Exergy analysis of a TMS (thermal management system) for range-extended EVs (electric vehicles)

This paper examines a TMS (thermal management system) of a range-extended EV (electric vehicle), which operates on its battery before the gasoline engine engages. In this period of independence of the ICE (internal combustion engine), the vehicle performance characteristics such as range, power for acceleration, fuel economy and emissions depend solely on the battery performance. Since the magnitude and uniformity of temperature in battery packs has significant impact on their performance, it is imperative to keep the battery temperature within optimal performance levels through a capable TMS that can efficiently transfer heat within the vehicle. The objective of this paper is to analyze the refrigerant and coolant circuits in the vehicle for cooling during high ambient temperatures and determine the irreversibilities and areas for improvement within these circuits. A second law analysis is used to examine the areas of low exergy efficiency in the system and minimize the entropy generation. Based on the analysis, the energetic COP (coefficient of performance) ranges of 1.8–2.4 and exergetic COP ranges of 0.26–0.39 are calculated for the system. Various parametric studies have been conducted and the most significant impact on the overall exergetic COP is found to be the ambient temperature.