Numerical Study on Heat Transfer Characteristics of Dielectric Fluid Immersion Cooling with Fin Structures for Lithium-Ion Batteries

Abstract

Electric vehicles (EVs) are incorporated with higher energy density batteries to improve the driving range and performance. The lithium-ion batteries with higher energy density generate a larger amount of heat which deteriorates their efficiency and operating life. The currently commercially employed cooling techniques are not able to achieve the effective thermal management of batteries with increasing energy density. Direct liquid cooling offers enhanced thermal management of battery packs at high discharging rates compared to all other cooling techniques. However, the flow distribution of coolant around the battery module needs to be maintained to achieve the superior performance of direct liquid cooling. The objective of the present work is to investigate the heat transfer characteristics of the lithium-ion battery pack with dielectric fluid immersion cooling for different fin structures. The base structure without fins, circular, rectangular and triangular fin structures are compared for heat transfer characteristics of maximum temperature, temperature difference, average temperature, Nusselt number, pressure drop and performance evaluation criteria (PEC). Furthermore, the heat transfer characteristics are evaluated for various fin dimensions of the best fin structure. The heat transfer characteristics of the battery pack with dielectric fluid immersion cooling according to considered fin structures and dimensions are simulated using ANSYS Fluent commercial code. The results reveal that the symmetrical temperature distribution and temperature uniformity of the battery pack are achieved in the case of all fin structures. The maximum temperature of the battery pack is lower by 2.41%, 2.57% and 4.45% for circular, rectangular, and triangular fin structures, respectively, compared to the base structure. The triangular fin structure shows higher values of Nusselt number and pressure drop with a maximum value of PEC compared to other fin structures. The triangular fin structure is the best fin structure with optimum heat transfer characteristics of the battery pack with dielectric fluid immersion cooling. The heat transfer characteristics of a battery pack with dielectric fluid immersion cooling are further improved for triangular fin structures with a base length -to -height ratio (A/B) of 4.304. The research outputs from the present work could be referred to as a database to commercialize the dielectric fluid immersion cooling for the efficient battery thermal management system at fast and higher charging/discharging rates.

Advancements in Battery Cooling Techniques for Enhanced Performance and Safety in Electric Vehicles: A Comprehensive Review

“…First, there is a drive to optimize the design of cooling channels, which significantly impacts the system's thermal performance. [164,165] Second, advanced heat exchangers are explored to facilitate more efficient heat transfer. [166] Finally, integrating flow control mechanisms is being considered to ensure uniform cooling across the battery cells, thereby improving overall battery performance and longevity.…”

A Review of Advanced Cooling Strategies for Battery Thermal Management Systems in Electric Vehicles

“…The battery module temperatures for dielectric fluid immersion cooling with various fin structures are shown in Figure 15. Furthermore, the triangular fin structure with the base length to height ratio (A/B) of 4.304 is suggested as the best configuration for dielectric fluid immersion cooling system which achieves the lowest maximum temperature and temperature difference of the battery as 35.07 • C and 7.95 • C, respectively [128]. Anisha et al analyzed liquid cooling methods, namely direct/immersive liquid cooling and indirect liquid cooling, to improve the efficiency of battery thermal management systems in EVs.…”