## Fluids

#### Flux Reports Heat Transfer Rate

• Arcube
Subscriber

My CFD study involves a compressor room with 2 heat sources and ventilation inlet and outlet. The air entering the room should absorb the heat from the 2 heat sources. However, the Flux Reports indicated a Total Heat Transfer Rate as follows:

Heat source 1 = 3,678W

Heat Source 2 = 3,678W

Velocity Inlet = 6,035W

Velocity Outlet = -13,585W

a) Although I can deduce that there is almost energy balance with some losses, I was wondering why the velocity inlet is a positive value? Shouldn't it be negative too since it absorbs the heat produced by the heat sources?

b) In the Volume Integrals Report, the fluid domain Mass Weighted Average temperature indicates a result of 37.47C. Does this represent the room average temperature?

Thank you very much for the response

• congmin
Subscriber

hi Arcube

I have also new question about Steady state thermal,can you this link see and answer it

https://studentcommunity.ansys.com/thread/maxwel-loss-imported-value-to-steady-state-thermal/

thank you

congmin

• Arcube
Subscriber
I found the answer to my own postna. For item a. the value depends on the operating temperature. If the operating temperature is higher than the incoming air temperature, i.e., velocity inlet condition, the value will be negative. All be it, the difference or the sum of velocity inlet and velocity outlet heat transfer rates is equal to the heat source/s transfer rates.nb. I think so. But I need the expert to explain thisnn
• Rob
Ansys Employee
Close, we calculate energy based on a reference value, 298.15K (I think, it's not the same as the Reference Values so have a very careful read of the User's Guide or even better try it on a test case). So if the temperature is higher than that value energy is +ve coming in. Mass is always positive coming in & negative leaving the domain. nThe volume average will represent the average for the domains chosen. For room average temperature, would that mean you want a mass or volume average?
• Arcube
Subscriber
Hi Rob,n Thank you very much, yes it must be the reference value that governs the equation rather than the operating condition.nI've got identical result for mass or volume average.nThis case is now closed.
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