Advanced thermal management systems for the electric vehicles

Research output: ThesisPhD Thesis

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Abstract

Electric vehicles (EVs) and hybrid electric vehicles (HEVs) are the most capable technologies to replace the Internal Combustion Engine (ICE) in the transport sector. A huge environmental issue can be decreased by using EVs. The battery pack is a source of energy that combines a noticeable number of cells where electrochemical reactions occur to provide power to any electrical device. Lithium-ion (Li-ion) batteries are one of the most significant power sources owing to their advantages including high energy storage density, long cyclic lifespan, and low self-discharge. However, Li-ion batteries generate a noticeable amount of heat that may cause overheating, swelling, and even explosion. Therefore, designing an efficient battery thermal management system (BTMS) is a big challenge in EVs to control and remove the generated heat by the cells. In this Ph.D. thesis, the target cell is a commercial prismatic LTO cell with a 23 Ah capacity. The Lithium Titanate (LTO) cell is a kind of rechargeable battery that benefits from a long-life cycle, fast charging, and high discharge current. The battery cell consists of Nickel Manganese Cobalt Oxide (NMC) in the cathode and LTO in the anode. The anode material is a promising substance with a spinal structure that provides a surface area that is considerably larger than other kinds of lithium-based batteries. Moreover, LTO chemistry has
a low risk of thermal runaway and has the ability for a recharge efficiency of up to 98%, which is considerably more than conventional energy storage mechanisms. A holistic approach is developed for thermal models capable of predicting the thermal parameters of the cell under fast charging/discharging. The model is validated against the results of the experiment under different conditions.

The main properties of designed BTMS are low manufacturing cost, simple layout requirements, high reliability, small in size and rigid, inexpensive, and low weight. In this study, several cooling systems are applied for BTMS at the cell/module level using different active, passive, and hybrid cooling technologies. Active cooling systems are including air cooling and liquid cooling which need an external source of energy. On the other hand, passive cooling systems comprise natural air cooling, phase change material (PCM), and heat pipe that do not consume any external energy. In addition, in the following thesis, hybrid cooling methods have been introduced in order to take the most advantageous benefits of aactive and passive cooling systems. As it is mentioned by many researchers the safe temperature range for Li-ion batteries is between 25–40 ℃ which results in a balance between performance and lifetime. This Ph.D. research aims in designing efficient thermal management systems for automotive applications. In this Ph.D. research, different BTMSs are designed, built and their performance is analyzed by computational fluid dynamics (CFD) software, COMSOL Multiphysics.
Original languageEnglish
Awarding Institution
  • Vrije Universiteit Brussel
Supervisors/Advisors
  • Van Mierlo, Joeri, Supervisor
  • Berecibar, Maitane, Supervisor
Award date29 Nov 2022
Place of PublicationBrussel
Publisher
Print ISBNs9789464443486
Publication statusPublished - 2022

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