A look at cooling plate design and some of the example designs, circuits and hopefully some posts looking at the CFD.
An encapsulated cooling fluid that is circulated to the battery where heat is transfered to and from the fluid. Heat is removed and added to this fluid away from the battery pack using a radiator and/or heat exchanger.
Probably the most common battery cooling system used in electrified vehicles as the system can use water-glycol as the cooling fluid.
Examples: Porsche Taycan
- heat transfer coefficient is typically 1000 to 5000 W/m2.K
- cooling fluid temperature increases with heat rejected from a cell, leading to higher delta temperatures on wide spans of the cooling plate
- cools just one surface of the cell, hence creating a delta temperature across the cell
- typically made from thin aluminium for low weight and high thermal conductivity, means they need to be electrically isolated from the cells
- thermal interface material required to bridge the gap between coolant plate and cell surface
- power required to cool and flow the fluid needs to be considered in most applications
- coolant liquid can leak from plates, hoses and most likely joints thus risking electrical isolation
The two stacked modules at the rear of the pack appear to be fed from the two outer coolant plates in series.
The concern is that these two rear modules will see higher coolant temperatures than the 3 modules that run the length of the pack.
The two stacked rear modules are likely to age faster.
The water enters at the centre on one side of the plate and then flows around the “race track” and back via each side to the central outlet. The dimples manage the structural offset of the two halves of the plates and break up the liquid flow.
- The pressure drop offered by this type of a design is less compared to a standard S bend for the same channel height.
- The density of these dimples are adjusted to spread the flow towards the edges of the plate from the centre and also to locally increase the fluid velocity by decreasing the sectional area.
- The person in the video was talking about turbulent flow. When a flow exits into a large cross sectional area such as this, the flow is mainly laminar.
- Not much information is available on the distance between the top plate and the bottom plate. This is an important factor that decides the pressure drop and the heat transfer coefficient. However, this design heavily relies on the large surface area for convective heat transfer rather having a high heat transfer coefficient.
- The top plate is used to reduce the temperature difference between the inlet and outlet of the coolant due to its higher conductivity.