Energy and exergy analysis of cooling systems in office building

Abstract

Consulta en la Biblioteca ETSI Industriales (7985)

[EN] The purpose of this study is to gain insight into the process of cooling of buildings with a standard installation. The relation between work and changes in entropy generation arise from the simultaneous treatment of the first and second laws referred as exergy (or available energy) analysis. In this study , it is discuss a thermodynamic analysis of the whole facility. A parametric study of each sub-system, in which the whole system is divided to, is carried out to determine the variation of the second law efficiency as a function of mass flow rate, relative humidity and temperature. An energetic analysis is also studied in addition to the irreversible losses, which are calculated by a further application of the second law, and it is double checked , by applying an exergy balance on each sub-system. The great importance of this exergy analysis is that it allows a direct comparison between different energy types (e.g. heat, electricity, fuel) on a common basis, and the concept of exergy consumption is useful for expressing how and where energy is dispersed in the course of the energy conversion and heat transfer steps. And this is one of the main goals of this study, to calculate the exergy flows of the system, and finally be able to draw the energy and exergy flow diagrams. The results show that most of the exergy losses take place in the refrigerant cycle and in the heat transfer through the heat exchangers. In addition the energetic parameters, the COP and the energetic efficiency is not as high as it could be. The common solution suggested to improve these two last parameters and decrease the exergy losses is to reduce the inner temperature lift in the refrigerant cycle.