Exergy analysis of the thermal behavior of battery cooling processes for HEV and BEV applications

摘要

This paper presents the results of a holistic exergy analysis of the cooling circuits for HEV and BEV battery cooling systems.The aim of the performed analysis is to give a proposal for the best possible thermohydraulic solution of the coolingsystem for battery units. The exergy analysis helps to detect possibilities to improve thermal processes and systems. Exergyis defined as the maximum useful work possible during a reversible process that brings the system into equilibrium with thelocal ambient parameters. The exergy analysis can help to establish a quality rating of counter-clockwise cyclic processes(e.g. air conditioning, heat pump) with a COP value smaller or even greater than 1. Using evaluation coefficients for thehierarchic exergetic analysis (efficiency, loss coefficient, significance factor and loss component), it is possible to identifythe maximum potential of each individual component and also of the total cooling system itself. New optimized conceptsfor the cooling and heating of battery units are proposed by a numerical analysis of the current cooling circuit for selectedoperation points. The final effect of the proposed solution is an increase of the vehicle cruising range, an increase of theoverall vehicle efficiency and finally—a reduction of the lifecycle costs.