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A Novel Design for Lithium ion Battery cooling using
Mineral Oil
Mahesh Suresh Patil1 , Jae-Hyeong Seo2, You-Ma Bang1, Dae-Wan Kim2, Gihan
Ekanayake1, Gurpreet Singh1, Hak-Min Kim1, Yong-Hwan Choi3, and Moo-Yeon
Lee1,* 1 Dong-A University, 37, Nakdong-daero 550beon-gil, Saha-gu, Busan, Republic of Korea
2 NTF Tech Company, 37, Nakdong-daero 550beon-gil, Saha-gu, Busan, Republic of Korea 3 Hyundai Motor Group, 772-1, Jangduk-Dong, Hwaseong-Si, Gyeonggi-Do, 445-706,
Republic of Korea
{[email protected], [email protected], [email protected],
[email protected], [email protected],
[email protected],[email protected], [email protected],
Abstract. The battery thermal management system has become an important
aspect of the development of electric vehicles (EVs) which are widely
considered as a promising option instead of internal combustion based vehicles
(ICEs) for reducing the climate change effects. Particularly, advances in
Lithium ion batteries with high energy density are considered key elements for
wide spread acceptance of EVs. Batteries with larger energy densities exhibit
the thermal issues, which creates decreased performances at higher operating
temperatures and eventually turning thermal runaway into fire or explosion. In
this paper, a novel design is presented with mineral oil as a coolant with
channel guide. The temperature distribution is recorded at various coolant mass
flow rates and pressure drop variation is discussed.
Keywords: Lithium ion, battery thermal management system, cooling, mineral
oil
1 Introduction
The energy crisis and rapidly degrading climate condition have prompted to slowly
phase out fossil fuel based ICE vehicles and adopt more environment friendly electric
vehicles. The battery technology is one of the core technologies of EVs industry. The
EV travel range has been under focus as limiting factor for penetration of EV in the
market as commercial vehicle. Therefore, considerable research is being carried out to
enhance the EV travel range by adding more batteries with higher energy densities.
Many studied have reflected that Lithium ion battery performance decreases when
operated outside the operating temperature of 0-40 ºC [1, 2]. This creates a serious
problem of battery thermal management system (BTMS), as higher energy density in
battery dissipates large heat and that needs to be removed continuously and efficiently
Advanced Science and Technology Letters Vol.141 (GST 2016), pp.164-168
http://dx.doi.org/10.14257/astl.2016.141.34
ISSN: 2287-1233 ASTL Copyright © 2016 SERSC
during the EV battery charging and discharging. In addition, it is desirable to keep the
temperature uniformity within battery pack less than 5 ºC [3, 4].
Previously, air-cooling and liquid cooling have been considered as coolants for
BTMS. The air-cooling although easier to construct and operate with low
maintenance, the system becomes rather bulkier due to lower thermal conductivity of
air. The direct and in-direct cooling methods include the liquid as coolant (especially
water or water-ethylene glycol mixture). Indirect cooling uses fins, which are used to
transfer heat from battery cells to coolant [5]. In direct cooling, small coolant
channels are developed in plate attached to battery cell [6]. In this paper, a novel
battery cooling method is designed and proposed. Mineral oil is used as cooling fluid
and a channel guide is developed for channelizing mineral oil flow and maintaining
the distance between cells while cells start swelling. Due to electrically non-
conductive nature, mineral oil can be a good option as coolant for electrical devices.
The parametric study is conducted considering the mass flow rates.
2 Numerical Simulation
The battery pack model is developed using commercial CAD software. The mesh
development and simulation is conducted in commercial CFD software ANSYS 17
[7]. The pouch cell size considered is 300 (l) x 100 (w) x 10 (t) mm3. One module
under consideration consists of 16 pouch cells and 1 battery pack under consideration
consists of 3 modules. The mineral oil properties are shown in table 1 [8]. The
viscosity of mineral oil is quite high which creates requirement of higher pumping
power compared to water. Table 2 shows the initial condition of the numerical
simulation. The mass flow rates of 1, 5 and 10 LPM (Liter/min) are considered.
Table 1. Mineral oil property [8].
Property Specifications
Density (kg/m3)
Specific Heat Capacity (J/kg·K)
Dynamic viscosity (Pa·s)
924
1900
0.05
Thermal conductivity (W/m·K) 0.13
Table 2. Numerical simulation conditions.
Property Specifications
Working fluid
Cooling method
Heat generation rate
Mineral oil
Coolant circulation
30000 W/m3 (~6W/cell)
Mass flow rate (LPM) 1, 5, 10
Advanced Science and Technology Letters Vol.141 (GST 2016)
Copyright © 2016 SERSC 165
3 Results and Discussion
The results discussed using temperature distribution and pressure drop discussions.
Fig. 1 shows the comparison of the temperature distribution along the single pouch
cell plane. The maximum temperature observed is 32.75 ºC, 30.84 ºC and 30.55 ºC
whereas the minimum temperature observed is 31.86 ºC, 30.31 ºC and 30.13 ºC, for 1,
5, 10 LPM, respectively. The temperature difference between maximum and
minimum are 0.89 ºC, 0.53 ºC and 0.42 ºC for 1, 5 and 10 LPM, respectively. It is
very important to keep the temperature uniformity within 3 ºC along each of the
pouch cell as well as in overall battery pack within 5 ºC. The results of the numerical
simulation shows that temperature uniformity is well maintained below 1 ºC. The
interesting point to note here is that, although the mass flow rate increased 10 times,
the maximum cell temperature decreased only 6.71%. This underlines that the mineral
oil mass flow rate has very limited effect of the thermal performance of the cell. The
advantage of this is that the lower mass flow rates would also give the similar
performance as higher mass flow rates.
(a)
(b)
(c)
Fig. 1. Temperature distribution along battery cell in plane for different mass flow rates (a) 1
Advanced Science and Technology Letters Vol.141 (GST 2016)
166 Copyright © 2016 SERSC
LPM (b) 5 LPM (c) 10 LPM.
Fig. 2. Pressure head loss with respect to different mass flow rate
The similar discussions extended to pressure drop analysis. Pressure drop is a crucial
parameter to judge the cost effectiveness of cooling system using liquid coolant. The
fig. 2 shows the pressure drop variation with respect to mass flow rate. The pressure
head loss across inlet and outlet for 10 LPM is 4 times higher when compared to 5
LPM. The increase of pressure drop with increase in mass flow rate attributes to high
viscosity of the mineral oil.
4 Conclusion
In this study, the numerical investigation was carried to check the feasibility and
analyze the oil cooling performance for Lithium ion battery pack with mineral oil as
coolant. The study reveals that the mineral oil cooling can be a promising option to
resolve three issues related to thermal performance of Lithium ion battery for EVs.
Firstly, the bulkiness of the battery system can be reduced due to effective direct
cooling method using mineral oil. Secondly, the risk of explosion due leakage of
coolant into the battery system can be reduced due to electric non-conductive
behavior of mineral oil. Thirdly, the temperature uniformity can be maintained below
1 ºC, which is crucial to extend lifetime and ensure operating safety. In addition, the
results indicates that the pressure drop can be minimized using lesser mass flow rates
of mineral oil, which give similar cooling performance as higher mass flow rates. The
findings highlights that the cooling performance of Lithium ion pouch cell can be
enhanced using low mass flow rate of mineral oil.
Acknowledgments. This research was supported by Basic Science Research Program
through the National Research Foundation of Korea (NRF) funded by the Ministry of
Education (2016R1D1A1B03935822). And, this work (Grants No. C0398373) was
supported by Business for Cooperative R&D between Industry, Academy, and
Advanced Science and Technology Letters Vol.141 (GST 2016)
Copyright © 2016 SERSC 167
Research Institute funded Korea Small and Medium Business Administration in 2016
and the Bicycle and Marine Leisure Equipment Technology Development Program of
MOTIE [20161016]. And, following are results of a study on the "Leaders Industry-
university Cooperation" Project, supported by the Ministry of Education, Science &
Technology (MEST).
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