Novel and environmental design optimization for battery thermal management system in electric vehicle

Rekabra Youssef

Research output: ThesisPhD Thesis

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Lithium-ion (Li-ion) batteries play an essential role in our daily lives and are considered the main power source
in electric vehicles. The process of charging and discharging the battery continuously drives to a significant
amount of heat generation which results in temperature differences, non-uniformity, and thermal runaway. An
effective battery thermal management strategy (BTMS) is required to maintain battery temperature in the
optimal range and thus ensure high performance, safety, and longevity of lithium-ion batteries. Many cooling
mediums have been conducted into BTMS to absorb, transfer, and dissipate the heat generated from the
batteries. Thermal conductivity, heat transfer coefficient, cooling performance, cost, toxicity, environment,
system size, and equipment needed are critical factors in choosing the ideal heat transfer methods for the BTMS.
Air cooling systems with either passive or active control are considered one of the most traditional, common,
and widely embraced cooling strategies in automotive applications. This is due to their simplicity in structure,
flexibility in maintenance and packaging, water leakage avoidance, low weight and power consumption.
However, the main concerning points are low cooling efficiency and nonuniform temperature distribution within
the cells.
Phase change material (PCM) is a substance that change its material structure from one physical phase to
another, and can absorb or release heat at specific temperature ranges. Therefore, towards reaching the melting
point liquid-solid PCMs absorb heat energy and eventually transform from solid phase to liquid. The PCM
absorbs the heat accumulated on the battery surface by conduction. It has large latent heat and constitutes a low-
cost thermal management strategy. On the other hand, PCMs suffer from low thermal conductivity, and thermal
management systems based on them are considered volumetric and massive.
Therefore, power consumption and low thermal conductivity in air-cooling systems and passive cooling system
with PCM assisted need further design optimization. In this PhD thesis, a novel and environmental material
called jute is integrated with both cooling strategies, air-cooling, and passive cooling PCM assisted. Jute is a
cheap, light, eco-friendly, widely available material well-known for its cooling properties, Jute fibers haven’t
been investigated and integrated before with battery thermal management strategies.
Firstly, a unique battery thermal management depends on using the jute as a plant-based, cheap, environmental,
economic, renewable and lightweight fiber is proposed to be integrated with air cooling. Thorough experiments
are carried out on a 50Ah prismatic high-energy battery cell with an integrated evaporative cooling system and
its effects on battery thermal behavior are studied. The maximum cell surface temperature, temperature
difference, and temperature uniformity on the cell surface are compared under different ambient and loading
conditions, considering natural convection cooling, forced air cooling, and evaporative cooling. The results
confirm that using the jute for the proposed BTMS improves the performance of air cooling with a better
temperature uniformity as well as reduced equipment and weight. Then, jute was integrated with a passive PCM
cooling system, and the thermal performance of a 50 Ah prismatic battery was studied. Cell surface temperature
evolution and uniformity were investigated. Afterwards, a comparison between the thermal behavior of the air-
based and PCM-assisted BTMS cooling system was performed. The results indicated that adding jute to the
BTMS increased the cooling improvement and especially decreased the temperature development. Furthermore,
the temperature difference (ΔT) was enhanced by 60% when integrating jute with PCM, and temperature
uniformity improved by 3% when integrating jute with air-based BTMS.
This study compared the integration of jute with active and passive cooling; thus, it sheds the light on the
importance of jute as a novel, eco-friendly, lightweight, cheap, available, and non-toxic material added to two
strategies of BTMS. The setup was physically made and experimentally studied for the purpose of BTMS
optimization. The results of this research confirm that the proposed designs with jute fibers combination
improved the cooling performance besides reduced the equipment and weight.
Original languageEnglish
Awarding Institution
  • Vrije Universiteit Brussel
  • Berecibar, Maitane, Supervisor
  • Kalogiannis, Theodoros, Supervisor
Award date11 Dec 2023
Publication statusPublished - 2023


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