Tbulk for HTC
 

Hi all,

Hope everybody doing fine.
I want to use expert parameter "Tbulk for HTC" which later I will use to calculate Nusselt number.

The problem is what value should I give while inserting expert control parameter "Tbulk for HTC" as I have complex geometry (integrated heat exchanger and tube) in which one fluid is flowing through tube, one fluid flowing outside HX and one inside HX.
The initial temperature of all three fluids are different.

Also, how does this initial affects? can we give it considering any reference as per our choice (like inlet average temperature for one fluid)?

Can anybody give a shot to this query?

Thanks,
Mahesh

T-bulk can only be set globaly as far as I know, it cant be diferent for diferent fluids.

It is also imposible for it to be based on expresion as you are not alowed to put expression for t-bulk, that way it >could< be based on inlet temperature.
But if you have a fixed inlet temperature let say 25°C than T-bulk can be set at (25°c+273.15K) => 298.15 as it is in [K].

I usualy set it at 298.15 as in my case I am transfering HTC contour from cfx into another cfx where i am than able to set anbient temperature to those 25°c.
otherwise I would be forced to transfer adjacent temperature contour and compute it later on in the second simulation.

I hope I did not complicated it to much with an example of my case.

See the FAQ for some general info on HTC and Nusselt number post processing if you have not already:
http://www.cfd-online.com/Wiki/Ansys...ficient_in_CFX

tbulk for different domains
 

Hello!

Is there a chance to specify different <tbulk for htc> for each and every domain i have in my model ?

I am simulating an axial turbine and each domain has its own average Temperature (volumeAve(T)).

Any help is highly appreciated!

That capability is not available to my knowledge.

But it is easy to work out. If you set a constant tbulk for htc then output the average wall temperature and heat transfer in each domain with a bit of mathematical juggling you can evaluate it for any tbulk you like.