Heat exchanger (G-G) parameter

Hello,

I have a question regarding a parameter in the heat exchanger block in simscape. When I select the Nusselt-Reynolds-Prandlt correlations for the heat transfer parametrization I have to define the "Length of flow path for heat transfer". What is this parameter exactly defining?

At first, I thought it was the total length of the pipe of the heat exchanger for each side, as the default parameter was 1 meter. But reading the description I got confused as it says: "Characteristic length traversed in heat transfer between fluid and wall. This length factors in the calculation of the hydraulic diameter from which the heat transfer coefficient and the Reynolds number, as defined in the tabulated heat transfer parameterizations, derives.", reading this description makes me think it is the distance from the center of the pipe to the exterior face of the same.

If anyone could clarify this It would be great

Thank you in advance,

Answer 1

[Sarah McElman]

Hi Carlos,

Your first impression is correct.

The Length of flow path for heat transfer corresponds to the length of the piping or channel between the exchanger inlet and outlet. I've let our documentation team know about the error in the parameter definition section.

Please let me know if you have any further questions.

Best,

Sarah

[carlos Hernando]

Thank you Sarah for the clarification.

I am having problems to initialize and resolve my model when I include two or more Heat Exchangers (I have two in series). ¿Any recommendation on how to set the initial conditions or the solver I must use?

Best,

Carlos

[Sarah McElman]

Hi Carlos,

Would you be able to share your model? I'd have a better idea of what the problem may be that way.

Best,

Sarah

Answer 2

[carlos Hernando]

Ok,

I attached an image (I don't know if there is a better way to do this). Hope it helps, please let me know if you need more info on the subsystems.

[Sarah McElman]

Hi - you should be able to attach your .slx file to a comment or the original posting. Which version of Matlab are you using?

[carlos Hernando]

Oh, okay. Sorry... I just attached them to my previous comment

Edit: I attached a .zip with all the information