Simscape how to set up a multi-process evaporator or condenser

Hello, I want to create a parallel flow microchannel condenser with four processes but there doesn't seem to be a similar module in simscape, what should I do.

[Yifeng Tang]

Could you please clarify what you mean by "four processes". Is that four passes where the refrigerant zig-zag two times?

What about the external fluid? You mentioned "parallel flow" but I am not sure if it's about the refrigerant channels being parallel to each other or the external fluid (air?) flow in parallel with the refrigerant. The latter feels uncommon. I usually see air flow perpendicular to the refrigerant flow.

Answer 1

[Yifeng Tang]

The architecture looks right: refrigerant in series and air flow in parallel, like the actual heat exchanger.

A few things to pay attention to, based on my past experience with this type of heat exchanger:

1. pay attention to the air flow through each pass and make sure the flow rate is proportional to the overall cross section area
2. if necessary, you may add some volume between the passes, to represent the "collector" volumes that may exist at the two sides of the passes
3. start with maybe two passes, by bundling some together, and gradually increase the passes. Observe any difference in results and simulation speed.

Good luck and happy modeling.

[柯]

Thank you for your answer, here I set the cross-sectional area is the same, are their traffic all consistent? Then I hit a model and ran it all the time, and the solver couldn't reduce the step size 10 times in a row without violating the minimum step value of 2.84126E-13. What does this have to do with it?

[Yifeng Tang]

If you could share the model, I can be more sure of my answer. My best guess right now is (1) parameter and (2) initial conditions.

[柯]

How do I share files?

[Yifeng Tang]

If you feel comfortable, you may upload using the attachment function.

Everyone will be able to see it though.

[柯]

I mind a little, is there any other way? I also have another question, I want to simulate a two-phase flow heat exchanger, but there is no corresponding module in Simscape, what should I do.

[Yifeng Tang]

For sharing the model, I suggest that you reach out to Technical Support and you may mention that you have been in contact with the Application Engineering Group via MATLAB Answer and ask them to forward the request to me. We can proceed from there.

On "two-phase flow heat exchanger", I'll need some clarification. What do you mean by that?

[柯]

Hello, I have sent a request for technical support. When I say two-phase flow heat exchanger, I mean that the heat exchange medium on both sides of the heat exchanger is refrigerant, and there is only System-Level HeatExchanger (2P-2P) in simscape, but this does not seem to define some model parameters of the heat exchanger.

[Yifeng Tang]

You are right. There isn't a geometry-based 2P-2P Heat Exchanger yet. Is this for an intercooler in a refrigeration system? You'll most likely need to build one from some foundation blocks, if the system-level one won't be sufficient for your engineering purpose.

It may make sense if you can put this question as a new question, as it is a separate one from the original one. This way, more people may see it and learn. I'll try to provide more details there.

[柯]

Hello, I reposted this issue Below is a link to this issue: https://ww2.mathworks.cn/matlabcentral/answers/2023352-2p-2p-heat-exchanger.

If you have time, please take a look, thank you very much.