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andrey_rushin November 16, 2011 09:09

Heat Exchanger Model
I try to use the Heat Exchanger Model of FLUENT and detect, that using of more then one HX produces wrong temperature difference between in- and outflow on one of used HX. Determination of one HX only in system deliveres correct temperature values...

Does somebody know something about this problem?

andrey_rushin November 17, 2011 06:38

you are right, I give too much information:D

Easiest way to establish communication is to discribe one example. Please imagine to have in your system two heat exchangers - radiator and condenser. For each HX you define in FLUENT a table that consits of heat rejections with coolant flow and air massflow. So far ok.
Regarding to actual flow field conditions one appropriate combination of heat rejection, coolant massflow and air massflow will be extracted from given table. As a result I expect one HX inlet temperature, which corresponds to formula:

Tin = Tamb + Q/(e*Cp*Mp)

Tin - coolant inlet temperature (predicted)
Tamb - environment temperature
Q - actual heat rejection
e - effectiveness
Cp - heat capacity of air
Mp - massflow air

If I use in system only one HX, the solved Tin is exactly one like solved using the formula. Two HX in same system deliver wrong Tin...

I am sorry for broken english:)

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