Exergy Analysis of a Solar-Driven Dual Parallel-Connected Ejector Refrigeration System

2016 ◽  
Vol 839 ◽  
pp. 100-106
Author(s):  
Yahya Gaafar Abdella Mohammed ◽  
Tawat Suriwong ◽  
Sakda Somkun ◽  
Timeyo Mkamanga Maroyi
Keyword(s):  
Solar Collector ◽  
Exergy Analysis ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Saturated Steam ◽  
Working Fluid ◽  
Electric Heater ◽  
Exergy Destruction ◽  
Refrigeration System ◽  
Exergetic Efficiency

Nowadays, developing solar cooling technologies, especially ejector refrigeration system, has become preferable to scientific researchers. Exergy analysis is a technique in which the basis of evaluation of thermodynamic losses follows the second law rather than the first law of thermodynamics. An experimental exergy analysis of a solar-driven dual parallel-connected ejector (DPE) refrigeration system was conducted using water as working fluid. Saturated steam with 2 bar and 120oC was provided by heat–pipe evacuated tube solar collector with an assistant of an electric heater. The saturated stream was used as a motive flow for the ejectors. The exergy destruction and exergetic efficiency of the main components of the DPE refrigeration system were determined and compared with those when using a single ejector (SE) under same operating conditions. It was found that the most irreversibilities of both systems occurred at the solar collector, electric boiler and ejectors, respectively. Also, the total irreversibility (Exergy destruction) of the system when using DPE was lower than using a SE. In additions, the exergetic efficiency of the ejector, evaporator, and overall system when using DPE were increased by 21%, 10%, and 27%, respectively. The system thermal ratio (STR) and coefficient of performance (COP) of the system using DPE compared with SE were increased by 20% and 23%, respectively.

scholarly journals Exergy Analysis of VCR Systemwith Air-Cooled Condenser Working with Refrigerants R-134a & Hydrocarbon

2019 ◽  
Vol 9 (2) ◽  
pp. 2834-2839
Keyword(s):  
Global Warming ◽  
Global Warming Potential ◽  
Exergy Analysis ◽  
Exergy Destruction ◽  
Refrigeration System ◽  
Exergetic Efficiency ◽  
Domestic Refrigerator ◽  
R 134A ◽  
Main Components ◽  
Vapour Compression

This paper gives a detailed exergy analysis of a Vapour Compression Refrigeration System with the refrigerants R-134a and HC (mixture of R-290/R-600a). The aim of this paper is to find out the Exergy Analysis, Exergetic efficiency, Exergy Product, Exergy Destruction Ratio (EDR), Co-efficient of performance and 2nd law efficiency for the main components of the system such as compressor, condenser, evaporator and expansion device (throttle valve). The objective of this work is to find out an exergy analysis of the Hydrocarbon refrigerant as an alternative for R-134a. The VCRS performance using R134a will be evaluated for the effect of evaporating temperature on COP, exergetic efficiency and EDR and then compared with Hydrocarbon refrigerant. Due to prevention of GWP (Global Warming Potential), Hydrocarbon and R-134a are used as refrigerants to give better result for domestic refrigerator operation[8] .

scholarly journals Energy and exergy analysis of vapour compression refrigeration system using selected eco-friendly hydrocarbon refrigerants enhanced with tio2-nanoparticle

2017 ◽  
Vol 6 (4) ◽  
pp. 91 ◽  
Author(s):  
Luke Ajuka ◽  
Moradeyo Odunfa ◽  
Olayinka Ohunakin ◽  
Miracle Oyewola
Keyword(s):  
Power Consumption ◽  
Exergy Analysis ◽  
Capillary Tube ◽  
Coefficient Of Performance ◽  
Refrigeration System ◽  
Exergetic Efficiency ◽  
Evaporator Temperature ◽  
Energy And Exergy ◽  
Nano Lubricant ◽  
Energy And Exergy Analysis

The experimental study investigated the energy and exergy performance of a domestic refrigerator using eco-friendly hydrocarbon refrigerants R600a and LPG (R290/R600a: 50%/50%) at 0, 0.05, 0.15 and 0.3wt % concentrations of 15nm particle size of TiO2 nano-lubricant, and R134a. The effects of evaporator temperature on power consumption, coefficients of performance, exergetic efficiency and efficiency defects in the compressor, condenser, capillary tube and evaporator of the system were examined. The results showed that LPG + TiO2 (0.15wt %) and R600a + TiO2 (0. 15wt %) had the best of performances with an average of 27.6% and 14.3% higher coefficient of Performance, 34.6% and 35.15% lower power consumption, 13.8% and 17.53% higher exergetic efficiency, a total exergetic defect of 45.8% and 64.7% lower compared to R134a. The exergetic defects in the evaporator, compressor, condenser, and capillary tube were 38.27% and 35.5%, 49.19% and 55.56%, 29.7% and 33.7%, 39.1% and 73.8% lower in the system when compared to R134a respectively. Generally, the refrigerants with nano-lubricant mixture gave better results with an appreciable reduction in the exergy defect in the compressor than the pure refrigerants, and LPG + TiO2 (0. 15wt %) gave the best result in the refrigeration system based on energy and exergy analysis.

scholarly journals Exergetic performance analysis of low GWP alternative refrigerants for R404A in a refrigeration system

2021 ◽  
Author(s):  
Mehmet Altinkaynak
Keyword(s):  
Cooling System ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Refrigeration System ◽  
Alternative Refrigerants ◽  
Condenser Temperature ◽  
Parametric Analyses ◽  
Low Global Warming Potential ◽  
Very High

Abstract According to the regulation of European Union laws in 2014, it was inevitable to switch to low global warming potential (GWP) fluids in the refrigeration systems where the R404A working fluid is currently used. The GWP of R404A is very high, and the potential for ozone depletion is zero. In this study, energetic and exergetic performance assessment of a theoretical refrigeration system was carried out for R404 refrigerant and its alternatives, comparatively. The analyses were made for R448A, R449A, R452A and R404A. The results of the analysis were presented separately in the tables and graphs. According to the results, the cooling system working with R448A exhibited the best performance with a coefficient of performance (COP) value of 2.467 within the alternatives of R404A followed by R449A and R452A, where the COP values were calculated as 2.419 and 2.313, respectively. In addition, the exergy efficiencies of the system were calculated as 20.62%, 20.22% and 19.33% for R448A, R449A and R452A, respectively. For the base calculations made for R404A, the COP of the system was estimated as 2.477, where the exergy efficiency was 20.71%. Under the same operating conditions, the total exergy destruction rates for R404A, R448A, R449A and R452A working fluids were found to be 3.201 kW, 3.217 kW, 3.298 kW and 3.488 kW, respectively. Furthermore, parametric analyses were carried out in order to investigate the effects of different system parameters such as evaporator and condenser temperature.

scholarly journals Energetic Optimization and Exergetic Performance Investigation of an Ejector System Using HCFO-1233zd(E) as a Refrigerant

2021 ◽  
Author(s):  
Aggrey Mwesigye ◽  
Amir Kiamari ◽  
Seth B. Dworkin
Keyword(s):  
Exergy Analysis ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Small Contribution ◽  
Analysis Method ◽  
Refrigeration System ◽  
Critical Mode ◽  
Mode Of Operation ◽  
Ejector System ◽  
Loss Coefficients

In this study, the performance of an ejector refrigeration system using HCFO-1233zd(E) as the working fluid is investigated and presented. A novel improved modeling approach that considers ejector loss coefficients as functions of the ejector pressure lift and area ratio has been used. The resulting mathematical model developed using the first and second laws of thermodynamics and gas dynamics is solved using Engineering Equation Solver. Different ejector geometries with area ratios of 6.44, 7.04, 7.51, 7.73, 8.28, 8.62, 9.13, 9.41 and 10.64 were used in this study. The evaporator temperatures were between 0 °C and 16 °C, the generator temperatures were between 75 °C and 120 °C and the condensing temperatures varied between 20 °C and 40 °C. For the range of parameters used, the optimal coefficient of performance (COP) is in the range 0.11 and 0.88 for evaporator temperatures between 4 °C and 16 °C. At the optimal working conditions, the COP improves with higher area ratios, lower condensing temperatures and requires increased generator temperatures. In the critical mode of operation, both the energetic and exegetic performance of the ejector are shown to decline as generator temperatures increase, evaporator temperatures reduce and as the area ratios decrease. Thermodynamic investigation using the exergy analysis method indicates that most of the exergetic losses come from the ejector (46-56%) followed by the condenser (18-29%), the generator (21-26%), the evaporator (0.8-3%), and the throttle valve (1- 1.6%), with the pump having a very small contribution. Moreover, correlations for the optimal generator and optimal COP were derived and presented. Keywords: Coefficient of performance, Critical mode, Ejector refrigeration system, Ejector loss coefficients, Exergetic performance, Hydroflouroolefins

Investigation on the Optimum Performance of an Irreversible Solar Powered Absorption Refrigeration System

2011 ◽  
Author(s):  
Fang Wei ◽  
Houcheng Zhang ◽  
Lanmei Wu ◽  
Guoxing Lin
Keyword(s):  
Heat Transfer ◽  
Heat Loss ◽  
Solar Collector ◽  
Optimal Parameter ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Absorption Refrigeration ◽  
Refrigeration System ◽  
Absorption Refrigeration System ◽  
Solar Powered

An irreversible solar powered absorption refrigeration system is put forward, in which finite-rate heat transfer with the convection mode from the solar collector to the absorption refrigerator and the radiation-convection heat loss from the solar collector to the ambient, the internal irreversibility inside the working fluid are taken into account. On the basis of thermodynamic analysis and log mean temperature difference (LMTD) methods, the expression between the overall coefficient of performance (COP) of the solar powered absorption refrigeration system and the operating temperature of the solar collector is derived. The influences of heat loss of the solar collector, the irreversibility inside the working fluid, the isobaric temperature ratio, the ratio of heat-transfer coefficients on the optimal performance characteristic of the solar powered absorption refrigeration system are revealed. The results obtained in the present paper are helpful to the optimal parameter design of actual solar powered absorption refrigerators.

scholarly journals Energetic Optimization and Exergetic Performance Investigation of an Ejector System Using HCFO-1233zd(E) as a Refrigerant

2021 ◽  
Author(s):  
Aggrey Mwesigye ◽  
Amir Kiamari ◽  
Seth B. Dworkin
Keyword(s):  
Exergy Analysis ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Small Contribution ◽  
Analysis Method ◽  
Refrigeration System ◽  
Critical Mode ◽  
Mode Of Operation ◽  
Ejector System ◽  
Loss Coefficients

In this study, the performance of an ejector refrigeration system using HCFO-1233zd(E) as the working fluid is investigated and presented. A novel improved modeling approach that considers ejector loss coefficients as functions of the ejector pressure lift and area ratio has been used. The resulting mathematical model developed using the first and second laws of thermodynamics and gas dynamics is solved using Engineering Equation Solver. Different ejector geometries with area ratios of 6.44, 7.04, 7.51, 7.73, 8.28, 8.62, 9.13, 9.41 and 10.64 were used in this study. The evaporator temperatures were between 0 °C and 16 °C, the generator temperatures were between 75 °C and 120 °C and the condensing temperatures varied between 20 °C and 40 °C. For the range of parameters used, the optimal coefficient of performance (COP) is in the range 0.11 and 0.88 for evaporator temperatures between 4 °C and 16 °C. At the optimal working conditions, the COP improves with higher area ratios, lower condensing temperatures and requires increased generator temperatures. In the critical mode of operation, both the energetic and exegetic performance of the ejector are shown to decline as generator temperatures increase, evaporator temperatures reduce and as the area ratios decrease. Thermodynamic investigation using the exergy analysis method indicates that most of the exergetic losses come from the ejector (46-56%) followed by the condenser (18-29%), the generator (21-26%), the evaporator (0.8-3%), and the throttle valve (1- 1.6%), with the pump having a very small contribution. Moreover, correlations for the optimal generator and optimal COP were derived and presented. Keywords: Coefficient of performance, Critical mode, Ejector refrigeration system, Ejector loss coefficients, Exergetic performance, Hydroflouroolefins

Exergetic efficiency optimization of a refrigeration system with multi-irreversibilities

2006 ◽  
Vol 220 (8) ◽  
pp. 1179-1187 ◽  
Author(s):  
Y-F Su ◽  
C-K Chen
Keyword(s):  
Heat Exchangers ◽  
Thermal Conductance ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Refrigeration System ◽  
Exergetic Efficiency ◽  
Cold Side ◽  
Finite Rate ◽  
Efficiency Optimization ◽  
Internal Dissipation

Exergetic efficiency optimization has been carried out for a refrigeration system with multi-irreversibilities, including finite-rate heat transfer, internal dissipation of the working fluid and heat leak between the heat reservoirs. The exergetic efficiency is defined as the ratio of the rate of exergy output to the rate of exergy input in the refrigeration system and is considered as an objective function to be maximized. By combining the exergy concept and finite-time thermodynamic theory, the maximum exergetic efficiency is determined analytically. The optimum values of the cycle cooling rate and the coefficient of performance of the system are obtained simultaneously. The influences of various parameters on the maximum exergetic efficiency are investigated by numerical calculation. The allocation problem of a fixed total thermal conductance between the hot-side and the cold-side heat exchangers is also studied. The results show that the method of exergetic efficiency optimization is practical and effective for the evaluation of an irreversible refrigeration system.

Exergy Analysis of a Combined Power and Refrigeration Thermodynamic Cycle Driven by a Solar Heat Source

2003 ◽  
Vol 125 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Afif Akel Hasan ◽  
D. Y. Goswami
Keyword(s):  
Heat Source ◽  
Exergy Analysis ◽  
Thermodynamic Cycle ◽  
Exergy Efficiency ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Water Mixture ◽  
Exergy Destruction ◽  
Ammonia Water ◽  
Solar Heat

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.

An Experimental Investigation on Vapor Compression Refrigeration System Cascaded with Ejector Refrigeration System

2021 ◽  
pp. 2150028
Author(s):  
Vikas Kumar ◽  
Gulshan Sachdeva ◽  
Sandeep Tiwari ◽  
Parinam Anuradha ◽  
Vaibhav Jain
Keyword(s):  
Experimental Investigation ◽  
Thermal Equilibrium ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Compression System ◽  
Vapor Compression System ◽  
Vapor Compression Refrigeration ◽  
Cascaded System

A conventional vapor compression refrigeration system (VCRS) cascaded with a heat-assisted ejector refrigeration system (ERS) has been experimentally analyzed. Cascading allows the VCRS to operate at lower condenser temperatures and thus achieve a higher coefficient of performance. In this cascaded system, the condenser of the vapor compression system does not dissipate its heat directly to the evaporator of the ERS; instead, water circulates between the condenser of VCRS and the evaporator of ERS to exchange the heat. Seven ejectors of different geometries have been used in the ERS; however, all the ejectors could not maintain thermal equilibrium at the desired operating conditions. The compressor of the cascaded VCRS consumed 1.3 times less power than the noncascaded VCRS. Furthermore, the cascaded system provided a maximum 87.74% improvement in COP over the noncascaded system for the same operating conditions. The performance of the system remained constant until the critical condenser pressure of the ERS.

scholarly journals Exergetic and Economic Evaluation of a Transcritical Heat-Driven Compression Refrigeration System with CO2 as the Working Fluid under Hot Climatic Conditions

Entropy ◽  
2019 ◽  
Vol 21 (12) ◽  
pp. 1164 ◽  
Author(s):  
Jing Luo ◽  
Tatiana Morosuk ◽  
George Tsatsaronis ◽  
Bourhan Tashtoush
Keyword(s):  
Ambient Temperature ◽  
Climatic Conditions ◽  
Working Fluid ◽  
Refrigeration System ◽  
Exergetic Efficiency ◽  
Evaporation Temperature ◽  
Aspen Hysys ◽  
Operation Conditions ◽  
Heating Capacity ◽  
Refrigeration Machine

The purpose of this research is to evaluate a transcritical heat-driven compression refrigeration machine with CO2 as the working fluid from thermodynamic and economic viewpoints. Particular attention was paid to air-conditioning applications under hot climatic conditions. The system was simulated by Aspen HYSYS® (AspenTech, Bedford, MA, USA) and optimized by automation based on a genetic algorithm for achieving the highest exergetic efficiency. In the case of producing only refrigeration, the scenario with the ambient temperature of 35 °C and the evaporation temperature of 5 °C showed the best performance with 4.7% exergetic efficiency, while the exergetic efficiency can be improved to 22% by operating the system at the ambient temperature of 45 °C and the evaporation temperature of 5 °C if the available heating capacity within the gas cooler is utilized (cogeneration operation conditions). Besides, an economic analysis based on the total revenue requirement method was given in detail.

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