Termodinámica

 

Exergetic analysis of a refrigeration system

 

Análisis exergético de un sistema de refrigeración

 

J. M. Belman-Flores*, A. Gallegos-Muñoz, J. M. Riesco-Ávila, A. Zaleta-Aguilar, J. M. Mendoza-Miranda

 

Department of Mechanical Engineering, Engineering Division, Campus Irapuato-Salamanca, University of Guanajuato, Salamanca, Gto., México * Autor para la correspondencia. E-mail: jfbelman@ugto.mx.

 

Received March 4, 2014.
Accepted October 4, 2014.

 

Abstract

This paper presents the exergy analysis of an experimental refrigeration system that operates with the refrigerant R134a. The research is based on analyzing the influence of six operational and controllable parameters of the experimental setup such as the compressor frequency of operation, the degree of static superheat, and the temperature of the secondary fluids (at the inlet of the evaporator and the condenser) on the exergy destruction. Thus, the results show that most exergy destruction is located in the condenser, followed by the compressor, the expansion valve and the evaporator. Furthermore, the highest exergetic efficiency is obtained by a decrease in the temperature of the secondary fluid inside the evaporator, and by an operation of the compressor at low speed. The efficiency of the compressor is also included in the analysis, which is a parameter that determines the exergy destruction of the largest component. Finally, a function of the exergetic efficiency is established in order to find those magnitudes of operational parameters that contribute to improving this efficiency.

Keywords: irreversibilities, vapor compression, exergy, R134a, controllable parameters, combined efficiency.

 

Resumen

En este trabajo se presenta el análisis exergético de un sistema experimental de refrigeración que trabaja con el refrigerante R134a. El trabajo desarrollado analiza la influencia de seis parámetros operacionales y controlables de la instalación experimental como: la frecuencia de operación del compresor, el grado de sobrecalentamiento estático y la temperatura de los fluidos secundarios (a la entrada del evaporador y condensador), sobre la destrucción de exergía. Así pues, los resultados muestran que la mayor destrucción de exergía es localizada en el condensador seguida por el compresor, la válvula de expansión y el evaporador. Por otro lado, la eficiencia exergética más alta es obtenida mediante un decremento de la temperatura del fluido secundario en el evaporador, además de un manejo bajo de la velocidad del compresor. También en el análisis se involucra la eficiencia combinada del compresor, la cual resulta en un parámetro que determina el componente con mayor destrucción de exergía. Asimismo, se establece una función de la eficiencia exergética para la búsqueda de aquellas magnitudes de los parámetros operacionales que contribuyan a mejorar dicha eficiencia.

Palabras clave: irreversibilidades, compresión de vapor, exergía, R134a, parámetros controlables, eficiencia combinada.

 

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