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Abstract

This paper introduces a novel concept of mini-hybrid solar power plant integrating a field of solar concentrators, two superposed Organic Rankine Cycles (ORC) and a (bio-)Diesel engine. The Organic Rankine Cycles include hermetic scroll expander-generators1 and the sun tracking solar collectors are composed of rows of flat mirror bands (CEP) arranged in a plane, that focus the solar energy onto a collector tube similar to those used in SEGS plants in California. Waste heat from both the exhaust gases and the block cooling of the thermal engine are also heat sources for the ORCs. Such units meet electricity, cooling and pumping needs of remote settlements. The thermal engine guarantees a minimum level of both power and heat availability at night or during cloudy periods. Laboratory tests, made with the superposed ORCs only, confirmed adequate operational characteristics with good performances over a broad range of conditions. A few preliminary tests on the site of the solar power plant when coupled with the engine confirmed a reasonable behavior and the interest of the concept even at part load or during sharp variations of the thermal supply.

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... Hence, less empirical coecients were necessary compared to previous work. A power output of 5.08kW and a thermal cycle eciency of 10.42% has been predicted for a larger built-in volume ratio of 6.Kane et al. (2003) [98] applied combined topping and bottoming ORCs to a hybrid solar thermal power plant using R134a and R123 as the working uids respectively. The system was equipped with two hermetic lubricated scroll expanders with the built-in volume ratios of 2.3. ...
... Hence, less empirical coecients were necessary compared to previous work. A power output of 5.08kW and a thermal cycle eciency of 10.42% has been predicted for a larger built-in volume ratio of 6.Kane et al. (2003) [98] applied combined topping and bottoming ORCs to a hybrid solar thermal power plant using R134a and R123 as the working uids respectively. The system was equipped with two hermetic lubricated scroll expanders with the built-in volume ratios of 2.3. ...
... Variation of isentropic eciency with pressure ratio[98] Experimental work on a hermetic lubricated scroll expander fed with refrigerant R134a was conducted by Zanelli and Favrat (1994)[12]. The original compressor was characterised by a built-in volume ratio of 2.44. ...
... A thermal output of 224.25 kW th is still available for water heating. HSPS is a small scale CSP plant based on linear Fresnel technology of 10-25 kWe [41] without storage. Its solar field, composed of two lines of collectors, is thermally coupled with a Diesel engine of 15 kW e to guarantee a level of heat and electric power at night or cloudy periods. ...
... The concentrators may be assimilated to Fresnel mirrors. They are made of plate mirrors bands with different widths for an active collecting area of 100 m 2 [41] and fixed to their structure in a way to allow a practical change in case of breakage. The receiver is a vacuum isolated focal tube in which flows pressurized water as HTF. ...
... R123 and R134a were used as working fluids respectively for the topping and the bottoming cycle. Nominal power of the topping cycle expander-generator is 5 kW e whereas the bottoming cycle is oversized to 8 kW e [41] due to the additional heat from the 15 kW e Diesel engine cooling system. ...
Article
Concentrating solar power (CSP) seems to be a promising solution for rural electrification in Sub-Saharan Africa. Small scale CSP plant appears to be most appropriate because it is suitable to the needs of rural communities: most of components can be found to be of low cost in the African market and there are available qualified local human resource to build the systems. A state of art of small scale CSP plants in the range of 1–500 kWe are reviewed in this paper to showcase previous and current works undertaken throughout the world. 35 small scale CSP plants are identified and reviewed in the paper. Technical analysis is conducted on the identified plants to understand their operating principles. The technical analysis highlighted reasons behind the choices made for every component from the solar field to the power block.
... Thus, fluids can be selected to effectively remove sub-atmospheric condensation pressures in both cycles, which could lead to more compact heat exchangers. A few early studies have demonstrated the potential of cascaded ORC systems for low-temperature systems below 200 • C [5,6]. More recently, the authors have presented preliminary investigations into the optimisation of cascaded ORC systems for higher temperature heat sources, and found that both cascaded and single-stage systems can produce similar power outputs [7]. ...
... which corresponds to R 2 = 0.9328. Thus, neglecting any scaling effects and assuming a maximum efficiency of η max = 0.89, the efficiency of the turbine operating for a particular volumetric expansion ratio can be estimated using Equation 5. ...
Article
Full-text available
Compared to single-stage organic Rankine cycle (ORC) systems, cascaded ORC systems, in which a high-temperature topping cycle and low-temperature bottoming cycle are coupled together, could have advantages in terms of removing the potential for sub-atmospheric condensation conditions and improving expander performance as the expansion process is effectively divided across two stages. Moreover, reducing the expansion volume ratio could facilitate the use of volumetric expanders, such as twin-screw expanders, which, in turn, could facilitate two-phase expansion to be utilised in one, or both, of the cycles. The aim of this paper is to compare single-stage and cascaded ORC systems, accounting for the effect of the expander volume ratio on expander performance. To investigate this, thermodynamic models for single-stage and cascaded ORC systems are developed, which include variable efficiency expander models for both radial turbines and twin-screw expanders that can estimate the effect of the expansion volume ratio on the expander isentropic efficiency. Using this model, three different scenarios are compared for different temperature heat-source temperatures, namely: (i) single-stage ORC systems with vapour-phase expansion obtained using a turboexpander; (ii) single-stage ORC systems operating with a twin-screw expander, with the possibility for two-phase expansion; and (iii) cascaded cycles with either vapour- or two-phase expansion. The results from this comparison are used to identify applications where cascaded ORC systems could offer performance benefits.
... Kane et al. [11] also proposed the expansion in several stages, but using two ORC in cascade. A cascade ORC consists in two ORC cycles with two different working temperatures, so that the heat dissipated in the condenser of the first cycle is used to evaporate the fluid of the lower temperature cycle. ...
... And up to date there is not any experimental test for ORC with two expanders in series, but only theoretical projects [14,15]. Cascade cycles have only one experimental set up by Kane et al. [11]. ...
Article
The objective of this work was to simulate the behavior of an Organic Rankine Cycle (ORC) system with two expanders in series at off-design working conditions. The influence of both the intermediate pressure and the volumetric expansion ratio of the expanders on the off-design performance of the ORC was studied and the irreversibilities of the components were analyzed. The performance of the ORC with two expanders for two different designs was also discussed. The thermal efficiency reached using two expanders was higher than the obtained using only one. However, this increase conveyed an increase in the complexity of the design and control of the expanders. As an additional conclusion, it was found that the influence of the intermediate pressure is higher than that of the volume expansion ratio of each expander. The irreversibility of the first expander was mainly due to leaks. However, the performance of the second expander was particularly affected by the difference between the discharged pressure and the condensation pressure. The off-design analysis allowed the definition of a methodology to achieve the desired power with the maximum thermal efficiency, and the identification of the best actuation for the part load operation.
... Lu and Goswami [4] presented an energy analysis for a power and refrigeration cogeneration system that included a solar collector heat supply at 90 C. The result of the thermodynamic analysis showed that the first law efficiency varied from 10.5% to 15.7% for an ambient temperature variation of 7 C-27 C. Wali [5] studied the safety requirement of the refrigerant and disclosed that halocarbon and fluorinated compounds meet these requirements. Kane et al. [6] presented an energy analysis of an organic-Rankine cycle, which included a hermetic-scroll expansion device with a generator and solar energy unit. ...
... The steam Transactions of the ASME then passes through the ERC and a water-cooled condenser providing refrigeration in the ejector cycle. The temperature of the molten salt decreased to approximately 315 C, and then, it flows to the generator (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) to provide the required heat energy to separate LiBr and water [11][12][13][14][15][16]. ...
Article
The main objective of the current work is to investigate the thermodynamic performance of a novel solar powered multi-effect refrigeration system. The proposed cycle consists of a solar tower system with a heliostat field and central receiver (CR) that has molten salt as the heat transfer fluid, an absorption refrigeration cycle (ARC), an ejector refrigeration cycle (ERC), and a cascade refrigeration cycle (CRC). Energy and exergy analyses were carried out to measure the thermodynamic performance of the proposed cycle, using Dhahran weather data and operating conditions. The largest contribution to cycle irreversibility was found to be from the CR system (52.5%), followed by the heliostat field (25%). The first and second-law efficiencies improved due to the increase in the following parameters: ejector evaporator temperature, turbine inlet and exit pressures, and cascade evaporator temperature. Parametric analysis showed that the compressor delivery pressure, turbine inlet and exit pressures, hot molten salt outlet temperature, and ejector evaporator temperature significantly affect the refrigeration output.
... Une dernière solution serait de séparer l'huile à l'admission de la turbine à haute pression ( Figure 111) pour permettre une injection efficace dans toutes les zones de la turbine comme testé par (Kane et al., 2003) et récemment proposé par (Lei et al., 2014). Dans ce cas, il faut prévoir une nouvelle conception pour le séparateur d'huile intégré dans le compresseur Sanden. ...
Thesis
La récupération de chaleur dans les véhicules est une solution prometteuse permettant de réduire la consommation du moteur et de ses émissions. Les fortes contraintes de poids, compacité et coût présentes dans le domaine automobile empêchent l’intégration d’un système de récupération de chaleur dans le véhicule. Une solution proposée dans ce travail consiste en un système de multi-génération appelé ReverCycle. Ce dernier fonctionne avec trois modes: climatisation à compression de vapeur, cycle de Rankine Organique (ORC) et cycle de réfrigération à éjecteur. Le système peut assurer un seul mode de fonctionnement à la fois. Les avantages du système sont sa compacité et son coût réduit étant donné la possibilité d’exploiter les composants du système de climatisation déjà présents dans le véhicule. En effet, le compresseur scroll de la climatisation peut être converti en machine réversible compresseur/turbine et le condenseur peut être mutualisé pour les trois modes de fonctionnement. Une double démarche de modélisation et d’expérimentation a été menée pour évaluer le potentiel de réduction de la consommation de ReverCycle et pour vérifier sa faisabilité technique. Un modèle global du véhicule a été développé pour reproduire les conditions de fonctionnement dynamique du véhicule et pour décrire l’interaction entre ses différents sous-systèmes. Le modèle a ensuite permis de calculer le gain en consommation moyenné sur une année pour différentes régions climatiques. Deux différentes architectures de véhicules ont été étudiées : un véhicule conventionnel et un véhicule hybride série. Pour un véhicule conventionnel, le gain en consommation maximal est obtenu dans un climat océanique (e.g. Paris) avec une valeur de 2,1% avec un démarrage à chaud du moteur et 1,3% avec un démarrage à froid. Le cycle de conduite de référence pour l’évaluation du gain est le cycle WLTC (Worldwide harmonized Light vehicles Test Cycles). Dans le cas du véhicule hybride série, le gain en consommation maximal est obtenu dans un climat continental (e.g. Moscou) avec une valeur de 2,2% avec un démarrage à chaud du moteur et 1,2% avec un démarrage à froid. La réalisation d’une preuve de concept de ReverCycle a permis de valider sa faisabilité technique. Les essais se sont focalisés surtout sur le mode de fonctionnement en ORC. Les résultats des essais ont montré un rendement maximal de récupération pour le cycle de 3,9% sur un point de fonctionnement stabilisé. Le rendement maximal moyenné sur un cycle dynamique, représentatif des conditions opératoires sur un véhicule conventionnel, a été de 3,3%.
... The rapid growth of the world's population, industrialization, and development in developing countries have all contributed to a significant increase in global energy consumption [1,2]. The solar power market has grown rapidly in the past decade [3,4] and is the fastest growing renewable energy technology both in the US and globally [5][6][7][8]. ...
Conference Paper
Full-text available
The availability of the projected solar power market in Indonesia is affected by the lower cost and business of solar power systems. In this study, projection of solar power panel system market for 2021-2030 periods calculated by the aid of analyzing the data provided by Indonesian State Electricity Enterprise (PLN), International Renewable Energy Agency (IRENA), and US Renewable Energy Laboratory (NREL). There are three market types such as optimistic, medium, and low were identified. The Solar power system market might reach 37 GWp by 2030 for the optimistic market (3% of the total energy required by 2030) and 13 GWp for a low market. Based on IRENA data, an optimum scenario for the solar power system market is likely to reach 34 GWp in 2030, while National Energy Master Plan (RUEN) data projects will be 13 GWp for low market scenarios. The scenarios are in line with the 2024 PLN transformation plan.
... • Condenser, and Evaporator Condenser, and evaporator are tube heat exchangers. They were chosen based on Kane et al. [18] recommendation as a result of in the laminar heat exchanger the heat transfer is reduced by the effect of evaporation pressure. While other studies have worked using laminar exchangers as in [19] and other used finned tube heat exchangers as in [20] • Pump The Choosing of a pump was difficult due to the low flows and finding an centrifugal pump of this specification was very hard. ...
Article
Full-text available
Heat losses in industrial processes can be divided into three sections (high-, medium-, and low-temperature heat), depending on the temperature of the exhaust gases. This heat is usually recovered either by heat exchangers or by a closed Rankine cycle. However, about 60% of low-temperature heat losses remain irreplaceable. Currently, the organic Rankine cycle has become a promising method of low-temperature energy recovery, and several theoretical studies on this topic have appeared, but a small number of experimental studies have been performed. In our work, we have built a 2 kW heat recovery laboratory test bench using tube-type heat exchangers, a gear pump and a turbo expander on the working fluid R141b. As a result, we found that the efficiency of the cycle increases as the boiling point and pressure increase, but an increase in overheating at the inlet of the expander leads to a decrease in efficiency due to the use of the working fluid R141b. At the inlet of the evaporator and the outlet of the condenser, respectively, overheating and supercooling of the working fluid occurs, which negatively affects the efficiency of the cycle. The amount of useful heat obtained was 45.4 W with an efficiency of 2.24%. as a result of low efficiency of the expander and pump, as well as leaks during the test. The development of an experimental test bench with working on organic Rankin cycle requires long-term research work and great scientific potential. In the future, it will be necessary to create a new test bench based on a deeper study, so that we can get a higher efficiency of the expander and pump, which would affect the efficiency of this cycle. Also, we need to replace the working fluid in the cycle with a more efficient one.
... Different ORC working fluids were considered and the system showed maximum performance with toluene (up to 19.7%). Moreover, Kane et al. [212] experimentally investigated a hybrid power system (using LFR and diesel engine waste heat) in cascade configuration with two ORCs. The system could produce heating and cooling when needed. ...
Article
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The organic Rankine cycle (ORC) is an effective technology for power generation from temperatures of up to 400 • C and for capacities of up to 10 MW el. The use of solar irradiation for driving an ORC is a promising renewable energy-based technology due to the high compatibility between the operating temperatures of solar thermal collector technologies and the temperature needs of the cycle. The objective of this review paper is to present and discuss the operation principles of solar-ORC technology and the wide range of solar-ORC systems that have been studied in the literature. Various solar thermal technologies that can drive the ORC are investigated , such as the flat plate collector, evacuated tube collector, compound parabolic collector, parabolic trough collector, linear Fresnel reflectors, dish concentrators and solar towers. Both simulation studies and experimental investigations are included in the study. Hybrid systems and different thermal storage techniques are also examined in detail. Moreover, systems with ORC which produce many useful outputs such as cooling, heating and fresh water are studied because they present high sustainability indexes. The limitations of the technology are also highlighted, along with critical suggestions aimed at steering future research in this field. The final conclusions indicate that the development of trigeneration and polygeneration systems with ORC subsystems is a promising avenue, not only for the future development of solar-ORC technology but also for the development of renewable and sustainable energy systems in a broader context.
... • Condenser, and Evaporator Condenser, and evaporator are tube heat exchangers. They were chosen based on Kane et al. [18] recommendation as a result of in the laminar heat exchanger the heat transfer is reduced by the effect of evaporation pressure. While other studies have worked using laminar exchangers as in [19] and other used finned tube heat exchangers as in [20] • Pump The Choosing of a pump was difficult due to the low flows and finding an centrifugal pump of this specification was very hard. ...
Conference Paper
Full-text available
— Nowadays, Organic Rankine Cycle (ORC) poses a good solution for waste heat recovery. In this research, we have chosen the appropriate working fluid for ORC to be tested and worked out among a range of wet and isentropic working fluids available to us in the domestic market. A test bench for the ORC has been developed to recover heat at a temperature 85°C using R141b, which resulted in a thermal efficiency of about 2.24 due to the low efficiency of the equipment. In spite of the low thermal efficiency of ORC, it is effective in heat recovery processes
... To overcome this problem, the organic Rankine cycle (ORC) system which at low source temperatures to increase system efficiency is considered to be an important alternative for waste heat recovery. According to the literature, the ORC system and equipment have been investigated by many researchers (Zanelli and Favrat 1994;Kane et al. 2003;Tarique 2011;Hoque 2011;Ko et al. 2013;Jradi et al. 2014;Muhammad et al. 2015;Chul et al. 2015;Turunen-Saaresti et al. 2017). ...
Article
In power plants, a special type of oil is used for the lubrication and cooling of turbine bearings. The temperature of the cooling oil used for heat extraction from the bearings varies between 78 and 90 °C. Using waste heat from this oil will be a great advantage in terms of heat recovery. The overall thermal efficiency of gas turbine in power plants will also increase using this heat. In the literature, there are studies on organic Rankine cycle systems, but it has been seen that there are no studies on the use of waste heat from gas turbine bearings. In this paper, low-temperature organic Rankine cycle using waste heat from gas turbine bearings for different working conditions was investigated as experimentally. For this purpose, a prototype experiment setup was designed and thermodynamic analyses were carried out experimentally. Experimental organic Rankine cycle system was designed to operate in the temperature range of 78–90 °C using the waste heat in the lubricating oil. R134a was used as the working fluid in the prototype organic Rankine cycle system. The thermal efficiency, turbine expansion ratio and turbine power of the prototype organic Rankine cycle system were determined depending on different waste heat source temperatures and working fluid volumetric flow rates. According to experimental results for prototype organic Rankine cycle system, the highest thermal efficiency, turbine expansion ratio and turbine power are 6.84%, 1.94 and 1.22 kW, respectively, at a waste heat source temperature of 86.5 °C and volumetric flow rate of working fluid is 4.7 L/min.
... Energies 2021, 1, 0 4 Solar Assisted HVAC Systems Solar Photovoltaic PV Panels [14,15] PV Thermal [23][24][25] Concentrated Solar Power Parabolic Troughs [26][27][28][29][30][31][32][33] Dish Stirling [34,35] Linear Fresnel [36][37][38] Solar Tower [39] Solar Thermal Evacuated ...
Article
Full-text available
Heating, ventilation, and air-conditioning (HVAC) systems are omnipresent in modern buildings and are responsible for a considerable share of consumed energy and the electricity bill in buildings. On the other hand, solar energy is abundant and could be used to support the building HVAC system through cogeneration of electricity and heat. Micro-scale concentrated solar power (MicroCSP) is a propitious solution for such applications that can be integrated into the building HVAC system to optimally provide both electricity and heat, on-demand via application of optimal control techniques. The use of thermal energy storage (TES) in MicroCSP adds dispatching capabilities to the MicroCSP energy production that will assist in optimal energy management in buildings. This work presents a review of the existing contributions on the combination of MicroCSP and HVAC systems in buildings and how it compares to other thermal-assisted HVAC applications. Different topologies and architectures for the integration of MicroCSP and building HVAC systems are proposed, and the components of standard MicroCSP systems with their control-oriented models are explained. Furthermore, this paper details the different control strategies to optimally manage the energy flow, both electrical and thermal, from the solar field to the building HVAC system to minimize energy consumption and/or operational cost.
... In recent years, renewable energy sources have played increasingly important roles in meeting growing energy demand while curbing carbon emissions. Among various technologies, the organic Rankine cycle (ORC) is a relatively mature technology and has been effective in converting thermal energy sources such as geothermal [2], solar thermal [3,4], and waste heat to power [5][6][7]. Dependent upon the source temperature, a wide range of working fluids have been studied by various research groups [8][9][10][11]. ...
Article
A unique hybrid cooling, heating, and power (HCHP) concept has been recently developed as an alternative to environmental control units. It combines a small-scale organic Rankine cycle (ORC) with a vapor compression cycle. The unique drive-train design flexibly and efficiently converts engine waste heat into useful energy in the form of cooling, heating, and power depending upon the energy needs. Compared to a standard military environmental control unit which puts an electric load on a diesel generator, the HCHP system uses engine exhaust heat as the primary energy input. Utilizing the exhaust heat can potentially provide 27% reduction on fuel consumption when operating in the cooling mode. When cooling is not needed, it is able to provide power and/or heating output using engine waste heat—a significant advantage over other heat activated cooling technologies. The prototype unit based on the HCHP design has been developed to demonstrate the concept. It leveraged the microchannel heat exchanger and scroll expander technologies to achieve high-performance, small-size, and low-cost design in order to meet the growing distributed energy applications.
... Kane et al. [8] developed a mini-scale hybrid power plant, based on a cascaded system, that used two scroll expanders with R123 and R134a as working fluids. Their experimental results demonstrate adequate behaviour over a range of operating conditions, which confirmed system stability. ...
Article
Full-text available
The design of single-stage organic Rankine cycle (ORC) systems can be challenging owing to large volumetric expansion ratios and sub-atmospheric condensation pressures. Cascaded systems could lead to more efficient expansion processes, higher condensation pressures, whilst introducing the possibility of two-phase expansion to enhance performance. The aim of this paper is to compare single-stage ORC systems to a novel two-phase cascaded system that combines a two-phase expansion topping cycle and a single-phase bottoming cycle for waste-heat recovery applications. Thermodynamic cycle models are integrated with variable efficiency expander models and discretised heat-exchanger sizing models, and single-and multi-objective optimisation studies are completed for three heat-source temperatures (473, 523 and 573 K). The results indicate the relative performance improvement of cascaded systems increases as the heat-source temperature and relative heat-sink size increase, and could increase power output and first-law thermal efficiency by up to 11.1% and 9.5% respectively. The multi-objective opti-misation reveals that for a fixed total heat-transfer area the cascaded systems produce approximately 3.6% and 10.5% more power than the single-stage systems for the 523 and 573 K cases respectively with a heat-sink mass-flow rate of 1 kg/s. This increases to 11.7% and 14.5% for heat-sink mass-flow rate of 4 kg/s.
... here Depending on the operational point, the cuircit device, in practice, operates as a mixed performance of the current source or the voltage source (49,53). Practically, for the cercuit panel, the effect of RP parallel resistance will be greater in the operating area having a current source, while the RS series resistance has a bigger effect on the functioning of the photovoltaic modules when the device works in the area having a voltage source [8,20,59]. ...
Preprint
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Background Green Technology, a sustainable mechanism is being proposed to fulfill the complete need of energy for a building that can be created by the building itself by the transformation process of domestic biowaste into electricity energy in site. Results The results suggested that the transformation of domestic biowaste including human feces to execute into converting process into an anaerobic tank bioreactor (BR) in the cellar which can form biogas (CH4) by methanogenesis that can be converted into electricity energy to power the entire building. Besides, the discharged waste water in another detention tank can be conducted a complete treatment process of primary, secondary, tertiary and UV application to utilize it for gardening. Conclusions Implementation of this technology indeed shall be an inventive field of science where a building can form electricity by itself to complete its total energy need without any connection with the utility authorities which is benevolent to environment.
... Organic Rankine cycles (ORC) employ an organic fluid (refrigerants or hydrocarbons) occurring at a lower temperature as compared to the vapour steam used in the steam power cycle. Saitoh et al. [39], Kane et al. [40] and Yagoub et al. [41] proposed and deliberate different micro-ORCs designed for electricity generation. Prigmore et al. [42] investigated cooling systems coupled with Rankine engines. ...
Chapter
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This chapter contains sections titled: Introduction Literature Review Solar Operated Ejector Cooling and Power Cycle Ejector Cooling and Power Cycle with Various Ecofriendly Refrigerants Ejector Organic Rankine Cycle Integrated with a Triple Pressure Level Vapour Absorption System Combined Organic Rankine Cycle with Double Ejector Result and Discussions Conclusion Nomenclatures Greek symbols Subscript
... Thermal efficiency in the order of 4% and maximum isentropic efficiencies about 65% were measured. The integration of a Diesel engine with Organic Rankine Cycles has been experimentally studied by Kane et al. [21]. Measured thermal efficiency in hybrid mode was of the order of 41%. ...
Article
The current paper investigates the performance behavior of an ORC unit in which the expansion process is realized by two in series scroll expanders. The heating load varies from 50 to 120 kWth and the heat supply temperature to the employed organic fluid (R245fa) from 80 to 130 °C. The two expanders in series configuration is chosen so that to achieve operation as close as possible to the nominal pressure ratio of each scroll machine at high evaporation temperatures where a total pressure ratio in the order of 10 is met. An extensive discussion and analysis is provided on how the key variables, such as pressure ratio, intermediate pressure and filling factor, interact between the two expanders and how this interaction affects each expander separately. This analysis leads to better understanding the overall performance in terms of isentropic and thermal efficiency and power generation. Emphasis is paid in off-design performance comprehension, while useful conclusions on how such split expansion process can be efficiently controlled by speed regulation are extracted. Focus is given on the interpretation of results for the partial heat load of 50 kWth at 130 °C, which show a very large scattering of both isentropic efficiencies of expanders and thermal efficiency. Accordingly, a variation of thermal efficiency is detected from slightly above 3% to about 10%. The results show that there are certain operating conditions where system performance is ameliorated and the maximum thermal efficiency of almost 10% is achieved, while the isentropic efficiency of high pressure expander reaches a maximum of 68% and that of low pressure expander 57%.
... A few early studies demonstrated the potential of cascaded systems for low-temperature systems below 200 ○ C (Kane, 2003;Kosmadakis et al., 2009). More recently, the authors have conducted comparisons ...
Conference Paper
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Compared to single-stage ORC systems, cascaded ORC systems could have benefits for relatively high-temperature waste-heat recovery applications, which include the potential for higher expander isentropic efficiencies owing to lower expansion ratios, the removal of sub-atmospheric condensation pressures and the possibility to utilise two-phase expansion. Previous investigations suggest that cascaded systems could produce up to 5% more power than an equivalent single-stage system. The aim of this paper is to compare the different systems in terms of exergy destruction within the system and the heat-transfer area requirements. Firstly, the exergy analysis reveals that cascaded systems reduce the total exergy destruction related to the expansion process, but this is offset by the exergy destruction within the additional heat exchange process. However, cascaded cycles also lead to less exergy destruction within the heat-addition process. To assess the heat-transfer area requirements, a discretised double-pipe heat-exchanger model is developed for the condenser and intermediate heat exchanger that transfers heat from the topping cycle into the bottoming cycle, whilst a discretised finned-tube cross-flow heat-exchanger model is developed for the evaporator. The geometry of each heat exchanger is optimised to minimise the heat-transfer area subject to imposed pressure drop constraints. The results reveal that cascaded cycles require larger heat-transfer areas, which is due to the additional heat-transfer process and reduced temperature differences within the evaporator. Ultimately, the best performing cascaded cycles, which produce 4.0% and 5.9% more power than their single-stage counterparts, require 22.7% and 23.2% more heat-transfer area. Future investigations should investigate how this trade-off impacts economic performance.
... A micro solar power station project has been realized as part of the Solar Power System (SPS) research program. It is a hybrid system based on hermetic volumetric expanders-generators of "scroll" type operating with superposed Rankine cycles where the analysis of the project demonstrates clearly the feasibility of the concept, its correct operation over a wide range of power range from a few Watts to a few kWe [12]. ...
Article
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This work is devoted to the study of a new power plant with multiple cascaded sorption heat transformers and power generation devices. The plant is powered from flat thermal solar collectors. The project objective is to of meet the electricity needs of up to 100 households, i.e. the equivalent of 10 kWe. Two assembly schemes are proposed. The first one includes an Ericsson heat engine as a mechanical work conversion device. While the second includes a heat to mechanical conversion machine operating according to the subcritical and supercritical ORC (Organic Rankine Cycles). The mathematical modeling revealed that mechanical work production is quite possible by the second power plant configuration. The thermal efficiencies obtained for the absorption and adsorption heat-transformers are equal to 59.6% and 10.4% respectively. For the two ORC subcritical and supercritical these values are equal to 5.64% and 7.02% respectively for the low heat source temperature TSC equal to 343 K. The concept analysis clearly shows the feasibility of the second configuration which can satisfy the specified power needs of 10 kWe from thermal solar collectors at 358 K. The maximal overall conversion efficiency of this second configuration reaches 18%, which is much above photovoltaic conversion systems efficiency.
... Today, modernistic industrial societies are highly depending on fossil fuel as an energy prime mover. In fact, this energy is decreasing fast with rising in price, besides, scientists noticed a deterioration in environment due to enormous utilization of this kind of sources [1]. For this reasons, an extensive awareness is being paid to other sustainable and clean sources [2]. ...
Conference Paper
The applications of renewable energy systems have become very interesting in various sectors nowadays. One of the most well-known applications is a photovoltaic system. However, the outcomes power generated by the photovoltaic conversion hinges on climatic condition at the site location. In this work, an experimental examination was done to evaluate the performance of photovoltaic system; installation was at the LAGE laboratory (Ouargla University). The system contains two polycrystalline photovoltaic modules, power management unit, a lighting lamp and a data acquisition unit, the solar modules generate a direct current to charge the electric accumulators via solar regulation unit. The power management extension, including a solar controller, a DC-AC inverter, a DC-DC converter (to supply AC and DC loads) and a battery bank. The aim of these experimental tests is to supply such a lamp with clean electricity without using the electrical network, after that to evaluate photovoltaic system components efficiency.
... ORC technology has not yet been used on a commercial scale in small-scale power plants although smaller ORC systems have significant potential to use near the areas where heat sources exist for various applications such as: power generation for isolated homes, cogeneration plants or heat-treated heat pumps [5]. For this reason, a number of theoretical and experimental researches have been carried out in recent years with the aim of developing compact units suitable for small capacities applications [6][7][8][9][10][11][12]. ...
Article
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This paper refers to recovering of waste heat from hot gases discharged by internal combustion engines (ICE) at partial or full load using a Rankine Organic (ORC) cycle which drives a compressor of a mechanical compression refrigeration system (MCRS) to convert heat recovered into cooling power. The subject is of particular interest to the automotive and refrigeration industry with the aim of finding a feasible solution for the recovery of residual heat and turning it into a real source of commercial or industrial refrigeration. The heat recovery system is based on an ORC driven by SES36, a working fluid with good thermodynamic properties for the recovery of low temperature heat, as well as refrigeration or air conditioning refrigeration cycles. A scheme was proposed that combines the two systems so as to use the same working fluid, thus using a small number of subassemblies. After the energetic and exergetic calculations, it was proved that the ICE-ORC-MCRS system is of real interest due to the recorded performances, while the optimization of the thermodynamic scheme can be upgraded by improving the heat transfer at the level of the exchangers, but also constructively trying to streamline the scheme with new heat recovery.
... Some other studies focus more on solar ORC driven micro-grids. Kane et al. [12] studied CSP-ORCs combined with a bio-Diesel engine; Orosz et al. [13] proposed a low-cost system consisting of parabolic trough collectors (PTCs) coupled with an ORC that produces electricity via a scroll expander. The performance of different solar collectors have been addressed in the past. ...
Conference Paper
The recent interest in the installation of micro-grids in developing countries led researchers to the investigation of different renewable energy concepts to the strongly decentralized ("localized") generation of electric and thermal energy in remote locations. Among the different technologies proposed, Solar-powered Organic Rankine Cycle (S-ORC) results as a promising option for the combined production of heat and power, since it can reach fairly high electrical efficiencies within rather low heat source temperatures (350-500 K). This work presents a performance assessment of a small-scale S-ORC system capable of producing 10KWe. The system consists of an array of solar collectors and an Organic Rankine Cycle engine. The capability of the aforementioned system to produce combined heat and power at various latitudes and at different heat source temperatures is investigated. The paper is organized as follows. First, the mathematical model of the S-ORC system is presented. Then, the size and cost of the solar collector are evaluated, based on different inlet temperature for the heat source. This study highlights the potential of S-ORC systems in providing thermal and electrical energy in off-grid applications.
... Energy production from medium and low temperature heat sources has attracted many interests recently. Unlike traditional power plants, ORC systems showed a flexible approach for heat recovery as small-scale power plants [1]. Heat sources can be renewable energy sources including solar, geothermal, and biomass, or waste heat sources such as engine exhaust and industrial waste heat. ...
Article
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The development of small-scale efficient and low-cost Organic Rankine Cycle (ORC) units using low temperature waste heat for electricity production is attracting a lot of interest nowadays. This paper presents the thermodynamic simulation of a small scale regenerative ORC testing facility. The facility mainly consists of an electric steam generator to produce steam at 170oC and 7.5 bar as hot source, water at 20oC as cold sink and a scroll compressor converted to be used as expander. Simulation was performed by means of MATLAB, and CoolProp external library was used for the thermo-physical properties of the R245fa, the organic working fluid. The performance of the system in a certain range of working conditions has been calculated, obtaining maximum efficiency of 9.6% and net power of 17 kW. Simulations are used to understand the effect of different characteristics of main components on the performance of the system before running the test bench. Thus, allowing the future experimental campaign that will verify the validity of the model.
... Energy production from medium and low temperature heat sources has attracted many interests recently. Unlike traditional power plants, ORC systems showed a flexible approach for heat recovery as small-scale power plants [1]. Heat sources can be renewable energy sources including solar, geothermal, and biomass, or waste heat sources such as engine exhaust and industrial waste heat. ...
Conference Paper
Full-text available
The development of small-scale efficient and low-cost Organic Rankine Cycle (ORC) units using low temperature waste heat for electricity production is attracting a lot of interest nowadays. This paper presents the thermodynamic simulation of a small scale regenerative ORC testing facility. The facility mainly consists of an electric steam generator to produce steam at 170oC and 7.5 bar as hot source, water at 20oC as cold sink and a scroll compressor converted to be used as expander. Simulation was performed by means of MATLAB, and CoolProp external library was used for the thermo-physical properties of the R245fa, the organic working fluid. The performance of the system in a certain range of working conditions has been calculated, obtaining maximum efficiency of 9.6% and net power of 17 kW. Simulations are used to understand the effect of different characteristics of main components on the performance of the system before running the test bench. Thus, allowing the future experimental campaign that will verify the validity of the model.
... At the condenser output (A), the working fluid is expected to be found in a liquid phase in order to be pumped again, by means of some energy inputẆ in , towards the evaporator. This technology has been also used for waste heat recovery in industry [4,88,129,134,153], renewable energy generation [80,90,129,133,134,151,152,153] and automotive applica- 1 Final energy consumption is the total energy consumed by end users, such as households, industry and agriculture. It is the energy which reaches the final consumer's door and excludes that which is used by the energy sector itself. 2 We will define the concept of a phase more precisely in Chapter 2. 3 Idem. ...
Thesis
This thesis aims at the investigation and development of the control of waste heat recovery systems (WHR) for heavy duty trucks based on the organic Rankine cycle. It is desired to control these systems in real time so that they recover as much energy as possible, but this is no trivial task since their highly nonlinear dynamics are strongly affected by external inputs (disturbances). Additionally, nonlinear operational constraints must be satisfied. To deal with this problem, in this thesis a dynamic model of a WHR that is based on first principles and empirical relationships from thermodynamics and heat transfer is formulated. This model corresponds to a DAE of index 1. In view of the requirements of the employed numerical methods, it includes a spline-based evaluation method for the thermophysical properties needed to evaluate the model. Therewith, the continuous differentiability of the state trajectories with respect to controls and states on its domain of evaluation is achieved. Next, an optimal control problem (OCP) for a fixed time horizon is formulated. From the OCP, a nonlinear model-predictive control (NMPC) scheme is formulated as well. Since NMPC corresponds to a state feedback strategy, a state estimator is also formulated in the form of a moving horizon estimation (MHE) scheme. In this thesis, we make use of efficient numerical methods based on the direct multiple shooting (DMS) method for optimal control, backward differentiation formulae for the solution of initial value problems for DAE, and the corresponding versions of the real-time iteration (RTI) scheme in order to approximately solve the OCP and implement the MHE and NMPC schemes. The simultaneous implementation of NMPC and MHE schemes based on RTI has been already proven to be stable in the control literature. Several numerical instances of the DMS method for the proposed OCP, NMPC and MHE schemes are tested assuming a given real-world operation scenario consisting of truck exhaust gas data recorded during a real trip. These data have been kindly provided by our industry cooperation partner Daimler AG. Additionally, the PI and LQGI control strategies, of wide-spread use in the literature of control of WHR, are also considered for comparison with the proposed scheme. An important result of this thesis is that, considering the highest energy recovery obtained from both strategies as a reference for the given operation scenario, the proposed NMPC scheme is able to reach an additional energy generation of around 3% when the full state vector is assumed to be known, and its computational speed allows it to update the control function in times shorter than the considered sampling time of 100 [ms], which makes it a suitable candidate for real-time implementation. In a more realistic scenario in which the state has to be estimated from noisy measurements, a combination of both aforementioned NMPC and MHE schemes yields an additional energy generation of around 2%. Concretely, this thesis presents novel results and advances in the following areas: • A first principles DAE model of the WHR is presented. The model is derived from the energy and mass conservation considerations and empirical heat transfer relationships; and features a tailored evaluation method of thermophysical properties with which it possesses the property of being at least continuously differentiable with respect to its controls and states on its whole domain of evaluation. • A new real-time optimization control strategy for the WHR is developed. It consists of an NMPC strategy based on efficient simulation, optimization and control tools developed in previous works. The scheme is able to explicitly handle nonlinear constraints on controls and states. In contrast to other NMPC instances for the WHR found in the literature, our scheme's efficient numerical treatment make it real-time feasible even if the full nonlinear WHR dynamics are considered. • To the author's knowledge, this is the first implementation that considers both the NMPC and the MHE approaches used simultaneously in the control of the WHR. The combination of NMPC and MHE produces a closed-loop, model-based implementation that can treat realistic measurements as inputs and calculates the corresponding control functions as outputs.
... [10] Few studies have provided experimental data from operational solar ORC systems. Kane et al. (2003) [11] studied the coupling of linear Fresnel collectors with a cascaded 9-kWe ORC, using R123 and R134a as working fluids. An overall efficiency (solar to electricity) of 7.74% was opbtained, with a collector efficiency of 57%. ...
... In 2003, Kane et al. [143] tested an ORC system to recover the thermal energy from a bio-gas diesel engine. The cycle was a bottoming cycle with R134a as the working fluid and the scroll expander was modified from standard hermetic scroll compressor units. ...
Article
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The strive towards ever increasing automotive engine efficiencies for both diesel and gasoline engines has in recent years been forced by ever-stringent emissions regulations, as well as the introduction of fuel consumption regulations. The untapped availability of waste heat in the internal combustion engine (ICE) exhaust and coolant systems has become a very attractive focus of research attention by industry and academia alike. Even state of the art diesel engines operating at their optimum lose approximately 50% of their fuel energy in the form of heat. As a result, waste heat recovery (WHR) systems have gained popularity as they can deliver a reduction in fuel consumption and associated CO2 emissions. Of these, the Organic Rankine Cycle (ORC) is a well matured waste heat recovery technology that can be applied in vehicle powertrains, mainly due to the low additional exhaust backpressure on the engine and the potential opportunity to utilize various engine waste heat sources. ORCs have attracted high interest again recently but without commercial exploitation as of today due to the significant on-cost they represent to the engine and vehicle. In ORCs, expansion machines are the interface where useable power production takes place; therefore, selection of the expander technology is directly related to the thermal efficiency of the system. Moreover, the cost of the expander-generator units accounts for the largest proportion of the total cost. Therefore, selection of the most appropriate expander is of great importance at the early stage of any automotive powertrain project. This study aims to review the relevant research studies for expansion machines in ORC-ICE applications, analyzing the effects of specific speed on expander selection, exploring the operational characteristics of each expander to further assist in the selection of the most appropriate expander, and comparing the costs of various expanders based on publically available data and correlations.
... One alternative to a simple ORC system is the cascaded ORC system, in which a high-temperature topping cycle and a low-temperature bottoming cycle are coupled together. Kane et al. [7] developed an experimental setup of a cascaded ORC system, driven by solar energy and waste-heat, whilst Kosmadakis et al. [8] assessed the use of a cascaded ORC system for reverse osmosis desalination. Both authors comment on the potential promise of such systems, but consider relatively low temperatures (< 200 °C). ...
Conference Paper
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The selection of an optimal working fluid and the design of the system components for a small-scale (<100 kW) high-temperature (250-400 °C) organic Rankine cycle (ORC) can be challenging owing to the possibility of sub-atmospheric condensation pressures and high expander volume-ratios. The latter means that volumetric expanders are not suitable, whilst a single-stage turbine would be characterised by supersonic flow and small blade heights. Alternatively, a cascaded cycle can be considered, in which the heat-rejection from a topping cycle drives a bottoming cycle. Through the proper selection of working fluids for the two cycles, sub-atmospheric condensation pressures can be avoided, whilst the volume-ratio is divided across two separate expansions. Moreover, two-phase expansion in the topping cycle can be considered to increase the power output from the system. At present, there are limited guidelines for the selection of fluids for each cycle. In this paper, the development of a novel method to identify the optimal pairing of fluids for cascaded ORC systems is discussed. The model is comprised of a cascaded ORC thermodynamic model and the Peng-Robinson equation of state. Using this equation of state allows the fluid parameters to be included within the optimisation, which allows the identification of optimal fluid parameters for both the topping and bottoming cycles, alongside the optimal operating conditions. The model has been used to identify optimal fluids for cascaded systems for heat-source temperatures ranging between 250 and 400 °C. The results have been verified by separate optimisation studies completed using REFPROP. Finally, a comparative study has shown that optimal cascaded systems can achieve similar power outputs to simple ORC systems and have lower expander volumetric ratios. However, cascaded systems require larger heat exchangers. The performance of cascaded systems could be further improved through two-phase expansion, and this should be studied in the future.
Preprint
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Sustainable and alternative energy sources of biofuel and solar power panel have been revolutionizing the lives and economy of many countries. However, these changes mainly occur in the urban areas and the rural population section has long been ignored by policy makers and government in the provision of energy. It is only recently that solar and biofuel are finally making in road to provide cheap and clean energy sources to rural population. As a result, literature on consumer behavior of rural population towards sustainable energy sources are still very scarce. The present research aims to fulfil this gap by developing a conceptual model to investigate the adoption of solar power and biofuel energy resources in the cross-cultural setting of Malaysia and Pakistan. The data was collected from the rural areas of Pakistan and Malaysia. The two-stage data analysis method of partial least square structural equation modeling (PLS-SEM) and artificial neural network (ANN) have been applied to satisfy both linear and non-linear regression assumption respectively. The results show that consumer in rural areas of Pakistan are willing and possess intention to adopt both biofuel and solar power for commercial and domestic use. Additionally, the results confirm that Branding, Economic and Altruistic factors are important in yielding intention to use towards biofuel and solar power panel in Pakistan which are validated by the results obtained in Malaysia. Other factors such as climate change awareness, retailer services quality and ease of use are also important. The results offer wide ranging theoretical and managerial implications.
Chapter
Green Science, a sustainable mechanism, is being described to fulfill the complete need of energy for a building that can be created by the building itself. To meet the complete energy demand for a building, the domestic biowaste including human empathetic excrement (stool) is suggested to be executed into converting process in situ where separated sludge is to be collected into an anaerobic shut tank bioreactor (BR) into the basement, facilitating to form biogas (CH4) by methanogenesis in order to convert biogas into electricity energy to power the entire building. Thereafter, the discharged wastewater is to be stored into another detention tank in situ in order to conduct a complete treatment process of primary, secondary, tertiary and UV application to utilize the treated wastewater for gardening. Implementation of this technology indeed shall be an inventive field of science where a building can form electricity by itself to complete its total energy need without any connection with the utility authorities which is benevolent to environment.KeywordsDomestic biowasteBioreactorIn site biowaste treatment technologyMethanogenesisBioenergyEnvironmental sustainability
Article
Building and transportation sectors together account for two-thirds of the total energy consumption in the US. There is a need to make these energy systems (i.e., buildings and vehicles) more energy efficient. One way to make grid-connected buildings more energy efficient is to integrate the heating, ventilation and air conditioning (HVAC) system of the building with a micro-scale concentrated solar power (MicroCSP) sys- tem. Additionally, one way to make vehicles driven by internal combustion engine (ICE) more energy efficient is by integrating the ICE with a waste heat recovery (WHR) system. But, both the resulting energy systems need a smart supervisory controller, such as a model predictive controller (MPC), to optimally satisfy the en- ergy demand. Consequently, this dissertation centers on development of models and design of MPCs to optimally control the combined (i) building HVAC system and the MicroCSP system, and (ii) ICE system and the WHR system. In this PhD dissertation, MPCs are designed based on the (i) First Law of Thermo- dynamics (FLT), and (ii) Second Law of Thermodynamics (SLT) for each of the two energy systems. Maximizing the FLT efficiency of an energy system will minimise energy consumption of the system. MPC designed based on FLT efficiency are de- noted as energy based MPC (EMPC). Furthermore, maximizing the SLT efficiency of the energy system will maximise the available energy for a given energy input and a given surroundings. MPC designed based on SLT efficiency are denoted as exergy based MPC (XMPC). Optimal EMPC and XMPC are designed and applied to the combined building HVAC and MicroCSP system. In order to evaluate the designed EMPC and XMPC, a com- mon rule based controller (RBC) was designed and applied to the combined building HVAC and MicroCSP system. The results show that the building energy consump- tion reduces by 38% when EMPC is applied to the combined MicroCSP and building HVAC system instead of using the RBC. XMPC applied to the combined MicroCSP and building HVAC system reduces the building energy consumption by 45%, com- pared to when RBC is applied. Optimal EMPC and XMPC are designed and applied to the combined ICE and WHR system. The results show that the fuel consumption of the ICE reduces by 4% when WHR system is added to the ICE and when RBC is applied to both ICE and WHR systems. EMPC applied to the combined ICE and WHR system reduces the fuel consumption of the ICE by 6.2%, compared to when RBC is applied to ICE without WHR system. XMPC applied to the combined ICE and WHR system reduces the fuel consumption of the ICE by 7.2%, compared to when RBC is applied to ICE without WHR system.
Article
As the heat exchange component of the organic Rankine cycle (ORC) system, the evaporator directly affects the overall operation performance of the system. In this paper, an analytical method for energy level on the working fluid side of evaporator is proposed based on the energy level and enerty theory. The reliability, validity, and correlation of the proposed analytical method are studied by means of theoretical analysis, experimental evaluation, and Elman neural network (ElmanNN). The bilinear interpolation algorithm is used to analyze the non-linear relationship between the system parameters and the energy level on the working fluid side. In addition, the correlation between the heat exchange efficiency of the evaporator and the operating performance of the system is compared. Based on the back propagation neural network (BPNN), the high energy level area on working fluid side is accurately evaluated and verified, the direction and degree of the non-linear mapping relationship between the working fluid side energy level and the system performance are quantitatively evaluated, and the sensitivity of thermodynamic cycle parameters in the high energy level area on working fluid side is quantitatively evaluated. This study provides a novel approach to evaluate the operation of the evaporator in the ORC system. In addition, this study also provides guidance on how to keep the evaporator operating continuously in the high energy level area throughout the experiment.
Chapter
Solar Fuels and chemicals from CO2 can be produced through two main reactions: one is CO2 photoreduction, using different catalysts and different reducing agents; the other is CO2 fixation, which is usually performed through natural photosynthesis. The research nowadays is directed on the production of fuels and chemicals with one or two atoms of carbon, for example CH4, CO, HCOOH, HCHO, CH3OH, C2H5OH, etc. The chapter aims at comparing natural photosynthesis processes and reactions with artificial photosynthesis. After taking into consideration the natural photosynthetic process, the chapter focuses on heterogeneous and homogeneous photocatalysis. Heterogeneous catalysis can be performed with semiconductors and powder catalysts. Special attention is given to TiO2 as a promising photocatalyst. Homogeneous photocatalysts are usually represented by molecular catalysts, which are dissolved in water or another solvent. Usually, homogeneous photocatalysis is performed in complex systems which are composed by: a light harvesting unit (LHU) (i.e. the photosensitizer); one catalytic site for the oxidation process, where the electrons are supplied by a sacrificial donor; one reduction site, where the electrons are transmitted to CO2. Finally, even more complex systems are represented by those based on photoelectrocatalysis. These have the main advantage to separate the oxidation and reduction reactions at the two different electrodes of the system. In principle photoelectrochemical cells can be a way to mimic artificially the working principle of natural photosynthesis.
Chapter
Green Technology, a sustainable technology is being proposed to fulfill the complete energy need for a building that can be generated by the building itself. To meet the complete energy demand for a building, the domestic biowaste including human feces is suggested to executed into converting process in situ where separated sludge is be collected into an anaerobic shut tank bioreactor (BR) into the basement. Thereafter, it has been facilitated to form biogas (CH4) by the process of methanogenesis to convert biogas into electricity energy which has been calculated as 1.4 eV/moles. Since the 0.4 kg biowaste can produce 81 mole biogas, thus, the total electricity generation from 0.4kg biowaste equivalent to 1.4 × 81 = 113.4 eV. Here the 1.4eV is equal to 27.77 kWT, thus, the total electricity energy production is being calculated (27.77 kW × 81) = 2249.37 kW • eV per day. Since a standard commercial building (length 20m × width 20m × height 20m) consume roughly 2,200 kWh/day, thus, the 0.4kg/day biowaste is sufficiently enough to meet total energy demand for this size building. Simply, implementation of this technology indeed would be an inventive field of science where a building can form electricity by itself to complete its total energy need without any connection with the utility authorities, which is benevolent to theenvironment.
Thesis
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Solar power is a renewable energy source and can meet the growing world demand for electricity. The thermal energy produces by solar is an attractive solution to handle the environmental issues caused by fossil fuels. This research focuses on the theoretical modelling of components of solar thermal power plants for performance enhancement. It involves the modelling of the solar collector and organic Rankine power cycle. The overall solar thermal power plant comprises such components as a collector, evaporator, turbine, condenser, pump, heat exchanger, and thermal storage system. The present research studies the Linear Fresnel Reflector's performance in providing the heat input to the Organic Rankine Cycle and investigate the annual energy production of the power plant, located at the testing site in Almatret, Catalonia, Spain. The work includes step-by-step modification of the actual system design with a performance analysis of the non-concentrating and concentrating power plant systems. The mathematical model of the ORC was developed based on the thermodynamic equations with simulations performed using MATLAB/Thermolib software. The ORC system performance was investigated for different working fluids at their critical operating conditions. The considered working fluids include the HCFC-245fa, HCFC-134a, Propane, butane, ethanol, and methanol. The ORC model was upgraded by taking into account the heat exchanger to recover the system waste heat, and results were compared to that from a simple ORC model. The recovery of the heat in the cycle increases the thermal efficiency of the ORC, but its benefits depend on the critical parameters of the working fluid. The effect is considerable for R134a and negligible for Ethanol. The Solar Organic Rankine Cycle (SORC) mathematical model was developed, and simulation designed on the MATLAB/Thermolib software. The evacuated tube collector designed for the Almatret latitude position and supplied the power input to the Rankine system. The model based on the water heat transfer fluid of the solar field, and it is transferring the heat to HCFC-134fa, the working fluid of the Rankine cycle via a heat exchanger without a tracking and thermal storage system. The thermal performance of the model investigated base on the day scan results. The solar organic Rankine cycle has an area 600 m2 to generate peak thermal power 71 kW, and the mechanical output power of the Rankine cycle is 4.274 kW using 30 bar evaporation pressure and 10 bar condensation pressure. The 4 Generic Algorithm code developed on MATLAB and connected with the Thermolib model to operate the SORC system with optimum variables and thermal efficiency increases from 10.58 % to 11.87 % using the peak value solar irradiance. Fresnel solar reflector model simulated by using the light tools simulation software and have a one-axis tracking system. The actual weather data was imported to the simulation software to investigate the system performance using the day scan results. The theoretical model derived to determine the system thermal energy and conduction, convection, and radiation heat transfer of the receiver tube. The thermal losses of the model investigated and derived solar angles of the specific day. The tracking system based on the incidence angle modifier model (IAM) and calculated the system optical efficiency corresponds to the IAM in terms of the longitudinal and transverse components of the incidence of rays. The analysis performed from ambient conditions to determine the peak value by using the Therminol-62 working fluid. The LFR field produces 106.425 kW thermal energy during peak hour using a high value of IAM, and the reflector area is 214.38 m2. The thermal losses during the peak time of day at 1:00 PM is 7.872 kW. The system advisor simulation software used to validate the solar power linear Fresnel system. The complete model simulated with the thermal storage system. The actual weather data and Therminol-62 heat transfer fluid and NOVECTM649 working fluid import to the simulation model. The simulation model based on the exact power plant is located in the Almatret location and investigated the model thermal performance. The results show that the LFR field with a tracking system and Therminol-62 working fluid increases the system thermal performance. The Therminol-62 have high-temperature ranges at low operating pressure as compare to the steam working fluid. The ORC has a higher value of thermal efficiency NOVECTM649 than HCFC-134a and produces 7.2 kW output power of the ORC plant during the peak hour of solar irradiance with specific operating conditions. The two-tank thermal storage system extends the Plant four hours of operation and produces the highest power output of 2160 kWh in July.
Chapter
An advanced sustainable mechanism is being described to fulfill the complete need of energy for a building that can be created by the building itself. To meet the complete energy demand for a building, the domestic biowaste including human feces is suggested to be executed into converting process in situ where separated sludge is to be collected into an anaerobic shut-tank bioreactor (BR) into the basement, facilitating to form biogas (CH4) by methanogenesis in order to convert biogas into electricity energy to power the entire building. Then, the discharged wastewater is to be stored in another detention tank in situ in order to conduct a complete treatment process of primary, secondary, tertiary, and UV application to utilize the treated wastewater for gardening. Execution of this technology indeed shall be an inventive field of green building science where a building can form electricity by itself to satisfy its total energy need without any connection with the utility companies which is benevolent to environment.
Article
A waste heat recovery system consisting of a hybrid power and cooling cycle is described in this paper. It couples a thermoelectric generator (TEG) and an organic Rankine cycle driving a vapor compression cycle to implement heat activated power and cooling. The system was designed, developed, and tested under laboratory conditions using a hot air source simulating a heavy-vehicle exhaust stream. The hybrid or so-called cofunctional power and cooling system was designed to approach the size of a fieldable unit for testing with mobile diesel generators or heavy-vehicle exhaust streams, which have strict requirements for size, weight, and efficiency. As a result, microchannel heat exchangers were used extensively throughout the system design. High-temperature bismuth telluride (Bi2Te3) thermoelectric (TE) modules were used, and the TEG section contained 20 modules in two distinct electrical strings sandwiched between microchannel cold-side and hot-side heat exchangers. The cofunctional system has shown stable operation during tests conducted at various incoming hot air temperatures up to 388°C, simulating common heavy-vehicle exhaust stream conditions. Although the TEG power output was significantly lower than the design value because of reduced heat transfer into the TE modules due to contact area mismatch and significant heat loss, many system performance parameters reached or even exceeded the target values at design conditions. Design modifications are being implemented to incorporate custom-designed TE modules into the system and to reduce the TE cold-side temperature to improve the TEG output.
Article
Compared to single-stage organic Rankine cycle (ORC) systems, cascaded ORC systems, in which a high-temperature topping cycle and low-temperature bottoming cycle are coupled together, could have advantages in terms of removing the potential for sub-atmospheric condensation conditions and improving expander performance as the expansion process is effectively divided across two stages. Moreover, reducing the expansion volume ratio could facilitate the use of volumetric expanders, such as twin-screw expanders, which, in turn, could facilitate two-phase expansion to be utilised in one, or both, of the cycles. The aim of this paper is to compare single-stage and cascaded ORC systems, accounting for the effect of the expander volume ratio on expander performance. To investigate this, thermodynamic models for single-stage and cascaded ORC systems are developed, which include variable efficiency expander models for both radial turbines and twin-screw expanders that can estimate the effect of the expansion volume ratio on the expander isentropic efficiency. Using this model, three different scenarios are compared for different temperature heat-source temperatures, namely: (i) single-stage ORC systems with vapour-phase expansion obtained using a turboexpander; (ii) single-stage ORC systems operating with a twin-screw expander, with the possibility for two-phase expansion; and (iii) cascaded cycles with either vapour- or two-phase expansion. The results from this comparison are used to identify applications where cascaded ORC systems could offer performance benefits
Article
Waste heat recovery systems are proposed to be an environmentally benign and a cost-effective application for efficiency improvement of energy conversion systems. In this research, three different subsystems—gas turbine cycle, steam Rankine cycle, and a coupled organic Rankine cycle–vapor compression refrigeration—are integrated to obtain a high-efficiency layout from technical, economic, and environmental viewpoints. The whole system is simulated and analyzed with regard to energy, exergy, and exergoeconomic models. Furthermore, a sensitivity analysis is made to enable a better understanding of the effect of design parameters on the final performance of the total system. Based upon a parametric study, R602 demonstrates advantageous features such as higher thermal efficiency and improved exergetic efficiency in the ORC–VCR subsystem. Overall, analyses show that the proposed integrated system obtains the total energy and exergy efficiencies of 46.1% and 40.57%, respectively. Moreover, it has been illustrated that the overall structure is able to provide a 3810 kW net output power and a 303.8 kW cooling load. Besides, exergoeconomic evaluation depicts an exergy cost of 49.84 ($ GJ−1) and an exergy cost rate of 826.4 ($ h−1).
Article
Building heating, ventilating, and air-conditioning systems have high impacts on the energy and environmental performance of residential buildings. To reduce the energy consumption of the building for sustainable buildings and cities, this research proposed the organic Rankine cycle (ORC) applied to a centralized liquid desiccant (LD) and evaporative cooling-assisted ventilation system serving an apartment building and evaluated the energy impact of the proposed system via detailed energy simulations. As a small combined heat and power application in residential buildings, the ORC produces heat and power that are consumed by the proposed system and the building. A conventional decentralized energy recovery ventilator powered by the existing power grid was selected as a reference system. The combination of the ORC, LD, and evaporative cooling-assisted ventilation system allows decoupling of the sensible and latent cooling and offers energy benefits by reclaiming heat from the ORC compared with the reference system owing to the parallel system of energy consumption. Energy simulations were conducted for one floor of a 30-story apartment building. The proposed system exhibited 28% annual primary energy savings and provided a 54% higher annual average coefficient of performance compared with the reference system, although the proposed system consumed more fan and pump energy. The majority of the operating energy savings of the proposed system were achieved by reclaiming the waste heat from the ORC condenser.
Thesis
This dissertation is devoted to the analysis of selected operating parameters of a prototype micro-cogeneration system with a biomass-fired boiler. The work presents the relevant steps in installation development and the results of research, along with an analysis of the obtained results. Chapters 1 and 2 present an introduction to the thesis (justification for the selection of research topics) and a list of main symbols used in the dissertation. Chapter 3 contains an introduction to the issues of using straw in microscale energy systems, including biomass characteristics as a fuel, presentation of biomass conversion possibilities, and comparison of selected micro-cogeneration technologies. Chapter 4 presents the objectives and thesis. The main goal was the analysis of the possibility of extending the basic functionality of the biomass-fired batch boiler (i.e. heat generation for heating purposes) with electricity generation. This analysis includes (i) the selection of technology, design, construction, and launching the research version of the micro-cogeneration system, (ii) conducting measurement campaigns with implementation of the necessary improvements and (iii) analysis of results in terms of creating a prototype system design, and mathematical models for future analysis of the system. The main thesis was the statement that it is possible and expedient to develop a micro-cogeneration system based on a dedicated biomass-fired batch boiler, which will have high implementation potential with support to manufacturers at the stage of technology development and implementation. Chapter 5 discusses the theoretical foundations and current state of research in the area of microscale biomass cogeneration systems. The theoretical foundations of the Clausius-Rankine cycle with the use of saturated steam and superheated steam and the possibilities of increasing the efficiency of this type of cycle are discussed. Also, the efficiency of power devices is discussed, and the Clausius-Rankine cycle is compared with the organic Rankine cycle. Then, the current state of research on micro-cogeneration systems is presented, taking into account the work on various micro-scale technologies of combined heat and electricity generation based on biomass and biogas combustion. Chapter 6 discusses the construction of the experimental rig, taking into account the two heat sources tested (batch boilers), the oil circuit, the steam-condensate circuit, the water circuit, the power generation system, and the control and measurement system with data acquisition. Chapter 7 presents information on measuring and computational methodology as well as measurement results and the discussion thereof. The experimental section presents the operating characteristics of the KW1 boiler in the oil circuit in the base system, the KW2 boiler in the prototype system, the oil circuit, the steam-condensate circuit, the water circuit, and the power generator. Based on the results obtained, an analysis of data is carried out covering the working characteristics of the KW2 boiler, working characteristics of the evaporator and superheater, the characteristics of changes in steam pressure as a function of temperature as well as issues regarding the pressure drop and temperature of steam in the steam pipeline together with the parameters of the steam engine and generator. Based on the results of the measurements and the analyses, a mobile container installation project and the first version of the computational model for the needs of dynamic simulations in TRNSYS software were developed. Chapter 8 presents the summary and conclusions resulting from the implementation of this dissertation. This chapter sets out to justify achieving the assumed goals of work and confirms the truthfulness of the theses.
Article
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Organic Rankine cycle an alternative way of generating energy from waste heat, fuel and gases at low-temperature. Method (ORC) proved successful and high efficiency to reduce environmental pollution, fuel consumption and convert low to medium heat sources. The paper will be presenting a review investigation on the organic Rankine cycle(ORC), cycle Background, (ORC) configuration, and selecting of working fluids and experimental studied of expansion apparatuses, which are classified into two type volumetric type such as (expander of rotary vane, scroll, reciprocating piston expander and screw) velocity kind (for example axial and radial turbine). Heat exchanger and expander apparatuses are considered economically expensive parts in (ORC).
Article
Solar thermal electricity generating technology is an alternative solution to energy crises and environmental problems, which has caused wide concern in recent decades. In this paper, a molten salt parabolic trough‐based concentrated organic Rankine cycle system is proposed and investigated. A quadribasic nitrate salt with low melting temperature is employed as a heat transfer and storage medium. A stable heat transfer and economic model is established with Matlab. The radial and axial temperature distributions in the collector tube are obtained, and the impact of condensation and evaporation temperatures on the heat transfer area is analyzed. Results show that the temperature along the axial direction linearly increases, and the temperature at the collector tube exit decreases with the increase of molten salt mass flow rate. The maximum temperature difference along the radial direction of the collector tube happens in the annular gap. Heat transfer and thermodymanic analysis indicates that condensation temperature has a more evident effect on heat transfer area than that of evaporation temperature. An increase in condensation temperature leads to a decrease in the evaporator area, the condenser area increases, and the total area decreases. Economic analysis indicates the collector cost plays a predominant role in total capital costs, and decreasing molten salt mass flow rate can considerably reduce collector cost. Levelized energy cost sensitivity analysis indicated that operation time per year has a more evident effect than that of the four factors. Heat transfer and economic analysis on the system helps in the selection of operation parameters. Using a quadribasic molten salt with low melting temperature as heat transfer and storage medium Obtaining radial and axial temperature distribution of collector tube Analyzing evaporation and condensation temperature effects on the heat exchange area Computing system capital cost and dissect the predominant factor
Article
This study evaluated the effect of an organic Rankine cycle (ORC), powered by various renewable heat sources, on enhancing the primary energy benefits in a liquid desiccant (LD) and indirect and direct outdoor evaporative cooling-assisted air system (LD-IDECOAS). Combining an LD-assisted air conditioning system with the ORC, which uses renewable or waste heat sources, may be beneficial in terms of energy saving and environment efficiency. However, only a few studies have addressed the benefits of integrating the ORC with this air conditioning system as the heat source for the ORC. A solar thermal system, district heat source, and conventional boiler were used respectively in a 2-kW ORC which was integrated with the LD-IDECOAS to establish three system cases, and a comparative investigation was conducted. The power and heat generated by the ORC are supplied to the LD-IDECOAS to satisfy the power and solution heating demands, respectively. By performing a detailed energy simulation, the primary energy consumption in each ORC-integrated case was calculated during the cooling season and compared with that of a conventional LD-IDECOAS driven by grid power and a gas boiler. The results revealed that three ORC-integrated system cases consumed additional electric power compared with the base case (21.6% more electric power consumed in case 1 and 20.0% more electric power consumed in cases 2 and 3). Additional heat input to the ORC evaporator was also required, however, the ORC-integrated LD-IDECOAS powered by a solar thermal system (case 1) and district heat source (case 2), which are renewable energy sources, achieved a primary energy saving of 15.7% and 35.4%, respectively, compared with the base case. In conclusion, the district heat source was more feasible than the other heat sources considered in this study, achieving the best primary energy saving (35.4%) and CO2 emission reduction (23.9%).
Chapter
This chapter investigates the production of electricity (to be subsequently used for hydrogen production) using solar thermal systems. Among the renewable energy sources, solar energy is considered as the main option due to its abundance. However, the key to the expansion of the solar-driven power production systems market is the development of efficient and reliable systems. Higher temperature is a key challenge to the solar harvesting technologies as it would allow for higher efficiencies in the power subsystems. In order to allow for higher temperatures, most medium to large-scale solar thermal power plants use concentrated collectors and for this reason, this technology is named as concentrated solar power (CSP). The main available CSP technologies are being discussed below, namely: parabolic trough collectors coupled with Rankine or organic Rankine cycles (ORC), power tower systems, dish systems, linear Fresnel reflector, and hybrid systems. All the aforementioned technologies are being discussed thoroughly in terms of their key features, R&D progress, with a focus on the commercial and demonstration applications.
Article
Nature offers an enormous amount of free energy in the form of Sun [Photovoltaic (PV)]. Therefore, it is interesting to integrate this renewable, everlasting, and echo friendly energy into traditional grid connected power supply. In this study, an energy management system (EMS) is proposed for the proper PV energy integration and utilization into microgrids. For prototype, simulations were performed for 1 kW PV array, 1.5 kV A inverter, and 1.5 kW load employing Lab VIEW. Boolean algebraic operators were incorporated for decisions. A sine wave frequency generator with the desired voltage and frequency measurements was introduced for both grid and PV sources. Numerical indicators are used for current, voltage, and frequency display. The proposed system offers integration and management of PV and national grid power for domestic power utilization. To test the capabilities of the developed EMS, the results were compared with the already established methods. In the developed method, PV is considered as a primary power source for domestic appliances (load) during daytime along with the national grid as a secondary power source. Moreover, to establish its feasibility, economic implications are also discussed.
Conference Paper
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A special turbomachinery based engine ©GICE has been proposed for the concurrent production of power and cool. The High Temperature Heat injected into the cycle allows an expansion under cryogenic conditions. A ©GICE engine coupled with a novel seawater ©CryoDesalination plant has been investigated to concurrently product the power, pure water and cool suitable for air conditioning. An amply discussion of results has been reported in the paper.
Thesis
La situation énergétique et économique actuelle nous pousse à revoir nos modes de productions d'énergie, il apparait urgent de développer des alternatives à l'utilisation des énergies fossiles. L'heure actuelle est donc au développement de systèmes utilisant des énergies propres dans le respect de l'environnement. De plus chaque système doit être étudié et optimisé au mieux afin de tirer le meilleur parti des sources à notre disposition. Le travail réaliser dans ce rapport répond parfaitement à cette problématique. Il consiste en l'étude par la thermodynamique à vitesse finie d'un cycle de Rankine puisant l'énergie qui lui est nécessaire à partir de la source solaire par le biais d'un dispositif concentrateur. Il sera tout d'abord alors étudié l'influence des irréversibilités sur les performances du dispositif grâce à la Thermodynamique à Vitesse Finie (TVF), une méthode d'étude très poussé qui permet de modéliser un système piston-cylindre au plus proche de la réalité. Ensuite il sera dimensionné le concentrateur solaire, formé d'un miroir cylindro-parabolique concentrant le rayonnement solaire sur un absorbeur dans lequel circule le fluide cyclé. Et pour finir, il sera comparé selon les mêmes critères les performances de divers Cycles de Rankine Organique, fonctionnant avec un siloxane ou du benzène.
Conference Paper
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The five Solar Electric Generating Systems (SEGS) at Kramer Junction, California, now have nearly 30 years of cumulative operating experience. These 30 MW plants employ parabolic trough technology originally deployed by LUZ International in the late 1980`s and are now managed, operated and maintained by the Kramer Junction Company. In this paper, Sandia National Laboratories performed an analysis of the annual energy production from the five plants. Annual solar-to-electric conversion efficiencies are calculated and the major factors that influenced the results are presented. The generally good efficiencies are primarily attributed to the excellent equipment availabilities achieved at all plants.
Article
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p>Hybrid solar thermal power plants (with parabolic trough type of solar collectors) featuring gas burners and Rankine steam cycles have been successfully demonstrated by California's Solar Electric Generating System (SEGS). This system has been proven to be one of the most efficient and economical schemes to convert solar energy into electricity. Recent technological progress opens interesting prospects for advanced cycle concepts: a) the ISCCS (Integrated Solar Combined Cycle System) that integrates the parabolic trough into a fossil fired combined cycle, which allows a larger exergy potential of the fuel to be converted. b) the HSTS (Hybrid Solar Tower System) which uses high concentration optics (via a power tower generator) and high temperature air receivers to drive the combined cycle power plant. In the latter case, solar energy is used at a higher exergy level as a heat source of the topping cycle. This paper presents the results of a thermoeconomic investigation of an ISCCS envisaged in Tunisia. The study is realized in two phases. In the first phase, a mixed approach, based on pinch technology principles coupled with a mathematical optimization algorithm, is used to minimize the heat transfer exergy losses in the steam generators, respecting the off design operating conditions of the steam turbine (cone law). In the second phase, an economic analysis based on the Levelized Electricity Cost (LEC) approach was carried out for the configurations, which provided the best concepts during the first phase. A comparison of ISCCS with pure fossil fueled plants (CC+GT) is reported for the same electrical power load. A sensitivity analysis based on the relative size of the solar field is presented. This paper was presented at the ECOS'00 Conference in Enschede, July 5-7, 2000 </ul
Article
Full-text available
This paper describes a 1 to 3.5 kWe hermetic scroll expander generator modified from a standard hermetic compressor, an organic Rankine cycle test facility built to test expanders up to 10 kWe and a set of experimental results using HFC 134a in the dry vapor domain. Peak overall isentropic efficiencies in the range of 63 to 65% for speeds of rotation varying between 2400 and 3600 rpm are reported. Performance is fairly constant in the range of pressure ratios considered (2.4<PR<4.0).
Article
Integrated solar combined cycle systems (ISCCS) represent, both economically and energetically, a promising alternative for the conversion of solar energy while offering a guarantee of a minimum power supply independent of the level of solar radiation. Their performances are, however, strongly dependent on the intensity of the solar input. The approach proposed in this paper allows, from the characteristics of the turbines (gas turbines and steam turbines) and of the solar field, to rationalize the choice of the pressure levels and of the massflows of a steam cycle with multiple pressure levels. It is based on the coupling of a pinch technology approach with a thermodynamic modelling, allowing an optimisation with deterministic algorithms. Results are applied to a dual pressure steam cycle and account for the respect of the 'cone law' for steam turbines. It is shown that an increase of the exergetic losses linked to heat transfer in the steam generators is inevitable at certain operational regimes and depends directly on the level of solar supply. The variations of the main steam cycle parameters as a function of the thermal supply (combustion gases + solar thermal oil) are shown for an 80 to 120 MWe power plant equipped with two gas turbines and one steam turbine train. (C) Elsevier, Paris.
Conference Paper
Kokhala is the name of a new hybridized power tower design which integrates a nitrate-salt solar power tower with a gas turbine combined-cycle power plant. This integration achieves high value energy, low costs, and lower investor risk than a conventional solar only power tower plant. One of the primary advantages of this system is that it makes small power tower plants much more economically competitive with conventional power generation technologies. This paper is an overview of a study that performed a conceptual evaluation of a small (30 MWe) commercial plant suitable for the Sacramento Municipal Utility District`s (SMUD) Rancho Seco power plant site near Sacramento, California. This paper discusses the motivation for using a small hybrid solar plant and provides an overview of the analysis methodology used in the study. The results indicate that a power tower integrated with an advanced gas turbine, combined with Sacramento`s summer solar resource, could produce a low- risk, economically viable power generation project in the near future.
Conference Paper
Solar thermal power plants of the parabolic trough type have been successfully demonstrated for 10 years, the electricity costs, however, are still too high. For commercialization on a large scale these plants have to be integrated into fossil fired combined cycles. A strategy how to meet this goal is proposed. For further cost reduction three advanced concepts are presented: Direct steam generation in parabolic trough systems, preheating of combustion air for gas turbines and upgrading of natural gas by solar reforming in tower systems. These solar systems only serve as fuel saver (8 to 25% for full load operation hours of 4000 h/y), however, have high potential for cost reduction down to 5 cts/kWh. To demonstrate their technical feasibility, governmental and European Community-funded prototype systems are being built. The state of development and economic analysis and comparisons are reported.
Article
The subject of this analysis is a novel hybrid steam Rankine cycle, which was designed to drive a conventional open-compressor chiller, but is equally applicable to power generation. Steam is to be generated by the use of solar energy collected at about 100°C, and is then to be superheated to about 600°C in a fossil-fuel fired superheater. The steam is to drive a novel counter-rotating turbine, and most of its exhaust heat is regenerated. A comprehensive computer program developed to analyze the operation and performance of the basic power cycle is described. Each component was defined by a separate subroutine which computes its realistic off-design performance from basic principles. Detailed predicted performance maps of the turbine and the basic power cycle were obtained as a function of turbine speed, inlet pressure, inlet temperature, condensing temperature, steam mass flow rate, and the superheater's fuel consumption rate. Some of the major conclusions are: (1) the turbine's efficiency is quite constant, varying in the range of 68.5–76.5 per cent (75 per cent at design) for all conditions, (2) the efficiency of the basic power cycle is 18.3 per cent at design, more than double as compared to organic fluid cycles operating at similar solar input temperatures, at the expense of adding only 20 per cent non-solar energy. This, combined with the fact that actual organic Rankine cycles operate typically at temperatures above 140°C, predicts that this system would be economically superior by using less than half of the collector area and by also using less expensive collectors.
Article
This paper reviews some leading novel energy conversion approaches which are aimed at improving power generation efficiency and/or reducing harmful emissions. Some of the concepts used for cycle improvement are higher top temperatures, improved combustion systems, evasion of the Carnot limit by integration with fuel cells and direct nuclear energy conversion to power (the nuclear generator), reduction of exergy destruction by staging and the use of exergy-efficient combustion processes, the use of lower temperature heat sinks and the use of renewable, environmentally-benign energy sources. Some of the systems described in this paper are hybrid multi-temperature source cycles (including the hybrid solar-powered/fuel-assisted Rankine cycle), high-temperature chemical gas turbine cycles, fuel-cell-topped Rankine cycles, high temperature ejector-topping power cycles and hybrid nuclear/fossil fuel power generation systems. The use of space (the extra-terrestrial environment) for energy conversion improvement is also discussed.
Article
Steam production units (HRSG and HSSG) of ISCCS include several heat exchangers (economizers, evaporator, superheater, reheaters, etc.). The knowledge of the extended composites as a function of the solar input, allows the determination of the most critical zones for heat transfer but does not allow, in itself, the full knowledge of the real streams needed to be able to design an optimum heat exchanger network. The procedure proposed in this paper permits, from so called interaction factors which characterize the interdependancy between streams, the determination of the massflows in each stream. The choice of the best heat exchanger network must respected, for each set of operational conditions, the optimum evaporation levels (including pressures and temperatures) determined in part I, as well as the particular practical operational factors (independence or not between the various heat recovery units, etc.). The network design is performed using the standard guidelines of pinch technology (respect of the minimum pinch ΔTmin for each heat exchanger close to the pinch temperature, separate design of the zone above and below the pinch temperature, etc). The respect of the ΔTmin in the critical zones of heat transfer requires the use of stream splitting and the network includes heat exchanger tubes which are interlaced at the same level of the stack. One example of the best performing power plant designed on the basis of this approach is given.
Article
Integrated solar combined cycle systems (ISCCS) represent, both economically and energetically, a promising alternative for the conversion of solar energy while offering a guarantee of a minimum power supply independant of the level of solar radiation. Their performances are however strongly dependant on the intensity of the solar input. The approach proposed in this paper allows, from the characteristics of the turbines (gas turbines and steam turbines) and of the solar field, to rationalize the choice of the pressure levels and of the massflows of a steam cycle with multiple pressure levels. It is based on the coupling of a pinch technology approach with a thermodynamic modeling allowing an optimisation with deterministic algorithms. Results are applied to a dual pressure steam cycle and accounts for the respect of the "cone law" for the steam turbines. It is shown that an increase of the exergetic losses linked to heat transfer in the steam generators is inevitable at certain operational regimes and depends directly on the level of solar supply. The variations of the main steam cycle parameters as a function of the thermal supply (combustion gases + solar thermal oil) are shown for an 80 to 120 MWel power plant equipped with two gas turbine and one steam turbine train.
Article
The integration of a solar collector field generating steam into a conventional combined cycle in order to partially replace the fossil fuel required by the latter results in a substantial reduction in greenhouse gases, in an increase in the return on investments associated with the solar field and in an almost complete elimination of the need for solar energy storage. This paper discusses the design of such an integrated hybrid solar-fossil combined cycle with maximum daily and nightly power outputs of 88 MWe and 58 MWe, respectively. This cycle is currently being evaluated from a technical and economic risk feasibility standpoint for possible implementation as a pilot plant in Tunisia. This paper outlines pertinent design considerations utilized in the thermoeconomic optimization approach employed for developing the hybrid combined cycle proposed here. The approach shows that there are several advantages to this type of design when compared with a purely solar steam cycle or any of the several other hybrid solar concepts which exist today. In addition to these advantages, the design presented revolves around the definition of a number of degrees of freedom which allow the solar energy part of the cycle to be highly integrated into the conventional part. A discussion of them is given. Finally, from an environmental standpoint, the obvious advantage of this type of cycle is that due to the substitution of fossil fuel, there is a marked mitigation in CO2 and NOx emissions when compared to a conventional cycle and to other hybrid concepts. Pertinent results for these reductions are presented.
Article
Cet article présente un concept original de centrale électrothermosolaire comprenant des unités de puissance modulaires à cycles de Rankine superposés utilisant pour la première fois des expandeurs-génératuers hermétiques de type scroll, des capteurs à concentration à lamelles ajourées, et une évaporation et condensation directe des fluides de travail. Les performances expérimentales des principaux composants sont présentées.
Article
Parmi les techniques de conversion d'énergie solaire en électricité, la voie électrothermosolaire à l'aide de cycle de Rankine et de turbine à vapeur est, à grande échelle, celle qui permet de se rapprocher le plus du coût de production économiquement viable (320 MWe des centrales SEGS californiennes). Les progrès technologiques récents ouvrent des perspectives intéressantes aux concepts de centrales solaires hybrides avancés tels que : a) les concepts dits ISCCS (Integrated Solar Combined Cycle System) basés sur l'intégrtion de capteurs cylindro-paraboliques à des cycles combinés permettant d'optimiser autant que possible l'efficacité du cycle en mode fossile simple, et b) les concepts dits HSTS (Hybrid Solar Tower System) utilisant des héliostats à haut rendement de conversion permettant l'intégration du solaire à un niveau d'exergie plus élevé pour le préchauffage ou le chauffage complet en pointe de l'air de combustion des turbines à gaz. Le présent travail contribue au développment de nouveaux outils méthodologiques ouvrant la voie à la conception, à l'optimisation et à la réalisation de centrales solaires hybrides performantes.
Nouveau concept de lubrification appliqué a ` une turbine scroll au sein d'un cycle de Rankine
  • Kane M Favrat
Kane M, Favrat D. Nouveau concept de lubrification appliqué a ` une turbine scroll au sein d'un cycle de Rankine. Internal Report LENI no. 99.09i. Lausanne, Switzerland: EPFL, 1999.
Solar energy and the environment
  • O Y Goswami
Goswami OY. Solar energy and the environment. In: Szargut J, editor. ASME 1993 International Conference on Energy Systems and Ecology, Cracow, Poland, vol. 1. 1993. p. 77-85.
Centrale solaire hybrid. Final Report to Swiss Federal Office of Energy
  • M Kane
  • F Brand
  • D Favrat
Kane M, Brand F, Favrat D. Centrale solaire hybrid. Final Report to Swiss Federal Office of Energy, 1999.
Verein Deutscher Intgenieure): ORC-HP-Technology, Working fluid Problems in: VDI Bericht
VDI (Verein Deutscher Intgenieure): ORC-HP-Technology, Working fluid Problems in: VDI Bericht 539, VDI- Verlag Dusseldorf (1984).
Status Report on Solar Thermal Power Plants
  • Pilkington Solar
  • International Gmbh
Pilkington Solar International GmbH. Status Report on Solar Thermal Power Plants. ISBN 3-9804901-0-6. January 1996. Mühlengasse 7,D-50667, Köln, Germany.
Experimental investigation of a hermetic scroll expander-generator
  • R Zanelli
  • D Favrat
Zanelli R, Favrat D. Experimental investigation of a hermetic scroll expander-generator. In: Soedel W, editor. 12th International Compressor Engineering Conference, Purdue, USA. 1994. p. 459-64.
Nouveau concept de lubrification appliqué à une turbine scroll au sein d'un cycle de Rankine
  • M Kane
  • D Favrat
Kane M, Favrat D. Nouveau concept de lubrification appliqué à une turbine scroll au sein d'un cycle de Rankine. Internal Report LENI no. 99.09i. Lausanne, Switzerland: EPFL, 1999.