Active Cooling for the Thermal-Management of Batteries by Means of Pulsating Channel Flows

The ability of a pulsating flow to improve heat-exchange performances in active liquid cooling systems for batteries in electric vehicles is investigated using a numerical approach. Computations are performed using operating conditions and thermo-physical parameters of the indirect liquid cooling method in which the heat is transferred from the battery to a fluid flowing inside a metal plate equipped with internal flow channels. Improvement of the heat transfer with a pulsating flow corresponds to periodic unstable phase during the pulsation period and appear at specific moments of the period according to three main parameters: velocity, frequency, and pulsation amplitude. These unstable dynamics lead to vortices spanning the entire channel and thereby improves convective heat exchanges throughout the entire cooling system, and this without modifying the existing design. The pulsation enables to activate unstable resonant frequencies, which are identified as the driver for the heat-transfer improvement. Depending on the pulsation parameters, the numerical computations allows for identifying regimes where the mean heat transfer at the internal-channel wall is enhanced by at least a factor eight. In particular, we demonstrate a successful application using a direct-numerical simulation of the full-scale problem in two-dimensions and a large-eddy simulations in three-dimensions. Cooling efficiency enhancement with this pulsating liquid cooling concept could enable either downsizing the battery thermal management system for electric vehicles or target ultra-fast charge constraints.