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A review of solar thermo-mechanical refrigeration and cooling methods

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Abstract

Use of solar energy to produce refrigeration and air conditioning can be a viable option to replace conventional cooling systems. Research and development activities on solar cooling systems started in the 1970s because of the energy crisis and has picked up again in the past few years due to greater awareness of the necessity to reduce emission of greenhouse and Ozone depletion gases. Although, most of the attention in the past has been on using solar heat to run absorption refrigeration systems, solar thermo-mechanical cooling systems have received a renewed attention in recent years due to the advantages such as, ability to produce low refrigeration temperatures (<0 °C) by using appropriate working fluids, ability to produce electricity when cooling is not needed by coupling the prime mover with an electric generator, maintaining high performance at off-design conditions and utilization of a wide range of temperatures from solar collectors. In a solar thermo-mechanical cooling system, the heat gained from the solar collector is converted into mechanical work, which is used to compress the working fluid in a vapor compression cycle directly (i.e. ejector cooling cycle) or indirectly (i.e. coupled with an organic Rankine cycle). Hybrid solar thermo-mechanical cooling with conventional cooling systems also offers a great potential for energy demand reduction for buildings.

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... The basic operating principle of an ejector is the use of a high-pressure motive fluid to induce flow from a lower pressure source (i.e., suction fluid) and eject the mixture at an intermediate pressure [7]. Ejector-based refrigeration systems offer simplicity of assembly and installation, compatibility with low-temperature renewable/excess heat (e.g., solar, geothermal, waste heat) and a range of working fluids, the absence of moving parts, low maintenance requirements, and affordability [6,8]. Their disadvantages are the complexity of detailed ejector geometric design optimization associated with a complex flow field, limited ejector operating range, and overall coefficient of performance (COP)-typically less than 0.3 [6,8]. ...
... Ejector-based refrigeration systems offer simplicity of assembly and installation, compatibility with low-temperature renewable/excess heat (e.g., solar, geothermal, waste heat) and a range of working fluids, the absence of moving parts, low maintenance requirements, and affordability [6,8]. Their disadvantages are the complexity of detailed ejector geometric design optimization associated with a complex flow field, limited ejector operating range, and overall coefficient of performance (COP)-typically less than 0.3 [6,8]. In general, the performance of solar ejector refrigeration systems is constrained by the lowtemperature heat input (i.e., 85-95 °C), and degrades at increasing condenser temperatures [9] imposed by the ambient temperature. ...
... Complex cycles previously proposed to improve the performance of ejector refrigeration systems include cascaded, hybrid (e.g., compression-, absorption-, adsorptionbased), regenerative, multi-ejector, and multi-stage ejector cycles and variable geometry ejectors [7,8,10]. Despite the variety of cycle configurations proposed, few specifically tackle the limited operating range of ejectors, and hence the ability to cope with varying off-design conditions in actual space cooling conditions. ...
Article
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In year-round hot climatic conditions, conventional air conditioning systems consume significant amounts of electricity primarily generated by conventional power plants. A compression-assisted, multi-ejector space cooling system driven by low-grade solar thermal energy is investigated in terms of energy and exergy performance, using a real gas property-based ejector model for a 36 kW-scale air conditioning application, exposed to annually high outdoor temperatures (i.e., up to 42 °C), for four working fluids (R11, R141b, R245fa, R600a). Using R245fa, the multi-ejector system effectively triples the operating condenser temperature range of a single ejector system to cover the range of annual outdoor conditions, while compression boosting reduces the generator heat input requirement and improves the overall refrigeration coefficient of performance (COP) by factors of ~3–8 at medium- to high-bound condenser temperatures, relative to simple ejector cycles. The system solar fraction varies from ~0.2 to 0.9 in summer and winter, respectively, with annual average mechanical and overall COPs of 24.5 and 0.21, respectively. Exergy destruction primarily takes place in the ejector assembly, but ejector exergy efficiency improves with compression boosting. The system could reduce annual electric cooling loads by over 40% compared with a conventional local split air conditioner, with corresponding savings in electricity expenditure and GHG emissions.
... In literature, the thermal energy-based systems categorized according to their operating mechanism into thermos-chemical refrigeration (TCR) systems [5] and thermo-mechanical refrigeration (TMR) systems [6]. On one hand, TCR systems include closed-sorption and opensorption processes, which have complex configurations, limitations on the evaporator and generator temperatures, and a low coefficient of performance (COP) [7]. ...
... They used R245fa with a heat source temperature of 105 • C and evaporation temperature of 8 • C with a COP that varies between 0.52 and 0.60. For ejector-based systems, several experimental studies were conducted at cooling capacity less than 1 kW as reviewed by Zeyghami et al. [6]. Recently, Huang et al. [24] conducted an experimental and modeling investigation on thermally-driven subcritical and transcritical ejector refrigeration systems using refrigerant R32 as the working fluid. ...
... Therefore, the ECU-based TMR systems overcomes these limitations enjoying its simplicity, flexibility in the cooling capacity, and efficient operability even at an ultra-low heat source with a minimum temperature of 70 • C. From the aforementioned results, it is clear that the ECU-based refrigeration system provides a cooling load with evaporation temperature up to less than − 10 • C with COP varies between from 1.50 to 2.60. This implies that the average COP of the present ECU-based system (2.05) is three times higher than the average COP of the ejector-based systems (0.62) and 2.70 times higher than that of the ORC-based systems (0.75) [6]. Furthermore, the COP of the ECU-based system is comparable for the double-mode electric-based refrigeration system, which varies from 1.42 to 5.20 at evaporation temperature of − 35 • C to 10 • C at a condensation temperature of 35 • C [31,32]. ...
Article
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Operating thermos-mechanical refrigeration (TMR) ejector-based and organic Rankine cycle-based refrigeration systems at ultra-low temperature heat source (60 oC to 100 oC) is challenging and limited by their low coefficient of performance (COP), instability, and high cost. To overcome these limitations, an innovative TMR system consists of a power loop coupled with a cooling loop through an expander-compressor unit (ECU) was introduced. To ensure the efficient operation, reliability, and flexibility, of the ECU-based TMR system, a thorough experimental investigation is presented in this study. In the present setup, an air compressor is used to provide pressurized air to drive the ECU at a desired pressure of 620 kPa. Using R134a as a refrigerant, the performance of the ECU-based refrigeration system is systematically tested for various operating conditions including refrigerant mass, evaporator pressure, temperature and flow rate of the water used for evaporation and condensation loads. All tests are performed at two operating frequencies of the ECU (0.50 Hz and 0.33 Hz). Over a wide range of testing conditions, the results show that the average COP Hz varies from 1.57 to 2.73 at 0.50 Hz and from 1.56 to 2.39 at 0.33 Hz. Moreover, the evaporator temperature reaches less than -10 oC at 0.50 Hz and -9.60 oC at 0.33 Hz. These experimental results prove that the COP of the ECU-based refrigeration system is three times higher than the ejector-based systems and 2.70 times higher than the organic Rankine cycle-based systems.
... Zeyghami et al. [17] reported that heat from solar collectors in a solar thermal cooling system, can be utilized to deliver mechanical power to compress the refrigerant vapor in a conventional or as a heat source for the generator in a cooling cycle. Various researchers reported that single effect absorption chillers using LiBr-H2O working pairs are the most commercially developed [18]. ...
... However, these cooling systems have some downsides that can be addressed by thermomechanical cooling systems [17]. In a thermal cooling system, mechanical work is obtained from solar collector heating source, which can be utilized to increase the pressure of the working fluid in a VCC. ...
... 16,17,18,19 represent the variation of useful energy gain (Q coll) from FPC ,required heating rate (Q aux) and generator load (Q gen) during summer season (June:September) for single effect. The generator load value must be equal to the total energy gained from both solar collectors and auxiliary heater in order to harvest the most out of the system without energy losses. ...
Thesis
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.
... Recently, Nwaji et al. [174] summarized the progress and challenges of the use of hybrid solar water heating with PV/T collectors with nocturnal radiant cooling. Solar cooling has been widely studied [175,176] . It includes different technologies such as solar thermal cooling (including absorption and adsorption) and PV solar cooling [177] ; a classification is presented in Fig. 44 . ...
... Solar thermo-mechanical cooling systems produce low refrigeration temperatures and produce electricity when cooling is not needed maintaining high performance at design conditions and utilization of a wide range of temperatures from solar collectors ( Fig. 49 ) [175] . In a solar thermo-mechanical cooling system, the heat gained from the solar collector is converted into mechanical work, which is used to compress the working fluid in a vapor compression cycle directly (i.e. ...
... Comparison of performance of cooling production systems (adapted from [175,176,179] tricity storage include batteries (including lead acid and lithiumion ones), thermal batteries include water tanks, ice chillers, PCM tanks, PCM slurries, and sorption thermal energy storage ( Table 21 ) [62,65,71,72,74,110,[202][203][204][205][206][207][208] . Given the importance of energy management and optimization in systems including renewable energy production and energy storage, several methods have been studied, such as real-time energy convex optimization [209] . ...
Article
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.
... Energy storage systems have been suggested for extending the working hours of PV-VCC systems. 10 For instance, the integration of a thermochemical reactor as an energy storage system in a PV-VCC system was studied in Ferrucci et al 11 The proposed system exhibited a cooling capacity of 4 kWh/day per square meter of PV panel area, which is more than that of PV-VCC systems using conventional electrochemical batteries. Solar thermal cooling technology has drawn more attention compared to solar electricity driven cooling systems owing to its distinct advantages. ...
... Although the COP is usually lower for the ejector cooling cycle than other systems, the simple structure and low maintenance cost of this technology makes the solar ejector cooling system a viable option for building cooling. 10, 14 Salimpour et al, 15 a comparative exergoeconomic study, were performed on four solar ejector cooling configurations utilizing flat plate solar collectors. A preheater and precooler were employed to enhance the performance of the ejector cooling system. ...
... The heat-activated refrigeration technology can be realized by absorption refrigeration, ejector refrigeration cycle and ORC-VCC system [11,12] and so on. Compared with absorption refrigeration [13,14] and ejector refrigeration cycle [15][16][17], ORC-VCC system has several advantages. Firstly, the mechanical energy loss can be reduced by coupling the turbine and compressor to meet the cooling demand in the area of lack of electricity, and mechanical energy can be converted to electrical energy output without the need of refrigeration [11,18]. ...
... Secondly, the range of refrigeration temperature is wider. Therefore, wide attentions have been paid to ORC-VCC system [13,15,19]. ...
Article
Combined organic Rankine cycle and vapor compression cycle (ORC-VCC) systems for heat activated cooling are widely concerned because of their simple structures and convenient maintenance. According to the number of the working fluids, there are two different ORC-VCC systems, which are single-fluid and dual-fluid ORC-VCC systems. However, it lacks a deep understanding of their applicability. In this paper, using the geothermal water of 140 °C as heat source, the flash tank vapor injection cycle is coupled with ORC (ORC-FTVIC) in order to improve the efficiency. Meanwhile, four different systems of ORC-VCC and ORC-FTVIC based on single-fluid and dual-fluid are compared. Six kinds of working fluids are selected to analyze the effects of system parameters on the system performance. Taking the second law efficiency of thermodynamic as the objective function, the key parameters and working fluids of four heat activated cooling systems are optimized simultaneously and compared. When the heat source temperature is 140 °C, the cooling capacity of dual-fluid ORC-FTVIC system is maximum (2282.0 kW), followed by single-fluid ORC-FTVIC system (2177.5 kW), dual-fluid ORC-VCC system (2132.8 kW), single-fluid ORC-VCC system (1918.8 kW). The corresponding optimum working fluids are R1234yf-R152a, R1234yf, R1234yf-R152a and R1234yf, respectively.
... According to the four-level evaluation index system, the first-level evaluation index U i ( i = 1, 2, 3, 4 ); the second-level evaluation index U 1j (J = 1, 2 ), U 2 ( j j = 1, 2, 3 ), U 3j (J = 1, 2 ) and U 4j (J = 1, 2, 3, 4 ); three-level evaluation indicators U 11k (k = 1, 2, 3, 4 ), U 12j Table 4 Classification of emerging concepts related to uses of solar energy technology (Aboelwafa et al., 2018;Agostini, et al., 1707;Al-Juamily et al., 2007;Annamalai et al., 2015;Antonanzas-Torres et al., 2015;Asgarov, et al., 2018;Assuncao et al., 2003;Baidya et al., 2019;Bataineh & Taamneh, 2016;Bayindir et al., 2016;Behar et al., 2014;Bellos et al., 2017;Brodrick et al., 2005;Calise et al., 2017;Critoph & Zhong, 2005;Darawsheh et al., 2019;Deitz et al., 1963;Derick et al., 2017;Desai & Bandyopadhyay, 2017;Dongare, et al., 2019;Dunham & Iverson, 2014;Elminir et al., 2006;Fan et al., 2007;Ge et al., 2018;Ghafoor & Munir, 2015;Goossens & Kerschaever, 1999;Gunnewiek et al., 1996;Hamid et al., 2019;Hassanien et al., 2016;Heras-Saizarbitoria & Boiral, 2013;Herez et al., 2018;Holck et al., 2003;Hottel & Woertz, 1942;Huang et al., 2008;Hussain & AlAlili, 2017;Islam et al., 2018;Jefferies et al., 2006;Kasaeian et al., 2019;Khan & Arsalan, 2016;Kossyvakis et al., 2015;Kumar et al., 2017;Lingayat et al., 2017;Mani & Chacko, 1980;Mastekbayeva & Kumar, 2000;McCormick & Suehrcke, 2018;Michalsky, 1988;Modi et al., 2019;Moore & Hackett, 2016;Nazir et al., 2020;Nimmo & Seid, 1979;Nojavan et al., 2019;Noro & Lazzarin, 2014;Okoroigwe & Madhlopa, 2016;Otanicar et al., 2012;Palenzuela & Alarcón-Padilla, 2019;Riis, et al., xxxx;Roma-Dollase et al., 2018;Sayigh et al., 1985;Sezer et al., 2019;Sfyri et al., 2016;Shah et al., 2015;Sharma et al., 2012;Solanki & Chavda, 2012;Stroup, 2019;Suehrcke & McCormick, 1992;Sun, et al., 2012;Suresh et al., 2014;Taha & Eldighidy, 1980;Wang et al., 2011;Weinstein et al., 2015;Yang et al., 2018;Yuan & Lin, 1997;Zeyghami et al., 2015;Zheng et al., 2014;Zhou et al., 2016;Zhu et al., 2014;Zou et al., 2007) Application Methodology adopted Content courtesy of Springer Nature, terms of use apply. Rights reserved. ...
... air conditioning Solar thermo-mechanical refrigeration and cooling methodsZeyghami et al. (2015) No Solar cooling technologies Solar cooling for both thermal and photovoltaic: a comparative energy and economic study under Mediterranean conditionsNoro and Lazzarin (2014) No Content courtesy of Springer Nature, terms of use apply. Rights reserved. ...
Article
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Although fossil fuels leave environmentally hazardous gases like carbon dioxide, to date, global energy production is mostly dependent on these sources. Depletion of fossil resource and changes in the price make it a major concert for the sustainable use in future and utilization of energy resources which is environmentally safe and sustainable. Therefore, an increase in the use natural sustainable energy like solar power observed to be increased recently. Effective use of solar energy depends on the proper knowledge on its use and techniques. This article reviews different solar storage technologies to obtain green sustainable energy generation. We discussed the variation, mechanism, effectiveness, and worth of greenhouse for solar heat storage and concentrated solar power technologies (CSP). The multi-level evaluation method establishes an evaluation index system, adopts the expert scoring method to determine the weight and score of the index, and combines qualitative and quantitative to obtain a comprehensive evaluation value. There is the evaluation of the socio-economic impact of the green power station construction. The detail of for socio-economic environmental factor for on large-scale operation applications dependence on the use and conditions both solar storage and technologies have advantage and disadvantages. Finally, directions for significant of waste to energy for safe environment are presented.
... Pour conclure à la suite de ces résumés générales tirées de la littérature, il est intéressant de dire que: le COP de réfrigérateurs thermoélectriques de refroidissement (système à effet Peltier) sont généralement dans la gamme 0.16-0.64 avec une différence de température autour de 20°C, en fonction de la performance des dissipateurs de chaleur du côté chaud et froid [71]. ...
... Une configuration (a) utilise un générateur séparé du cycle de réfrigération, où l'expansion du cycle Rankine fondamental (CRF) et le compresseur du cycle de compression sont couplés mécaniquement. L'autre configuration (b) est un cycle intégré, en utilisant un expandeur-compresseur combinée et un condenseur commun pour les deux cycles[71]. ...
Preprint
Full-text available
... Various thermal refrigeration systems, reviewed in [8], can be powered with low-temperature heat sources such as absorption/adsorption systems [9]- [11], ejector systems [12], [13], Organic Rankine Cycle (ORC) systems [12], [14] [15] [16], and Stirling engine systems [17] [18]. Nevertheless, each of these systems has its own technical problems that limit their applications. ...
... Various thermal refrigeration systems, reviewed in [8], can be powered with low-temperature heat sources such as absorption/adsorption systems [9]- [11], ejector systems [12], [13], Organic Rankine Cycle (ORC) systems [12], [14] [15] [16], and Stirling engine systems [17] [18]. Nevertheless, each of these systems has its own technical problems that limit their applications. ...
Article
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A database is developed for the most suitable working fluids for Worthington-type and Bush-type isobaric engines based on their performances for a wide range of heat source temperature, T H from 40 to 300 o C and operating pressures P from 1 to 100 bar. Thermodynamics models are developed and simulated to study the effects of different operating temperatures and pressures on the efficiency and back work ratio of both engine types. Results showed that in T H range from 40 o C to 60 o C, the achieved efficiency is less than 4% for most cases, suggesting that practical applications in this T H range are very limited. Ammonia and R32 showed the highest efficiencies (about 11%) at high P of 50 bar for T H range of 100 to 300 o C. Refrigerant R161 has high performance for P between 10-50 bar for the full range of T H from 80 to 300 o C, which makes R161 the choice fluid for a wide range of applications. For category I (T H = 80 o C), the best performer is Ammonia at P = 20 bar, followed by R161 at the same P, Dimethyl Ether at P = 10 bar and n-Butane at P = 5 bar, respectively. For category II (T H = 100 o C), category III (T H = 140 o C) and category IV (T H = 180 o C), the best performers are Ammonia, Dimethyl Ether and R161, respectively all at P = 20 bar. For category V (T H = 300 o C), the best performers, in addition to Ammonia, Dimethyl Ether and R161, are methanol and water at P = 20 and 50 bar. Novel applications are introduced, which integrate these isobaric engines with vapor compression refrigeration systems. The thermodynamic cycles of the heat driven compressor with dense working fluids as in the current study have never been used in heat engines. The technological solutions (mainly towards simplification of the design) are crucial components of the study novelty.
... Energy storage systems have been suggested for extending the working hours of PV-VCC systems. 10 For instance, the integration of a thermochemical reactor as an energy storage system in a PV-VCC system was studied in Ferrucci et al 11 The proposed system exhibited a cooling capacity of 4 kWh/day per square meter of PV panel area, which is more than that of PV-VCC systems using conventional electrochemical batteries. Solar thermal cooling technology has drawn more attention compared to solar electricity driven cooling systems owing to its distinct advantages. ...
... Although the COP is usually lower for the ejector cooling cycle than other systems, the simple structure and low maintenance cost of this technology makes the solar ejector cooling system a viable option for building cooling. 10, 14 Salimpour et al, 15 a comparative exergoeconomic study, were performed on four solar ejector cooling configurations utilizing flat plate solar collectors. A preheater and precooler were employed to enhance the performance of the ejector cooling system. ...
Article
Full-text available
The yearly thermo‐economic performance is dynamically investigated for three solar heating and cooling systems: solar heating and absorption cooling (SHAC), solar heating and ejector cooling (SHEC), and heating and solar vapor compression cooling (HSVC). First, the effects of important design parameters on the thermo‐economic performance of the systems to supply the heating and cooling loads of the building are evaluated. The systems are parametrically analyzed with the weather conditions of Tehran, Iran. The results show that the life cycle costs (LCC) of the SHAC and HSVC systems are alike and much lower than those of the SHEC system. The HSVC system exhibits the best performance from exergetic and solar fraction viewpoints. The comparative analysis shows that the energy efficiencies of the SHAC and SHEC systems are higher in colder climatic conditions. However, the collector efficiency of the HSVC system declines in colder climates, mainly due to the lower solar intensities relative to in hotter climates. Further, the solar fraction of the SHAC system is higher than the SHEC technology under all climatic conditions. Moreover, higher values of solar fractions are obtained under colder weather conditions for the SHEC and HSVC systems. The best economic performance is observed for the SHAC and HSVC technologies, having significantly lower LCCs than the SHEC system. These lower LCCs under colder climatic conditions are due to the lower cost of supplying the heating load compared to the cooling load. Furthermore, all systems exhibit enhanced exergetic performance in colder weather conditions. The yearly thermo‐economic performance is dynamically investigated for three solar heating and cooling systems: SHAC, SHEC, and HSVC. In addition, the effects of important design parameters on the thermo‐economic performance of the systems to supply the heating and cooling loads of the building are evaluated.
... From the point of view of heat processes, the use of solar collectors (SC) makes it possible to increase the solar fraction by improving the techno-economic relationship of the system. Previous reviews regarding solar thermal cooling technologies have focused on the operating principles, working temperatures and equations of state of the adsorption [10][11][12][13], absorption [14][15][16], and thermomechanical [17,18] machines. In addition, the technical limits of the operational aspects and the conversion efficiency were detailed [11,[19][20][21]. ...
... Ejector cooling systems (EJC) have been evaluated since the 1970s but became more relevant during the 1990s [26,[84][85][86]. The EJCs are sensitive to meteorological variations and the size of the solar field, being of interest to improve the global COP of the system (SC-TES) -EJC [17,[87][88][89][90][91]. In this sense, the use of cold storage with phase change material (PCM) and a variable geometry ejector nozzle is proposed [92][93][94][95][96]. ...
Article
Full-text available
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 energy is the adequate solution for today and long term energy crises and important green resource because of its flexibility, simplicity and abundant supply of energy. The solar energy is an excellent option to generate clean electricity, and it has been exploited for different domestic and engineering applications [9][10][11][12][13][14].Solar refrigeration could be an alternative to conventional refrigerators. In a solar refrigeration system, solar energy is converted into electrical energy by photovoltaic (PV) technology, utilized to drive the refrigeration systems [15]. ...
... The amount of heat transferred at the hot side of the TEM (Q h ) can be calculated by taking into account heat balance Eqs (8), (9), and (10): ...
Article
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Preservation of perishable foods is a major issue where inconsistent electricity supply. In this study, a solar thermoelectric cooler (STEC) was fabricated by exploiting the solar energy and evaluated its cooling performance with and without product load. The STEC comprised of a thermoelectric module (TEM), inner and outer heat sink-fan fixed in the cooler box wall, and photovoltaic (PV) panel connected with the device through battery and PV charge controller. The PV power utilized to drive the device, charge the battery in the daytime, and the store electricity exploited during night time. The effect of varying input electric current on the cold side temperature of TEM, cooling capacity, power consumption and coefficient-of-performance (COP) were investigated. The results showed that the cold side temperature decreased to 5±0.2ºC in 120 and 180 min for without and with product load (0.5 kg fish fillets), respectively. The cooling capacity, power consumption and COP of the STEC were 23.8 W, 53.5 W and 0.44, respectively, at the input electric current of 3.5 A. The battery power was utilized to drive STEC for 5-6 h after sunset. The STEC could be considered as an alternate "green-option" to the domestic refrigerator where electricity is not accessible.
... Comprehensive reviews of the ejector systems have been introduced in. 13 one review paper focused on both systems together as TMR technologies was introduced by Zeyghami et al. 25 However, these reviews either focus on the design or applications (or both) of the ejector and ORC systems with no review that presents these systems from the improvement approaches point of view. This is important for researchers to understand and compare the improvements techniques that are investigated. ...
... Several factors should be taken into account in selecting the working fluid. These factors, as summarized by Zeyghami et al, 25 depend on the thermo-physical properties of the working fluid (such as a large molecular mass, large latent heat of vaporization, low viscosity, etc.), environmental effects, stability and compatibility properties, safety aspects (such as non-toxic, non-explosive, etc.), and the economic viability. Table 3 shows a summary of published studies that investigate the working fluid characteristics and effects. ...
Article
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Cooling and refrigeration systems consume around 17% of the worldwide electricity. Enhancing the performance of these systems, using renewable energy resources and waste heat recovered from industrial processes, will lead to reduced fossil fuel consumption. Improvements of these systems using eco-friendly working fluids are of equal importance. Both options contribute to the minimization of the emissions of greenhouse gases and ozone depletion substances. In this paper, a detailed and comprehensive review of the innovative and improvement approaches of the thermo-mechanical refrigeration (TMR) systems is introduced and analyzed. The reviewed TMR systems include ejector-driven, organic Rankine cycle-driven, and the new novel isobaric heat-engine driven refrigeration systems. The features and limitations of each approach and system have been detailed and discussed. The improvement approaches found in literature were achieved by improving the performance of conventional systems via optimizing the operating conditions, selection of promising working fluids, introducing new integration configurations of two cycles or more, or via replacing the mechanical compression process with improved thermo-mechanical compression process. The review revealed that there is a lack in the experimental validation, especially for the innovative proposed systems. Also, simplicity and flexibility (in operating conditions, heat sources, and outputs) are major features of the TMR systems compared to the other thermal-driven cooling technologies. However, further improvements including higher coeffecient of performance (COP) and lower cost are still major challenges for TMR systems compared to the conventional vapor-compression refrigeration systems.
... In recent years, the predominant technology in cooling systems worldwide is the conventional vapor compression cycle, which is known for its significant consumption of electricity due to the existence of a compressor and extremely high peak loads on the hottest summer days [1,2]. Solar energy is an attractive solution for operating air conditioning systems. ...
Article
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The main objective of this paper is to simulate solar absorption cooling systems that use ammonia mixture as a working fluid to produce cooling. In this study, we have considered different configurations based on the ammonia–water (NH3–H2O) cooling cycle depending on the solar thermal technology: Evacuated tube collectors (ETC) and parabolic trough (PTC) solar collectors. To compare the configurations we have performed the energy, exergy, and economic analysis. The effect of heat source temperature on the critical parameters such as coefficient of performance (COP) and exegetic efficiency has been investigated for each configuration. Furthermore, the required optimum area and associated cost for each collector type have been determined. The methodology is applied in a specific case study for a sports arena with a 700~800 kW total cooling load. Results reveal that (PTC/NH3-H2O)configuration gives lower design aspects and minimum rates of hourly costs (USD 11.3/h) while (ETC/NH3-H2O) configuration (USD 12.16/h). (ETC/NH3-H2O) gives lower thermo-economic product cost (USD 0.14/GJ). The cycle coefficient of performance (COP) (of 0.5).
... The technology of thermal-solar-assisted cooling has three different means: open cycle, closed cycle and thermomechanical process [205,206]. As the open cycle is more focused on desiccating and the thermomechanical process on refrigeration [205][206][207], closed cycle by absorption is the most suitable for building cooling [205,206]. ...
Article
In this document a review of three active as well as ten passive cooling methods suitable for residential buildings is carried out. The review firstly addresses how the various technologies cool the space according to the terms of the building heat balance, under what technical conditions they might be applied, and what their energy needs are. Secondly, what scientific analysis has been carried out and what the major findings are. Thirdly, what their economic and technical feasibility of use at the stage of implementation and operation within a dwelling are. Then, either with the reviewed studies or with a simulation modelling, an assessment of temperature drop of each cooling method within a standard-size dwelling is carried out. Also, a comparison of initial investment, energy consumption, maintenance, retrofitting and required space is done. Thereafter, with this information, a decision-making program is developed in order to find out the most suitable cooling method of this dwelling in each case study according to the climate, status (new or existing), and the affordability. With that, and taking the Mexican housing sector as case study, it is found that building color, shading system, night ventilation, controlled ventilation, roof coating and eco-evaporative cooling are the most suitable passive methods for an extensive use in this country.
... For instance, the VCC powered by PV cell is considered as an attractive option in countries that have high solar radiation intensity . However, the cost of their batteries still very high ( Zeyghami et al., 2015 ). The application of ORC is not economical at heat source temperatures lower than 100 °C . ...
Article
Refrigeration and air conditioning systems consume about 17% of the world-wide electricity and their conventional refrigerants cause ozone depletion and global warming. In this study a novel thermo-mechanical refrigeration (TMR) system is developed and analyzed that is powered, instead of electricity, by thermal energy from waste heat or renewable sources in the ultra-low temperature range of 60 to 100 ˚C. A novel isobaric expander-compressor unit (ECU) is designed and combined with vapor compression refrigeration cycle to constitute the TMR system. The technological solutions (mainly towards simplification of the design) are crucial components of the study novelty. The suitable refrigerants for the system are systematically investigated, analyzed and selected from a list of 43 refrigerants. Nine fluids for the power loop (the isobaric expansion cycle) and nine fluids for the cooling loop (the thermal refrigeration cycle) were selected and compared based on their mode of operation (subcritical and supercritical), environmental effects and safety class. It is found that the HFO refrigerants such as R1234yf and R1234ze have acceptable performance with no ODP and very low GWP. Natural refrigerants R717 (ammonia) has the best performance in subcritical mode with toxicity as the main drawback. At heat source temperatures less than 85 ˚C, the system operation in subcritical mode is more efficient and more compact than in the supercritical mode. Thorough analysis and recommendations are made for the size of the ECU in terms of the diameters of the expander and the compressor.
... For using ETC at a driving temperature of at 160 C, the double effect absorption cooler and Rankine engine-driven compressor can achieve a maximum COPs of 0.55 and 0.38, respectively. 36,44 However, the Stirling-cycle technology developed in this study has the advantages of using stationary thermal collectors, fewer components and devises, no toxic materials, the same technology for the engine and refrigerator, and benign refrigerants. In addition, it enjoys quiet operation, low maintenance requirements, and wide range of temperatures for refrigeration and heat pumping without changing the refrigerant (air). ...
Article
The global cooling demand is one of the fastest growing energy demands and is putting a strain on the electricity infrastructure. Solar‐powered cooling could provide most of the cooling demand due to the coincidence of the cooling demand and the solar irradiance. In particular, the solar‐powered Stirling‐cycle cooler has low maintenance requirement, high theoretical efficiency, and use of environmentally friendly gases. However, Stirling‐cycle coolers are expensive due to high driving temperatures, complex heat exchangers, and expensive solar tracking so that they have so far only been successful at high‐temperature difference applications. This study introduces a novel directly coupled solar Stirling cooler for which the hot engine cylinders are deployed inside evacuated tube collectors. The machine uses air as working fluid, and its driving mechanism is based on the free‐piston, balanced compound technology that was patented by Finkelstein. A second‐order mathematical model is used to investigate the performance of the machine for different cylinder arrangements, gas leakage rates, chilling temperatures, and solar irradiance. In addition, the regenerators are optimised to maximise the cold production. It is shown that mechanical frictions can be reduced to 20% by selecting an appropriate cylinder arrangement. The solar cooler achieves a maximum cold production rate of 367.5 W/m2 without using external heat exchangers at load temperature of 7°C, which is comparable with photovoltaic powered coolers. In addition, the machine is relatively simple, has safe and quiet operation, uses ambient air as working gas, and is able to produce a wide range of chilling including sub‐zero temperatures without changing the working gas. The direct thermal coupling of the Stirling cooler to evacuated tube collectors significantly reduces the complexity of the machine and removes intermediate heat transfer steps which reduce the performance. Thus, the suggested cooling technology has great potential for solar refrigeration, especially for low power and near ambient cooling.
... Berdasarkan penelitian dari (Farhana dkk., 2007;Mahmoud, 2017) bahwa nilai COP untuk mesin pendingin adsorpsi tenaga surya berkisar dari 0,01 hingga 0,2. Penerapan dari mesin pendingin adsorpsi umumnya terdiri atas tiga fungsi yaitu untuk refrijerasi makanan dan penyimpanan vaksin (0-8 o C), untuk mendinginkan udara ruangan (8-18 o C), dan untuk pembekuan es serta tujuan pengentalan (< 0 o C) (Mehdi, Yogi & Elias, 2015). ...
... Different techniques have been proposed to create refrigeration systems powered by medium to low temperature heat sources such as absorption/adsorption systems [7], ejector systems [8], ORC [9] , and Stirling engine systems [10]. However, there are technical problems that limit their applications. ...
Conference Paper
Refrigeration systems contribute to the critical environmental concerns including global warming and ozone depletion. It is necessary to develop new systems that use renewable energy resources and waste heat to perform the cooling function with eco-friendly working fluids. This improves the energy efficiency of the power systems and minimizes the harmful effects of conventional refrigeration systems. This paper introduces an analysis of a regenerative thermo-mechanical refrigeration system that is powered with renewable heat sources (solar, geothermal) or waste heat (from internal combustion engines, gas power plants, and steam power plants). The system operates at the supercritical conditions of the working fluids. The performance of the system is evaluated based on power efficiency, the COP, and the expander-compressor diameters. Also, a number of working fluids were compared with each other based on their performance and environmental effects. There is a trade-off between high-performance fluids and their environmental effects. Using R32 as a working fluid at Th=150 o C and Tc1=40 o C, the system produces a cooling capacity of 1 kW with power efficiency of 10.23 %, expander diameter of 53.12 mm and compressor diameter of 75.4mm. The regenerator increases the power efficiency by about 1 %. However, the size of the regenerator is small (Dr = 6.5 mm, Lr = 142 mm].
... However, in recent years, the theoretical and experimental research activities associated with the vapour absorption refrigeration system (VARS) have been increased because VARS harnesses inexpensive low-grade heat energy sources such as waste heat or renewable energy (Aliane et al., 2016;Allouhi et al., 2015). The principle difference between the VARS and VCR is the replacement of mechanical compression by the physico-chemical refrigerant compression by use of a low grade heat instead ofthe electricity (Moya et al., 2011;Ouadha and El-Gotni, 2013;Rêgo et al., 2014;Salmi et al., 2017;Zeyghami et al., 2015). (Fernandes et al., 2014;Ghafoor and Munir, 2015;Siddiqui and Said, 2015;Srikhirin et al., 2001) To be more specific, industries apply NH 3 -H 2 O [termed as ammonia absorption refrigeration (AAR)] as the working pairs because it is operated below zero temperature with minimum refrigeration temperature < 253.15 ...
... Air-conditioning is an important application due to the increasing need for air-conditioning associated with locations where solar utilization is available [16]. Solar cooling can be achieved by several techniques and principles and is basically classified as electric solar photovoltaic and thermal solar [11,17,18]. An electric solar system consists of a solar panel made of photovoltaic cells (PV panels) to generate electrical energy to power a compression vapor chiller (conventional system) with a good coefficient of performance, COP, typically, 3 for air-cooled and 4.5 for water-cooling in average [17]. ...
Article
Nowadays, data processing is a fundamental operation for modern businesses such as banks, technology companies, and factories, among others. However, computers dissipate significant amounts of heat yielding to an operational temperature rise. Considering that these machines cannot operate properly in inappropriate temperatures or at extreme conditions, they can come to a stop due to overheating. Consequently, cooling and air-conditioning systems are necessary to keep the proper operating temperature as well as the room temperature itself. On the other hand, a data center air-conditioning system drains a large amount of electrical power. Based on this, this paper evaluates a solar-powered absorption cooling system to assist the traditional electric chiller system resulting in energy saving, an advantage over conventional cooling, and day availability for this system. A case study is analyzed in a conventional data center located in the city of São Paulo, Brazil. First, the electric power density consumed by computers is 2.0 kW/m2, which represents a typical power load of an IT room. In addition, some other power density cases are also analyzed, namely: 0.5, 1.0, 4.0, and 8.0 kW/m2; these would occur at partial or at high operational loads. Local solar irradiation indexes are based on ASHRAE temperature and solar data for that city. The results are valid for a typical year and are compared to (1) a conventional data center and (2) the event combined with the solar-powered cooling system.
... Thus, it is an attractive and logic way to use solar energy to drive space cooling systems that will be able to reduce both peak electricity demand and GHG emissions. Interest in solar cooling began in the 1970s, when the energy crisis occurred (Qu et al., 2010;Zeyghami et al., 2015). Solar cooling is an application of solar energy for cooling purpose (Koroneos et al., 2010). ...
Article
Solar cooling technologies have been proven to have great potential for energy saving during cooling season. Meanwhile, glass has become one of the primary structural materials used in building construction since the middle of the 20th century. Although common glass adds to the aesthetic appeal of a building, it has serious drawbacks, such as creating heat traps, preventing natural ventilation and causing glare. Highly glazed façades would cause unwanted heat transmission from the ambient, which must be extracted to outside using an air-conditioning system. Internal heat resulting from façade configurations can be responsible for up to 45% of a building’s cooling requirements. A façade integrated solar cooling system can simultaneously improve building’s energy efficiency, utilise solar energy and still maintain a high level of architectural and aesthetic quality. This investigation presents a consistent approach for optimising and comparing façade integrated solar cooling systems in terms of technical and financial performance. Four systems (a vapour compression cycle (VCC) chiller driven by semi-transparent photovoltaics (STPV) arrays, a single-stage absorption chiller, an adsorption chiller and a vapour compression chiller coupled with organic Rankine cycle (ORC) driven by evacuated tube solar collectors) were assessed and compared with a conventional electric vapour compression chiller. The systems investigated were modelled in TRNSYS and the models were applied to predict performance parameters in various climate zones (seven cities) in Australia. The solar fraction (SF) and unit cooling cost (UCC) were the two parameters applied to quantify the technical and financial aspects of each solar cooling system in seven cities in Australia. It was found that among the systems investigated, the VCC chiller with STPV system has the highest SF (100% except in Darwin) and lowest UCC ($0.21 kWhr−1) for all seven cities in Australia. In general, due to the grid as a virtual storage, ORC-VCC system has higher SF (40% and 50%) and lower UCC (5% and 10%) compared with adsorption and absorption chiller respectively in subtropical and temperate climate zones.
... Along with their high energy consumption, these systems, due to their use of chlorinated fluorocarbon compounds, lead to the ozone layer depletion thus to global warming [2]. Knowing that solar energy is obtainable worldwide and produces electrical and thermal energy [3], and the maximum available solar power and the peak cooling load happen at once, combining solar energy with the cooling system may be a solution for the energy consumption problem [4] and also for the environmental problems, since solar cooling is an environmental-friendly substitute for conventional cooling [5]. Several technologies for solar cooling exist currently in the market such as: The solid/liquid desiccant, the solid adsorption and the absorption systems which are in turn the most developed technologies [6,7]. ...
Preprint
Solar cooling systems, specifically solar absorption cooling systems, are becoming an attractive subject since they are great alternatives to the conventional cooling systems which lead to high electrical consumption. In addition, this system can provide cooling without greenhouse gas emissions. Hence, many combinations of different components might be adopted to apply the solar absorption cooling system. This paper will discuss the absorption chiller working cycle, the absorption chiller working fluids, the solar collectors to be combined with solar cooling systems and the single-effect absorption chiller. Furthermore, the variation of the coefficient of performance, the solar fraction and the economical studies will be discussed. The goal of this review is to present previous studies and analyze their results; highlight the environmental, energetic, and economic viability of such systems and tackle future challenges in regards to solar absorption cooling system in order to apply this system on new climates and more specifically on Lebanon.
... A la fecha se han desarrollado varias tecnologías de refrigeración solar que podemos dividir en: eléctricas, con el uso de paneles fotovoltaicos; solares térmicas que a su vez se sub dividen en ciclos abiertos con sistemas de desecantes líquidos y sólidos, ciclos cerrados como adsorción, absorción, y sistemas termo mecánicos utilizando un ciclo con eyectores. Cada una de estas tecnologías tienen diferentes coeficientes de desempeño (COP), fluidos de trabajo, equipos adicionales para su funcionamiento y diferentes parámetros, comparándolas con el sistema de refrigeración tradicional por compresión de vapor alimentado con energía eléctrica producida por combustibles fósiles [3][4][5][6][7][8]. Estas tecnologías solares no tradicionales actualmente tienen las desventajas de poseer menores COP y de ser en general más caras por el equipo requerido para su funcionamiento. ...
Conference Paper
Full-text available
Se desarrolló un modelo numérico mediante CFD de un eyector de una fase, considerando que opera en condiciones de un ciclo de refrigeración solar. Con este modelo se estudió el efecto de la contrapresión, , en el flujo másico secundario, , y en la relación de arrastre,. Los resultados numéricos se compararon con resultados reportados en la literatura, dando validez al modelo computacional propuesto. El modelo numérico es capaz de predecir los tres modos de operación del eyector. El modelo desarrollado predice en mayor medida el comportamiento dentro del eyector para un modo de trabajo de doble estrangulamiento. Palabras Clave: eyector, relación de arrastre, CFD, refrigeración solar. A B S T R A C T A CFD model for a single phase ejector was developed. The ejector is considered to work under solar refrigeration cycle conditions. The effect of the back pressure, , on the secondary mass flow, ̇, and the entrainment ratio, was examined with this model. The numerical results were compared with those reported in the open literature, validating the proposed computational model. The numeric model is able to predict the three ejector working modes. This model better predicts the behaviour of the ejector while working on the double choked mode.
... Different techniques have been proposed to create refrigeration systems powered by medium to low-temperature heat sources such as absorption/adsorption systems [9][10][11], ejector systems [12][13][14][15], organic Rankine cycle (ORC) [16][17][18], and Stirling engine systems [19]. However, there are technical problems that limit their applications. ...
Article
Refrigerants of the conventional cooling systems contribute to global warming and ozone depletion significantly, therefore it is necessary to develop new cooling systems that use renewable energy resources and waste heat to perform the cooling function with eco-friendly working fluids. To address this, the present study introduces and analyzes a novel regenerative thermo-mechanical refrigeration system that can be powered by renewable heat sources (solar, geothermal, or waste heat). The system consists of a novel expander-compressor unit (ECU) integrated with a vapor compression refrigeration system. The integrated system operates at the higher-performance supercritical conditions of the working fluids as opposed to the lower-performance subcritical conditions. The performance of the system is evaluated based on several indicators including the power loop efficiency, the coefficient of performance (COP) of the cooling loop, and the expander-compressor diameters. Several working fluids were selected and compared for their suitability based on their performance and environmental effects. It was found that for heat source temperature below 100 °C, adding the regenerator to the system has no benefit. However, the regenerator increases the power efficiency by about 1 % for a heat source temperature above 130 °C. This was achieved with a very small size regenerator (Dr = 6.5 mm, Lr = 142 mm). Results show that there is a trade-off between high-performance fluids and their environmental effects. Using R32 as a working fluid at heat source temperature Th=150 °C and cold temperature Tc1=40 °C, the system produces a cooling capacity of 1 kW with power efficiency of 10.23 %, expander diameter of 53.12 mm, and compressor diameter of 75.4mm.
... cooling [5]. Several technologies for solar cooling exist currently in the market such as: The solid/liquid desiccant, the solid adsorption and the absorption systems which are the most developed technologies [6,7]. ...
Article
Solar cooling systems, specifically solar absorption cooling systems, are becoming an attractive subject since they are great alternatives to the conventional cooling systems which lead to high electrical consumption. In addition, this system can provide cooling without greenhouse gas emissions. Hence, many combinations of different components might be adopted to apply the solar absorption cooling system. This paper will discuss the absorption chiller working cycle, the absorption chiller working fluids, the solar collectors to be combined with solar cooling systems and the single-effect absorption chiller. Furthermore, the variation of the coefficient of performance, the solar fraction and the economic study will be discussed. The goal of this review is to present previous studies and analyze their results; highlight the environmental, energetic, and economic viability of such systems and tackle future challenges regarding solar absorption cooling system and discuss the application of this system on new climates and more specifically on Lebanon.
... Solar cooling systems mainly include steam condensing solar cooling system [89,90], mechanical solar cooling system [91,92], absorption cooling system [93], adsorption cooling system (solid surface) [94], and dry cooling system [95]. ...
Article
Photovoltaic off-grid systems are essential in supplying power to areas remote from the grid. Mobile homes are used in various cases in remote areas, most of which are far from the power supply grid. It is not economically feasible to develop electricity networks in these areas. One of the best ways to supply power in such cases is to implement photovoltaic systems. These systems can produce electricity through solar irradiation and are environmental-friendly. However, due to the high capital cost of these systems, it is necessary to determine the optimal number of components, such as photovoltaic panels and batteries, to optimize the initial cost and achieve a desirable level of availability. In this study, the TRNSYS software is utilized to investigate the energy required by mobile homes for the ventilation system and power supply operation for different regions. A numerical method is developed to quantify the optimal photovoltaic system for each region for the optimal sizing of these systems. Also, generators have been considered in particular cases to ensure a continuous power supply. Finally, the cities are divided into different categories, showing the off-grid system performance in these regions. Results obtained for the city of Tehran, Iran, suggest that the Levelized energy cost is 0.23 USD/kWh. This system lacks 2.45%, equivalent to 118 h, of required energy and produces 56% surplus energy.
... Solar thermally-driven refrigeration (absorption, adsorption and desiccant cooling systems), solar electric refrigeration and hybrid systems with ST collectors or PV modules are extensively reviewed and compared in [48]. Meanwhile, in [49], only solar thermomechanical refrigeration and cooling methods considering ST collectors are reviewed. The review presented in [18] is also limited to solar thermal cooling technologies, as well as the work presented in [50]; the latter work also reviews research on solar cooling systems' simulation. ...
Article
Full-text available
Heating and cooling (H/C) represent the largest share of energy consumption worldwide. Buildings are the main consumers of H/C, while the share of renewable energy for H/C provision still represents a low percentage, 22.0% in 2019. Hybrid photovoltaic-thermal (PV-T) systems are gaining increasing attention both in research and in applications, as they generate both electricity and useful heat simultaneously. The relevance and potential of PV-T collectors and their integration into wider systems are evident, but there is still a lack of review articles that address the potential of these systems in building applications in a comprehensive way. This work aims to review the state-of-the-art of PV-T collectors for building applications, as well as the corresponding PV-T systems for solar combined cooling, heating and power (S-CCHP) provision. The novelties of this work involve the comparison of these systems with conventional solar H/C technologies, the review of the market of H/C technologies, a summary of the challenges for the wider integration of S-CCHP systems and proposal lines of work to improve the cost-competitiveness of these systems. The first section summarises the focus and findings of previous reviews, followed by an overview of the current development status of the main types of PV-T collectors. Then, PV-T-based S-CCHP systems are reviewed, and the potential of PV-T systems’ penetration in the built environment is evaluated and discussed.
... A positive, negative, and extremely broad slope represents dry, wet, and isentropic fluid, respectively. With the present cycle architect, following criteria [29] was observed while selecting the working fluids; ...
Article
Full-text available
This study focuses on the thermal performance analysis of an organic Rankine cycle powered vapor compression refrigeration cycle for a set of working fluids for each cycle, also known as a dual fluid system. Both cycles are coupled using a common shaft to maintain a constant transmission ratio of one. Eight working fluids have been studied for the vapor compression refrigeration cycle, and a total of sixty-four combinations of working fluids have been analyzed for the dual fluid combined cycle system. The analysis has been performed to achieve a temperature of −16 °C for a set of condenser temperatures 34 °C, 36 °C, 38 °C, and 40 °C. For the desired temperature in the refrigeration cycle, the required work input, mass flow rate, and heat input for the organic Rankine cycle were determined systematically. Based on the manifestation of performance criteria, three working fluids (R123, R134a, and R245fa) were chosen for the refrigeration cycle and two (Propane and R245fa) were picked for the organic Rankine cycle. Further, a combination of R123 in the refrigeration cycle with propane in the Rankine cycle was scrutinized for their highest efficiency value of 16.48% with the corresponding highest coefficient of performance value of 2.85 at 40 °C.
... Sorption cooling systems are categorized as; absorption, adsorption, solid desiccant and liquid desiccant systems [49,50]. Evidently, an amalgamation of sorption cooling systems with conventional compression cooling systems, a.k.a. ...
Article
This paper thoroughly reviews the integration of absorption, adsorption and desiccant cooling technologies into vapor compression cooling/refrigeration systems. Different configurations of hybrid absorption-compression cooling systems have been collectively listed and studied based on energetic, exergetic, economic and environmental analysis. Several reviewed studies revealed that such systems could diminish the electricity consumption by 45-88% in comparison with conventional compression systems. Besides, various arrangements of hybrid adsorption-compression cooling systems have been intensively investigated using cascade, partially integrated and fully integrated systems. These layouts of integrated adsorption-compression cooling systems focus on escalating the performance of vapor compression cooling systems by dwindling their condensation temperatures. Surveys showed that using adsorption cooling systems with oversized capacity could result in increasing the performance until approaching freezing limits, while downscaled adsorption cooling systems could worsen the system performance as a result of increasing the intermediate condensation temperature. The amalgamation of vapor compression systems with both solid and liquid desiccant cooling cycles has also been reported and compared with different regeneration schemes; for instance, electric energy, solar energy and heat rejected from the assisted vapor compression cooling systems. Considerable studies confirmed that using multi-stage solid desiccant cooling systems compared with single-stage solid desiccant cooling systems can be operated at lower regeneration temperatures. Also by introducing integrated liquid desiccant-vapor compression systems, cooling can be attained with a dehumidification process that cools the supply air lesser than its dew point with an energy provision of 30-80%. This work is beneficial for researchers involved in the field of multi-integrated cooling systems.
... cooling [5]. Several technologies for solar cooling exist currently in the market such as: The solid/liquid desiccant, the solid adsorption and the absorption systems which are the most developed technologies [6,7]. ...
Article
Full-text available
Solar cooling systems, specifically solar absorption cooling systems, are becoming an attractive subject since they are great alternatives to the conventional cooling systems which lead to high electrical consumption. In addition, this system can provide cooling without greenhouse gas emissions. Hence, many combinations of different components might be adopted to apply the solar absorption cooling system. This paper will discuss the absorption chiller working cycle, the absorption chiller working fluids, the solar collectors to be combined with solar cooling systems and the single-effect absorption chiller. Furthermore, the variation of the coefficient of performance, the solar fraction and the economic study will be discussed. The goal of this review is to present previous studies and analyze their results; highlight the environmental, energetic, and economic viability of such systems and tackle future challenges regarding solar absorption cooling system and discuss the application of this system on new climates and more specifically on Lebanon.
Article
Sustainable buildings have recently become a global priority. In hot climates, meeting the cooling demand in the sustainable buildings is challenging. To meet this demand in office buildings during summer, a holistic configuration of integrating an active solar cooling technology (ASCT) into a passively designed facade is proposed. Three hot climates, namely, humid subtropical, hot semi-arid, and hot desert, were investigated using a building energy model. First, the passive solar design strategies (PSDSs), window-to-wall ratio (WWR), glazing type, shading devices, and wall material were sequentially applied to the facade. Then, an absorption chiller driven by a solar thermal collector (STC) was integrated into this passively designed façade. The best tilt angle, area, and dimensions of STC were specified for the main façade orientations. The results reveal that WWR has the highest impact on the cooling demand reduction, whereas the least effect results from the shading devices. The passively designed facade reduces the cooling demand by 43.5%–65.7%. The sloped STC at a tilt angle of 30° is the most efficient option for all orientations except the north where the horizontal STC is considered the best. For these tilt angles, STC area required for meeting the cooling demand ranges from 2.88 m² to 4.5 m², corresponding to an STC-to-façade width ratio of 74.1%–84.3%. In the case of the vertical STC, the ASCT is unable to meet the cooling demands. This study provides design guidelines for integrating ASCT into the façade of sustainable buildings in hot climates.
Article
The Rankine cycle, as a common way of solar power generation, is receiving more and more attention. However, the adoption of a mechanical booster pump in the conventional Rankine cycle affects the compactness of the power system. Based on this, a new booster cavity is proposed in this paper for an integrated thermal-electric conversion device, to replace the mechanical booster pump. For this proposed structure, the pressurization of low pressure condensate liquid is achieved by utilizing the internal energy of high temperature and high pressure vapor. To verify its feasibility, the theoretical description of the physical process, mathematical modeling, simulation analysis, and experimental verification of the structure are presented in this paper. It can be found that the structure is workable, and no power transmission from an external energy source is required for the thermal-electric conversion device adopting this structure. Although the conversion efficiency of the proposed cycle is 15.23%, which is slightly lower than the 15.71% efficiency of the conventional Rankine cycle under the same operating condition, it is a true thermal driven power generation, which enables a more compact system.
Article
Faced with the ever-increasing pressures from climate change and environmental pollution, stand-alone photovoltaic (PV) power generation is promising in providing electricity to the air conditioners. However, the solar energy is usually susceptible to the weather changes, making the power supply unreliable. To mitigate the effects caused by the solar intermittency, additional energy storage buffer is necessary. In this paper, stand-alone PV chilling systems with water tank thermal energy storage (TES) and battery electric energy storage (EES) strategies are quantitatively compared by evaluating the thermodynamic efficiency, respectively. A chiller model is firstly built, based on which the initial steady states are derived. Secondly, the EES and TES system models are built based on the compressor speed control strategy and refrigeration cycle model. The resulting chilled water temperature fluctuation curves in TES and EES PV chillers are subsequently obtained. Quantitative comparative results in this paper are threefold. i) The average chilled water temperature of the TES strategy is 11.08% lower than that in the EES strategy; ii) The average cooling energy amount stored in the TES strategy is 43.6% larger than that in the EES strategy, indicating that the chilled water tank has a better energy storage potential in the given PV chiller system; iii) The water volume of TES is optimized to derive the maximum cooling energy storage rate which is 76.92% larger than that in the EES system.
Article
The performance of renewable energy systems can be significantly improved if power is produced from low‐temperature heat sources. The organic Rankine cycle (ORC) is suitable for producing power from low‐temperature heat sources. ORC finds applications alongside solar power, geothermal power, waste heat and biomass. ORC‐enabled systems can contribute significantly to raising the effectiveness of renewable power sources. Solar power, for example, can deliver affordable electricity to remote locations and small industries. By employing ORC, power generation is possible at lower temperatures on cloudy days. Its main difference from the steam Rankine cycle is its working fluid. The ORC makes use of an organic, high molecular mass fluid as the working fluid. Compared to steam Rankine cycles, ORC works at a lower temperature (<250°C) and pressure. The only working fluid in the steam Rankine cycle is water, but the ORC can operate on hundreds of different working fluids. The design and performance of ORC systems are entirely dependent upon the suitable working fluid and, hence identification of the working fluid for ORCs is of utmost importance for diverse applications. Properties of working fluid have a considerable impact on the efficiency of the system. The main objective of this study is to identify the most suitable organic fluids having characteristics necessary for use in solar ORCs. In addition, a detailed review of the various types of heat transfer fluids now available in the market that are often used in ORC systems was conducted. This research assists in selecting the most appropriate organic fluids for various solar ORC applications in terms of operating circumstances. Heat transfer fluids (HTF) are used to collect heat from the sun through a solar collector. Organic fluids (working fluids) extract heat from the HTF in an evaporator and run the turbine. Identification of a suitable combination of HTF and organic fluid is the key for the development of a solar organic Rankine cycle system. This system can be used for generating electricity for small‐scale applications like residential buildings and small industries. Novelty is the identification of a suitable combination of HTF and organic fluids.
Article
There is a significant global opportunity to capture and utilize low grade waste heat to reduce fossil fuel consumption, greenhouse gas emissions, and improve energy efficiency across a wide range of industries. In this work, an advanced type of thermally activated cooling system, an organic Rankine-vapor compression cycle (ORVC) with novel heat integration strategies, was designed and tested at a relevant scale for industrial waste heat recovery (300 kWth cooling capacity). The ORVC linked an organic Rankine power cycle and a vapor compression cooling cycle using a turbine and compressor that shared a single shaft. The ORVC test facility absorbed waste heat from a liquid stream at 91℃ to simulate engine coolant in diesel generator sets, rejected heat to a glycol stream at 30 ℃, and generated chilled water at 7 ℃. A cooling capacity of 264 kW ± 3.5 kW was experimentally validated with a COP of 0.56 ± 0.01 during steady-state operation at the design temperatures. The thermal efficiency, accounting for pump work, of the Rankine cycle was 7.7% ± 0.22% and the COP of the vapor compression cycle was 5.25 ± 0.09. The centrifugal turbo-compressor operated at 31.5 kRPM ± 0.3 kRPM, with a turbine and compressor isentropic efficiencies of 76.7% ± 0.90% and 84.8% ± 0.54%, respectively, with near-perfect power transmission between these components. The pressure drop in the piping and heat exchangers were significantly larger than expected which had a detrimental impact on the performance of the ORVC. In addition, the condenser on the cooling cycle could not deliver the subcooling as specified from the design point modeling. The results from the sensitivity analysis showed that the higher condenser glycol outlet temperature had the largest impact on performance, which is consistent with other analytical models in the literature. When the ORVC simulations were updated with experimental values for isentropic efficiencies of the turbomachinery, the thermal COP was 0.66 which represents an estimate of the predicted performance if test facility limitations are overcome.
Article
The combination of an ORC (Organic Rankine Cycle) with a VCC (Vapor Compression Cycle) is studied analytically. In this work, the two cycles use the same fluid and operate with a common condenser. Elementary transformations of the fluid between two consecutive points of the system are calculated using a one-dimensional thermodynamic approach considering real fluid properties, the pressure losses and irreversibilities present in the compressor, in the expander and in the pump. The performances and the recommended inlet and outlet diameters of the expander and the compressor are established for various operating conditions and 12 fluids. The system can produce a typical useful cooling capacity of 0.60 kW at 5.5°C when using a 2 kW heating source at 65°C and when the condenser temperature is 30°C. The cooling capacity reaches 1.0 kW if the cold source temperature is 15.5°C. Results show the required diameters ratios at inputs and outputs of the compressor and the expander. They indicate the situations for which the compressor is smaller than the expander and vice versa. They identify the particular cases in which the compressor and the expander have exactly the same inlet and outlet diameters. This particular case allows using two identical compressors, one working as a compressor, the second as an expander.
Article
To meet the high cooling and fresh water demands in hot and arid regions, a novel integrated solar cooling and solar distillation system is introduced. The system consists of a solar ejector cooling system integrated with single-slope solar still. The proposed novel system is the first study to integrate two solar systems for cooling and water production with outputs significantly higher than any existing system. A steady state thermodynamics model is developed based on the mass, momentum and energy conservations and the performance of the integrated system is investigated. Results showed that the productivity of the solar still is enhanced by increasing the evaporation rate (using heating coil) and by increasing the condensation rate (using cooling coil). Simultaneously, this improved the COP of the ejector system by enhancing its entrainment ratio with slight increase in the required solar collector area. The performance of the system is investigated further for four different scenarios of integration between the solar ejector cooling and solar distillation systems. Results showed that the productivity of the still is five times higher than that of the conventional solar still. The effects of the major operating parameters on the performance of the system with R134a as the working fluid are investigated and analyzed. At a solar radiation of 500 W/m2, generator pressure of 3.3 MPa, generator temperature of 365 K, evaporator temperature of 283 K, a cooling capacity of 10.4 kW and distilled water of 8.10 kg/day are obtained. The annual produced water considering the hourly variation of the radiant flux was 5067 kg/year, which is 5.7 times more than the conventional systems. The estimated cost of one liter distilled water per 1 m2 area of the present solar still is $0.04, which is only 18% of the water cost of other still technologies. Moreover, the performance of additional four working fluids is compared in terms of COP, cooling capacity, required solar collector area and still productivity, based on which, R134a working fluid was recommended for its overall performance.
Article
Full-text available
A new solar lithium bromide absorption - compression refrigeration cycle system was proposed for temperature and humidity independent control. MATLAB programming language is used to perform the thermal calculation of the new system, and the cycle characteristics of the typical day of the new system are analyzed. The influence of solar radiation intensity is analyzed. The results show that the new system can realize the cascade preparation and utilization of cooling capacity, and the optimal evaporation temperature makes the new system have higher performance.
Article
Evaporative cooling technology is limited by the environmental wet-bulb temperature and is not suitable for humid climates. Desiccant wheels adsorb water vapour, thereby converting high-humidity air into low-humidity air, and they can be regenerated by solar energy or waste heat. In this study, a desiccant evaporative combined chilled air/chilled water air-conditioning system is proposed. The proposed system integrates a desiccant wheel air conditioning system and a direct-evaporative cooler, which can be used for temperature and humidity independent control systems in humid climates. An experimental setup was built and used to test the system performance and important system parameter effects under moderate temperature and humidity (32 °C, 60% RH), moderate temperature and high humidity (32 °C, 80% RH), and high temperature and humidity (36 °C, 80% RH). The results indicated that for the system at a regeneration temperature of 70 °C, the chilled air temperature was lower than 20 °C, the chilled air humidity ratio was lower than 13 g/kg, and the chilled water temperature was lower than 18 °C, which meets the temperature and humidity independent control requirements.
Article
In the present study, the direct contact condensation (DCC) performance of the superheat GOX in subcooling LOX is explored by numerical simulations based on the VOF two-phase model. The flow condensation characteristics are analyzed in a practical condenser of a cryogenic liquid rocket. The coalescence phenomenon of the GOX streams is examined. The possible regimes of the coalescence are summarized and their effects on the condensation performance are explored. Besides, an improved GOX entrance layout is proposed to avoid the coalescence phenomenon and improve condensation performance. The main conclusions are concluded as follows: The gas condensation is the main heat transfer form in most of the pipe region. The bending section of the condenser pipe that connects the vertical section and horizontal section is the most active region for DCC. It is found that there can be two types of coalescences namely, transverse coalescence and longitudinal coalescence. Both coalescence regimes have strong negative effects on the heat transfer ability and condensation performance of the condenser pipe. The improved entrance layout can successfully avoid the coalescence of the GOX streams and reduce the flow distance of the GOX by about 93%. It is also concluded that an improvement of the condenser pipe should be effectively accomplished by controlling the coalescence of the GOX streams after injection.
Presentation
Full-text available
Heat Transfer Analysis of regenerative thermo-mechanical refrigeration system. Paper Number: SHTC2020-4891
Article
To meet the high cooling and fresh water demands in hot and arid regions, a novel integrated solar cooling and solar distillation system is introduced. The system consists of a solar ejector cooling system integrated with single-slope solar still. The proposed novel system is the first study to integrate two solar systems for cooling and water production with outputs significantly higher than any existing system. A steady state thermodynamics model is developed based on the mass, momentum and energy conservations and the performance of the integrated system is investigated. Results showed that the productivity of the solar still is enhanced by increasing the evaporation rate (using heating coil) and by increasing the condensation rate (using cooling coil). Simultaneously, this improved the COP of the ejector system by enhancing its entrainment ratio with slight increase in the required solar collector area. The performance of the system is investigated further for four different scenarios of integration between the solar ejector cooling and solar distillation systems. Results showed that the productivity of the still is five times higher than that of the conventional solar still. The effects of the major operating parameters on the performance of the system with R134a as the working fluid are investigated and analyzed. At a solar radiation of 500 W/m2, generator pressure of 3.3 MPa, generator temperature of 365 K, evaporator temperature of 283 K, a cooling capacity of 10.4 kW and distilled water of 8.10 kg/day are obtained. The annual produced water considering the hourly variation of the radiant flux was 5067 kg/year, which is 5.7 times more than the conventional systems. The estimated cost of one liter distilled water per 1 m2 area of the present solar still is $0.04, which is only 18% of the water cost of other still technologies. Moreover, the performance of additional four working fluids is compared in terms of COP, cooling capacity, required solar collector area and still productivity, based on which, R134a working fluid was recommended for its overall performance.
Chapter
In the past, attention has been created to use solar energy due to increased environmental pollution. Solar energy utilization through photovoltaic (PV) and thermal technologies is required to replace the conventional use of fossil fuels across the globe. Different types of solar PV (SPV) technologies utilizing the photons as input are driving the life of people. On the other hand, utilizing the solar heat for various applications is categorized as the solar thermal application which includes desalination, heating, cooling, cooking and power generation. Hence the objective of this work is to discuss the fundamentals, recent advancements and applications of different solar utilization technologies. The chapter is categorized into two major sections namely solar PV techniques and solar thermal techniques. In the first section SPV techniques, the principle, operation and recent advancements in the SPV system have been covered. In the second section solar thermal techniques, the principle, construction, working mechanism and current state of the art in recent research on solar collectors, solar cooling techniques, solar pond, solar cooking techniques and solar desalination have been addressed.
Article
For the traditional Rankine cycle, mechanical pump driven by electricity is the only power-consuming part. Based on this, a steam-water supercharger is proposed in this paper, which can realize the pressurization of low-pressure condensate only using high-pressure and high-temperature steam. In the structural design, the crank slider mechanism is selected to realize automatic control of steam-intake and steam-exhaust passages. Besides the overview of principle, the mathematical modeling for performance analysis is also conducted. Then the theoretical study, including pressurizing performance and parameters study, and experimental verification are carried out to prove the feasibility of the proposed supercharger. The results show that: the proposed supercharger can be an alternative to the mechanical pump, and there is no requirement for external electric energy or power transmission, which is conducive to the promotion of small-scale portable solar power generation systems.
Article
A pump is needed in an ejector refrigeration system, which makes the system high cost and complicated and hinders its application. A pump-free double heat source ejector refrigeration system using R1234yf as working fluid is proposed in which an injector driven by another heat source replaces the liquid circulating pump, making the system more affordable, simpler and more stable. The effect of different operation conditions on entrainment ratios and the influence of different factors on system performance are analyzed on the basis of mass, momentum and energy conservation equations. The influence degree of each factor on system performance is investigated by the orthogonal test method. The condenser temperature has the largest effect on system performance. The pressure drop in the suction chamber of gas-liquid injector has the least impact on system performance. The COP can reach about 0.35 under a certain working condition. The system can be driven by two different temperature heat sources with no electricity needed, and it is a good choice for places with abundant heat resources or lack of electricity.
Article
Full-text available
When they were first conceived, solar cooling systems were designed to be cost-effective and environmentally safe alternatives for the majority of the developing nations that are characterised by their hot climates in contrast with the traditional air conditioning systems powered by electricity that is produced from fossil fuel resources. Nevertheless, developments in photovoltaic (PV) and air-conditioning technologies have impacted on the prospects of solar cooling systems. This study examined two different options: a coupled PV and air conditioner system and a solar cooling system (absorption chillers where thermal energy is provided by solar collectors) for a specific developing country located in the Eastern Mediterranean region whose climate is hot and dry (Jordan). The cooling system comprised a pair of cooled multistage compression, both of which were 700 kW, while the PV system’s size was 2.1 MWp, the utility grid connection was a 0.4 kV 50 Hz net meter (2 meters) and it was anticipated that 3300 MWh/year would be generated. The solar cooling system operated at a maximum coefficient of performance (COP) of 0.79 and had an actual recorded COP of 0.32 on the site; when the electricity tariff of $0.1/kWh was considered, the respective levelised cost of energy (LCOE) values were $0.9/kWh and $2.35/kWh respectively. The findings indicate that the initial costs for the solar thermal cooling system and the PV system were approximately $3.150M and $3M, respectively. The current value of future cash payments when discounts of 6% per year were applied to the payments for the combination of PV and air conditioning was about $9,745,000, whereas the solar thermal cooling system will not reach the breakeven point at negative $1,730,000. It is clear the absorption chiller did not display economic feasibility, whereas the value for the coupled PV and air-conditioning systems was under $0.05/kWh. In addition to the extensive maintenance needs, the reduced COP and the practicality and feasibility of the solar thermal cooling systems mean these kinds of technologies are under significant pressure to remain competitive when faced with the development of new air conditioning and PV technologies.
Article
India is the fifth economic power in the World, and 20% of its GDP is contributed by the agriculture and allied sector. The agricultural sector entails various activities involving land preparation, irrigation, crop growth, harvesting, food processing, etc. For meeting the current agricultural energy demand in India, renewable solar energy has come up as a prime energy source that can reduce the farmer’s dependency on the use of conventional energy sources. The regular usage of fossil fuels leads to its depletion and releases considerable CO2 into the atmosphere. It is estimated that 4600 GW of installed solar energy systems would circumvent about 4 gigatons of CO2 emissions yearly by 2050. As a result, solar energy has been recognized as one of the most promising renewable alternatives to create heat and electricity via solar technologies for agriculture as well as various industrial processes. This review focuses on the status, importance, availability, and applications of solar energy technologies in numerous agricultural operations that are currently taking place all over India. This review also highlights the socioeconomic importance, environmental impact, economic analysis, SWOT analysis, and future technological potential of solar energy uses along with some limitations to its extensive utilization in India.
Chapter
Full-text available
A solar operated Freon-Jet refrigerator with a cooling capacity of 216 W has been designed, constructed and tested to study its feasibility as an air conditioning machine. Design conditions were: irradiance: 800W/m2, ambient temperature: 25°C, evaporator temperature: 12°C. Both, indoor and outdoor tests were carried out. Total efficiency (cooling power/solar power) lies between 4% and 8%. The most critical operating aspect is the balancing between the motive loop and the refrigerating loop in order to keep the ejector performance.
Article
This paper presents an experimental study of energy output and efficiency of solar collectors in a refrigerant ejector refrigeration machine using R113 as the refrigerant. Based on a theoretical study, the oil transformer is used as a working fluid in the solar system. The concentrating collectors show encouraging results for operating the system. The maximum collector efficiency was 20%. The system can be used for both cooling and heating purposes. © 1997 John Wiley & Sons, Ltd.
Article
Desiccant cooling has the ability to provide efficient indoor humidity and temperature control, while at the same time reducing the electrical energy requirement as compared to conventional vapor compression systems. Unlike other surveys on desiccant cooling, this review focuses on a more detailed coverage of liquid desiccant systems. Physical properties are compared for commonly used liquid desiccants (salt solutions and trithylene glycol). Findings from studies considering desiccant/air contact equipment such as packed towers, finned coils, and solar collector regenerators have been summarized in tables for easy comparison. Key features of these tables include the desiccant material, the influence of design variables on the dehumidifier/regenerator performance, and whether experiments were performed. Finally, system configurations are presented schematically, with additional information listed in tabular form.
Article
A novel auto-cascade low-temperature solar Rankine cycle (ALSRC) system is proposed. Compared to the single stage lowtemperature solar Rankine cycle (SSLSRC) system, the ALSRC system is different because it consists of two solar collectors, two expanders, a regenerator, and an internal heat exchanger (IHE). The working fluid for the ALSRC is the zeotropic mixture Isopentane/ R245fa. The main advantages of the ALSRC system is that heat from the exhaust stream of the expanders are reclaimed twice, once using an IHE and another time using a regenerator. System parameters such as regeneration, mixture composition, the outlet temperature of the low temperature solar collector, and the inlet temperature of two expanders are investigated to determine their effects on thermal efficiency. Results showed that with a regenerator, the thermal efficiency of the ALSRC system using a mixture of 0.32 R245fa by mass was significantly higher than that of the SSLSRC system. It was determined that regeneration, the mixture composition, and the outlet temperature of the low temperature solar collector are all important factors that affect the system’s thermal efficiency.
Conference Paper
A detailed parametric analysis is carried out on both simple and GAX based combined power and cooling cycle. The effect of various parameters such as heat source temperature, refrigeration temperature, sink temperature, split ratio (refrigerant flow ration between power and cooling systems), spilt factor (solution flow ratio between absorber and GAX heat exchanger) on the performance of the cycle is studied. The results of the analysis shows that using the GAX heat exchanger about 20 % of internal heat is recovered within the cycle. The optimum spilt ratio is 0.8-0.9 and flow ratio is 0.5:0.5. The maximum combined thermal efficiency of 35-45 % and coefficient of performance of about 0.35 is attained at the optimum conditions.
Article
A combined organic Rankine cycle and vapor compression cycle (ORC–VCC) system activated by low temperature heat sources was studied. Two low GWP fluids were considered as working fluids for the VCC and two different low GWP fluids for the ORC. System performance was evaluated through computational modeling over different operating conditions. The computed thermal COP of the ORC–VCC system varied between 0.30 and 1.10 over the range of operating conditions studied. The computed electrical COP of the ORC–VCC system, defined as the ratio of the rate of cooling and the ORC pump power consumption, varied between 15 and 110. The choice of VCC working fluid had only a limited influence on system thermal or electrical efficiency, with HFO-1234ze(E) presenting slightly better results. Use of HFO-1336mzz(Z) as the ORC working fluid resulted in slightly higher system thermal efficiencies and significantly higher system electrical efficiencies throughout the range of operating conditions studied. Furthermore, the system is evaluated for a typical application and the feasibility study shows good economical results.
Article
This paper presents a useful knowledge of ejector working principles and the versatility and diversity of its applications in refrigeration technologies. Various ejector refrigeration systems are described with the associated studies, and categorized as conventional ejector refrigeration system, advanced ejector refrigeration systems, combined refrigeration systems and ejector enhanced vapor compression systems. This paper also presents the important elements that affect the optimum performance of the ejector system, and the results of studies that have generally confirmed their energy saving, great potential for large refrigerating temperature scales and performance enhancement.
Article
Liquid desiccant air-conditioning system is a novel air-conditioner with good energy saving potential. For the liquid desiccant air-conditioning system, the energy consumption mainly relies on the regeneration process of desiccant solution. As the regeneration process of the liquid desiccant air-conditioning system only needs low-grade energy, solar energy (a kind of renewable energy) can be used to regenerate the desiccant solution and the solar desiccant regeneration system has attracted many attentions. In this paper, recent theoretical and experimental works on solar thermal regeneration method and solar electrodialysis regeneration method of the liquid desiccant air-conditioning system are extensively reviewed. Moreover, the comparison of solar TH regeneration method and solar electrodialysis regeneration method is discussed. The results showed that compared to the solar thermal regeneration system, the solar electrodialysis regeneration system is more energy-efficient but expensive.
Article
In this paper, the calibration factor of the superconducting gravimeter 057 (SG057) at the Lhasa station is accurately determined for the first time with a frequency-domain approach and the data recorded by the LaCoste Romberg Earth Tides No. 20 (LCR-ET20) gravimeter which is installed nearby SG057. The advantage of the frequency-domain approach is that it eliminates the influence of different gravimeter drifts on the determination of the calibration factor. The determined calibration factor of SG057 is (-77.7358 0.0409) x 10(-8) m s(-2) V-1, and the relative accuracy is about 0.5%. The newly determined calibration factor has been calculated with the Wuhan international tidal gravity reference values (ITGRVs) based on the data recorded by LCR-ET20 at the Wuhan station before it was installed at the Lhasa station. A high-precision synthesized gravity tide is achieved at the Lhasa station with accurate tidal parameters and theoretical tidal parameters for the long tidal waves from the Dehant-Defraigne-Wahr (DDW) earth tide model. The synthesized gravity tide can be used for tidal gravity corrections of future gravity measurements in the Tibetan area. The linear gravimeter drift of SG057 is estimated by gravity records without the effects of land uplift, atmosphere and polar motion yielding a rate of 6.8 x 10(-8) m s(-2) yr(-1).
Article
There is a growing interest in ejector cooling systems driven by solar heat. One of the main problems with solar cooling using ejectors is that the ejector cannot operate well if the operating conditions stray from the design point temperatures. Ejectors with variable geometry have been proposed and modelling shows that they are able to increase the operating range of an ejector. In particular, ejectors with a variable primary nozzle throat diameter have been experimentally shown to enhance ejector performance. This paper extends the work of others to provide a means to design a primary nozzle with variable throat diameter and variable nozzle exit diameter. The algorithm is extended to account for the behaviour of the solar collector and vapour generator. In this way, the nozzle diameters are determined as a function of the operating conditions ambient temperature and solar radiation. This correlation provides the basis for a practical nozzle control system.
Article
Cooling by solar energy is one of the key solutions to the global energy and environmental degradation issues. Solar liquid desiccant based on evaporative cooling is proposed as an eco-friendly alternative to the conventional vapour compression systems due to its huge untapped energy savings potential. In this paper, the recent works on solar assisted liquid desiccant cooling and its various applications combined with evaporative airconditioning under different climates are reviewed and advantages the system may offer in terms of energy savings are underscored. A basic description of the principles of hybrid solar liquid desiccant with direct and indirect evaporative cooling is provided. Finally, solar regeneration methods and recent developments for the liquid desiccant air conditioning system are presented.
Article
This paper evaluates the potential of integrating renewable energy technological resources for tri-generation applications in an island. The integrated tri-generation system has to be self-sustaining in delivering cooling, heating and power. Several CCHP (combined cooling heating and power) systems at different penetration levels were proposed. The CCHP systems comprising key prime movers include microturbines, photovoltaic, solar Stirling dish, fuel cell system, biomass power generator and an absorption cooling technology. The systems are judiciously designed to provide the island’s tri-generation needs. Three different operational schemes of varying renewable energy penetration were considered - peak shaving, 20% and 40% renewable energy penetration. Key results have suggested that reductions of approximately 20% in primary energy savings are realizable for all three cases. Additionally, a renewable energy penetration level of 40% yielded the largest reduction in terms of carbon dioxide emission. In terms of cost benefits for the proposed system combinations, peak shaving and 20% renewable energy penetration can realize savings of up to USD $150,000 per annum.
Article
To develop the organic Rankine cycle/vapor compression cycle (ORC/VCC) ice maker driven by solar energy, a thermodynamic model was developed, and four working fluids of R123, R245fa, R600a and R600 were selected and evaluated to identify suitable working fluids which may yield high system efficiencies. Besides, the effects of generation temperature and condensation temperature on the system performance were also analyzed. In terms of power efficiency and expander size, R600 and R600a are more suitable working fluids for ORC. Also, R600a and R600 are more appropriate working fluids for VCC in terms of pressure ratio and coefficient of performance. In terms of overall efficiency and ice production per square meter collector per day, R123 is most suitable working fluid for ORC/VCC. The generation temperature and condensation temperature have important effects on overall efficiency and ice production. There is always an optimal generation temperature at which overall efficiency and ice production can achieve the maximum values, while the generation temperature can be controlled by changing the mass flow rate of working fluid for ORC. In addition, the system performance and payback period should be comprehensively considered so as to decide to adopt air cooled or water cooled condenser due to having different condensation temperature. Crown Copyright
Article
As natural fluids, several hydrocarbons with excellent thermophysical properties are recognized as alternative refrigerants to chlorofluorocarbons, hydrochlorofluorocarbons and hydrofluorocarbons. In this paper, the hydrocarbons including propane, butane, isobutane and propylene as working fluids used in an organic Rankine cycle powered vapor compression refrigeration (ORC-VCR) system are analyzed and evaluated. With the overall COP and working fluid mass flow rate of per kW cooling capacity as key performance indicators, the results indicate that butane is the best refrigerant for the ORC-VCR system as the boiler exit temperature is between 60 and 90 degrees C. the condensation temperature varies from 30 to 55 degrees C and the evaporation temperature ranges from -15 to 15 degrees C. When the boiler exit temperature reaches 90 degrees C and the other input parameters are in typical values, the overall COP of the butane case reaches 0.470.
Article
This study aims to simulate the 3 dimensional (3D) model of Keum-man connection canal using geographic information system (GIS) as well as considering design in viewpoint of engineering. The canal connects from Keumkang to Mangyungkang in order to supply fresh water into Saemankeum lake. This study used 3 dimensional spatial planning model (3DSPLAM) process to generate the 3D model, which has not only several planning layers in actual process, but also their corresponding layers in modeling process to simulate 3D space of rural villages. The discharge of the canal is 20m^3/s on slope of 1/28,400 in the canal length of 14.2km, which consists of pipe line and open channel. This study surveyed the route of the canal and its surrounding environment for facilities to make images in the 3D graphic model. Besides, the present study developed data set in GIS for geogrphical surface modeling as well as parameters in hydraulic analysis for water surface profile on the canal using HEC-RAS model. From the data set constructed, this study performed analysis of water surface profile with HEC-RAS, generation of digital elevation model (DEM) and 3D objects, design of the canal section and route on DEM in AutoCAD, and 3D canal model and its surrounding 3D space in 3DMAX with virtual reality. The study result showed that the process making 3D canal model tried in this study is very useful to generate computer graphic model with the designed canal on the surface of DEM. The generated 3D canal can be used to assist decision support for the canal policy.
Article
In this paper, a brief overview of different available and actually installed solar thermal driven technologies used for cooling or air-conditioning purposes have been presented. A review analysis has been performed taking into account research on experimental and simulated solar cooling systems in terms of COP, area of collector (Ac) per unit chiller capacity (Pch) and volume of storage tank (V) per unit area of collector. The COP of absorption chillers lies between 0.6 and 0.8 for simulated and 0.40-0.85 for experimental systems for generator inlet temperature between 70 and 100 °C with dominance in the market. Adsorption chillers have lower COP in the range of 0.2-0.6 both for simulated and experimental systems. However, adsorption chillers can work at lower generator inlet temperatures in the range of 45-65 °C. The ratio of Ac to Pch presents a wide spread ranging from 1.5 to 11.5 m2 kWch−1. It shows that some installation may have additional area of collector installed resulting in higher thermal energy losses and initial cost of the system while others may have lower Ac installed resulting in lower solar fraction and lesser primary energy savings. Similarly, the ratio of V to Ac also shows a large variation in both simulated and experimental systems ranging from 5 to 130 l m−2. However, most of these systems lie in the range of 20-80 l m−2. The range of storage volume is suggested between 50 and 110 l m−2 but at a first glance it seems that keeping fixed storage volume linked to area of collector may not be an economical solution for large collector areas. Although these installations are designed for solar cooling/air-conditioning purposes only but utilization of these installations further for space heating and sanitary hot water production so called multi-purpose solar thermal systems (MPSTS) will provide better results of primary energy savings.
Article
The optimum instantaneous driving temperature of a solar cooling facility is determined along a day. The chillers compared use single effect cycles working with NH3/LiNO3, either conventional or hybridised by incorporating a low pressure booster compressor. Their performances are compared with a H2O/LiBr single effect absorption chiller as part of the same solar system. The results of a detailed thermodynamic cycle for the absorption chillers allow synthesizing them in a modified characteristic temperature difference model. The day accumulated solar cold production is determined using this optimum temperature during two sunny days in mid-July and mid-September, located in Madrid, Spain. The work shows the influences of operational variables and a striking result: selection of a time-constant temperature during all the day does not necessarily imply a substantial loss, being the temperature chosen a key parameter. The results indicate that the NH3/LiNO3 option with no boosting offers a smaller production above-zero Celsius degrees temperatures, but does not require higher hot water driving temperatures than H2O/LiBr. The boosted cycle offers superior performance. Some operational details are discussed.
Article
This paper aims at providing a literature review on the recent development in ejectors, applications of ejector refrigeration systems and system performance enhancement. The paper presents useful guidelines regarding background and operating principles of ejector. A number of studies are reported and categorized in several topics including, refrigerant selections, mathematical modelling and numerical simulation Of ejector system, geometric optimizations, operating conditions optimizations and combinations with other refrigeration systems. Most of the works that have been carried out recently are still limited to computer modelling, more experimental and large-scale work are needed in order to provide better understanding for the real industrial application.
Article
Solar energy is an alternative energy source for cooling systems where electricity is demand or expensive. Many solar assisted cooling systems have been installed in different countries for domestic purpose. Many researches are going on to achieve economical and efficient thermal systems when compared with conventional systems. This paper reviews the past efforts of solar assisted-single effect vapour absorption cooling system using LiBr–H2O mixture for residential buildings. Solar assisted single-effect absorption cooling systems were capable of working in the driving temperature range of 70–100 °C. In this system LiBr–H2O are the major working pairs and has a higher COP than any other working fluids. Besides the review of the past theoretical and experimental investigations of solar single effect absorption cooling systems, some new ideas were introduced to minimize the capital and operational cost, to reduce heat loss from generator and thus to increase COP to get effective cooling.
Article
The paper tries to review the argument of the use of working fluids for binary cycle power plants and has been dedicated to this specific argument with a more general perspective. Binary cycle that allows the production of electricity from geothermal energy sources is one of these systems. In this cycle, thermal energy obtained from geothermal sources is transferred to second working fluid. Therefore, selection of second working fluid plays a key role on the cycle performance. In this study, a sample geothermal binary power cycle was modeled and 12 refrigerants that are HFC, HC, and zoetrope refrigerant mixtures were selected as working fluid. Energy and exergy efficiencies of binary cycle were calculated for 12 refrigerants. Dry type fluids of investigated refrigerants R 236ea, R 600, R 600a, and R 227ea showed higher energy and exergy efficiencies, respectively. On the other hand, R 143a, R 415A, R 290, and R 413A that are wet fluids indicated lower energy and exergy efficiencies, respectively.
Article
Generation temperatures from 110 degrees C to 140 degrees C are not enough to drive a double effect LiBr-water absorption cycle but too high for a single effect cycle under typical operating conditions. A novel LiBr-water absorption cycle which contains an AGX (absorber generator heat exchanger) is introduced for this. The AGX absorption cycle is able to make use of the high pressure condensation heats of different temperature, and get different amounts of extra refrigeration thus obtains 1.n effect refrigeration. The novel cycle can work under generation temperatures from 85 degrees C to 150 degrees C with evaporation temperature of 5 degrees C, absorption temperature of 35 degrees C and condensation temperature of 40 degrees C. The results of simulation show that the novel cycle can work in single effect mode, 1.n effect mode and double effect mode when the generation temperatures are in the ranges of 85 degrees C-93 degrees C, 93oC-140 degrees C and 140 degrees C-150 degrees C, and reach a COP (coefficient of performance) of 0.75, 0.75-1.08 and 1.08-1.25 respectively. Comparison between this novel cycle and existing cycle working under similar generation temperature range shows that the novel cycle has a better performance. The large working range also makes the cycle suitable for solar cooling utilizing medium temperature solar collector.
Article
This paper presents a review of the available technologies to provide cooling from solar energy for both thermal and photovoltaic ways. Several multi-criteria performance indicators figuring in the literature are presented followed by a pros and cons analysis of the different solar thermal cooling processes. A market study is also carried out to evidence the potential of these solar cooling technologies. Finally, an overview of various solar cooling installations in Europe, Egypt and China is presented.
Chapter
There has been an increased demand for use of cooling/refrigeration systems that make use of renewable energy sources and in particular solar thermal energy as a driving force due to its abundance and simplicity to harness. Solar powered cooling systems have been and continue to be utilized worldwide, for air conditioning in a range of applications and using different configurations, i.e., liquid and solid desiccant, absorption and adsorption, ejector and photovoltaic-compression cooling technologies. The specific benefits of solar-powered cooling have been highlighted through the review and comparison of the technologies in terms of solar coefficient of performance, capital cost, and life cycle cost.
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A variable effect absorption refrigeration cycle is proposed which can obtain a rising COP (Coefficient of Performance) versus the rising generation temperature. This novel cycle could be applied for solar absorption cooling efficiently. In this paper, a 50 kw variable effect (also named as 1.n effect) absorption chiller using LiBr-water as working fluid was designed. Its rated condition is generation temperature of 125 °C, condensation temperature of 40 °C, absorption temperature of 35 °C and evaporation temperature of 5 °C. The variable effect absorption chiller was then manufactured and tested. Data from the experiment showed that the chiller can get a rising COP from 0.69 to 1.08 under generation temperature from 95 °C to 120 °C as it was expected. The average error between theoretical COP and experimental COP was 7.3%. Feasibility of the variable effect absorption chiller and the effectiveness of the design have been verified.
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This paper presents a review on combined cooling, heating, and power (CCHP) systems. This work summarizes the methods used to perform energetic and exergetic analyses, system optimization, performance improvement studies, and development and analysis of CCHP systems, as reported in existing literature. In addition, this work highlights the most current research and emerging trends in CCHP technologies. It is envisioned that the information collected in this review paper will be a valuable source of information, for researchers, designers, and engineers, and provides direction and guidance for future research in CCHP technology.