Theoretical Analysis of Ammonia-Based Combined Power/Refrigeration Cycle at Low Refrigeration Temperatures

Solar Energy ◽  
2002 ◽  
Author(s):  
Shaoguang Lu ◽  
D. Yogi Goswami
Keyword(s):  
Low Temperatures ◽  
Working Fluid ◽  
Total Output ◽  
Second Law ◽  
Refrigeration Cycle ◽  
Thermal System ◽  
Water Mixture ◽  
Reduced Gradient ◽  
Generalized Reduced Gradient ◽  
Solar Thermal System

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.

Optimization of a Novel Combined Power/Refrigeration Thermodynamic Cycle

Solar Energy ◽  
2002 ◽  
Author(s):  
Shaoguang Lu ◽  
D. Yogi Goswami
Keyword(s):  
Waste Heat ◽  
Thermodynamic Cycle ◽  
Cycle Performance ◽  
Working Fluid ◽  
Second Law ◽  
Optimum Conditions ◽  
Ambient Temperatures ◽  
Reduced Gradient ◽  
Generalized Reduced Gradient ◽  
Performance Conditions

A novel combined power/refrigeration thermodynamic cycle is optimized for thermal performance in this paper. The cycle uses ammonia-water binary mixture as a working fluid and can be driven by various heat sources, such as solar, geothermal and low temperature waste heat. It could produce power as well as refrigeration with power output as a primary goal. The optimization program, which is based on the Generalized Reduced Gradient (GRG) algorithm, can be used to optimize for different objective functions. Examples that maximize second law efficiency, work output and refrigeration output are presented, showing the cycle may be optimized for any desired performance parameter. In addition, cycle performance over a range of ambient temperatures was investigated. It was found that for a source temperature of 360K, which is in the range of flat plate solar collectors, both power and refrigeration outputs are achieved under optimum conditions. All performance parameters, including first and second law efficiencies, power and refrigeration output decrease as the ambient temperature goes up. On the other hand, for a source of 440K, optimum conditions do not provide any refrigeration. However, refrigeration can be obtained even for this temperature under non-optimum performance conditions.

A Novel Combined Power and Cooling Thermodynamic Cycle for Low Temperature Heat Sources: Part I — Theoretical Investigation

Solar Energy ◽  
2002 ◽  
Author(s):  
Gunmar Tamm ◽  
D. Yogi Goswami ◽  
Shaoguang Lu ◽  
Afif A. Hasan
Keyword(s):  
Low Temperature ◽  
Heat Source ◽  
Waste Heat ◽  
Thermal Power ◽  
Thermodynamic Cycle ◽  
Working Fluid ◽  
Second Law ◽  
Water Mixture ◽  
Reduced Gradient Method ◽  
Generalized Reduced Gradient

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, producing refrigeration while power is the primary goal. A binary ammonia-water mixture is used 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.

On Evaluating Efficiency of a Combined Power and Cooling Cycle

2003 ◽  
Vol 125 (3) ◽  
pp. 221-227 ◽  
Author(s):  
Sanjay Vijayaraghavan ◽  
D. Y. Goswami
Keyword(s):  
Rankine Cycle ◽  
Exergy Efficiency ◽  
Combined Cycle ◽  
Maximum Efficiency ◽  
Second Law ◽  
Refrigeration Cycle ◽  
Absorption Refrigeration ◽  
Cooling Cycle ◽  
Reduced Gradient ◽  
Generalized Reduced Gradient

A combined power and cooling cycle is being investigated. The cycle is a combination of the Rankine cycle and an absorption refrigeration cycle. Evaluating the efficiency of this cycle is made difficult by the fact that there are two different simultaneous outputs, namely power and refrigeration. An efficiency expression has to appropriately weigh the cooling component in order to allow comparison of this cycle with other cycles. This paper develops several expressions for the first law, second law and exergy efficiency definitions for the combined cycle based on existing definitions in the literature. Some of the developed equations have been recommended for use over others, depending on the comparison being made. Finally, some of these definitions have been applied to the cycle and the performance of the cycle optimized for maximum efficiency. A Generalized Reduced Gradient (GRG) method was used to perform the optimization. The results of these optimizations are presented and discussed.

On Evaluating Efficiency of a Combined Power and Cooling Cycle

2002 ◽  
Author(s):  
Sanjay Vijayaraghavan ◽  
D. Yogi Goswami
Keyword(s):  
Rankine Cycle ◽  
Exergy Efficiency ◽  
Combined Cycle ◽  
Maximum Efficiency ◽  
Second Law ◽  
Refrigeration Cycle ◽  
Absorption Refrigeration ◽  
Cooling Cycle ◽  
Reduced Gradient ◽  
Generalized Reduced Gradient

A combined power and cooling cycle is being investigated. The cycle is a combination of the Rankine cycle and an absorption refrigeration cycle. Evaluating the efficiency of this cycle is made difficult by the fact that there are two different simultaneous outputs, namely power and refrigeration. An efficiency expression has to appropriately weigh the cooling component in order to allow comparison of this cycle with other cycles. This paper develops several expressions for the first law, second law and exergy efficiency definitions for the combined cycle based on existing definitions in the literature. Some of the developed equations have been recommended for use over others, depending on the comparison being made. Finally, some of these definitions have been applied to the cycle and the performance of the cycle optimized for maximum efficiency. A Generalized Reduced Gradient (GRG) method was used to perform the optimization. The results of these optimizations are presented and discussed.

scholarly journals Thermodynamic analysis and simulation of a new combined power and refrigeration cycle using artificial neural network

2011 ◽  
Vol 15 (1) ◽  
pp. 29-41 ◽  
Author(s):  
Abdolreza Fazeli ◽  
Hossein Rezvantalab ◽  
Farshad Kowsary
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Heat Source ◽  
Exergy Efficiency ◽  
Combined Cycle ◽  
Cycle Performance ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Water Mixture ◽  
Artificial Neural

In this study, a new combined power and refrigeration cycle is proposed, which combines the Rankine and absorption refrigeration cycles. Using a binary ammonia-water mixture as the working fluid, this combined cycle produces both power and refrigeration output simultaneously by employing only one external heat source. In order to achieve the highest possible exergy efficiency, a secondary turbine is inserted to expand the hot weak solution leaving the boiler. Moreover, an artificial neural network (ANN) is used to simulate the thermodynamic properties and the relationship between the input thermodynamic variables on the cycle performance. It is shown that turbine inlet pressure, as well as heat source and refrigeration temperatures have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. In addition, the results of ANN are in excellent agreement with the mathematical simulation and cover a wider range for evaluation of cycle performance.

A Totally Heat-Driven Refrigeration System Using Low-Temperature Heat Sources for Low-Temperature Applications

2019 ◽  
Vol 27 (02) ◽  
pp. 1950012 ◽  
Author(s):  
Zeynab Seyfouri ◽  
Mehran Ameri ◽  
Mozaffar Ali Mehrabian
Keyword(s):  
Low Temperature ◽  
Heat Source ◽  
Rankine Cycle ◽  
Exergy Efficiency ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Water Mixture ◽  
Refrigeration System ◽  
Power Requirement ◽  
Temperature Heat

In the present study, a totally heat-driven refrigeration system is proposed and thermodynamically analyzed. This system uses a low-temperature heat source such as geothermal energy or solar energy to produce cooling at freezing temperatures. The proposed system comprises a Rankine cycle (RC) and a hybrid GAX (HGAX) refrigeration cycle, in which the RC provides the power requirement of the HGAX cycle. An ammonia–water mixture is used in both RC and HGAX cycles as the working fluid. A comparative study is conducted in which the proposed system is compared with two other systems using GAX cycle and/or a single stage cycle, as the refrigeration cycle. The study shows that the proposed system is preferred to produce cooling at temperatures from 2∘C to [Formula: see text]C. A detailed parametric analysis of the proposed system is carried out. The results of the analysis show that the system can produce cooling at [Formula: see text]C using a low-temperature heat source at 133.5∘C with the exergy efficiency of about 20% without any input power. By increasing the heat source temperature to 160∘C, an exergy efficiency of 25% can be achieved.

Development and Simulation of a Magnetohydrodynamic Solar Generator Operated With NaCl Electrolyte Solution

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Steffanie Jiménez-Flores ◽  
J. Guillermo Pérez-Luna ◽  
J. Joaquín Alvarado-Pulido ◽  
Antonio E. Jiménez-González
Keyword(s):  
Current Density ◽  
Check Valve ◽  
Electrical Energy ◽  
Solar Thermal ◽  
Working Fluid ◽  
Thermal System ◽  
Mhd Generator ◽  
Solar Generator ◽  
Neodymium Magnets ◽  
Solar Thermal System

Abstract A magnetohydrodynamic (MHD) generator is a device that generates electrical energy through the interaction between a conductive fluid and a magnetic field. This method of direct energy conversion allows the use of a renewable energy source such as solar energy and represents an alternative to tackle the greenhouse effect. This paper presents the development of an MHD solar generator, which is constituted by a solar thermal system and an MHD cell. The solar thermal system consists of a set of tubes with copper fins, connected in parallel and placed inside of a 1 m2 panel. In which, an electrolytic mixture of H2O and NaCl at 20% vol. was introduced as a working fluid. In order to increase the kinetic energy of the fluid, the panel was exposed to solar radiation, where it reached temperatures above 373 K and pressures above 96 kPa. This solar thermal system operates in closed cycle conditions by including a check valve in its inlet–outlet junction; in this way, the fluid travels through the MHD generator. The MHD cell was composed of a block of polytetrafluoroethylene, two cylindrical stainless-steel electrodes, and four neodymium magnets. For simulation purposes, comsol multiphysics was used to reproduce the current density produced by the MHD solar generator. Pressure and temperature quantities obtained experimentally in the MHD cell were employed as boundary conditions. The experimental maximal current density obtained corresponds to 4.30 mA/m2, and the comparison between theoretical and experimental results shows that the model fits fairly well.

Analysis of a Combined Power and Refrigeration Cycle Working on Solar Energy

2008 ◽  
Author(s):  
Bijan Kumar Mandal ◽  
Kousik Sadhukhan ◽  
Achin Kumar Chowdhuri ◽  
Arup Jyoti Bhowal
Keyword(s):  
Solar Energy ◽  
Working Conditions ◽  
Exergy Efficiency ◽  
Combined Cycle ◽  
Cooling Effect ◽  
Second Law ◽  
Carnot Cycle ◽  
Refrigeration Cycle ◽  
Water Mixture ◽  
The Ideal

Thermodynamic analysis of a combined cycle producing power and refrigeration (cooling) effect simultaneously using solar energy has been analyzed. The working substance of the cycle is a binary mixture of ammonia and water. The effect of variation of absorber pressure, boiler pressure, boiler temperature and superheater temperature on the turbine work, refrigeration (cooling) effect and net output has been investigated. For different conditions of the above variables, the first law efficiency, the second law efficiency and the exergy efficiency of the cycle have been investigated. Since the ammonia water mixture boils at varying temperatures, Lorenz cycle instead of Carnot cycle is considered as the ideal cycle for this analysis. It is observed that the first law and the second law efficiencies are maximum under the same working conditions, but the exergy efficiency is maximum at some other working conditions. The maximum values of the first law, the second law and the exergy efficiencies are found to be 21.72%, 27.30% and 62.53% respectively.

Optimization of a Novel Combined Power/Refrigeration Thermodynamic Cycle

2003 ◽  
Vol 125 (2) ◽  
pp. 212-217 ◽  
Author(s):  
Shaoguang Lu ◽  
D. Yogi Goswami
Keyword(s):  
Waste Heat ◽  
Thermodynamic Cycle ◽  
Gradient Algorithm ◽  
Cycle Performance ◽  
Working Fluid ◽  
Heat Sources ◽  
Objective Functions ◽  
Ambient Temperatures ◽  
Reduced Gradient ◽  
Generalized Reduced Gradient

A novel combined power/refrigeration thermodynamic cycle is optimized for thermal performance in this paper. The cycle uses ammonia-water binary mixture as a working fluid and can be driven by various heat sources, such as solar, geothermal, and low temperature waste heat. The optimization program, which is based on the Generalized Reduced Gradient algorithm, can be used to optimize for different objective functions. In addition, cycle performance over a range of ambient temperatures was investigated.

Novel Combined Power and Cooling Thermodynamic Cycle for Low Temperature Heat Sources, Part I: Theoretical Investigation

2003 ◽  
Vol 125 (2) ◽  
pp. 218-222 ◽  
Author(s):  
Gunnar Tamm ◽  
D. Yogi Goswami ◽  
Shaoguang Lu ◽  
Afif A. Hasan
Keyword(s):  
Low Temperature ◽  
Heat Source ◽  
Waste Heat ◽  
Thermal Power ◽  
Thermodynamic Cycle ◽  
Working Fluid ◽  
Second Law ◽  
Water Mixture ◽  
Parametric Studies ◽  
Intensive Investigation

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, producing refrigeration while power is the primary goal. A binary ammonia-water mixture is used as the working fluid. This 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. 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. Theoretical results were extended to include realistic irreversibilities in the cycle, in preparation for the experimental study.

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