Nanofluids in battery cooling system
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Date
2018-06
Authors
Chern Khai, Lee
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Abstract
Thermal implications related to heat generation and potential temperature
excursions during operation in lithium-ion batteries are of critical importance for electric
vehicle safety, performance and life. Concurrently, appropriate thermal management
strategies for lithium-ion batteries are crucial to maintain cell temperatures within a
desired range. Hence, the development of nanofluids to improve heat transfer capabilities
in car batteries have attracted intense research activities in recent years. Nanofluids,
which are stably dispersed or suspended nanosized particles in heat transfer liquids have
attracted substantial interest because they offer a promising alternative to the inherent
problems of conventional working fluids. Besides, the nanoparticles do not settle in the
fluid and do not cause clogging and damage to surfaces as with micron sized particles.
The problem statement of the project is to analyze the efficiency of nanofluids as heat
transfer fluids for active thermal management in car batteries. The research
experimentally investigates the use of silica nanofluids and distilled water. In order to
determine the efficiency of nanofluid as heat transfer fluids, experimental data such as
Reynolds number, heat transfer coefficient and Nusselt number of water and water based
silica nanofluid that flow through a circular tube (Di=0.8 mm) are obtained. The flow
was assumed as fully laminar flow with uniform heat flux applied to the tube surface.
Different weight concentrations of silica/water nanofluids (0.1, 0.2, 0.3, 0.4, 0.5wt %)
were used in the experiment. Based on the data collected, graphs of heat transfer
coefficient of nanofluids at different concentrations and distilled water versus axial viii
distance over inner diameter of tube (Z/Di) and % heat transfer enhancement of nanofluis
at different concentrations and distilled water versus (Z/Di) were plotted and analyzed.
The results concluded that heat transfer coefficient and Nusselt number was significantly
enhanced using silica nanofluids as compared to distilled water as heat transfer fluids.
Higher values of heat transfer coefficient and Nusselt number indicate that more heat is
being transferred from the tube to the fluid which results in a significant reduction of the
overall tube surface temperature. The heat transfer enhancement was found to be
dependent on the nanoparticle concentrations. The maximum enhancement was recorded
for 0.4 wt. % silica nanofluids with 6.9% increase in heat transfer coefficient.