Three dimensional numerical validation and investigation on air cooling system of Li-ion battery used in hybrid electric vehicles

Abstract

The lithium ion batteries are most commonly used in hybrid electric vehicles for obtaining high energy density among the condemnatory issues that have been in automotive industry. As the thermal management system is very prominent in automotive batteries, an effective design consideration is to be carefully opted for cooling the battery. Especially, a forced cooling is followed as an empirical choice rather than natural cooling in the automotive industry. In this paper, a three dimensional battery pack with multiple cells and cooling passages is modelled and validated to maximize the durability and battery performance. An enumerated design of air-cooled system is validated from the literature and then numerically investigated the overall distribution of the temperature with different cases by changing the positions of the inlets and outlets of the battery to satisfy the thermal specification requirements of the battery. Since, a distinctive battery system is used in hybrid electric vehicle which contains multiple cells in parallel, cooling efficiency is accomplished by a uniform diffusion of air flow in the coolant passages which dissipates the heat evolved from the individual lithium-ion battery cell. The above four cases are compared and demonstrated that the efficient cooling performance is attained with the one inlet and one outlet which are placed at the opposite sides of the battery. This is acquired because, the faster the air flow rate, the more the system cools due to the high temperature dissipation.