Optimization on the Performance Characteristics of a Magnetic Ericsson Refrigeration Cycle Affected by Multi-Irreversibilities

2003 ◽  
Vol 125 (4) ◽  
pp. 318-324 ◽  
Author(s):  
Jizhou He ◽  
Jincan Chen ◽  
Chih Wu
Keyword(s):  
Cooling Rate ◽  
External Heat ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Cycle Model ◽  
Optimal Operating ◽  
Finite Rate ◽  
Operating Region ◽  
Maximum Coefficient ◽  
Optimum Relation

A general irreversible cycle model of a magnetic Ericsson refrigerator is established. The irreversibilities in the cycle model result from the finite-rate heat transfer between the working substance and the external heat reservoirs, the inherent regenerative loss, the additional regenerative loss due to thermal resistances, and the heat leak loss between the external heat reservoirs. The cycle model is used to optimize the performance of the magnetic Ericsson refrigeration cycle. The fundamental optimum relation between the cooling rate and the coefficient of performance of the cycle is derived. The maximum coefficient of performance, maximum cooling rate and other relevant important parameters are calculated. The optimal operating region of the cycle is determined. The results obtained here are very general and will be helpful for the optimal design and operation of the magnetic Ericsson refrigerators.

Experimental Evaluation of Window-Type Air-Conditioning Unit with New Expansion Device and R404A Alternative Refrigerant

2020 ◽  
Vol 28 (04) ◽  
pp. 2050031
Author(s):  
Ali K. Shaker Al-Sayyab
Keyword(s):  
Experimental Evaluation ◽  
Air Conditioning ◽  
Capillary Tube ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Cycle Model ◽  
Ansys Fluent ◽  
Compressor Power

In this study, the performance of a window-type air-conditioning unit with an alternative, ozone-friendly refrigerant was enhanced by incorporating a nozzle instead of a capillary tube as an expansion device. An experimental evaluation was adopted on a 1.5 RT window-type air-conditioning unit with a controlled environmental zone. According to operating conditions, an ANSYS-Fluent program was used to predict an appropriate nozzle size for a lower pressure ratio. The refrigeration cycle model was simulated using the Engineering Equation Solver (EES).27 The results showed that using a nozzle of 30[Formula: see text]mm length and inner and outer diameters of 9 and 2[Formula: see text]mm, respectively instead of the capillary tube with R404A reduces compressor power consumption by 7.7% and increases the coefficient of performance (COP) by 7.4%.

THE INFLUENCE OF HEAT LEAKAGE AND INTERNAL IRREVERSIBILITY ON THE PERFORMANCE OF A QUANTUM SPIN REFRIGERATION CYCLE

2010 ◽  
Vol 24 (23) ◽  
pp. 4595-4610
Author(s):  
JI-ZHOU HE ◽  
JIAN-HUI WANG ◽  
XIN-FA DENG
Keyword(s):  
Entropy Production ◽  
Cooling Rate ◽  
Rate Coefficient ◽  
Power Input ◽  
Quantum Spin ◽  
Coefficient Of Performance ◽  
Quantum Master Equation ◽  
Refrigeration Cycle ◽  
Heat Leakage ◽  
Internal Irreversibility

The cycle model established here, for which the heat leakage and internal irreversibility are considered, consists of two irreversible non-isentropic adiabatic and two isomagnetic field processes. The working substance is composed of many non-interacting spin systems. Based on quantum master equation of an open system in the Heisenberg picture and semi-group approach, the general performance analysis of quantum refrigeration cycle is performed. Expressions for several important performance parameters, such as the cooling rate, coefficient of performance, rate of entropy production and power input, are derived. By using numerical calculations, the cooling rate as a natural optimization goal for a refrigerator is optimized with respect to external magnetic field. The characteristic curves of the cooling rate, rate of entropy production and power input subject to coefficient of performance are plotted. The optimal regions of the cooling rate, coefficient of the performance (COP) and temperatures of the working substance, are determined.

Performance of Ejector Refrigeration Cycle for Automotive Air Conditioning

2016 ◽  
Vol 819 ◽  
pp. 202-206
Author(s):  
Reza Maziar ◽  
Kasni Sumeru ◽  
M.Y. Senawi ◽  
Farid Nasir Ani
Keyword(s):  
Compression Ratio ◽  
Air Conditioning ◽  
The Other ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Entrainment Ratio ◽  
Automotive Air Conditioning ◽  
Average Improvement

In this study, two experiments were performed, one with the conventional compression refrigeration cycle (CRC) and the other with an ejector refrigeration cycle (ERC). The CRC system for automotive air conditioning was designed, fabricated and experiments were conducted. The system was then retrofitted with an ejector as the expansion device and experiments were repeated for the ERC system. Calculations of the entrainment ratio, compressor compression ratio and coefficient of performance (COP) were made for each cycle. The calculations showed that ERC has some advantages over the CRC. In this study, an average improvement of 5% in COP has been obtained for the ERC compared with the CRC.

scholarly journals Efficiency Evaluation of the Ejector Cooling Cycle using a New Generation of HFO/HCFO Refrigerant as a R134a Replacement

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2136 ◽  
Author(s):  
Bartosz Gil ◽  
Jacek Kasperski
Keyword(s):  
High Efficiency ◽  
Coefficient Of Performance ◽  
Condensation Temperature ◽  
Evaporation And Condensation ◽  
Wide Range ◽  
Theoretical Investigations ◽  
Maximum Coefficient ◽  
C 30 ◽  
New Generation ◽  
And Control

Theoretical investigations of the ejector refrigeration system using hydrofluoroolefins (HFOs) and hydrochlorofluoroolefin (HCFO) refrigerants are presented and discussed. A comparative study for eight olefins and R134a as the reference fluid was made on the basis of a one-dimensional model. To facilitate and extend the possibility of comparing our results, three different levels of evaporation and condensation temperature were adopted. The generator temperature for each refrigerant was changed in the range from 60 °C to the critical temperature for a given substance. The performed analysis shown that hydrofluoroolefins obtain a high efficiency of the ejector system at low primary vapor temperatures. For the three analyzed sets of evaporation and condensation temperatures (te and tc equal to 0 °C/25 °C, 6 °C/30 °C, and 9 °C/40 °C) the maximum Coefficient of Performance (COP) was 0.35, 0.365, and 0.22, respectively. The best performance was received for HFO-1243zf and HFO-1234ze(E). However, they do not allow operation in a wide range of generator temperatures, and, therefore, it is necessary to correctly select and control the operating parameters of the ejector.

Modeling of Magnetic Refrigeration Device by Using Artificial Neural Networks Approach

2021 ◽  
Vol 10 (4) ◽  
pp. 68-76
Author(s):  
Younes Chiba ◽  
Yacine Marif ◽  
Noureddine Henini ◽  
Abdelhalim Tlemcani
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Room Temperature ◽  
Magnetic Refrigeration ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Multiple Linear Regressions ◽  
Artificial Neural ◽  
Experimental Data Collection ◽  
Linear Regressions

The aim of this work is to use multi-layered perceptron artificial neural networks and multiple linear regressions models to predict the efficiency of the magnetic refrigeration cycle device operating near room temperature. For this purpose, the experimental data collection was used in order to predict coefficient of performance and temperature span for active magnetic refrigeration device. In addition, the operating parameters of active magnetic refrigerator cycle are used for solid magnetocaloric material under application 1.5 T magnetic fields. The obtained results including temperature span and coefficient of performance are presented and discussed.

Multi-Objective Optimization of Two-Stage Thermo-Electric Cooler Using Differential Evolution

2016 ◽  
pp. 139-170
Author(s):  
Doan V. K. Khanh ◽  
Pandian Vasant ◽  
Irraivan Elamvazuthi ◽  
Vo N. Dieu
Keyword(s):  
Genetic Algorithm ◽  
Differential Evolution ◽  
Cooling Rate ◽  
Input Current ◽  
Coefficient Of Performance ◽  
Multi Objective Optimization ◽  
Two Stage ◽  
Thermo Electric ◽  
Multi Objective ◽  
Technical Issues

In this chapter, the technical issues of two-stage TEC were discussed. After that, a new method of optimizing the dimension of TECs using differential evolution to maximize the cooling rate and coefficient of performance was proposed. A input current to hot side and cold side of and the number ratio between the hot stage and cold stage are searched the optima solutions. Thermal resistance is taken into consideration. The results of optimization obtained by using differential evolution were validated by comparing with those obtained by using genetic algorithm and show better performance in terms of stability, computational efficiency, robustness. This work revealed that differential evolution more stable than genetic algorithm and the Pareto front obtained from multi-objective optimization balances the important role between cooling rate and coefficient of performance.

scholarly journals Parametric analysis of a combined ejector-vapor compression refrigeration cycle

2020 ◽  
Vol 15 (3) ◽  
pp. 398-408
Author(s):  
I Ouelhazi ◽  
Y Ezzaalouni ◽  
L Kairouani
Keyword(s):  
Current Model ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Entrainment Ratio ◽  
Constant Area ◽  
Vapor Compression Refrigeration Cycle ◽  
Vapor Compression Refrigeration

Abstract From the last few years, the use of efficient ejector in refrigeration systems has been paid a lot of attention. In this article a description of a refrigeration system that combines a basic vapor compression refrigeration cycle with an ejector cooling cycle is presented. A one-dimensional mathematical model is developed using the flow governing thermodynamic equations based on a constant area ejector flow model. The model includes effects of friction at the constant-area mixing chamber. The current model is based on the NIST-REFPROP database for refrigerant property calculations. The model has basically been used to determine the effect of the ejector geometry and operating conditions on the performance of the whole refrigeration system. The results show that the proposed model predicts ejector performance, entrainment ratio and the coefficient of performance of the system and their sensitivity to evaporating and generating temperature of the cascade refrigeration cycle. The simulated performance has been then compared with the available experimental data from the literature for validation.

scholarly journals Thermodynamic Analysis of Transcritical CO2 Ejector Expansion Refrigeration Cycle with Dedicated Mechanical Subcooling

Entropy ◽  
2019 ◽  
Vol 21 (9) ◽  
pp. 874
Author(s):  
Fu ◽  
Wang ◽  
Zheng ◽  
Yu ◽  
Liu ◽  
...  
Keyword(s):  
Thermodynamic Analysis ◽  
Environmental Temperature ◽  
Exergy Efficiency ◽  
Coefficient Of Performance ◽  
Refrigeration Cycle ◽  
Evaporation Temperature ◽  
Mass Ratios ◽  
Environmental Temperatures

: The new configuration of a transcritical CO2 ejector expansion refrigeration cycle combined with a dedicated mechanical subcooling cycle (EMS) is proposed. Three mass ratios of R32/R1234ze(Z) (0.4/0.6, 0.6/0.4, and 0.8/0.2) were selected as the refrigerants of the mechanical subcooling cycle (MS) to further explore the possibility of improving the EMS cycle’s performance. The thermodynamic performances of the new cycle were evaluated using energetic and exergetic methods and compared with those of the transcritical CO2 ejector expansion cycle integrated with a thermoelectric subcooling system (ETS). The results showed that the proposed cycle presents significant advantages over the ETS cycle in terms of the ejector performance and the system energetic and exergetic performances. Taking the EMS cycle using R32/R1234ze(Z) (0.6/0.4) as the MS refrigerant as an example, the improvements in the coefficient of performance and system exergy efficiency were able to reach up to 10.27% and 15.56%, respectively, at an environmental temperature of 35 C and evaporation temperature of −5 C. Additionally, the advantages of the EMS cycle were more pronounced at higher environmental temperatures.

Charge optimisation of a solar milk chiller with direct current compressors

2020 ◽  
pp. 095440892096400
Author(s):  
Shaji Sidney ◽  
Rajendran Prabakaran ◽  
Mohan Lal Dhasan
Keyword(s):  
Direct Current ◽  
Coefficient Of Performance ◽  
Ice Formation ◽  
Exergy Destruction ◽  
Hfc 134A ◽  
Refrigerant Circuit ◽  
Maximum Coefficient ◽  
Photo Voltaic ◽  
Solar Powered ◽  
Optimum Charge

In view of promoting the utilization of solar photo-voltaic energy for milk chilling application a custom designed milk chiller with DC compressors was fabricated. Two different DC compressors were used operating with HFC-134a and HC-600a refrigerants to ascertain the performance of HFC and HC refrigerants when used in solar powered application. In view of optimizing the performance of both refrigerants, charge optimization was experimentally carried out for both refrigerant circuits. The optimum charge was obtained based on the maximum coefficient of performance and exergy efficiency. When comparing ice formation and coefficient of performance, the HC-600a refrigerant circuit was lower than that of HFC-134a circuit. It was also observed that the total exergy destruction experienced was maximum in the HFC-134a circuit than that of the HC-600a circuit. The magnitude of exergy destruction was found to be maximum in the compressor and then followed by the condenser, evaporator and finally the capillary for both refrigeration circuits. This study showed an efficient way for using the solar power for operating a milk chiller with DC compressors and with ice bank tank to avoid the dependency on batteries.

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