Modelling heat transfer in a helically coiled tube heat exchanger

Lancashire · August 20, 2015, 07:28

I am trying to model the heat transfer in a helical tube heat exchanger. I have validated a model using single-phase flow with a comparison of the simulated velocity fields and pressure drop to experimental data. However, it seems that I have a few issues with respect to the heat transfer simulation.

I have specified the inlet temperature at the velocity-inlet as well as the heat flux and heat generation rate at the wall-fluid boundary conditions. I did not change the FLUENT default temperature at the pressure outlet. Any ideas whether I am on the right track?

LuckyTran · August 20, 2015, 13:30

Quote:

Originally Posted by Lancashire

I have specified the inlet temperature at the velocity-inlet as well as the heat flux and heat generation rate at the wall-fluid boundary conditions. I did not change the FLUENT default temperature at the pressure outlet. Any ideas whether I am on the right track?

The heat generation rate is not a wall "boundary condition". Did you overspecify the boundary condition? It should be specified temperature, heat flux, convective heat transfer, etc. Is this a coupled/conjugate heat transfer problem and you are modelling the wall conduction also?

By temperature at the pressure outlet, I think you are referring to the backflow temperature specification. This temperature is only used if there is backflow.

Lancashire · August 21, 2015, 09:06

Many thanks for your reply. It seems that I may have overspecified the boundary conditions. As such I am not really interested in the wall conduction at this stage. Hence, with the return (inlet) temperature and heat flux I should be able to simulate the change in the bulk fluid temperature with flow along the heat exchanger?

4asino · September 13, 2015, 13:15

Could you tell me as i have a similar case ?

I tried to study axial velocity along the helical body ,, but in fluent the axial velocity does not equal that velocity.
I have entered the inlet velocity b.c as absolute velocity,,the problem does not persist.
Also,Is there availability to get the axial velocity at any cross section/plane using the angle through the planer ?

August 20, 2015, 07:28	Modelling heat transfer in a helically coiled tube heat exchanger	#1
Lancashire New Member Andrew Vella Join Date: Feb 2015 Posts: 12 Rep Power: 11	I am trying to model the heat transfer in a helical tube heat exchanger. I have validated a model using single-phase flow with a comparison of the simulated velocity fields and pressure drop to experimental data. However, it seems that I have a few issues with respect to the heat transfer simulation. I have specified the inlet temperature at the velocity-inlet as well as the heat flux and heat generation rate at the wall-fluid boundary conditions. I did not change the FLUENT default temperature at the pressure outlet. Any ideas whether I am on the right track?

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August 21, 2015, 09:06		#3
Lancashire New Member Andrew Vella Join Date: Feb 2015 Posts: 12 Rep Power: 11	Many thanks for your reply. It seems that I may have overspecified the boundary conditions. As such I am not really interested in the wall conduction at this stage. Hence, with the return (inlet) temperature and heat flux I should be able to simulate the change in the bulk fluid temperature with flow along the heat exchanger?

September 13, 2015, 13:15		#4
4asino New Member Anwar Join Date: Nov 2014 Posts: 28 Rep Power: 12	Could you tell me as i have a similar case ? I tried to study axial velocity along the helical body ,, but in fluent the axial velocity does not equal that velocity. I have entered the inlet velocity b.c as absolute velocity,,the problem does not persist. Also,Is there availability to get the axial velocity at any cross section/plane using the angle through the planer ?