside the room is subjected to both sensible and latent heat transfer. ...
... In the current study, the restricting assumption that the outlet temperature of water from the cooling tower is equal to the ambient WBT, is relaxed. Moreover, the assumption that the amount of water evaporated in the regenerator is equal to the amount of water-vapour condensed in the dehumidifier is [44] Room sensible heat factor SHF 0.92 [10] relaxed in the present work. Furthermore, the air temperature at the DPIEC'S inlet is not assumed to be same as that of the ambient WBT in the current study. ...
... Compliance with ASHRAE Standard 55-2017 refers to room air conditions which are within the moderate thermal acceptability criterion for the occupants. The cooling system is simulated from 8 AM to 5 PM, which are the typical working hours in an office [44]. ...
In this paper, we provide thermal analysis and design methodology of a liquid desiccant assisted dew point indirect evaporative cooling system. The purpose of the system is to serve as an alternative for conventional vapour-compression based building air conditioning systems in providing satisfactory human thermal comfort conditions in the hot and humid climatic regions. The main features of the study are the following: i) novel incorporation of a forced parallel flow direct solar regenerator and a dew point indirect evaporative cooler within the same air conditioning unit; ii) detailed thermal modelling of each of the system components with lesser simplifying assumptions with respect to earlier works; iii) large cooling capacity (∼18.8 TR) under harsh climate; and, iv) a comprehensive year-around case study for system operation in a hot and humid location (Kolkata, India). Our thermal model is validated with a reference model study. The maximum room air temperature predicted by the current system for yearlong analysis is 26.7 °C. The thermal COP of the system for diurnal operation in the most humid month of a calendar year (July) varied between 0.40-0.96. The cooling system can prevent overheating of the conditioned space, as specified by ASHRAE Standard 55-2017, throughout the year.
... The application of solar energy to cover the cooling demand of buildings is also a well-known concept, for either residential, commercial or industrial fields. In particular, two main competing methods for cooling production starting from solar energy are possible: PV cooling and solar thermal cooling [1,3], whose technical and economic gap is continuously narrowing [4,5]. Among solar thermal technologies, different solutions are possible, mainly differing for the thermal cycle applied, e.g. ...
... However, despite the research on materials and components, design aspects as well as operation optimization can affect the overall performance, cost effectiveness and system reliability more than innovative and performant materials [4,36]. ...
... The typical layout of a solar cooling system consists of (i) a solar section, including solar collectors and a hot storage tank, (ii) the thermal chiller itself, that can be either an adsorption or absorption one, (iii) a component for heat rejection (e.g. a wet cooling tower or a dry cooler), (iv) a back-up system (either a gas heater connected to the hot storage or a vapour compression chiller), and (v) the cold distribution system to the user [4,37]. ...
In this paper, the activity carried out within the H2020 project ZEOSOL is introduced. Making use of the lessons learned from previous solar cooling projects, an advanced hybrid solar cooling system was developed. It consists of a thermal and an electric unit in parallel integrated in a single unit with the dry-cooler. ZEOSOL is based on commercial components but was optimised in order to guarantee optimal seasonal performance, high reliability (and therefore reduced maintenance) and easy installation. The components of the system were experimentally tested in the laboratories of AkoTec, CNR ITAE and Fahrenheit, with a specific attention to the definition of performance maps as a function of operating and design parameters. During the tests of each component, possible control strategies and rules were identified. Subsequently, a simplified sizing tool was developed, which can be adapted to different configurations and climates and takes into account user-experience for different stakeholders, such as engineers and installers. The methodology implemented is described, in order to be used as a guideline for the definition of standard sizing procedures for solar cooling systems. As exemplary cases, the results for three different climates (Athens, Berlin and Ryiad) are also presented.
... This corresponds to nearly 1.9% of unmet cooling energy which is deemed as a tolerable rate according to several researches (e.g. Calise, 2010;Calise et al., 2010;Eicker et al., 2015;Qu et al., 2010) especially considering the further fossil consumption that raising the auxiliary setpoint temperature could cause. Eicker et al. (2015) confirmed that it is recommendable to undersize the absorption cooling systems compared to the building's maximum cooling load. ...
... Calise, 2010;Calise et al., 2010;Eicker et al., 2015;Qu et al., 2010) especially considering the further fossil consumption that raising the auxiliary setpoint temperature could cause. Eicker et al. (2015) confirmed that it is recommendable to undersize the absorption cooling systems compared to the building's maximum cooling load. Such conclusion was also drawn by Calise (2010), Calise et al. (2010), Qu et al. (2010), Zhai et al. (2011), who stated that the use of an auxiliary gas-fired is acceptable only when the auxiliary energy to be supplied is low, the use of natural gas as a substitute of solar energy is opposing the objective of solar assisted systems. ...
... The cold storage tank is employed to reduce the discrepancy between energy supply and demand and could be either sensible, latent heat thermal storage or a thermo-chemical storage (e.g. Sarbu and Sebarchievici, 2015;Zhai et al., 2011;Eicker et al., 2015;Fan et al., 2014). ...
Due to the economic development and occupancy requests, building thermal comfort reached higher levels during the last years. Energy consumption rates have become excessive and engendered an increasing reliance on fossil-fuel reserves. Hence, the conception of energy-efficient buildings as well as applying solar cooling techniques has become a promising solution. In this context, the current work dealt with the appraisal of a solar system that drives the cooling process in an office building located in the Center of Researches and Energy Technologies in Tunisia. The solar system consisting of linear parabolic trough solar collectors' field coupled to a 16 kW double effect Lithium Bromide absorption chiller, supplies chilled water to a set of fan coils installed in the 126 m² laboratory building.
... However, several other studies have evaluated the technical and economic performance of solar cooling technologies to analyze how well they can perform when compared to conventional cooling systems [22,26]. These evaluations have been mainly done on residential cases of study, which have focused on air-conditioning processes highlighting design optimization methods, supply strategies, and the architectural integration of solar energy in buildings for cooling [27][28][29]. This fact, along with the previous argument, have resulted in a limited vision of the potential of solar cooling technologies applied to other commercial or industrial settings, where the potential to significantly impact CO 2 reduction is considerable. ...
... Despite the potential of alternative cooling equipment, heat-driven solar cooling systems have not achieved significant market penetration. According to general review articles focused on the design and operation of solar cooling, systems are significantly affected in the short and long term due to the natural variability of the solar resource [25,28,31,105]. Therefore, to overcome climate variability, systems require thermal storage (TES) and large solar fields that increase the initial investment cost. Consequently, at the end of the 2010s, solar heat cooling was considered unfeasible for the urban sector and PV-VCC systems were positioned as the best option for the residential sector [51,107,108]. ...
The trend to reduce CO2 emissions in cooling processes has made it possible to increase the alternatives for integrating solar energy with thermal equipment whose viability depends on its adaptation to polygeneration schemes. Despite the enormous potential offered by the industry for cooling and heating processes, solar cooling technologies (SCT) have been explored in a limited way in the industrial sector. This work discusses the potential applications of industrial SCTs and classifies hybrid polygeneration schemes based on supplying cold, heat, electricity, and desalination of water; summarizes the leading SCTs, and details the main indicators of polygeneration configurations in terms of reductions on primary energy consumption and payback times. To achieve an energy transition in refrigeration processes, the scenarios with the most significant potential are: the food manufacturing industry (water immersion and crystallization processes), the beverage industry (fermentation and storage processes), and the mining industry (underground air conditioning).
... Solar thermal cooling systems have been installed worldwide, and to evaluate their potential, Eicker et al. 2015 [180] studied their energy efficiency and costs in different locations ( Fig. 45 ). Results showed that these systems allow a reduction of 30% to 40% nominal chiller power improving the economics in operation (from 30% to 70% depending on the location and dimensioning). ...
... Cooling load profile examples of a solar thermal cooling system installed in well-insulated buildings with high internal loads[180] . ...
A systematic review of the technological options and strategies to achieve zero energy buildings was carried out to establish today state-of-the-art knowledge base and to present key design and performance factors that define those technologies with the final aim of contributing to climate change mitigation options of buildings. All relevant literature published from January 2013 to August 2019 was critically assessed. A total of 14895 papers were identified and 220 reviews were evaluated as first literature source; this literature showed that the published information is diverse and not organised, therefore climates and building typologies is not possible solely through published information. Collected evidence shows that with appropriate design, buildings can contribute to climate change mitigation decreasing the embodied energy in the materials used in their construction and decreasing the energy demand and use during their operation phase.
... The solar-assisted single-effect absorption refrigeration has been extensively studied [19,20] . Numerous experimental analysis and simulation studies have been conducted with regard to parametric optimization [21] , performance improvement [22] , thermal energy storage [23] , auxiliary energy alternative [24] , energetic [25] and economic analysis [26] etc. The alternative designs [27] , thermal enhancement methods [28] , daily performance [29] and working fluid investigation [30] of PTC also have been carried out among the available literatures. ...
... The refrigerant flow rate in the HPG and LPG can be calculated by Eqs. (26) and (27) . ...
With the increasing concerns on energy conservation and environmental protection, solar heating and cooling (SHC) system represents an attractive candidate in building sector. In this paper, an integrated SHC system driven by parabolic trough collector (PTC) and double-effect H2O/LiBr absorption chiller was presented. The energy generated by solar collectors was supplied to the absorption chiller during the cooling period, and was directly used for space heating with the integration of plate heat exchanger during the heating period. The mathematical models of the whole system including the collector, the double-effect absorption chiller and the plate heat exchanger were established and were validated by field tests. Based on the proposed models, comparison of the SHC system and the conventional gas-driven absorption heating and cooling system was carried out by case study. The annual performances as well as energetic, economic and environmental assessments of the proposed system were investigated. Results show that, 21.3% of the primary energy consumption and 18.8% of the CO2 emission can be reduced in SHC system. Therefore, the proposed integrated solar heating and cooling system has a promising application prospect in sustainable development in view of its considerable energy saving benefits, potential economic viability and environmental friendly characteristics.
... The DPIEC uses a fraction of the intake air as an evaporative sink and supplies the rest to the . This supply air aims to maintain suitable thermal comfort conditions inside the room with high internal load [4]. Finally, the cycle is completed by bringing the conditioned air inside the room back to the air blender. ...
... By solving equations (1) through (16), the conditions of supply air at the inlet to the room are found out. The heat load calculation for the office building is done by assuming a sensible heat factor of 0.92 using the approach provided in [4,10]. ...
In this paper, exergy analysis of a novel solar powered liquid desiccant assisted air
conditioning system is presented and simulated. The system aims to provide suitable thermal
comfort conditions inside large office buildings with high internal loads situated in the hot and
humid tropical/subtropical countries of the world. The system consists of process and
regenerating air streams, a liquid desiccant solution loop and a cooling water loop. The primary
objective of this study is to present the exergy of cooling capacity along with the overall
exergy efficiency of the proposed system. The study helps to quantify the optimum operating
and design parameters for system operation based on the second law of thermodynamics. For
the base case, which is representative of a hot and humid climatic condition, the proposed
system is able to maintain the room air conditions within the moderate thermal acceptability
criterion. The exergy of cooling capacity and exergy efficiency for the base case is about 2900
W and 2 % respectively. Parametric analyses show that the system performs the best under
conditions of high ambient insolation and temperature, low ambient humidity and a process air
to desiccant solution mass flow rate of about 3 in the dehumidifier.
... They concluded that the collector capital cost must be reduced to $360 per unit area of the collector in order for the modeled system to economically compete with conventional electrically-driven vapor compression heat pumps. Eicker et al. [188] investigated the primary energy use and economic performance of a solarassisted single-effect absorption chiller in several climatic regions in the world. The authors found that the unit cost of cooling for such systems in European locations with limited operating hours strongly depended on proper sizing of the system. ...
... The results also suggested that with a decrease in the system capital costs and an increase in the electricity price, this technology can become economically viable in the near future, especially in countries with high solar energy potential. In addition to the economics of solar-powered absorption chillers, the emissions produced by these systems should also be taken into account, as environmental concerns with regards to energy systems are accelerating [188,[190][191][192][193]. Bukoski et al. [194] developed a life cycle assessment method to study the environmental impacts of a solarpowered absorption chiller compared to a conventional air-conditioning system in a stadium in Bangkok, Thailand. ...
Solar heating and cooling (SHC) systems are currently under rapid development and deployment due to their potential to reduce fossil fuel use and to alleviate greenhouse gas emissions in the building sector – a sector which is responsible for ∼40% of the world energy use. The available technologies on the market for thermally driven cooling systems are absorption and adsorption chillers, solid and liquid desiccant cooling systems, and ejector refrigeration cycles. Of these, absorption chillers are considered as the most desirable method for harnessing solar thermal energy due to their relative maturity, reliability, and higher efficiency. In addition, absorption chillers can take advantage of economies of scale in large buildings to obtain a relatively good levelized cost of cooling as compared to other thermally-driven air-conditioning systems. In this paper, the background theory on solar-powered absorption chillers is presented followed by a comprehensive literature review of the recent existing theoretical and experimental investigations on this technology is conducted. The review shows that the majority of solar absorption chillers installed and much of the research around the world is based on single-effect chillers and low-temperature solar thermal collectors, while less emphasis has been placed on the combination of high-temperature solar thermal collectors and multi-effect absorption chillers, especially triple-effect chillers. Research studies indicate the use of gas-fired backup systems for single-effect chillers is inefficient due to its very low primary energy savings. It was also found that the storage tank and piping can be major sources of heat losses in solar absorption cooling systems. Thus, special care should be taken to ensure sufficient and appropriate insulation for all heat loss components. In regions with low direct normal incidence solar resources (e.g. most of Europe), solar multi-effect chillers are relatively inefficient, so single-effect chiller-based solar cooling systems are the best techno-economic choice in such regions. Conversely, multi-effect absorption chillers with high-temperature collectors are indeed promising in regions with high solar resources. However, the review shows that using currently available technology, SHC absorption chillers are not able to economically compete with conventional cooling without government subsidies and incentives. Therefore, improving the economic performance of these systems is essential. While there is clearly more that can be done on chiller and solar collector components themselves, we believe some R&D emphasis going forward should also be dedicated to the balance of the system, including optimization of the system configuration, minimizing parasitic losses, improved design and integration of thermal storage and auxiliary system, and numerous controls and operational aspects. To date, many of these topics have been largely overlooked in favor of chiller performance studies.
... [24]. This uncertainty was also reported in the study carried out by Eicker et al. [112], also performing a detailed economic analysis for different weather locations. Authors concluded that SHC systems may be profitable only when their cooling capacity is below 60% of the maximum building cooling load, in order to maximize the number of operating hours. ...
... Authors concluded that SHC systems may be profitable only when their cooling capacity is below 60% of the maximum building cooling load, in order to maximize the number of operating hours. Such economic performance is also significantly affected by the occurring climate conditions, showing a unitary cooling cost varying from 0.09 to 1.01 €/kWh [112]. ...
... In this present work, a dynamic simulation model has been developed in TRNSYS 17 in order to evaluate the primary energy consumption as well as water usage for different cooling systems in a 15 kW absorption chiller at different operating conditions. Much research has been carried out for the simulation of LiBr-H 2 O absorption chillers by TRNSYS 17 software [22][23][24][25][26][27]. This software is restricted only to the LiBr-H 2 O absorption chiller [28] and the simulation is independent of thermodynamic properties of the absorbent-refrigerant solution and the internal thermodynamic cycle performance. ...
... (c) It is important to consider primary energy consumption by auxiliaries and the cooling tower when analysing the total performance of an absorption refrigeration system. The performance of the absorption cooling system can be defined as a primary energy ratio (PER) [27], which is the ratio of useful energy output to the primary energy (electrical and thermal energy) input. The primary energy input is considered as the total energy input to the system, which includes the total electrical energy consumption and the thermal energy supplied to the system and it is defined as: ...
In tropical and sub-tropical regions, air-conditioning systems account for the greatest electricity consumption and high water use. Solar-driven absorption cooling systems can conveniently reduce electricity consumption at need. The performance of this cooling system depends on the system’s heat rejection. A simulation was performed for a 15 kW single effect ammonia-water absorption cooling system driven by low temperature thermal energy and with three different heat rejection methods (wet cooling, dry cooling, and hybrid cooling). This hybrid cooling system uses wet cooling on the absorber and dry cooling on the condenser. The system performance and economics of the chiller with these cooling methods were evaluated. The analysis showed that a wet cooling system has a higher system performance and water consumption compared to a dry cooling system, which has a high primary energy consumption with no water usage. In hot weather conditions and where there is scarcity of water, hybrid cooling can consume on average 41% less electrical energy than dry cooling and 49% less water than wet cooling and the payback period compared to a wet cooling system can be less than three years.
... Traditional refrigeration devices with an electric compressor consume large amounts of energy, so solar energy systems that operate by absorption and adsorption can replace them [139,140]. Eicker et al. [141] studied and analyzed absorption cooling systems covering most climatic regions worldwide. They concluded these systems could cover 80 % of the solar cooling fraction except for humid climates. ...
... Eicker et al. [13] presented the results of a systematic solar cooling system design study covering most climatic regions worldwide and different cooling technologies. According to the study, single-effect absorption cooling systems easily reach 80% solar cooling fraction for all but very humid climates, and primary energy savings between 30 and 79%, depending on system design and cooling load data. ...
In this paper, a solar absorption cooling system with a chilled water storage tank and peak load compression system was considered for cooling the Instituto Superior Tecnico Tower building in Lisbon, Portugal. To fulfill this task, a dynamic simulation of the building was performed using the DesignBuilder software, then a solar collector field was designed. The next step was to build a computational model of the absorption chiller in the Engineering Equation Solver software, which allowed for further simulation of the annual operation of the system supported by the chilled water tank and the backup system with compressed air conditioning. The last stage of the work was the economic analysis of such a system in com-parison with conventional compressed air conditioning. The simulation results and economic analysis showed that the solar absorption cooling system could be a beneficial cooling solution for the Instituto Superior Tecnico Tower building. How-ever, it would have to operate with an energy storage system and a peak load compression backup system to be able to cool the building efficiently all year round. Additionally, such a solution could have a significant positive impact on climate through considerable annual savings in electricity consumption. Results revealed that the proposed system meets the cool-ing demand of the building, mainly by solar-energy-driven absorption chiller. The annual contribution of a backup com-pression chiller ranges from 20% to 36% depending on the size of chilled water storage tanks. Financial calculations re-vealed discounted payback periods in the range of 4.5 to 12.5 years depending on the system configuration.
... The performance and physical principle of VC systems have been the subject of a very large number of studies on SC technologies (see, for instance [20][21][22][23]). On the other hand, several studies [23][24][25][26] have concentrated on alternatives (e.g. TDHPs). ...
This paper presents a comprehensive taxonomy and assessment of existing and emerging space cooling technologies in Europe. The study aims to categorize 32 alternative space cooling technologies based on eight scouting parameters (physical energy form, basic working/operating principle, refrigerant or heat transfer medium , phase of the working fluid, specific physical process/device, type of space cooling technology, fuel type and technology readiness level) and evaluate their key characteristics and development trends. The increasing demand for space cooling in Europe necessitates a thorough understanding of these technologies and their potential for energy efficiency. The majority of space cooling demand in Europe is currently met by conventional vapour compression systems, while a small portion is covered by thermally-driven heat pumps. The study reveals that several alternative space cooling technologies show promise for energy-efficient cooling but are not yet competitive with vapour compression systems in terms of efficiency and cost in the short-term and medium-term. However, technologies such as membrane heat pumps, thermionic systems, thermotunnel systems, and evapo-rative liquid desiccant systems demonstrate cost-competitiveness and energy efficiency in specific applications. The findings highlight the need for further research and development to improve the efficiency, costs, and market competitiveness of alternative space cooling technologies. The study also emphasizes the importance of policy support and the urgency to reduce greenhouse gas emissions, which can drive the adoption and advancement of sustainable cooling solutions.
... Eicker et al. [13] presented the results of a systematic solar cooling system design study covering most climatic regions worldwide and different cooling technologies. According to the study, singleeffect absorption cooling systems easily reach 80% solar cooling fraction for all but very humid climates, and primary energy savings between 30 and 79%, depending on system design and cooling load data. ...
In this paper, a solar absorption cooling system with a chilled water storage tank and peak load compression system was considered for cooling the Instituto Superior Tecnico (IST) Tower building in Lisbon, Portugal. To fulfill this task, a dynamic simulation of the building was performed using the DesignBuilder software, then a solar collector field was designed. The next step was to build a computational model of the absorption chiller in the Engineering Equation Solver software, which allowed for further simulation of the annual operation of the system supported by the chilled water tank and the backup system with compressed air conditioning. The last stage of the work was the economic analysis of such a system in comparison with conventional compressed air conditioning. The simulation results and economic analysis showed that the solar absorption cooling system could be a beneficial cooling solution for IST Tower building. However, it would have to operate with an energy storage system and a peak load compression backup system to be able to cool the building efficiently all year round. Additionally, such a solution could have a significant positive impact on climate through considerable annual savings in electricity consumption. Results revealed that the proposed system meets the cooling demand of the building, mainly by solar-energy-driven absorption chiller. The annual contribution of a backup compression chiller ranges from 20% to 36% depending on the size of chilled water storage tanks. Financial calculations revealed discounted payback periods in the range of 4.5 to 12.5 years depending on the system configuration.
... The performance of these systems is often compared to conventional heating or cooling generators with fossil fuel or electricity to estimate primary energy savings and economic benefits [7,8,[13][14][15][16][17] or environmental impact [7,9]. Sizing the absorption chiller for covering only a fraction of the design load leads to better economic indicators [6,9,11,17,18]. Thereby, it is also possible to achieve more operating hours with the chiller working at maximal load and thus less electrical energy consumption by auxiliary equipment required to run the system. Some of the first estimations of solar absorption cooling systems were carried out by Florides et al. [14,15] who concluded that the system could provide environmental and economic benefits in comparison with a conventional system based on an oil boiler and vapor compression chiller, but the limitation is high investment costs for the chiller. ...
Solar heating and cooling (SHC) systems are currently attracting attention, especially in times of increasing energy prices and supply crises. In times of lower energy prices, absorption SHC systems were not competitive to compression cooling supported by photovoltaic (PV) modules due to the high investment costs and total energy efficiency. This paper aims to discuss the current changes in energy supply and energy prices in terms of the feasibility of the application of a small absorption SHC system in a mild Mediterranean climate. The existing hospital complex restaurant SHC system with evacuated tube solar collectors and a small single-stage absorption chiller was used as a reference system for extended analysis. Dynamic simulation models based on solar thermal collectors, PV modules, absorption chillers and air-to-water heat pumps were developed for reliable research and system comparison. The results showed that primary energy consumption in SHC systems designed to cover base energy load strongly depends on the additional energy source, e.g., boiler or heat pump. Absorption SHC systems can be price competitive to air-to-water heat pump (AWHP) systems with PV collectors only in the case of reduced investment costs and increased electricity price. To reach acceptable economic viability of the absorption SHC system, investment price should be at least equal to or lower than a comparable AWHP system.
... The spatial patterns were similar for all insulation materials examined in this study. Energy savings depend on geographical and climatic conditions and are more important in hot climatic zones [64,65]. For example, Antalya, which is located in a hot region, saves more energy than provinces in a cold region (e.g., Erzurum and Ardahan) (Supplementary Material, Table S3). ...
Cold storage facilities consume a considerable amount of energy, especially in hot climates, which can be decreased using thermal insulators to maintain a stable temperature. The primary aim of this research study was to determine the effect of insulation thickness on the energy efficiency and cost savings of exterior walls for cold storage facilities in all climatic zones of Türkiye. To this end, data from the meteorological databases of 81 provinces were analyzed, and four insulation materials (expanded polystyrene, extruded polystyrene, rock wool, and polyurethane) were selected for different cold storage reference temperatures. The spatial distributions of optimal insulation thickness, energy savings, and payback periods were derived using a geographic information system (Ordinary Kriging). The optimum insulation thickness and energy savings were found to be 0.020–0.137 m and 0.030–6.883 USD/m², respectively. Depending on the insulation material and base temperature, the shortest payback periods (1.498–3.457 years) were obtained in the Aegean and Mediterranean regions. In addition, rock wool provided the highest energy savings and the shortest payback period among all the insulation materials studied. The results from this study can help investors to improve their design considerations for cold storage wall insulation.
... Shirazi et al. [57] investigated the utilization of several types of solar thermal collectors with absorption chillers. They found through their study that ETCs, EFPCs, and PTCs are the Eicker et al. [63] found that for solar single-effect absorption systems the cooling unit cost with limited operating hours is highly depended on system sizing in some locations. The results showed that under sizing the chiller capacity by 30-40% have a slight change on the solar fraction of the system, but significantly increased the chiller's operating hours and thus improve the system economics. ...
Solar energy has a great ability in cooling and air conditioning as the demand for cooling and air Conditioning increases worldwide. Absorption cooling cycles have the advantage of being environmental friendly and uses either solar or waste heat for cooling with very small electric power. In this thesis a mathematical model was developed using Engineering Equation Solver EES in order to perform an energy & exergy analysis of both single and double effect absorption system. The exergy analysis of the cycle had shown that the double effect absorption systems have several advantages in terms of coefficient of performance (COP) and exergetic coefficient of performance (ECOP) than the single effect absorption system. Results from simulations showed that COP and ECOP have values of 1.19 and 0.26 for the double effect cycle while for a single effect cycle COP and ECOP have values of 0.68 and 0.27, respectively. The exergy loss and exergy destruction for every component had been also calculated. The exergy destruction of both Evaporator and absorber represent about 50 % of the total destruction for both single and double effect. The required minimum generator temperature to operate the system had been evaluated. Analysis results showed that the optimum generator temperature decreases with the evaporator temperature and increases with the condenser temperature. Hence it is possible to determine the optimum generator temperature for various condenser-evaporator temperatures. An optimized function had been developed to determine the optimum operating conditions from the maximum COP point of view. Several runs were carried out using the TRNSYS simulation program on the proposed optimized system under different weather data of three Egyptian cities to investigate the performance of the system. The selected cities were Aswan, Cairo and Marsa Matrouh. Results from the proposed model showed that optimum generator temperature of the absorption chiller was not affected by the climate conditions, it also showed a huge improvement in terms of COP with a value ranging from 0.77 to 0.83 for single effect and from 1.32 to 1.5 for double effect, which is about 15:20 % enhancement.
... The results of the study showed that, with changing the control mechanism from C1 to C3, the solar fraction of the system may increase by 11%. Eicker et al. [10] proposed a detailed dynamic simulation model for the single effect solar absorption cooling systems. The influence of the nominal power of the absorption machine, and solar collector field on the energy performance, CO 2 emissions, and system cost were investigated under various climatic conditions. ...
In this study, a solar-powered absorption cooling system was modelled using the TRNSYS software. Theperformance of the system was investigated using dynamic modelling under the weather conditions ofMugla, Trabzon, Izmir, Konya, Canakkale and Istanbul. The external catalog datafile of the absorptionchiller model was created to get more realistic results. A parametric study was carried out to evaluate theselected parameters’influence on system efficiency. Various parameters such as solar collector type, area,storage tank volume, collector slope, boiler setpoint temperature, room thermostat set point tempera-ture were investigated to see their impact on the performance of the solar-absorption system, in everycity. Instead of using a constant boiler setpoint temperature, a novel control strategy is proposed. Besides,the payback period and the levelized cost of cooling of the optimized systems were studied. Resultsshowed that, in terms offinancial analysis, Izmir is the most suitable city for solar-based absorptioncooling system applications with a payback period of 10.7 years. Trabzon is found to be the least suitablecity due to the longest payback period, and the highest levelized cost of cooling among all locations.
... Common configurations of solar thermal driven cooling systems can be viewed in two perspectives (Desideri et al., 2009); (i) standalone system with or without thermal storage (Ibrahim et al., 2017;Lazzarin et al., 1993;Li et al., 2014) and (ii) assisted system. In assisted system, solar cooling is coupled with a vapour compression chiller or backed up by a gas fired heater (Eicker et al., 2015). This study falls under the first category of solar cooling, where the solar collector is directly coupled to the chiller without thermal storage. ...
... Among available solar thermal cooling systems, solar absorption cooling system is competitive due to its relatively high efficiency [9]. It is also environmentally safe since it works with natural refrigerants such water or ammonia [12]. ...
In the present paper, we investigate the feasibility of a thermal solar driven cold room in Gabes, southern region of Tunisia. The cold room of 109 m 3 is refrigerated using an ammonia absorption machine. It is destined to preserve dates during the hot months of the year. A detailed study of the cold room leads previously to the estimation of the cooling load of the proposed storage room in the operating conditions of the region. The next step consists of the estimation of the required heat in the generator of the absorption machine to ensure the desired cold temperature. A thermodynamic analysis was accomplished and complete description of the system is determined. We propose, here, to provide the needed heat thermally from the sun by using vacuum tube collectors. We found that at least 21m² of solar collectors are necessary to accomplish the work of the solar cold room.
... The potential for solar collection in facades has been explored through the development of building integrated photovoltaics (BIPV) and building integrated solar thermal collectors (BIST), resulting in guidelines, prototypes and commercialised products [18][19][20]. On the other hand, solar driven refrigeration has been described and categorised in terms of working principles [21,22], and evaluated and compared considering performance [23,24] and to a lesser degree, economic aspects [25,26]. However, besides stand-alone prototypes and integrated concepts, there is a knowledge gap regarding guidelines for building application and especially integration possibilities within façade components. ...
Increasing cooling demands in the built environment call for innovative technical solutions and systems for application in buildings. Cooling loads represent an important share of the total energy consumption in warm climates, especially in commercial and office buildings. Moreover, mechanical systems will still be needed in most cases to cope with cooling loads, even after considering passive cooling strategies in the design of the building and its façade. Solar cooling technologies present interesting assets, being based on environmentally friendly cooling processes, driven by solar and thus renewable energy. However, their application in the built environment remains greatly limited. This paper assesses several solar cooling technologies in terms of their potential for façade integration; aiming to promote widespread application in buildings throughout the development of integrated architectural façade products. The assessment is based on a state-of-the-art review and discussion of key attributes for façade integration of selected technologies; and a qualitative evaluation of their suitability to respond to main product related barriers for the integration of building services identified in an earlier work by the authors. The cooling principles behind the operation of the assessed technologies have been extensively presented in the literature, so this paper focuses exclusively on key aspects to overcome barriers related to the technical feasibility, physical integration, durability, performance, and aesthetics of future integrated concepts. Results show that the suitability of the assessed technologies varies according to each particular barrier. Hence, no technology currently fits all required aspects. Nonetheless, the use of thermoelectric modules and compact units based on absorption technologies are regarded as the most promising for the development of either integral building components, or modular plug & play systems for façade integration. In any case, this is heavily conditioned to further efforts and explorations in the field to overcome identified challenges and knowledge gaps.
... Their results show that the solar cooling system allows a substantial saving of electricity compared with a conventional systems. Eicker et al. [7][8][9] analyzed a Solar cooling plant in different climates, and focused on economic and energy performances, demonstrating that it is possible to reduce primary energy by 40 -70% and that the system design and energy load have an important role in system performance. Bellos and Tzivanidis [10] studied the productivity of Solar Cooling in various locations around the world. ...
The advantage of a solar cooling system is the simultaneity of strong sunlight and cooling demand in the summer season. In fact, when the demand of electricity reaches extreme peaks for the excessive use of air conditioners, solar energy is available. In this study, simulation based on a performance analysis of a solar cooling system is carried out by means of TRNSYS for an agro-industrial application. The configuration is fully modelled in TRNSYS and dynamic simulations are run for the entire year. First, the analysis determines the peak energy demand for a low-temperature room for an agro-industrial application located in the Naples area. The room is 11 m long, 9.50 m wide and 3.20 m high and a set-point temperature is assigned equal to 10°C. Two different types of collector (ETC and PTC) with a double effect (H2O-BrLi) chiller (150 kW) are considered. The analysis is carried out considering the optimal solar field area, collector slope and hot storage tank. A supplementary conventional boiler of 50 kW and a cold storage tank with volume 5 m³ are also present. The terminal part of the system is constituted by fan coils. Various performance factors such as solar fraction, collector efficiency and primary energy savings are evaluated to optimize the key system design variables which include collector tilt, storage volume, type and size of the solar collector. Besides, a financial analysis is carried out.
... Their results showed that if the hot water storage tank is well insulated, the solar fraction can be boosted by 60%. Eicker et al. [4][5] analyzed a solar cooling system in different climates, they focused on economic and energetic performance, showing that it is possible to reduce the primary energy of 40-70% and the system design and energetic load has important roles in the performance of the system. Cucumo et al. [6] have carried out a thermodynamic analysis and evaluation of the performance of solar plants with parabolic though collectors cooled by atmospheric air. ...
Solar cooling technologies are of great interest because the cooling load in buildings is directly correlated to the intensity of solar radiation. In this paper, a feasibility study of a solar cooling system for a cold room in the Southern part of Italy is carried out. This feasibility study can be an example for future achievements in Southern of Italy. The cold room is part of an agro-industrial structure; the set point of temperature is 10°C. The room is 11.0 m long, 9.5 m wide and 3.5 m high. Two sliding doors 3.0 m high are present and strawberries are inside mainly. Thermal loads are evaluated by means of the software TRNSYS 17. Parabolic Though Collectors (PTCs) are employed to capture the solar energy. The solar field extends for 210 m². Two double-effect chillers (with a total installed power equal to 150 kW) for the collectors are employed. In addition, a conventional heat pump is installed to meet the demand for refrigeration during unfavorable weather conditions or during the maintenance of chillers. There are two different storage tanks: a tank with volume 10 m³ for hot water storage and a tank with volume 40 m³ for cold storage. The terminal part is constituted by dry coolers. Results are given in terms of heat transfer rates and solar fraction. Besides, an economic analysis is carried out to evaluate the payback time.
... Their results shown that the proposed system consumed 47% less electrical energy than the conventional vapor compression cycles, besides they noted that the collector area have a predominant impact on the payback time in terms of economic performance. Eicker et al. [21][22][23] carried out an energetic and economic performance of a solar cooling system for office buildings under different climates worlwide. Their results showed that it is possible to reduce the primary energy of 40-70% and the system design and energetic load have important roles in the performance of the system. ...
... Their results showed that if the hot water storage tank was well insulated, the solar fraction could be boosted by 60%. Eicker et al. [22][23][24] analyzed a solar cooling system in different climates, they focused on economic and energetic performance, showing that it is possible to reduce the primary energy of 40-70% and the system design and energetic load had important roles in the performance of the system. Cucumo et al. [25] carried out a thermodynamic analysis and evaluation of the performance of solar plants with parabolic trough collectors cooled by atmospheric air. ...
The amount of energy for air conditioning in the summer time in Mediterranean Area is very high because of hot weather and high temperature values. Solar cooling technology is interesting because strong sunlight covers the cooling requirement. The heat energy from the sun it is available when the demand of electricity has high peaks for the strong use for air conditioning devices. In this work, an analysis by means of NEGST software (New Generation of Solar Thermal System) on a solar cooling and heating system located in the southern part of Italy has been carried out. The building is a Quality Assurance Office of a chemical industry. It is 48 m long, 23 m wide and 3.5 m high, and about 200 people work inside. Thermal loads from people, PC, machines etc. have been estimated by means of Energy Plus code. Three different type of collectors (FPC, ETC and PTC) and two different chillers have been considered: single effect for collectors FPC and ETC and double effect (H2O-BrLi) for the collectors PTC. Results in terms of solar fraction and PE-Saving for three different configurations are shown. Besides, the payback period for the best configuration is estimated.
... Solar electric systems can contribute to the reduction of primary energy consumption by 21-70% depending on the location, size of the building and size of solar panels (Eicker et al., 2015a). However, economic viability of such systems, especially solar thermal ones, currently is low (Eicker et al., 2015b). Coordination of financial and policy incentives would be needed to match the growth of electric AC with solar PV capacity. ...
Data on European residential space cooling demands are scarce and often of poor quality. This can be concluded from a review of the Comprehensive Assessments on the energy efficiency potential in the heating and cooling sector performed by European Union Member States under Art. 14 of the Energy Efficiency Directive. This article estimates the potential space cooling demands in the residential sector of the EU and the resulting impact on electricity generation and supply systems using the United States as a proxy. A georeferenced approach was used to establish the potential residential space cooling demand in NUTS-3 regions of EU. The total potential space cooling demand of the EU was estimated to be 292TWh for the residential sector in an average year. The additional electrical capacity needed was estimated to 79GW. With proper energy system development strategies, e.g. matching capacity of solar PV with cooling demand, or introduction of district cooling, the stresses on electricity system from increasing cooling demand can be mitigated. The estimated potential of space cooling demand, identified in this paper for all EU Members States, could be used while preparing the next iteration of EU MS Comprehensive Assessments or other energy related studies.
... They concluded that the collector capital cost must be reduced to $360/m 2 in order for the modeled system to economically compete with conventional electrically-driven vapor compression heat pumps. The primary energy use and economic performance of a solar-assisted single-effect absorption chiller in several climatic regions in the world were investigated by Eicker et al. [40]. They found that the unit cost of cooling for such systems in European locations with limited operating hours strongly depended on proper sizing of the system. ...
Solar heating and cooling (SHC) systems are currently under rapid development and deployment due to their potential to reduce the use of fossil fuel resources and to alleviate greenhouse gas emissions in the building sector – a sector which is responsible for ∼40% of the world energy use. Absorption chiller technology (traditionally powered by natural gas in large buildings), can easily be retrofitted to run on solar energy. However, numerous non-intuitive design choices must be analyzed to achieve the best techno-economic performance of these systems. To date, there has been little research into the optimal configurations among the long list of potential solar-driven absorption chiller systems. To address this lack of knowledge, this paper presents a systematic simulation-based, multi-objective optimization of three common, commercially available lithium bromide-water absorption chillers – single-effect, double-effect and triple-effect – powered by evacuated tube collectors (ETCs), evacuated flat plate collectors (EFPCs), and concentrating parabolic trough collectors (PTCs), respectively. To the best of authors’ knowledge, this is the first study of its kind that compares the optimized designs of the most promising configurations of solar-assisted absorption chillers against a common set of energy, economic, and environmental metrics from a holistic perspective. A simulation model of these three configurations is developed using TRNSYS 17. A combined energy, economic, and environmental analysis of the modeled systems is conducted to calculate the primary energy use as well as the levelized total annual cost of each plant, which are considered as two conflicting objective functions. By coupling TRNSYS and MATLAB, a multi-objective optimization model is formulated using a genetic algorithm to simultaneously minimize these objectives, thereby determining a set of optimal Pareto solutions corresponding to each SHC configuration. The performance of the proposed systems at their optimal designs is then compared to that of a reference conventional system. A sensitivity analysis is also performed to assess the influence of fuel cost, capital cost of innovative components, and the annual interest rate on the Pareto front of optimal solutions. Overall, the optimization results reveal that of the proposed configurations, the SHC double-effect chiller has the best trade-off between the energetic, economic and environmental performance of the system, having a total cost of ∼0.7–0.9 M$ per year and reducing the annual primary energy use and CO2 emissions by 44.5–53.8% and 49.1–58.2% respectively (relative to the reference conventional system). With the high capital cost associated with these systems, government subsidies and incentives are still required in order for them to achieve satisfactory payback times and become cost-competitive with conventional HVAC systems.
... Their results shown that the proposed system consumed 47% less electrical energy than the conventional vapor compression cycles, besides they noted that the collector area have a predominant impact on the payback time in terms of economic performance. Eicker et al. [21][22][23] carried out an energetic and economic performance of a solar cooling system for office buildings under different climates worlwide. Their results showed that it is possible to reduce the primary energy of 40-70% and the system design and energetic load have important roles in the performance of the system. ...
The high temperature values in the summer time in southern Europe involve a high demand of energy for air conditioning. The advantage of solar cooling is the simultaneity of strong sunlight and cooling requirement. In fact, when the demand of electricity reaches extreme peaks for the excessive use of air conditioners, heat energy from the sun it is available. In this paper, an analysis with NEGST (New Generation of Solar Thermal System) feasibility study for a solar cooling plant in southern part of Italy (Naples) is carried out. The building is an office of a chemical industry. It is 48 m long, 23 m wide and 3.5 m high, and 200 people work inside. Thermal loads by machines, people, PC etc. were evaluated by means the software Energy Plus. It is considered three different type of collectors (FPC, ETC and PTC) and two different chillers: single effect for collectors FPC and ETC and double effect (H2O-BrLi) for the collectors PTC. Results are given in terms of solar fraction and PE-Saving for three different configurations. Then, it calculated the payback time for the best plant configuration.
... While much of the literature is dedicated to solar-assisted single-effect absorption chillers [14][15][16][17], a few researchers have investigated the use of multi-effect absorption chillers fed by solar thermal energy. Ayadi et al. [11] reviewed the available studies employing concentrating solar collectors for solar cooling and defined the technical aspects necessary for future development. ...
The feasibility of solar-powered multi-effect LiBr-H2O absorption chillers is investigated under different climate conditions, and three configurations of solar absorption chillers are proposed with respect to the type of the chiller. In the first configuration, a single-effect absorption chiller is coupled with evacuated tube collectors (ETCs), while parabolic trough collectors (PTCs) are utilized to run double- and triple-effect LiBr-H2O chillers in the second and third configurations, respectively. A simulation model for each configuration is developed in TRNSYS 17 environment. A parametric study is conducted by varying the fraction of direct normal irradiance (DNI) under three global horizontal irradiance (GHI) categories (low, medium and high) to determine which configuration results in the most efficient and cost-effective performance of the plant under a given climate. The simulation results reveal that there is no advantage in using solar multi-effect absorption chillers over solar single-effect chillers when the DNI fraction is less than 60% of the total solar global irradiance. However, a significant decrease in the size of the solar field for both double- and triple-effect chillers can be achieved in climates where the DNI fraction is above 60%. The cost analysis results indicate that a minimum DNI fraction of about 70% is required in order for solar-driven multi-effect chillers to be cost-competitive compared to solar single-effect chillers. The sensitivity analysis shows that the capital cost of PTCs needs to be 20% below today's nominal cost for multi-effect absorption chillers to be more cost-effective than ETC powered single-effect chillers in climates with relatively high DNI fraction (>∼50–60%).
... The few studies of SHC systems in the literature differ with regard to the type of procedure. Some studies included a parametric study and cost analysis to determine the least cost systems [23,24], while others were based on the development of mathematical models [25]. More recent works used transient modelling [4,26,27]; most of these studies analysed only the case of European building types in their climates. ...
Parametric optimization using dynamic simulation of a solar thermal system for producing hot water, space heating and cooling was developed. The system layouts include a single-effect absorption chiller activated by heat generated by flat plate solar collectors and stored in a solar storage tank. Two construction types were compared; the first is the typical construction in Algeria (low thermal mass with U-values of 1.25 W/m 2 K, single glazing), which represents the majority in the country, while the second is a High-Energy-Performance building (with U-values of 0.35 W/m 2 K, double glazing), representing the pilot project called ECO-BAT. Three of Algeria's regions were considered to evaluate the climatic effect of solar systems integration. Algiers represents the coastal region; Djelfa, the highlands region; Tam-anrasset, the Sahara region. In parametric study, two solar collectors' field parameters were analysed, including the surface area and the tilt angle. The results indicated that building loads are significantly reduced (12%, 44% and 22% for Algiers, Djelfa and Tamanrasset, respectively). The solar energy contribution is more than 60% for all cases, a significant contribution for an efficient building. In all cases, we observed that the solar fraction reaches more than 45% when the optimum parameters of the solar system are selected.
... The results showed that the proposed system consumed 47% less electrical energy than the conventional vapor compression cycles, and the collector area was found to be the key parameter impacting the payback time of initial investment costs. Eicker et al. [29][30][31], in several studies, analyzed the energy efficiency performance and cooling costs of solar thermal cooling systems for office buildings in several climates worldwide. The results showed that the plant primary energy use can be reduced by 40-70%, depending on system design and cooling load data. ...
The present work investigates the feasibility of solar heating and cooling (SHC) absorption systems based on combining three types of LiBr–H2O absorption chillers (single-, double-, and triple-effect) with common solar thermal collectors available on the market. A single-effect chiller is coupled with evacuated tube collectors (ETCs) – SHC1. A double-effect chiller is integrated with parabolic trough collectors (PTCs), linear Fresnel micro-concentrating collectors (MCTs) and evacuated flat plate collectors (EFPCs) respectively – SHC2, SHC3, and SHC4. PTCs are employed to provide high-temperature heat to a triple-effect absorption chiller (SHC5). Although triple-effect chillers have been around for a while, this paper represents the first system-level analysis of these chillers coupled with high-temperature solar concentrating collectors for air-conditioning applications. A simulation model for each configuration is developed in a transient system simulation environment (TRNSYS 17). Furthermore, a unique, comprehensive perspective is given by investigating the impact of characteristic solar beam radiation to global radiation ratios on the techno-economic performance of the proposed SHC plants for a wide variety of climatic regions worldwide. The results of parametric study suggest that a storage volume of around 70 L/m2 is a good choice for SHC1, while 40–50 L/m2 storage capacity is sufficient for the other configurations (SHC2 to SHC5). The simulation results reveal that when the fraction of direct normal irradiance (DNI) is less than 50%, SHC2, SHC3, and SHC5 require larger collector area compared to SHC1, showing there is no advantage in using concentrating collector powered multi-effect chillers over solar single-effect chillers in climates with low DNI level. However, in climates with DNI fractions above 60%, the smallest solar field is achieved by SHC5, followed by SHC2. SHC4, which benefits from both relatively high COP of double-effect chiller and the diffuse component in the solar field, results in the most reasonable trade-off between energetic and economic performance of the system in a wide range of climatic conditions.
... If E loss,HE,(1) accounts for the main part of the total exergy destruction, the way to reduce E loss,HE is by enlarging the heat transfer area. If the exergy destruction is mainly composed of E loss,HE, (2) , enlarging the heat transfer area will have little improvement on the heat exchanger. Under these circumstances, the emphasis should be put on the improvement of DT uniformity, i.e., reducing x. ...
Two-stage desiccant wheel systems are an effective way to improve the dehumidification performance. In the present study, the performances of a one-stage system and a two-stage system with identical heat transfer areas are compared, with particular emphasis on the required heating source temperature. The exergy and unmatched coefficient (ξ) are applied to analyze the destruction of the heat and mass transfer processes. Compared to the one-stage system, the regeneration temperature (Tr) of the two-stage system is lower. The required hot water temperature (Th) depends on the supplied water flow rate and Ap/Ar of the desiccant wheel. When Ap/Ar = 1, Th of the two-stage system is lower only when the supplied water flow rate is relatively high. And due to different heat transfer area distribution demand, the exergy destruction of two-stage system is higher than one-stage system. When Ap/Ar = 3, the two-stage system has greater advantages. ξ of the desiccant wheel decreases from 2.9 to 2.2 when the number of stages increases from 1 to 2, leading to lower exergy destruction of the desiccant wheels and higher exergy efficiency.
The ever‐increasing cooling demands in China give rise to huge impact on power grid and lead to massive CO 2 emissions, exacerbating ecological issues, such as global warming. It is urgent to develop clean, environmental friendly, and low‐carbon refrigeration technology to achieve decarbonization in the cooling process. This work aims to evaluate the application potential of a solar adsorption cooling (SADC) system based on a novel aluminophosphate adsorbent in various climatic zones of China through TRNSYS simulation. For a comprehensive evaluation, solar absorption cooling (SABC) and vapor compression cooling systems are selected as reference systems. Energy, environment, and economy analyses of SADC are conducted in 12 representative Chinese cities. The results show that the studied solar adsorption system outperforms in energy conservation and emission reduction, particularly in hotter zones, where it can save up to 23% of primary energy and reduce at most 46% of CO 2 emission per year compared to vapor compression cycle. Meanwhile, the system demonstrates strong economic benefits and market competitiveness in hotter zones. Moreover, the proposed system shows higher energy efficiency and faster response speed than SABC system, especially in zones with moderate solar energy resources. The performances make the proposed system a practical alternative to realize near‐zero‐carbon refrigeration powered by renewable energy.
Green building is a concept in sustainable development which aims to reduce energy consumption and carbon emission of buildings. This study attempts to design and introduce a novel green HVAC system which reduces both energy consumption and carbon production of buildings. This system uses solar absorption chillers to provide the cooling demands of buildings. In addition, biofuel (biogas) fired boilers are also added to provide the heating demands. By using the novel approach of the study, such HVAC system can be coupled with other renewable technologies like photovoltaics and develop green buildings. In order to design, model and simulate the operation of this system, famous energy modeling tools are compared with each other and Design Builder software is chosen as the appropriate one. The paper also introduces a plan for establishment of such systems which is applicable to any locations. The results of modeling this green HVAC system for 10 various climates indicated considerable advantages of this system over traditional systems. The green HVAC system can save the maximum energy of 50 MWh per year in a four stories building. The maximum amount of 31 tons carbon can also be saved if the said building is equipped with this novel HVAC system. The results also made it clear that the solar cooling system is a great choice for providing cooling needs in hot climates. By coupling this kind of cooling system with biofuel heaters, the sustainable HVAC system can develop green buildings even in cold or cool climates. Adding green electricity producers like photovoltaic panels to this system and the building was successful. The maximum produced green energy in buildings was calculated as the amount of 17.9 MWh/yr.
Solar cooling technologies have considerable potential in reducing the energy consumption of buildings to realise carbon neutrality. However, they typically suffer during off-design operations due to variations in meteorological data and cooling demand. Hence, system optimization is extremely important to achieve the best thermo-economic performance considering all varying conditions. However, optimizations based on the two widely used approaches, i.e., annual simulation and exergoeconomics, can not fully resolve the aforementioned problems. Accordingly, the so-called full-condition exergoeconomic optimization is proposed and applied to a solar absorption-subcooled compression hybrid cooling system, which has potential for building cooling. First, a full-condition exergoeconomic model is formulated, and the impact of critical component size is subsequently analyzed. Finally, the size of key components is optimized based on the trade-off between capital investment and performance in all-working condition. Further, the variation among optimal sizes based on different meteorological data is compared. The total cost rate of the optimal case for the system utilized in Haikou is found to be 13.6% lower than that of the base case. The scales of the solar device and compression subsystem are found to be positively related to the local solar radiation intensity and cooling load. The study is anticipated to aid in rendering solar cooling facilities to be cost-effective in all-working condition.
Many government agencies everywhere in the globe, including those in the developing regions, are intimately involved in developing their Information Systems (IS) projects. To favourably develop these IS projects, those agencies have spent lots of funding, forces and time to assure that they are amply equipped with the latest system design and analysis methods. However, the literature is scarce with the published evidence showing that these government agencies are claiming that they have successfully used these cultivated analysis and design techniques. The intricate system analysis and design techniques may only remain theoretical with limited use. Many of these system analysis and design techniques had never succeeded the claimed benefits made when they were acquired, which begs the principal research question of what is the present deployment state of system analysis and design in these government institutions, particularly in the developing regions? The article thus discusses the exploratory case studies on the present state of system analysis and design methods deployed by the public institutions in East Malaysia, a developing region within South-East Asia.
With the 2010/31/EU directive, all new buildings shall be nearly zero-energy buildings (nZEB) from 2020 onward, with the aim of strongly reducing the energy consumption related to the building sector. To achieve this goal, it is not sufficient to focus on the design of the building envelope; smart and efficient energy management is necessary. Moreover, to ensure the adoption of RES systems in the built environment, innovative technologies need to be further developed in order to increase their cost-effectiveness, energy efficiency and integration capability. This paper proposes a synthesis, design and operation optimization of an integrated multi-energy system composed of traditional and innovative renewable technologies, developed within the European project Re-COGNITION. A biogas-based micro cogeneration unit, lightweight glass-free photovoltaic modules, a passive variable geometry small wind turbine optimized for an urban environment and latent heat thermal storage based on phase change materials are some of the technologies developed within the Re-COGNITION project. The optimization problem is solved to contemporarily evaluate (a) the optimal design and (b) the optimal operations of the set of technologies considering both investment and operating costs, using mixed integer non-linear programming. The optimization is applied to the four pilots that are developed during the project, in various European cities (Turin (Italy), Corby (United Kingdom), Thessaloniki (Greece), Cluj-Napoca (Romania). Simulation results show that the development and optimal exploitation of new technologies through optimization strategies provide significant benefits in terms of cost (between 11% and 42%) and emissions (between 10% and 25%), managing building import/export energy and charge/discharge storage cycles.
This paper takes the independent-developed special parabolic trough collector for the air-conditioning and the double-effect absorption chiller to build a solar cooling system, and simultaneously utilizes the ground heat exchanger(so-called SGAC system) to replace the traditional cooling tower as the heat exhausted side(so-called SAC system) in summer. The simulation model of SGAC is established on TRNSYS. The simulation calculation is performed for the building cooling during the whole cooling season in Beijing. The research results indicate that SGAC has a good stability and high efficiency during the whole cooling season. The performance comparison of SGAC and SAC has been carried out. The economy of SGAC system should also be considered in the determination of the main design and operating parameters.
A single-effect absorption cooling system was planned and simulated appropriate to a hot and dry climate, and optimization was made accordingly in the present study. TRNSYS software is a very comprehensive program that includes much equipment in its subprograms. For this reason, solar collectors, cooling tower, auxiliary heater, and storage tank used in this study are modeled in this software. The designed cooling system is considered as a market that has a cooling need of 35 kW and has a space of 275 m². It was examined in this study that how the performance of a single-effect LiBr-H2O absorption cooling system was affected by three different kinds of solar collectors such as flat plate collector (FPC), Non-tracking concentrating parabolic solar collector (XCPC), and evacuated tube collector (ETC). It was also evaluated that how different criteria such as solar fraction, hot water tank temperature and tank volume, collector area, and collector type affected system performance. In the study, it was noticed that collector area had an important effect on the collector efficiency, heater power and hot water tank temperature. It was found that minimum collector area for XCPC, ETC and FPC collectors were approximately 100 m², 125 m² and 150 m², respectively. Also, depending on the change in the tank volume, significant changes occurred in the tank temperature. The hot water tank volume was raised from 0.5 m³ to 6 m³ for XCPC, ETC and FPC collectors, the upper hot water tank temperature decreased about 15°C, 11°C and 8°C, respectively.
In conclusion, it has been observed that XCPC collectors perform better to improve system performance compared to other collectors used.
This work presents the benefits of using a model predictive control (MPC) approach for controlling a high efficiency absorption chiller-based solar cooling system with thermal energy storage, incorporating perfect solar resource and load forecasting information. A dynamic physics-based model of the solar air-conditioning system has been built for studying the system behavior. A genetic algorithm based predictive controller is utilized to minimize backup energy consumption while satisfying the cooling demand. The simulations have been carried out using the open-source programming language Python. Detailed investigation of the role of the predictive controller and its decision strategy have been carried out using ten and fifty days simulations. Effect of storage tank heat losses has been investigated.
For the simulated example case pertaining to a building, results show the model predictive controller usage delivers about 10% reduction in auxiliary energy use in the system. This is achieved through reduction in tank heat losses, better utilization of heat stored in the tank. It is seen that the MPC based controller enables new system operational capabilities by running the solar collector pump in variable flow mode and allowing the simultaneous heat delivery from storage and backup devices. Opportunities to improve the MPC benefits have been identified. The benefits of the MPC are seen to be sensitive to the system parameters and specific constraints. In summary, this paper provides valuable insights into solar cooling system design and control.
The solar absorption-subcooled compression hybrid cooling system (SASCHCS) is to be the economically feasible solution for the high-rise building. But the system has been seldom studied experimentally in the existing open literatures. Therefore, the prototype of SASCHCS is developed to measure the operational performance. The absorption subsystem is driven by the 27 m2 of stationary compound parabolic collector exclusively. And the test is based on the sunny day without and with fluctuation as well as cloudy day of subtropical Guangzhou. It is found that the outlet temperature of chilled water in the absorption chiller exceeds 22 °C since the cooling output of absorption subsystem serves as the subcooling power of compression subsystem. Consequently, the low grade solar energy of which temperature is higher than 60 °C can be used. The peak instantaneous cooling power and coefficient of performance (COP) of absorption subsystem is 4 kW and 0.69, respectively. Besides, the daily mean solar COP (SCOP) of absorption subsystem/daily average rise of COP in the compression subsystem on the sunny day, sunny day with fluctuation and cloudy day is 0.21/22.2%, 0.2/19.8% and 0.13/13.3%, respectively. The paper is helpful to adequately realize the real operation performance of SASCHCS and promote its further improvement.
El crecimiento económico incrementa las necesidades de aire acondicionado y refrigeración. Por tal, eficiencia energética en edificios, así como los recursos energéticos distribuidos son temas de alto interés. Los chillers de absorción impulsan procesos de enfriamiento, a partir de fuentes de calor tales como distritos térmicos, cogeneración, energía termosolar o calor industrial residual, con menores emisiones de CO2. Loschillers de absorción son máquinas térmicas no sencillas, lo que dificulta la evaluación del desempeño y requiere el uso de herramientas computacionales para simular su comportamiento. El presente trabajo ofrece resultados de una metodología propuesta, la cual a partir de las curvas de capacidad de enfriamiento dadas por los fabricantes y las ecuaciones básicas que modelan a un chiller de absorción, se obtiene al archivo de datos que el software TRNSYS requiere para simularlo.
The results of past and ongoing activities, in successive IEA SHC (solar heating and cooling) Tasks, suggest enormous potential for solar cooling technologies to reduce greenhouse gas emissions. However, solar thermal cooling still faces barriers to emerge as an economically competitive solution. IEA SHC Task 48 was introduced to gather learnings from existing installations, and to find technological and market solutions, which could enable industry to deliver solar thermal driven heating and cooling systems that are efficient, reliable and cost competitive.
The selected experiences of these research activities were clustered into 10 qualitative key principles for successful design and operation of SHC systems. Three existing systems are fully discussed in a solar cooling design guide (Mugnier et al., 2017). This paper aims to introduce these key principles in its general format. The background to the qualitative statements is explained, supplemented with examples from the context of Task 48 and compared with recent literature. Furthermore, a survey was conducted among SHC experts, who provide an assessment of the importance of the principles.
The result shows that all principles have their eligibility. However, it turns out that there are three main categories of principles: (i) essential, (ii) important and (iii) controversial. Following the key principles is not a guarantee, but they can support researchers, designers and contractors to implement solar heating and cooling systems successfully.
The study described in this paper results from the observation that, when dealing with solar-driven absorption chillers, a compromise situation very likely exists between the collector efficiency and the coefficient of performance (COP) of the absorption cycle. An idea of a control strategy pursuing this objective, and thereby increasing the solar fraction for a solar absorption cooling cycle is consequently presented. The advantage of operating the solar chiller on a variable driving temperature is demonstrated. The theoretical analysis considers a solar chiller operated under moderate climate conditions of Poland. The model of the ammonia-water absorption chiller is described in detail, and the main assumptions of the iterative control procedure are explained. The effects of its application are computationally tested for one location and one type of solar collector, for representative days of three months during the cooling season. The results of the simulation are compared with the reference case of fixed driving temperature. According to the simulation results, it is possible to increase the cooling power yield at various levels, up to 34 W per 1 m² of solar collector, by adjusting the chiller driving temperature throughout the cooling season. The same, it is possible to more than double the cooling effect for some hours, with respect to fixed-temperature control operation.
The utilization of renewable energy sources is commonly constrained by the building form and the site environment particularly in a densely-populated city which limits the space available to install the respective facilities. The hybrid use of solar and geothermal energy helps improve the situation as the roof and the ground can be fully utilized. A renewable cooling and heating system (RCHS) was therefore investigated based on this approach when applied to a three-storey office building in sub-tropical climate. Solar energy was used in absorption cooling and water heating while ground source was utilized by a high-temperature chiller for radiant cooling. Appropriate control and operation schemes were adopted for the ground-coupled radiant cooling system according to the ambient conditions in order to minimize the system energy demand. By performing dynamic system simulations using TRNSYS, the year-round performances of RCHS were thoroughly evaluated under different design factors including radiant panel type, ground thermal conductivity, borehole length and water heating demand. It was found that the RCHS was effective to tackle the high cooling demand for building in the hot-humid climate, with 44.4% annual primary energy saving against the conventional system.
Tools and experience on solar thermal cooling system sizing and design are still limited, as less than one thousand plants have been built until now. In this paper, a design tool for mid-size thermal solar cooling systems is presented. The tool consists of a model realised in TRNSYS and validated using the data of a real solar air conditioning system installed in the green building of Shanghai Research Institute of Building Science. Characteristic features of the system are the use of adsorption chillers driven by low-temperature solar heat from U-type and heat pipe evacuated solar collectors. The model has subsequently been employed for a technical analysis: the most relevant parameters have been varied and figures of merit calculated. An energy analysis has been performed for 6 reference cities, differing for climates and latitudes, highlighting the possibility to use only renewable energy for cooling purposes. Eventually, the systems have been compared with reference ones. Comparison highlighted that considerable savings in primary energy and CO2 emissions can be achieved: 0.97 MWh per installed square meter of solar collectors and up to 22 tons of CO2 annually, thus indicating a great potential for increasing energy efficiency and reduce CO2 emissions.
This paper presents a review of exergy analysis of solar thermal collectors and processes. It includes not only various types of solar collectors, but also various applications of solar thermal systems. Initially the fundamentals of second law analysis are briefly presented as well as the exergy of solar radiation, which is the input to any solar system. Concentrating and non-concentrating collectors have been analyzed, including parabolic dish and parabolic trough collectors from the first category, and flat-plate collectors, air solar heaters, and evacuated tube collectors from the second category. Hybrid photovoltaic/ thermal collectors have also been examined. Applications and processes include the use of phase change materials either in the collection or storage of thermal energy, drying, heating, multigeneration, trigeneration, solar cooling, solar assisted heat pumps, domestic cogeneration, hydrogen production, hybridization with other renewables, solar ponds, power plants and desalination/distillation. Through literature review on the above subjects it is shown that exergy analysis, which gives a representative performance evaluation, is emphasized as a valuable method to evaluate and compare possible configurations of these systems.
This paper aims to provide the current state of the art of solar sorption systems. Through comprehensive literature review of solar sorption systems, it was concluded that these technologies have several limitations and drawbacks. The low performance and the high cost are the main disadvantages of these technologies. However, solar cooling is considered attractive because solar radiation is in phase with the demand for cooling. Due to its attractiveness, the research is still going and focusing on solving the technical, economical, environmental problems, to achieve high performance and low cost of solar sorption systems. Improvements through investigating geometrical, system configurations, physical parameters, and operational modes on the performance of solar thermal sorption cooling systems are presented. A survey of the new configurations, novel additions, new techniques, new methodologies are also presented in this paper. Several cases studies in different climatic conditions are summarized. Economic feasibility for absorption and adsorption systems is discussed. It can be concluded that cost and energy effective solar sorption systems can be developed if suitable combinations of system components with operating conditions are selected. Finally, there is still the need for more research on solar sorption systems to make them both cost and energy competitive with the conventional cooling technologies.
Thermal cooling systems are particularly attractive in locations supplied by district heating based on cogeneration heating plants (CHP). Moreover, solar thermal energy is a major renewable source for the provision of thermal energy, fulfilling demands for space heating, domestic hot water, process heat, and cooling. This energy source can be suitably used also in Nordic Countries.
The presented paper focuses on two configurations of a cooling solar-driven thermal system for an office building located in Finland. Dynamic simulation approach has been used through TRNSYS software. In particular, the configurations differ from the connection between the hot storage tank, the solar collectors and the chiller. Particularly, in the first configuration only the tank can supply the chiller (Case 1), while in the second, the chiller can be supplied either by the tank or the solar collectors directly (Case 2). System performance indexes, in case of district heating as main building heating supply system in winter and as auxiliary heating system for the chiller in summer, have been evaluated as a function of the tank and solar thermal field sizes.
Results show that Case 2 has better performance than Case 1, because of the versatility shown in summer. Particularly, when the solar irradiance is low, Case 2 solutions perform far better than Case 1 solutions, benefitting from the direct connection between the solar collectors and the chiller. This study has highlighted also the potential of this technology in cold climate areas supplied by means of DH based on CHP plants. Indeed, the adoption of such cooling technology, in addition to reduce both heating and cooling consumed energy and to shave summer electricity peaks, can potentially allow some CHP plants to operate also in summer, fulfilling the future energy networks aims: being able to provide electricity, heat and cooling energy.
German
Die Fa. EAW und das ILK Dresden haben gemeinsam eine Wasser/Lithiumbromid-Absorptionskältemaschine (AKM) mit einer Kälteleistung von 15 kW entwickelt, die insbesondere für den Antrieb mit Solarwärme und BHKW-Abwärme konzipiert ist.
Zur Beurteilung der Leistungsfähigkeit und Zuverlässigkeit dieser Anlage unter rea-len Betriebsbedingungen wurde in den Jahren 2005 und 2006 ein von der DBU unterstütztes Monitoring-Projekt durchgeführt.
Innerhalb dieses Projektes konnten typische Anwendungsfälle hinsichtlich der Art der Wärmequelle und der Technologie der Rückkühlung umgesetzt und untersucht werden. In zwei Systemen wird Solarwärme zum Antrieb der Kältemaschine ver-wendet. In der dritten Anlage wird Wärme eines kleinen BHKW genutzt.
Die Rückkühlung thermischer Kältemaschinen insbesondere kleiner Leistung stellt eine Herausforderung dar. Offene Verdunstungskühler (direkter Kontakt) arbeiten energieeffizient (geringer Stromverbrauch) und stellen niedrige Kühlwassertempe-raturen bereit, was sich günstig auf das Betriebsverhalten der AKM auswirkt. Nach-teile sind der Wasserverbrauch und der höhere Wartungsaufwand (Verschmutzung, Entleerung im Winter etc). Trockene Rückkühler (indirekter Kontakt) können bei ho-hen Außentemperaturen nur vergleichsweise hohe Kühlwassertemperaturen be-reitstellen. Dies erfordert bei sonst gleichen Bedingungen höhere Heiztemperaturen für die AKM. Ein weiterer Nachteil trockener Rückkühler ist deren meist höhere Stromverbrauch. Geringerer Wartungsaufwand und kein Wasserbedarf sind die Vor-teile dieser Technologie.
Innerhalb des Monitoring-Projektes wurden zwei Anlagen mit Verdunstungskühlern und ein solar angetriebenes System mit einem Trockenkühler untersucht. Die Ziel-stellung des Vorhabens sowie erste Ergebnisse wurden bereits veröffentlicht. Schwerpunkt dieses Beitrages ist der Einsatz der Absorptionskältemaschine mit der Kombination Trockenkühler/Vakuumröhrenkollektoren und Verdunstungskühler/Flachkollektoren.
English
A water/lithium-bromide absorption chiller with a nominal capacity of 15 kW was de-veloped by the company EAW and the Institute of Air Conditioning and Refrigera-tion (both Germany). A monitoring project sponsored by the German Federal Envi-ronmental Foundation was realised for the cooling seasons of 2005 and 2006 to demonstrate the performance and reliability of the new chiller under the conditions of real applications. Within this project three installations with the new chiller were monitored.
The re-cooling of thermal driven chillers is one of the challenges in solar cooling (SC) technology. Open or wet (direct contact) re-coolers work very efficiently and provide low re-cooling temperatures which is favourable for thermal driven chillers. Their drawback is the water demand and a higher maintenance effort. Dry (indirect contact) re-coolers can provide significantly higher re-cooling temperatures only and have a higher electrical power requirement. No water needs and lower maintenance effort are the advantages of dry re-coolers.
To gain experience with a dry re-cooler in a solar cooling installation one of the monitored systems was equipped with this technology.
The application of the WEGRACAL SE 15 absorption chiller in a solar thermal cool-ing system in combination with a dry re-cooler was successfully demonstrated. If medium chilled water temperatures are sufficient for the cooling application a dry re-cooler in combination with high temperature collectors are an interesting alternative for solar thermal driven absorption cooling. By using variable speed fans inside the re-cooler the rotation speed can be adjusted to the fluctuating re-cooling needs and the electric power consumption can be reduced.
The SE 15 absorption chiller showed good results in combination with flat plate col-lectors and a low capacity cogeneration unit as well. Using a cogeneration unit as heat source allows more operation time of the chiller than in solar systems.
The two main market-available thermal cooling technologies with regeneration temperatures below 100°C are evaluated in this chapter. For closed cycle absorption chillers and open desiccant cooling systems, efficiencies, costs and optimization potentials are analysed. Measurements and simulation studies from realized demonstration projects are presented. If properly designed, both technologies offer significant primary energy savings. However, as coefficients of performance (COPs) are generally lower than for electrically driven compressor chillers, care has to be taken to reduce auxiliary energy demand. While measured average thermal COPs are between 0.6 and 0.7 for absorption chillers, desiccant units can reach higher values, as they often operate with evaporative cooling only. The electrical COPs can be as high as 11 for absorption systems with efficient cold distribution and recooling units and is about 7–8 for desiccant systems with an air-based distribution system. The total costs of both desiccant and absorption cooling systems are dominated by capital costs so that high full-load hours are crucial for an economic performance.
Performance variations of a solar-powered ejector cooling-system (SECS) using an evacuated-tube collector are presented for Antalya, Aydin, Konya and Urfa cities located in the southern region of Turkey by means of hourly and monthly average ambient temperature and solar radiation meteorological data. A SECS, based on a constant-area ejector flow model and using R-123, was considered. The cooling season and period were taken into account for the 6 months (May–October) and the hours 8:00–17:00, respectively. It was found that the evacuated-tube collector efficiency depending upon the ambient temperature and solar radiation within the day was remarkably varied. However, for all the cities, the cooling capacities of the SECS were very similar. When generator, condenser, and evaporator temperatures were taken, namely, 85 °C, 30 °C and 12 °C, the maximum overall coefficient of performance and the cooling capacity were obtained as 0.197 and 178.26 W/m2, respectively, at 12:00 in August for Aydin. The evacuated-tube collector area per ton cooling was found to be around 21 m2 at noontime in August for all the cities. Furthermore, at the off-design conditions, a performance map of the system was derived and discussed. It was determined that the SECS could be used for office-cooling purposes during the hours (8:00–15:00) in the southern region of Turkey.
Air conditioning (AC) is spreading in Spain, where summer weather reaches temperatures above 35 °C. This causes the increase, not only of electricity consumption, but also organic refrigerant leakage due to the use of vapour-compression machines.An experimental research on solar absorption cooling has been carried out at Universidad Carlos III de Madrid (UC3M) in order to evaluate alternative lower impact AC techniques. The facility is based on an on-Campus field of 50 m2 flat plate solar collectors driving a single-effect commercial LiBr/H2O absorption machine through a hot-water storage tank.Experimental operating parameters have been recorded during 2004 summer season in periods of 10 min showing all the relevant figures of merit.Results show that absorption machine cooling power reaches 6–10 kW, with a generator driving power input of 10–15 kW, achieving a mean cooling period of 6.5 h of complete solar autonomy on a seasonal average day.In order to measure the market applicability of this setup, the instantaneous thermal load and demand of a single detached housing of total floorspace of 90 m2 were calculated using standard techniques. Its peak ranged from 6 to 8 kW. Seasonal solar fraction of AC provided by the facility reached 56%.This work shows results on system performance, economic investing, energy and economic savings and includes environmental impact reduction, when comparing the solar absorption system with a conventional vapour-compression machine. A sensitivity study to solar field size has been performed to yield the reasonable share of the absorption machine in the seasonal cooling demand. The result indicates that the dimensioning of the facility is correct.
A classification of built forms is presented. It is based on a study of buildings surveyed at 3350 addresses in four English towns and has been designed for use in the national Non-Domestic Building Stock (NDBS) database developed for the Department of Environment, Transport and the Regions. As the prime use of the database is in energy analysis, the classification focuses on the external envelopes of buildings. (Materials of construction, servicing systems, and activities are classified separately.) Built forms are distinguished according to two main criteria: the broad 'texture' of their internal subdivision; and whether they are daylit or artificially lit.
The origins, purpose, and scope of the Non-Domestic Building Stock (NDBS) database of England and Wales are described. Nondomestic buildings are defined and sources of the data used in the database are identified. The structure of the database, and the role of the classification of nondomestic buildings, are described and discussed.
In this paper we describe the selection of four English urban areas in which the nondomestic building stocks might collectively be considered characteristic of the national stock. A brief history is provided of urban development in each of the four areas. The scope and methodology of comprehensive surveys of nondomestic buildings in the four survey areas are described and a brief summary of the characteristics of the building stocks in the four areas is derived from the survey data.
Efficient heat rejection is crucial for the overall primary energy balance of sorption systems, as it dominates the auxiliary energy consumption. Low ratios of cooling power to auxiliary electricity of 3.0 or less are still common in sorption system, so that the primary energy efficiency is not always higher than for conventional compression chillers.Whereas dry heat rejection systems require electricity for fan operation, hybrid or wet cooling systems in addition need pumping energy for the cooling water and the water itself. The energy efficiency can be improved for heat rejection to the ground, where only pumping energy is needed for the geothermal heat exchange.Dynamic simulation models were used for a single effect absorption chiller powered by solar thermal collectors via a hot storage tank. The chiller models were coupled to a three dimensional numerical ground heat exchanger model or to cooling tower models. The models were validated with operating data of a 15 kW solar cooling system installed in an office building.Primary energy efficiency ratios were determined for different heat rejection systems and improved control strategies were developed. The installed system primary energy ratios varied between 1.1 and 2.2 for auxiliary heating and between 1.2 and 2.5 for auxiliary cooling depending on the heat rejection and control strategy chosen. The low electrical energy consumption of the geothermal heat rejection saves 30% of auxiliary electricity and results in an electrical coefficient of performance of 13. The maximum primary energy ratios for solar fractions up to 88% are 2.7 for auxiliary heating and 3.2 for auxiliary cooling, i.e. nearly three times higher than for the reference electrical compression system of 1.2.
Producing refrigeration and/or air conditioning from solar energy remains an inviting prospect, given that a typical building’s cooling load peaks within 2 or 3 h of the time of maximum solar irradiation. The attractiveness of “free” cooling obtained from the sun has spawned a wealth of research over the last several decades, as summarized in a number of review articles. Obstacles—especially high initial costs—remain to the widespread commercialization of solar cooling technologies. It is not clear at the present time if thermally driven systems will prove to be more competitive than electrically driven systems. We therefore describe a technical and economic comparison of existing solar cooling approaches, including both thermally and electrically driven. We compare the initial costs of each technology, including projections about future costs of solar electric and solar thermal systems. Additionally we include estimates of the environmental impacts of the key components in each solar cooling system presented. One measure of particular importance for social acceptance of solar cooling technologies is the required “footprint,” or collector area, necessary for a given cooling capacity. We conclude with recommendations for future research and development to stimulate broader acceptance of solar cooling. The projections made show that solar electric cooling will require the lowest capital investment in 2030 due to the high COPs of vapor compression refrigeration and strong cost reduction targets for PV technology.
HVAC systems are the most energy consuming devices among building components. Therefore, to achieve the global aims in energy
reduction, the efficiency of HVAC systems has to improve significantly. Thermally driven air conditioning systems are a possible way to
reduce the dependency on traditional vapor compression cycles and to lower the primary energy consumption. Due to the separation of
dehumidification and cooling, natural heat sources, e.g. solar thermal energy, and natural heat sinks, e.g. shallow geothermal energy, can
be used or, when combined with a traditional vapor compression cycle, the temperature level of the heat sink can be increased. With the
separation of cooling and ventilation the overall efficiency can be increased even more.
This paper introduces a pilot installation of a solar thermal and geothermal assisted air conditioning system located in Hamburg, Germany. The combination of a desiccant assisted air conditioning system with radiant heat exchanger enables a highly efficient HVAC system. Due to the strong influence of outdoor air conditions, a system model is built to evaluate the performance of this system at different climate conditions worldwide. This paper presents an energy and economic evaluation of a highly efficient HVAC system at different geographical locations.
In the last years, the growing demand for air conditioning has caused a significant increase in demand for primary energy resources. Solar-powered cooling is one of the technologies which allows to obtain, by using the renewable solar source, an important energy saving compared to traditional air conditioning plants. The paper describes different technical installations for solar cooling, their way of operation, advantages and limits. The objective of the present study has been to analyze the technical and economic feasibility of solar absorption cooling systems, designed for two different application fields: industrial refrigeration and air conditioning. The possibility to replace or integrate the existing plants is studied, by considering the refrigeration requirements of a company, which works in meat manufacturing, and the heating and cooling demands of a hotel located in a tourist town in Italy. In the first case, the system comprises an absorption chiller coupled to solar flat plate collectors, whereas the second application is about a hybrid trigeneration plant, known as thermo-solar trigeneration; this option allows having greater operational flexibility at sites with demand for energy in the form of heating as well as cooling, for example in a hotel. In this way the authors could compare different results obtained by a technical and economic experimental analysis based on existing users and evaluate the advantages and disadvantages in order to suggest the best solution for the two studied cases.
Summer air conditioning represents a growing market in buildings worldwide, with a particularly significant growth rate observed in European commercial and residential buildings. Heat-driven cooling technologies are available, which can be used in combination with solar thermal collectors to alleviate the burden caused by air conditioning on the electric utilities and the environment. Solar air conditioning has progressed considerably over the past years as a result of efforts toward environmental protection and new developments in components and systems, and significant experience has been gained from demonstration projects. The main obstacles for large scale application, beside the high first cost, are the lack of practical experience and acquaintance among architects, builders and planners with the design, control and operation of these systems.This paper describes the main results of the EU project SACE (Solar Air Conditioning in Europe), aimed to assess the state-of-the-art, future needs and overall prospects of solar cooling in Europe. A group of researchers from five countries has surveyed and analyzed over 50 solar-powered cooling projects in different climatic zones. The paper presents a short overview on the state-of-the-art and potential of solar-assisted cooling and air conditioning technologies. The results of the study, including a database of the surveyed projects, an evaluation of these projects on a uniform basis, an economic analysis tool, user guidelines and a multimedia tool—are presented. The potential energy savings and limitations of solar thermal air conditioning in comparison to conventional technologies are illustrated and discussed.
The usage possibility of ejector-absorption cooling systems (EACSs) in Turkey using meteorological data has been investigated. This study also determines whether or not the required heat for the generator of an EACS can be obtained from solar energy in Turkey. There are two important reasons for the usage of EACSs in Turkey. One of them is that the production and use of the CFCs and HCFCs will be phased out a few years according to the Montreal Protocol, signed in 1987. The other is that Turkey is located between 36° and 42°N latitudes and has a typical Mediterranean climate. Therefore, Turkey has a high solar-energy potential, and the yearly average solar-radiation and the total yearly radiation period are 3.6 kW h/m2 day and ∼2610 h, respectively. Sixteen cities (Ordu, Tekirdağ, Sakarya, Çorum, Erzincan, Bursa, Balıkesir, Afyon, Bingöl, Burdur, Konya, Niğde, Adıyaman, Hakkari, Anamur, Finike) were selected in Turkey for which the radiation data and sunshine-duration information have been collected since 2000. The required optimum collector-surface area was identified by using the meteorological data for maximum coefficient-of-performance (COPmax) conditions of the EACS operated with aqua-ammonia. In addition, the required minimum energy for the auxiliary heater was also calculated so that the system can be used throughout the year. It is shown that the heat-gain factor (HGF) varies in the range from 1.34 to 2.85 for all the seasons in the selected cities. The maximum HGF is 2.85 for Finike. According to the results obtained in this study, for 8 → 9 months (March–October), it is sufficient to have a collector surface-area of 4 m2 with high-performance refrigeration all over of Turkey. This study will provide guidance for the efficient utilisation of renewable energy sources in Turkey, which is heavily dependent upon imported energy sources, i.e. natural gas.
In the last few years the solar-powered air-conditioning systems have been in intensive development and more often are considered as the viable application for the thermal solar systems in the regions of southern Europe. This is mainly due to the increasing higher electrical consumption in many countries (especially in Spain) which is moving from the winter to summer months due to expanding usage of cooling systems in this period of the year.In this paper we will analyze the behaviour of the solar-assisted air-conditioning system installed in the CIESOL building. This system consists mainly of flat-plate solar collectors and the simple effect LiBr–H2O absorption chiller. Different operation modes were analyzed. Coefficient of performance (COP) at various generator, absorber, condenser and evaporator temperatures is investigated and experimental results show that in practice it is easy to obtain values of about 0.6. The main goal of this paper is to describe the characteristics of the developing building and the solar-assisted air-conditioning system. Another useful purpose is to find the optimum conditions and operation parameters for the solar system through analyzing various systems' operation strategies.
We present a comparison of solar thermal and solar electric cooling for a typical small office building exposed to two different European climates (Freiburg and Madrid). The investigation is based on load series for heating and cooling obtained previously from annual building simulations in TRNSYS. A conventional compression chiller is used as the reference system against which the solar options are evaluated with respect to primary energy savings and additional cost. A parametric study on collector and storage size is carried out for the solar thermal system to reach achieve the minimal cost per unit of primary energy saved. The simulated solar electric system consists of the reference system, equipped with a grid connected photovoltaic module, which can be varied in size. For cost comparison of the two systems, the electric grid is assumed to function as a cost-free storage. A method to include macroeconomic effects in the comparison is presented and discussed.Within the system parameters and assumptions used here, the grid coupled PV system leads to lower costs of primary energy savings than the solar thermal system at both locations. The presumed macroeconomic advantages of the solar thermal system, due to the non-usage of energy during peak demand, can be confirmed for Madrid.
The use of solar energy in buildings is an important contribution for the reduction of fossil fuel consumption and harmful emissions to the environment. Solar thermal cooling systems are still in their infancy regarding practical applications, although the technology is sufficiently developed for a number of years. In many cases, their application has been conditioned by the lack of integration between cooling and heating systems. This study aims to evaluate the potential of integrated solar absorption cooling and heating systems for building applications. The TRNSYS software tool was used as a basis for assessment. Different building types were considered: residential, office and hotel. The TRNSYS models are able to run for a whole year (365 days), according to control rules (self-deciding whether to operate in heating or cooling modes), and with the possibility of combining cooling, heating and DHW applications. Three different locations and climates were considered: Berlin (Germany), Lisbon (Portugal), and Rome (Italy). Both energy and economic results are presented for all cases. The different local costs for energy (gas, electricity and water) were taken into account. Savings in CO2 emissions were also assessed. An optimization of solar collector size and other system parameters was also analysed.
In this study, performance assessment of an integrated cooling plant having both free cooling system and solar powered single-effect lithium bromide–water absorption chiller in operation since August 2002 in Oberhausen, Germany, was performed. A floor space of 270 m2 is air-conditioned by the plant. The plant includes 35.17 kW cooling (10-RT) absorption chiller, vacuum tube collectors’ aperture area of 108 m2, hot water storage capacity of 6.8 m3, cold water storage capacity of 1.5 m3 and a 134 kW cooling tower. The results show that free cooling in some cooling months can be up to 70% while it is about 25% during the 5 years period of the plant operation. For sunny clear sky days with equal incident solar radiation, the daily solar heat fraction ranged from 0.33 to 0.41, collectors’ field efficiency ranged from 0.352 to 0.492 and chiller COP varies from 0.37 to 0.81, respectively. The monthly average value of solar heat fraction varies from 31.1% up to 100% and the five years average value of about 60%. The monthly average collectors’ field efficiency value varies from 34.1% up 41.8% and the five-year average value amounts about 28.3%. Based on the obtained results, the specific collector area is 4.23 (m2/kWcold) and the solar energy system support of the institute heating system for the duration from August 2002 to November 2007 is 8124 kWh.
A solar-powered adsorption air-conditioning system was designed and installed in the green building of Shanghai Research Institute of Building Science. The system contained 150 m2 solar collectors and two adsorption chillers with nominal refrigeration capacity of 8.5 kW. Based on performance characteristics of the adsorption chiller, the operation mode of the solar-powered air-conditioning system was optimized by maintaining a phase shift of 540 s between the two adsorption chillers. Thereafter, the whole system realized stable operation by the balance of heat consumption and refrigeration output. From June to August of 2005, the solar-powered air-conditioning system continuously ran between 9:00 and 17:00. The operation performance of the system under representative working condition showed that the average refrigeration output of the solar-powered air-conditioning system was 15.3 kW during an 8 h operation and the maximum value exceeded 20 kW. Solar fraction for the system in summer was 71.7%, which corresponded to the designed cooling load (15 kW). Compared with the ambient temperature, it was deduced that solar radiant intensity had a more distinct influence on the performance of solar-powered air-conditioning system.
The paper contributes to the system design of solar thermal absorption chillers. A full simulation model was developed for absorption cooling systems, combined with a stratified storage tank, steady-state or dynamic collector model and hourly resolved building loads. The model was validated with experimental data from various solar cooling plants.As the absorption chillers can be operated at reduced generator temperatures under partial load conditions, the control strategy has a strong influence on the solar thermal system design and performance. It could be shown that buildings with the same maximum cooling load, but very different load time series, require collector areas varying by more than a factor 2 to achieve the same solar fraction. Depending on control strategy, recooling temperature levels, location and cooling load time series, between 1.7 and 3.6 m2 vacuum tube collectors per kW cooling load are required to cover 80% of the cooling load.The cost analysis shows that Southern European locations with higher cooling energy demand lead to significantly lower costs. For long operation hours, cooling costs are around 200 € MWh−1 and about 280 € MWh−1 for buildings with lower internal gains and shorter cooling periods. For a Southern German climate, the costs are more than double.
A transient one-dimensional model, capable of describing the performance of a newly-introduced adsorption chiller with continuous operation, is developed. Since the cycle time and the switching frequency have a great influence on chiller performance, a non-dimensional switching frequency is introduced and a systematic parametric study is carried out in order to determine regions of optimal operation. An optimization based on the thermodynamic efficiency yields a lower switching frequency than an optimization based on the maximum cooling capacity. In addition, the effect of the heat-exchanger design parameters on system performance is explored. An increase of either the bed’s Fourier number or the thermofluid’s Nusselt number has a positive effect on both COP and cooling capacity. An improvement of system performance can also be achieved by decreasing either the thermofluid’s Fourier number or the bed’s Biot number. Finally, the effect of space velocity of the thermofluid exhibits the most interesting behavior; an increase of the space velocity has a positive effect on cooling capacity and a negative effect on COP.
Solare Technologien fur Gebaude In: vollst. uberarb. und aktual. Aufl. 2012. Auflage 2
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Meerwasserentsalzung þ Offgrid für Industrie (Wind, CSP und Photovoltaik) German-Saudi Arabian Liasion Office for Economic Affairs (GESALO)
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German-Indonesian Chamber of Industry and Commerce
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