Design of Pulsating Flow Cooling System for Electric Vehicle Batteries

Sammanfattning

With the growing emphasis on sustainable development, electric vehicles (EVs) are becoming increasingly widespread, and the thermal management of EV power batteries has become a critical issue. The cooling technologies currently used in EVs still struggle to meet the demands of heat dissipation under highload conditions. Pulsating flow, which can enhance heat transfer by disrupting the boundary layer and reducing thermal resistance, shows great potential for improving battery cooling. As a relatively new technique in the field of heat transfer, pulsating flow has not yet been applied in real-world EV cooling systems. As a result, this project aims to use CFD simulations to explore the heat transfer enhancement capability of pulsating flow under the practical settings of EV battery cooling systems. Through a single-variable experimental design, it analyzes the effects of average flow velocity, pulsation frequency, pulsation amplitude, pipe diameter, and fluid physical properties (e.g. viscosity, thermal conductivity, and specific heat capacity) on the heat transfer performance. By combining the influence of different variables, the project identifies optimal pulsating flow settings for single-pipe cooling under various environmental and operating conditions. Compared to non-pulsating flow, the inner wall heat transfer coefficient is improved by 35.3%–54.7%. In addition, the project explores two innovative approaches: modifying the pulsation waveform and introducing nanoparticles. The study finds that simply shortening the rising period and extending the falling period of the waveform does not actually improve heat transfer. Optimizing the waveform requires matching it with factors such as vortex lifetime. Introducing nanoparticles into pulsating flow can further enhance heat transfer. Under the experimental settings defined in this project, the introduction of nanoparticles increased the heat transfer coefficient at the contact surface by 6.18%. However, the lubricating effect of nanoparticles is influenced by factors such as the base fluid, flow conditions, and particle concentration. Further research is needed to fully explore its potential.