Calculating total heat transfer

arash509 · December 16, 2016, 08:01

Hi

I designed a 2D canal with constant temperature walls. The fluid is Air and the inlet temperature is 300K. I want to calculate heat transfer rate. I use (Flux report>Total heat transfer rate). I have two questions:

1- when I change reference Depth in (Reference values>Depth) the Total heat transfer rate change. Why heat transfer rate depends on this reference value?

2- I don't know why that results is wrong because I choose (inlet) and calculate the Total heat transfer rate on inlet domain, But it is different with the Q=mh=mCpT (For ideal gas)

KevinZ09 · December 16, 2016, 10:08

Hi Aran,

Some, hopefully useful, quick answers:

1: The total heat transfer rate for conduction depends on the temperature gradient, which depends on the depth of the wall.
2: Enthalpies are always relative values; relative to a certain temperature. Fluent uses 25C (298.15K) I believe, but you may want to check that.

December 16, 2016, 08:01	Calculating total heat transfer	#1
arash509 New Member da Join Date: Oct 2016 Posts: 5 Rep Power: 10	Hi I designed a 2D canal with constant temperature walls. The fluid is Air and the inlet temperature is 300K. I want to calculate heat transfer rate. I use (Flux report>Total heat transfer rate). I have two questions: 1- when I change reference Depth in (Reference values>Depth) the Total heat transfer rate change. Why heat transfer rate depends on this reference value? 2- I don't know why that results is wrong because I choose (inlet) and calculate the Total heat transfer rate on inlet domain, But it is different with the Q=mh=mCpT (For ideal gas)

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December 16, 2016, 10:08		#2
KevinZ09 Senior Member Kevin Join Date: Dec 2016 Posts: 138 Rep Power: 9	Hi Aran, Some, hopefully useful, quick answers: 1: The total heat transfer rate for conduction depends on the temperature gradient, which depends on the depth of the wall. 2: Enthalpies are always relative values; relative to a certain temperature. Fluent uses 25C (298.15K) I believe, but you may want to check that.