Problem with simscape Heat Exchanger (TL) component

Hello,

I am trying to understand the working of Heat Exchanger component in the Simscape Fluids library. I have a basic model with thermal liquid on both sides on the heat exchanger (hot side and cold side) with heat exchanger in between.

But when I try to simulate this "simple" problem, the results I see are weird. The hot side fluid temperature reduces but the cold side fluid temperature remains constant (figure below). I don't understand where the heat is going?

Attaching the model for reference.

Any help would be greatly appreciated. Thanks in advance!

Answer 1

[Juan Sagarduy]

Hello Rohan

I think that the hot side is modelled as fluid flowing from a reservoir, through the exchanger and then ending in a second reservoir. This is correct.

On the cold side, you have accidentally fluid circulating in a steady state at a temperature determined by Simscape (looks like 293.15k often default temperature in the exchanger).This fluid cools down the hot one until equilibrium is reached.

Try setting two reservoirs in the cold side and adjust the temperature accordingly.

BR Juan

[Rohan Kokate]

Hi Juan,

Thank you for the response.

I still see no change on implementing your suggestions. That is something I feel is very weird. No matter what changes I do, the cold side fluid shows no change at all. This makes me doubt how I have set up my system. Do you mind taking a look at it?

Attaching the the image and file below.

Thank you!

[Rohan Kokate]

Hi Juan,

You were right the connections I was making was wrong. The absence of sink and reservoir on the cold side messed up with the results. I am getting the temperature profile as expected and as desired from hand calculations.

My problem with the custom Simscape heat exchanger code still persists though, please take a look if you can.

Thanks a lot!

[Juan Sagarduy]

Hi Rohan

Good to see that you manage to solve the issue. Devil is in the detail as always.

I am very busy in coming weeks, but I'll give your query some time before Xmas.

Of course, as soon as I have a slot I can dedicate to this.

Best Regards

Juan

[Rohan Kokate]

I appreciate that, thank you!

[Rohan Kokate]

Hi Juan,

I was able to solve the issue with regards to the question I have mentioned below. I have the custom heat exchanger (TL-TL) working as expected. I have moved on to the more difficult code for the custom heat exchanger (G-TL). I am encountering several issues in the transient solver for that problem. Please, if you can, have a look.

https://www.mathworks.com/matlabcentral/answers/652733-problem-with-custom-heat-exchanger-g-tl-model?s_tid=srchtitle

I really appreciate your time and efforts.

Thanks in advance.

Regards,

Rohan.

Answer 2

[Rohan Kokate]

Also, can you also please look at this question:

https://www.mathworks.com/matlabcentral/answers/621513-energy-balance-issue-with-simscape-heat-exchanger-model?s_tid=prof_contriblnk

I am trying to create my own heat exchanger component. But for some reason, I can't verify the mass and energy balance for the system.

Thanks in advance!