Abstract
It has become more apparent that vehicle electrification is a growing trend within
the automotive industry. A key technology driving this trend is lithium-ion batteries,
which power most electric vehicles. Lithium-ion batteries, however, can overheat
when they are operating at high dis/charge rate or in hot environments, resulting
in reduced lifespan and efficiency, as well as their performance can be greatly
reduced in cold weather. Modeling and experimental approaches were used in
conjunctions. As part of the modelling methodology, numerical simulations were
used to optimize heat pipe layout, cooling channel dimensions, and fin
configurations, and these simulations were validated using HPPC data and a
thermal resistance network. An experimental evaluation of thermal performance
was conducted under controlled conditions with prototypes demonstrating a
significant reduction in maximum temperature and uniformity across the system
as a result.. Therefore, appropriate battery thermal management system is
essential to ensure optimal performance and safety of lithium-ion batteries. The
aim of this PhD research is optimizing the design of the cooling channel and heat
pipe to address key fundamental challenges in the heat pipe-based hybrid cooling
battery thermal management system (HBTMS) by integrating active and passive
cooling techniques. By integrating active and passive cooling techniques the
main target of the design is to maintain the maximum temperature within 40°C,
and the temperature difference between batterie cells within 5°C, and minimise
the power consumption of the cooling system.
There are three main contributions of the research:
1) This research identifies the bottleneck of the BTMS system and optimises
the design, pinpointing the weakness of the system. The following
questions are answered:
- What effect does the size of the cooling channel have on the efficiency
of heat transfer?
- How does incorporating flow deflectors and fins affect the performance
of BTMS?
- In what ways do the material properties of fins affect the cooling
performance of the system?
Finally, it is found out that fins applied to heat pipes test cases dropped
maximum temperature from 59°C to 45°C, showing effective solution. In
addition, it is advised to study the materials of fins and its effects on BTMS.
2) The heat pipe layout is investigated in detail to optimize the system design.
– What are the effects of variations in the condensation and adiabatic
section ratios of heat pipes on their thermal resistance?
- How does bending the condenser section of the heat pipe at a 90°C
angle affect heat transfer efficiency?
As a result, bending heat pipe increased the thermal resistance of the
system by 8% from 52°C to 56°C while reducing adiabatic section from
60mm to 5mm achieved 3°C temperature drop.
3) A scalable module-level HBTMS model is developed. The model includes heat
pipe model, and ECM battery model that is created relying with HPPC data, as
well as a thermal resistance network model that is validated experimentally. This
approach allows the development of pack level thermal management solutions
that can be adapted and integrated in vehicle model. As a result, the study is able
to provide a comprehensive framework for system-level optimization, which
facilities the design of efficient, scalable thermal management systems for
batteries. Apart from that, as a result of this novel approach, EVs are able to
address critical challenges faced in extreme weather conditions by providing s
callable solution that can be used for cooling. in addition, advancing knowledge
of heat pipe optimization in TMSs, these results provide new opportunities for
designing efficient, dual-function BTMS designs for the next generation of EVs.