CFD-Based Performance Evaluation of Microchannel Cooling for Electric Vehicle Battery Packs

Abstract

This study presents a computational analysis of a microchannel-based liquid cooling system for cylindrical lithium-ion battery packs in electric vehicles (EVs), using ANSYS Fluent. The investigation compares water and ethylene glycol as coolants under high-load conditions, with simulations focusing on temperature distribution, wall heat flux, flow velocity, and pressure drop. Ethylene glycol achieved better thermal performance with a 42°C temperature drop and peak wall heat flux of 0.5518 W/m² but suffered from a high pressure drop (~1557.2 Pa) due to its higher viscosity. Water provided a more balanced solution, offering a 28°C temperature drop, lower pressure loss (~741.4 Pa), and superior flow uniformity, making it more practical for standard EV applications. The study underscores the trade-off between cooling efficiency and hydraulic resistance and recommends future research involving nanofluids, transient simulations, and AI-driven thermal management strategies to further enhance BTMS performance.

Introduction

As electric vehicles (EVs) rapidly grow in popularity, managing the heat generated by lithium-ion batteries has become essential for safety, performance, and longevity. The Battery Thermal Management System (BTMS) plays a crucial role in maintaining optimal operating temperatures (typically 20°C to 40°C) and avoiding risks like thermal runaway.

Thermal Management Challenges

• Overheating leads to faster battery degradation, while low temperatures impair charging efficiency.

• Traditional cooling methods include:

  • Air cooling: Low cost but inefficient.

  • Liquid cooling: Better heat transfer but bulky and sometimes uneven.

Microchannel Cooling Technology

To meet the demands of modern, compact, high-performance EV battery packs, microchannel cooling has emerged as an advanced solution:

• Microchannels (100–500 µm) provide high surface area for efficient heat removal.

• These systems can be integrated directly beneath battery cells for localized, uniform cooling.

• However, challenges include:

  • High-precision manufacturing needs.

  • Risk of clogging.

  • Higher pressure drop and pumping power due to small flow paths.

Coolant Comparison: Water vs. Ethylene Glycol

A CFD simulation was conducted using a 10s4p cylindrical Li-ion battery module to compare water and ethylene glycol as coolants in a microchannel BTMS setup.

Key Insights

• Water offers:

  • Better thermal uniformity.

  • Lower energy consumption due to minimal pumping power.

  • Smoother temperature distribution, avoiding hotspots or overcooling.

• Ethylene glycol provides:

  • Stronger cooling capacity (larger temperature drop).

  • Better freezing/boiling characteristics.

  • But suffers from higher resistance, pressure drop, and energy demand.

Conclusion

This study presents a comprehensive computational fluid dynamics (CFD) analysis of a microchannel-based Battery Thermal Management System (BTMS) for electric vehicle (EV) applications. By simulating a 10s4p lithium-ion battery module integrated with a serpentine microchannel cooling plate, the research evaluates the thermal and hydraulic performance of two common coolants—water and ethylene glycol—under steady-state, high-load conditions. The results clearly indicate that microchannel cooling is an effective strategy for managing the high heat flux generated in densely packed battery systems. The study concludes that microchannel-based liquid cooling is highly effective in managing heat in cylindrical lithium-ion battery packs for EVs, offering localized and efficient thermal control. Between the two coolants tested, ethylene glycol provided superior heat extraction (42°C drop, 0.5518 W/m² wall heat flux) but incurred a high pressure drop (~1557.2 Pa) due to its viscosity. Water delivered more balanced performance, with a 28°C temperature drop, lower wall heat flux (0.2267 W/m²), and reduced pressure loss (~741.4 Pa), making it more suitable for standard EV applications. Water also ensured smoother flow, better temperature uniformity, and improved safety by minimizing thermal hotspots and cell aging. The CFD simulations in ANSYS Fluent validated the design\'s effectiveness and supported informed coolant selection. Overall, water is recommended for general EV use, while ethylene glycol suits extreme conditions requiring enhanced thermal or antifreeze capabilities.

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Copyright

Copyright © 2025 Ankur Sahu, Aseem C Tiwari, Arvind Kumar Namdev. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.