Solidwork flow floefd - modeling heat exchanger in a system

mzreik · January 6, 2016, 14:23

I m trying to model a heat exchanger in an enclosed cabinet, however i m not intending to simulate the internal components since i do not have them.

I know the inlet outlet of the heat exchanger and the flow rating.

after running the simulation of the heat exchanger inside an enclosed cabinet, I see that the solution converges with the inlet and outlet of the heat exchanger having approximately the same temperature.

is this something that truly happens in an enclosed cabinet, i.e even if the rating of the heat exchanger says it is 30 C inlet air and 15 C outlet air, you end up with the inlet outlet close to 15 C !!

Boris_M · January 7, 2016, 09:06

I'm not sure I understand how you've modeled it.
What internal components don't you have? The heat exchanger?

Can you describe your assembly in more detail and tell what boundary conditions you used where exactly.
For me you tried to model an cabinet with a heat exchanger in it but you don't have the internal components. So there is nothing in there?
Where do you input the heat?

If there is a temperature difference then you need a positive or negative hear source of some sort.

mzreik · January 7, 2016, 12:41

- I do not have the internal components of the heat exchanger
- I have the internal components of the cabinet
- I have internal heat loads throughout the cabinet
- boundary conditions:
ambient temperature on the outside of the cabinet of 30C and ambient
atmospheric pressure
multiple internal heat loads in watts totaling 1200W
multiple internal fans for components

heat exchanger modeled with fan rating of 375 CFM and inlet outlet matrix of temperature relationship

as I said i see the temperature of the inlet and outlet of the heat exchanger approximately the same at the end of the simulation is that something that is expected (since i m not modeling the internal coil of the heat exchanger)

Boris_M · January 8, 2016, 12:30

I think I get closer to understand what you do.
So you have an enclosure with a lot of power dissipation in it from components and there is also a heat exchanger which is helping with the cooling or is used by one of the components for the cooling of the components and dissipating the heat into the airflow inside the enclosure.
Is that correct?

So almost like a liquid cooled CPU or so.
Now the heat transferred in or out of the heat exchanger should be calculated accurately. But if you see barely any difference and especially if you set the inlet air to 30°C and outlet should be calculated to 15°C (as you cannot suck out 15°C if the fluid is hotter) and you get already 15°C at the inlet boundary condition although it should be 30°C. I would think that the inlet fluid temperature is not set to 30°C.

Assuming the model is ok geometry wise and no error message appears during the calculation, then everything in the first glace should be ok.
However you can also try to shorten the test calculation by creating a clone of the project and simplify it to only the necessary part of the simulation and exclude any other possible mistake or problem.

I cannot help more without a detailed information on how it looks like and what boundary conditions you have used.
It is all to vague to understand it in detail and clearly identify the problem and give you a solution.

January 6, 2016, 14:23	Solidwork flow floefd - modeling heat exchanger in a system	#1
mzreik New Member Join Date: Jan 2016 Posts: 2 Rep Power: 0	I m trying to model a heat exchanger in an enclosed cabinet, however i m not intending to simulate the internal components since i do not have them. I know the inlet outlet of the heat exchanger and the flow rating. after running the simulation of the heat exchanger inside an enclosed cabinet, I see that the solution converges with the inlet and outlet of the heat exchanger having approximately the same temperature. is this something that truly happens in an enclosed cabinet, i.e even if the rating of the heat exchanger says it is 30 C inlet air and 15 C outlet air, you end up with the inlet outlet close to 15 C !!

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January 7, 2016, 09:06		#2
Boris_M Disabled Join Date: Jul 2009 Posts: 616 Rep Power: 24	I'm not sure I understand how you've modeled it. What internal components don't you have? The heat exchanger? Can you describe your assembly in more detail and tell what boundary conditions you used where exactly. For me you tried to model an cabinet with a heat exchanger in it but you don't have the internal components. So there is nothing in there? Where do you input the heat? If there is a temperature difference then you need a positive or negative hear source of some sort.

January 7, 2016, 12:41		#3
mzreik New Member Join Date: Jan 2016 Posts: 2 Rep Power: 0	- I do not have the internal components of the heat exchanger - I have the internal components of the cabinet - I have internal heat loads throughout the cabinet - boundary conditions: ambient temperature on the outside of the cabinet of 30C and ambient atmospheric pressure multiple internal heat loads in watts totaling 1200W multiple internal fans for components heat exchanger modeled with fan rating of 375 CFM and inlet outlet matrix of temperature relationship as I said i see the temperature of the inlet and outlet of the heat exchanger approximately the same at the end of the simulation is that something that is expected (since i m not modeling the internal coil of the heat exchanger)

January 8, 2016, 12:30		#4
Boris_M Disabled Join Date: Jul 2009 Posts: 616 Rep Power: 24	I think I get closer to understand what you do. So you have an enclosure with a lot of power dissipation in it from components and there is also a heat exchanger which is helping with the cooling or is used by one of the components for the cooling of the components and dissipating the heat into the airflow inside the enclosure. Is that correct? So almost like a liquid cooled CPU or so. Now the heat transferred in or out of the heat exchanger should be calculated accurately. But if you see barely any difference and especially if you set the inlet air to 30°C and outlet should be calculated to 15°C (as you cannot suck out 15°C if the fluid is hotter) and you get already 15°C at the inlet boundary condition although it should be 30°C. I would think that the inlet fluid temperature is not set to 30°C. Assuming the model is ok geometry wise and no error message appears during the calculation, then everything in the first glace should be ok. However you can also try to shorten the test calculation by creating a clone of the project and simplify it to only the necessary part of the simulation and exclude any other possible mistake or problem. I cannot help more without a detailed information on how it looks like and what boundary conditions you have used. It is all to vague to understand it in detail and clearly identify the problem and give you a solution.