Exergetic Analyses of a Particular Absorption Cooling System

2012 ◽  
Vol 326-328 ◽  
pp. 641-646 ◽  
Author(s):  
Nahla Bouaziz ◽  
D. Lounissi ◽  
Lakdar Kairouani ◽  
M. El Ganaoui
Keyword(s):  
Exergy Analysis ◽  
Cooling System ◽  
Working Fluid ◽  
Exergy Destruction ◽  
Mass Energy ◽  
Intermediate Pressure ◽  
Absorption Cooling ◽  
Energy And Exergy ◽  
Absorption Cycle ◽  
Absorption Cooling System

The objective of this work is to present an exergy analysis of a novel absorption configuration using water-ammonia as working fluid. The proposed configuration operates at three pressure levels. The absorber is at an intermediate pressure (Pint). A thermodynamic model based on the mass energy and exergy balances is developed for this purpose. The parameters analyzed are the refrigeration systems performance (COP), the exergy efficiency, the global exergy destruction in the system, the exergy destruction and the irreversibility in different components. The effects of generator, absorber, condenser and evaporator on the performance of the system are examined. Numerical results highlight the great importance of the intermediate pressure on the performance of the system and specially on reducing the operating generator temperature. Consequently, the intermediate pressure is directly responsible on the adaptability of the proposed cooling absorption cycle to low enthalpy sources.

scholarly journals Thermodynamic Analysis of a Solar Combined Ejector Absorption Cooling System

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Doniazed Sioud ◽  
Raoudha Garma ◽  
Ahmed Bellagi
Keyword(s):  
Cooling System ◽  
Lithium Bromide ◽  
Cooling Water ◽  
Double Effect ◽  
Cycle Performance ◽  
Working Fluid ◽  
Absorption Cooling ◽  
Single Effect ◽  
Absorption Cycle ◽  
Absorption Cooling System

The objective of this paper is to investigate theoretically a solar driven 60 kW absorption cooling system. The system is constituted of a combined ejector single-effect absorption cycle coupled with a linear Fresnel solar concentrator and using water/lithium bromide as working fluid. The combined ejector single-effect absorption cycle exhibits high performances, almost equal to that of double-effect absorption device. However, higher driving heat temperatures are required than in the case of conventional single-effect machines. A mathematical model is set up to analyze the optical performance of the linear Fresnel concentrator. Simulations are carried out to study the overall system performance COPsystem and the performances of the combined absorption machine COPcycle for generator driving temperatures and pressures in the ranges 180°C – 210°C and 198 kPa – 270 kPa, respectively. Further, the effect of operating parameters such as the cooling medium and chilled water temperatures is investigated. A maximum cycle performance of 1.03 is found for a generator pressure of 272 kPa and chilled and cooling water temperatures of 7°C and 25°C, respectively. A case study is investigated for a typical summer Tunisian day, from 8:00 to 18:00. The effect of ambient temperature and solar radiation on cycle and system performances is simulated. The optical performances of the concentrator are also analyzed. Simulation results show that between 11:00 and 14:00 the collector efficiency is 0.61 and that the COPcycle reaches values always higher than 0.9 and the COPsystem is larger than 0.55. Globally the performances of the investigated cycle are similar to those of double-effect conventional absorption system.

scholarly journals Energy and Exergy Analysis of Combined Organic Rankine Cycle-Single and Dual Evaporator Vapor Compression Refrigeration Cycle

2019 ◽  
Vol 9 (23) ◽  
pp. 5028 ◽  
Author(s):  
Pektezel ◽  
Acar
Keyword(s):  
Exergy Analysis ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Refrigeration Cycle ◽  
Vapor Compression ◽  
Exergy Destruction ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Vapor Compression Refrigeration

This paper presents energy and exergy analysis of two vapor compression refrigeration cycles powered by organic Rankine cycle. Refrigeration cycle of combined system was designed with single and dual evaporators. R134a, R1234ze(E), R227ea, and R600a fluids were used as working fluids in combined systems. Influences of different parameters such as evaporator, condenser, boiler temperatures, and turbine and compressor isentropic efficiencies on COPsys and ƞex,sys were analyzed. Second law efficiency, degree of thermodynamic perfection, exergy destruction rate, and exergy destruction ratio were detected for each component in systems. R600a was determined as the most efficient working fluid for proposed systems. Both COPsys and ƞex,sys of combined ORC-single evaporator VCR cycle was detected to be higher than the system with dual evaporator.

scholarly journals Energy, Conventional and Advanced Exergy Analysis of Low Temperature Geothermal Binary-flashing Cycle Using Zeotropic Mixtures

2022 ◽  
Author(s):  
Yuan Zhao ◽  
Bowen Du ◽  
Shunyi Chen ◽  
Jun Zhao ◽  
Lingbao Wang
Keyword(s):  
Exergy Analysis ◽  
Working Fluid ◽  
Total System ◽  
Exergy Destruction ◽  
High Pressure Pump ◽  
Pressure Pump ◽  
Energy And Exergy ◽  
Energy Conversion Systems ◽  
Power Generation Technology ◽  
Net Power Output

Abstract Due to deep utilization of geobrine and high net power output, binary flashing cycle (BFC) is deemed to be the future geothermal energy power generation technology. The BFC using R245/R600a zeotropic mixtures is presented in this paper. The thermodynamic model of the system is built, and energy, conventional and advanced exergy analysis are carried out, to reveal the real optimization potential. It is demonstrated that the optimal composition mass fraction of R245fa and dryness of working fluid at the evaporator outlet ranges are 0.30~0.50 and 0.40~0.60, considering the thermodynamic performance and the flammability of the mixtures, simultaneously. Conventional exergy analysis indicates that the maximum exergy destruction occurs in condenser, followed by expander, evaporator, flashing tank, preheater, high-pressure pump and low-pressure pump. While the advanced exergy analysis reveals that the expander should be given the first priority for optimization, followed by condenser and evaporator. The BFC has a large potential for improvement due to higher avoidable exergy destruction, about 48.6% of the total system exergy destruction can be reduced. And the interconnections among system components are not very strong, owing to small exogenous exergy destructions. It also demonstrates the effectiveness of advanced exergy analysis, and the approach can be extended to other energy conversion systems to maximize the energy and exergy savings for sustainable development.

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