Energy evaluation of a refrigeration system by calculating the coefficient of performance

Abstract

The calculation of the coefficient of performance for the refrigeration system in a dairy product processing plant is presented, with the objective of knowing the energy efficiency of the system based on the thermodynamic analysis of the refrigeration cycle. The operation of the cooling system is based on the physical principles related to the heat transfer between two flows, where the cooling fluid fulfills a closed thermodynamic cycle and the system needs to consume energy to extract certain amount of heat. The evaluation of the coefficient of performance was developed following an integrated methodology of three stages. Firstly, the amount of heat necessary to extract from the products to be cooled was determined to estimate the necessary energy consumption. Secondly, the heat gain in the cooling water pipe-lines was then calculated since this magnitude increases energy consumption. Finally, the operating coefficient was determined to evaluate the energy efficiency of the refrigeration cycle. It was verified that the capacity of the installed system is sufficient for the extraction of heat in the products to be cooled according to the operating conditions of the plant and the requirements to maintain the products. The analysis of heat transfer of the cooling water lines showed that the absorption of heat is caused by problems in the insulation of the pipe, which is necessary to inspect through maintenance activities to reduce energy consumption and maintain the thermodynamic efficiency of the cycle with values greater than 70%.