Electrical & Power: Intermediate CFD Training Package — Ep 06
Battery Thermal Management: Water Vapor Cooling
- Lesson
- 06
- Run Time
- 21m 48s
- Published
- Aug 29, 2026
- Category
- Electrical & Power
- Course Progress
- 0%
Description
In this project, a cooling system for a battery pack is designed using water vapor injection. The geometry consists of five battery cells arranged vertically, with a gap between the bottom of the batteries and the base of the enclosure. The mechanism at the heart of the study is species transport: air and water vapor are injected into the domain, and the mixing and transport of these species carry heat away from the cells. The geometry was created in ANSYS SpaceClaim and meshed in ANSYS Meshing using an unstructured grid, with a boundary layer applied on the battery walls to improve accuracy near these surfaces.
The top and side walls are treated as insulated, while mass transfer occurs through the bottom wall. A heat flux of 3 W/m² is applied to the battery walls, and air together with water vapor at 18 °C is injected at a velocity of 0.5 m/s through nozzles on the side walls. Accordingly, the Species Transport model is employed, and the equations are solved in pseudo-transient mode.
Grid Independence Study
The mesh over the computational domain consists of tetrahedral elements with a boundary layer on the battery walls. Four grids were tested. Mesh #1, with 75,000 elements, reported an average battery-wall temperature of 20.16 °C, while Mesh #2, with 172,000 elements, reported 19.93 °C — a difference of more than 1%. A finer Mesh #3 was therefore generated, giving 19.88 °C, only about a 0.25% change from the previous grid. Mesh #2 was selected as the best-fitted grid, and Mesh #4 was also tested to confirm this choice.
Mesh # | Element Size | No. of Elements | Avg. Temp (°C) | Error (%) |
|---|---|---|---|---|
1 | 16 mm | 75,000 | 20.16 | — |
2 | 8 mm | 172,000 | 19.93 | −1.15 |
3 | 4 mm | 263,000 | 19.88 | −0.25 |
4 | 2 mm | 990,000 | 19.86 | −0.25 |
Conclusion
In the first step, a steady simulation was performed without water vapor injection to establish the baseline. The results show that, with no cooling system applied, the batteries reach 27 °C. The standard operating range for most batteries, such as lithium-ion, is typically between 20 °C and 30 °C, though the exact range depends on the battery type and design. Introducing the water vapor cooling system reduces the battery temperature to about 20 °C — an improvement of roughly 5 degrees.
The results also show that the corners of the enclosure experience higher temperatures, where hot air becomes trapped. This confirms that the placement of the nozzles has a strong influence on cooling performance and requires careful design. Overall, the study demonstrates how a species-transport approach — injecting and transporting air and water vapor through the domain — provides effective thermal management for a battery pack, keeping the cells within their safe operating range.