Experimental evidence concerning the different behavior of energy and exergy performance indicators of refrigeration systems in transient regimes

2016 ◽  
Vol 41 (1) ◽  
Author(s):  
Elena Eugenia Vasilescu ◽  
Michel Feidt ◽  
Rahal Boussehain ◽  
Alexandru Dobrovicescu
Keyword(s):  
Exergy Analysis ◽  
Initial Temperature ◽  
Stationary Regime ◽  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Transient Regimes ◽  
Energy And Exergy ◽  
Vapor Compression Refrigeration ◽  
Exergy Performance

AbstractThis article presents the results obtained from an energy-exergy analysis of a vapor compression refrigeration system during induced transient regimes. Using experimental data, exergy destruction as a function of time under the influence of some factors that perturb the stationary regime, such as deactivation of piston, variation of mass flow rate and initial temperature of cooled fluid, and diminution of the compressor rotation speed, was calculated. Under the perturbation, an antagonistic increase in the coefficient of performance and a decrease in exergy efficiency were noted.

Energy and Exergy Analysis of Vapor Compression Refrigeration System with Flooded Evaporator

2019 ◽  
Vol 27 (04) ◽  
pp. 1950041 ◽  
Author(s):  
Chukwuemeka J. Okereke ◽  
Idehai O. Ohijeagbon ◽  
Olumuyiwa A. Lasode
Keyword(s):  
Exergy Analysis ◽  
Vapor Compression ◽  
Exergy Destruction ◽  
Refrigeration System ◽  
High Compression Ratio ◽  
Cooling Plate ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Vapor Compression Refrigeration ◽  
Potential Area

In this study, energy and exergy analysis was used to evaluate the performance of a vapor compression refrigeration system with a flooded evaporator and the causes of high temperatures of beverage during the production process determined. Subsequently, the components of the operation that require modification were identified in order to improve the system performance. The actual operating parameters related to energy and exergy analysis of the investigated beverage manufacturing plant were measured, the thermal properties of the beverage were determined from a calorimeter experiment, and mathematical models were developed based on the first and second laws of thermodynamics from the literature. The system energy and exergy efficiencies were 57.46% and 21.17%, respectively, whereas the system exergy destruction was 695.71[Formula: see text]kW. The highest exergy destruction among the components of the refrigeration system occurred at the cooling plate, followed by the ammonia compressor. The cooling plate also experienced a loss in the refrigerating effect of 43.59[Formula: see text]kW. Therefore, the cooling plate is the area with the highest potential for improvement. The ammonia compressor presents another potential area of improvement, which includes operating the compressor at a high compression ratio and high superheated temperature. However, the reduction of beverage inlet mass flow rate at the cooling plate offers the best opportunity to achieve a low beverage temperature between 1.00∘C and 2.00∘C and decreasing the system exergy destruction without incurring additional investment costs.

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.

Refrigeration Cooled Computers: Application and Review

2000 ◽  
Author(s):  
R. R. Schmidt ◽  
M. J. Ellsworth ◽  
R. C. Chu ◽  
D. Agonafer
Keyword(s):  
Temperature Stability ◽  
Continuous Operation ◽  
Coefficient Of Performance ◽  
System Level ◽  
Vapor Compression ◽  
Refrigeration System ◽  
Maintenance System ◽  
Vapor Compression Refrigeration ◽  
Computer Processor ◽  
Heat Loads

Abstract This paper outlines and discusses the application conditions pertinent to refrigeration cooling a computer processor at both the module and system level. Amongst the issues that are addressed are total refrigeration heat load (comprised of active and parasitic heat loads), coefficient of performance (COP), continuous operation (reliability, concurrent maintenance), system heat rejection, condensation formation, and temperature stability. The paper will then examine how a vapor compression refrigeration system has been incorporated in IBM’s high end (Gx) servers. Finally, the paper will touch upon some of the additional complexities of operation at very low temperatures (less than −40 °C).

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 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.

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