Designing a controller for cooling of heat exchangers

[janithw]

I'm currently building a thermal controller that can manage the cooling of various types of heat exchangers, and I'm specifically working on cooling a heat exchanger for an EV fast charger. I need to decide the optimal pump and fan speeds to achieve efficient cooling, but I'm not sure about the best methodology to follow.

Does anyone have any guidelines, references, or methods that could help determine the pump and fan speeds in a controlled manner?

I want to make sure I can apply this design to multiple types of heat exchangers in different setups, so something adaptable would be great. Are there specific parameters or control strategies I should focus on? Any standard guides that explain this in detail?

Thanks a lot for any help or direction you can provide!

 

[Lnewqban]

Welcome, @janithw !

Normally, such control receives input information from a temperature sensor, which is located at a convenient point to monitor the outlet airflow or coolant flow, whichever is cooling your charger.

The manufacturer of the heat exchanger provides charts and graphs of input/output flows versus exchaged heat.

The sizing of your pump and fan depends of maximum heat exchage demand at worst possible ambient conditions.

 

[janithw]

Thanks for the input @Lnewqban! In my case, we're actually designing and manufacturing the heat exchanger ourselves, so we don’t have a datasheet or pre-existing performance curves to rely on.

Before I determine the optimal pump and fan speeds for efficient heat dissipation, I assume I'll need to experimentally verify the performance of our heat exchanger. Could you provide any guidance on how to do this effectively? Specifically, are there recommended methods or key parameters I should be measuring during these tests to establish reliable control inputs for my thermal system?

Any advice or references would be really helpful. Thanks again!

 

[berkeman]

we're actually designing and manufacturing the heat exchanger ourselves

How big of a heat exchanger are you working on? How much heat do you need to pull out of the hot source and at what rate? Is the cold side just ambient air?

 

[berkeman]

Also, which type of heat exchanger are you working with?

https://www.linkedin.com/pulse/what-5-types-heat-exchanger-tianjin-anton-metal-manufacture-co-isagc/

 

[janithw]

Thanks for the input @berkeman! This is an air-cooled heat exchanger setup, where the heat source outputs 5 kW of heat. Throughout the charging process, I need to maintain the heat source temperature below 60°C.

How should I determine the optimal fan and pump speeds for effective cooling in this scenario? Also, if I need to measure the performance of the heat exchanger beforehand, is there a recommended method for doing this?

 

[erobz]

View attachment 353732
Thanks for the input @berkeman! This is an air-cooled heat exchanger setup, where the heat source outputs 5 kW of heat. Throughout the charging process, I need to maintain the heat source temperature below 60°C.

How should I determine the optimal fan and pump speeds for effective cooling in this scenario? Also, if I need to measure the performance of the heat exchanger beforehand, is there a recommended method for doing this?

I assume there is air blowing over the h.e. and water flowing though it (you mention fan and pump)? I think the idea here is to measure $q = \dot m c_p \Delta T$ ( inside the exchanger) for a fixed fan flowrate ( effectively the motive for the increasing the external convection coefficient).

You are trying to control all the other variables and measure the $\Delta T$ of the mass flowrate in the h.e. ( $\dot m$. That lets you compute the rate of heat absorption ($q$) from inlet to outlet of the h.e.