Experimental study on immersion cooling system for high-rate discharge of soft pack battery pack

doi:10.19799/j.cnki.2095-4239.2025.0272

Abstract

Abstract:

To address the heat dissipation challenge of submerged cooling for soft-pack battery modules under high-rate discharge, a submerged cooling experimental platform was constructed for 3S2P 32 Ah soft-pack battery module using Shell SK-3 as the cooling medium. A three-dimensional thermal evaluation system was used to analyze the cooling effect based on the temperature increase of the battery, the standard deviation of the temperature differences between cells, and overall temperature uniformity. First, a comparative experiment between static and flow-immersion cooling was conducted. Then, the effects of the discharge rate, coolant flow rate, and cell spacing on the cooling effect of the flow-immersion system were studied. The experimental results show that the static cooling system can maintain the temperature of the battery within safe limits up to a 3C discharge rate, while appropriately configured flow-immersion cooling can extend the effective temperature control range to a 5C discharge rate. Compared with natural air convection, the static submerged cooling system reduced the battery surface temperature by 29.79 ℃, and the flow-submerged cooling system achieved an additional 8.26 ℃ reduction, lowering the temperature difference between cells by 60.2%. The analysis of the experimental data revealed that at low coolant flow rates, simply increasing the cell spacing had a minimal effect. Conversely, with a small cell spacing, increasing the flow rate alone worsened the temperature uniformity. Additionally, the correlation analysis of Gr/Re² and h indicated that the combined effects of the internal spacing size of the battery pack and the flow rate of the cooling medium ultimately affect the temperature distribution characteristics of the battery pack by influencing the intensity ratio of natural convection to forced convection. For example, the inhomogeneity of forced convection can cause a large temperature difference between cells, suggesting that natural convection can be used to optimize the temperature consistency of the system design. Finally, the evaluation indexes, such as volumetric energy density, group efficiency, and heat dissipation effect, were compared with other cooling methods reported in the literature, confirming the superior performance and strong engineering application value of the flow-immersion cooling system.

Key words: battery module, pouch cells, immersion cooling, thermal management

CLC Number:

TM 912.8

Yuhang WANG, Qingyang YUAN, Hao WU, Bo ZHANG, Xin ZHAO, Yangkai GONG, Ningsheng WANG. Experimental study on immersion cooling system for high-rate discharge of soft pack battery pack[J]. Energy Storage Science and Technology, 2025, 14(10): 3730-3741.

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参数	数值	参数	数值
Nominal voltage/V	3.7	Charging upper limit voltage/V	4.15
Nominal capacity/Ah	32	Discharge cut-off voltage/V	2.75
Weight/kg	0.5	Discharge current/C	3~5
Resistance/mΩ	0.8	Suggestion for charging current/C	0.5
Size/mm	7.5×164×232	Operating temperature/℃	-30~55

Working fluid	Methyl silicone	Mineral oil	S3-X	HFE-7100
Density/(kg/m³)	968	895.5	845	1418.64
Viscosity/(mm²/s)	50	15	9.8	0.3
Specific heat capacity/[J/(kg·K)]	1350	2093	2274	1170
Thermal conductivity/[W/(m·K)]	0.1565	0.1287	0.17	0.068