First and second law analysis of a new power and refrigeration thermodynamic cycle using a solar heat source (original) (raw)
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Journal of Solar Energy Engineering, 2003
Exergy thermodynamics is employed to analyze a binary ammonia water mixture thermodynamic cycle that produces both power and refrigeration. The analysis includes exergy destruction for each component in the cycle as well as the first law and exergy efficiencies of the cycle. The optimum operating conditions are established by maximizing the cycle exergy efficiency for the case of a solar heat source. Performance of the cycle over a range of heat source temperatures of 320–460°K was investigated. It is found that increasing the heat source temperature does not necessarily produce higher exergy efficiency, as is the case for first law efficiency. The largest exergy destruction occurs in the absorber, while little exergy destruction takes place in the boiler.
A combined thermal power and cooling cycle proposed by Goswami is under intensive investigation, both theoretically and experimentally. The proposed cycle combines the Rankine and absorption refrigeration cycles, using a binary ammonia-water mixture as the working fluid. This cycle can be used as a bottoming cycle using waste heat from a conventional power cycle or an independent cycle using low temperature sources such as geothermal and solar energy. Initial parametric studies of the cycle showed the potential for the cycle to be optimized for first or second law efficiency, as well as work or cooling output. For a solar heat source, optimization of the second law efficiency is most appropriate, since the spent heat source fluid is recycled through the solar collectors. The optimization results verified that the cycle could be optimized using the generalized reduced gradient method. Theoretical results were extended to include realistic irreversibilities in the cycle, in preparation for the experimental study. An experimental system was constructed to demonstrate the feasibility of the cycle and to compare the experimental results with the theoretical simulation. Results showed that the vapor generation and absorption condensation processes work experimentally. The potential for combined turbine work and refrigeration output was evidenced in operating the system. Analysis of losses showed where improvements could be made, in preparation for further testing over a broader range of operating parameters.
Theoretical Investigation of Solar Energy Driven Combined Power and Refrigeration Cycle
; This investigation is done for energy and exergy analysis of a combined power refrigeration cycle using oil as the heat transfer medium. This cycle is an integration of Rankine cycle for power production and ejector refrigeration cycle for cold production. The effects of parameters like; steam temperature, and the evaporator temperature of ejector have been observed on first and second law performance. The first law efficiency of solar driven combined cycle is found to be is 20% while second law efficiency is 11%.
Volume 6: Emerging Technologies: Alternative Energy Systems; Energy Systems: Analysis, Thermodynamics and Sustainability, 2009
A combined power/cooling cycle, which combines the Rankine and absorption refrigeration cycles, uses ammonia-water mixture as a working fluid and produces power and refrigeration while power is the primary goal. This cycle, also known as the Goswami Cycle, can be used as a bottoming cycle using waste heat from a conventional power cycle or as an independent cycle using low temperature sources such as geothermal and solar energy. This paper presents a parametric analysis of the combined cycle. Parametric study of the cycle was carried out in the commercial software Chemcad 6.1. The thermodynamic property data used in simulations were validated with experimental data. Chemcad model was also compared with simulations previously carried out in the process simulator Aspen Plus. The agreement between the two sets has proved the accuracy of the model developed in Chemcad. Then, optimum operating conditions were found for a range of ammonia concentration in the basic solution, isentropic expander efficiency and boiler pressure. It * Address all correspondence to this author. is shown that the cycle can be optimized for net work, cooling output, effective first and exergy efficiencies.
THERMODYNAMICS ANALYSIS AND OPTIMIZATION FOR A COMBINED POWER AND REFRIGERATION CYCLE
A combined thermal power and cooling cycle using the combination of a Rankine Cycle and the Goswami Cycle has been analyzed in this study to assess its performance. It can provide power output as well as refrigeration with power generation as a primary goal. The Goswami Cycle uses very high concentration ammonia vapor in the turbine which can be expanded to a very low temperature in the turbine without condensation. This cycle uses an absorption condensation process instead of the conventional condensation process. In this study combined thermal power and cooling cycle (Goswami & Rankine Cycle combined) is first optimized for maximum thermal efficiency and then it is compared with conventional system. The combined cycle is also analyzed for different fraction of steam extracted from a pass out turbine of the topping cycle (Rankine Cycle) as heating source to the bottoming cycle (Goswami Cycle). The proposed heating sources are the waste heat at the exit of back pressure turbine and extracted steam from pass-out turbine. The main parameters that can be varied to influence the cycle are the heat source temperature, boiler pressure, basic solution ammonia mass fraction, ratio of working and heating fluid flow rates, and absorber pressure and temperature. However, the study focuses on the impact of change in the ratio of working and heating fluid flow rates. The combined power and cooling cycle is optimized for the maximum thermal efficiency.
Combined Cycle for Power Generation and Refrigeration Using Low Temperature Heat Sources
International Journal of Energy Optimization and Engineering, 2014
A combined refrigeration and power cycle, which uses ammonia-water as the working fluid, is proposed by combining Rankine and vapour absorption cycles with an advantage of varying refrigeration capacity to power output ratio. The study investigates the usage of low temperature heat sources for the cycle operation. Results of parametric analysis are presented, which show the scope for optimization. Results of thermodynamic optimization of the cycle for second law efficiency performed using genetic algorithm for different ambient temperatures are also presented. The cycle shows good potential for obtaining refrigeration and power generation.
Analysis of a combined power and cooling cycle for low grade heat sources
This paper presents a parametric analysis of a combined power/cooling cycle, which combines the Rankine and absorption refrigeration cycles, uses ammonia-water mixture as the working fluid and produces power and refrigeration, while power is the primary goal. This cycle, also known as the Goswami Cycle, can be used as a bottoming cycle using waste heat from a conventional power cycle or as an independent cycle using lowtemperature sources such as geothermal and solar energy. Optimum operating conditions were found for a range of ammonia concentration in the basic solution, isentropic turbine efficiency and boiler pressure. It is shown that the cycle can be optimized for net work, cooling output, effective first law and exergy efficiencies. The effect of rectification cooling source (external and internal) on the cycle output was investigated, and it was found that an internal rectification cooling source always produces higher efficiencies. When ammonia vapor is superheated after the rectification process, cycle efficiencies increase but cooling output decreases.
Solar Energy, 2002
A new combined power/refrigeration cycle uses ammonia/ water mixture as a working fluid to produce both power and refrigeration in the same cycle. The cycle may be designed for various combinations of power and refrigeration. In an earlier paper by the authors, the cycle was optimized for efficiency, with power as the main intended output. This study puts an emphasis on the refrigeration part of the total output especially at low refrigeration temperatures. The objective was to find out what kind of outputs could be obtained at very low temperatures for a possible application in the Mars mission. The thermal performance of this cycle at different refrigeration temperatures has been found. At each refrigeration temperature, the cycle is optimized for maximum second law efficiency using Generalized Reduced Gradient (GRG) algorithm. It is found that refrigeration temperatures as low as 205 K may be achieved using this cycle. Generally, both first and second law efficiencies decrease when refrigeration temperature drops. For a re-circulating type of solar thermal system with a source temperature of 360K, the first and second law efficiencies increase slightly as the refrigeration temperature goes down from 265K to 245K and then decrease with the refrigeration temperature, giving a maximum second law efficiency of 63.7% at 245K.
Analysis of power and cooling cogeneration using ammonia-water mixture
Energy, 2010
Development of innovative thermodynamic cycles is important for the efficient utilization of lowtemperature heat sources such as solar, geothermal and waste heat sources. This paper presents a parametric analysis of a combined power/cooling cycle, which combines the Rankine and absorption refrigeration cycles, uses ammonia-water mixture as the working fluid and produces power and cooling simultaneously. This cycle, also known as the Goswami Cycle, can be used as a bottoming cycle using waste heat from a conventional power cycle or as an independent cycle using solar or geothermal energy. A thermodynamic study of power and cooling cogeneration is presented. The performance of the cycle for a range of boiler pressures, ammonia concentrations and isentropic turbine efficiencies are studied to find out the sensitivities of net work, amount of cooling and effective efficiencies. The roles of rectifier and superheater on the cycle performance are investigated. The cycle heat source temperature is varied between 90-170 C and the maximum effective first law and exergy efficiencies for an absorber temperature of 30 C are calculated as 20% and 72%, respectively. The turbine exit quality of the cycle for different boiler exit scenarios shows that turbine exit quality decreases when the absorber temperature decreases.
Energy and Exergy Analysis of Solar Triple Effect Refrigeration Cycle
Journal of Clean Energy Technologies
In this paper solar driven triple effect refrigeration cycle is investigated from the viewpoint of both energy and exergy concepts of thermodynamics. In this cycle ejector organic Rankine cycle, absorption refrigeration cycle and transcritical CO 2 refrigeration cycles are integrated in order to obtain a range of temperature for varied simultaneous use. Parabolic trough collectors are used to utilize solar thermal energy for driving the refrigeration cycles. Exergy analysis determines the destruction and losses of exergy in various components and hence in overall system. Exergy efficiencies provide measure of approach to ideality while exergy destruction and losses provide measure of the deviation from ideality. Energy efficiency is found to be around 16.42% while exergy efficiency is 1.64%. The maximum thermodynamic irreversibility occurs in parabolic trough collector, followed by generator of absorption refrigeration system, heat recover vapour generator and ejector.