Best way to calculate bulk fluid temperature in case of steam-water flow

silviliril · September 12, 2023, 04:23

In order to get Heat Transfer Coefficient, I need to calculate bulk fluid temperature at different axial locations in a pipe flow boiling case. But, the getting bulk fluid temperature in two-phase flow doesn't seem straightaway. So, What will be the best strategy?

I am using RPI wall boiling model and post-processing is being done in tecplot.

Do I need to do area averaged or mass averaging or other suitable method? how to I combine phase-1 (liquid) and phase-2(vapor) temperatures into one?

LuckyTran · September 13, 2023, 00:33

Bulk temperature is defined as mass averaged

silviliril · September 13, 2023, 00:41

okay. Till now I have understood that mass flow averaged has to be considered. But, that can be found for single phase flow. what about two phase flow at cross section? How mass flow averaged temperature formula works for two-phase?

LuckyTran · September 13, 2023, 01:33

What happens if you have a glass of water with ice?

Bulk temperature was invented exactly to deal with these kinds of scenarios and yet you are questioning how bulk temperature would work as it was intended.

silviliril · September 13, 2023, 02:31

I just want to know if following formula is correct or not for bulk fluid temperature:

Code:

Tb=(Ti ui ρi Ai + Tj uj ρj Aj)/(ui ρi Ai + uj ρj Aj )

where, Ti=temperature of phase 1
ui=velocity of phase 1
ρi = density of phase 1
Ai = area occupied by phase 1
Same notations are for phase 2 with j.

September 12, 2023, 04:23	Best way to calculate bulk fluid temperature in case of steam-water flow	#1
silviliril Member L S Join Date: Apr 2016 Posts: 63 Rep Power: 10	In order to get Heat Transfer Coefficient, I need to calculate bulk fluid temperature at different axial locations in a pipe flow boiling case. But, the getting bulk fluid temperature in two-phase flow doesn't seem straightaway. So, What will be the best strategy? I am using RPI wall boiling model and post-processing is being done in tecplot. Do I need to do area averaged or mass averaging or other suitable method? how to I combine phase-1 (liquid) and phase-2(vapor) temperatures into one?

September 13, 2023, 02:31		#5
silviliril Member L S Join Date: Apr 2016 Posts: 63 Rep Power: 10	I just want to know if following formula is correct or not for bulk fluid temperature: Code: Tb=(Ti ui ρi Ai + Tj uj ρj Aj)/(ui ρi Ai + uj ρj Aj ) where, Ti=temperature of phase 1 ui=velocity of phase 1 ρi = density of phase 1 Ai = area occupied by phase 1 Same notations are for phase 2 with j. Last edited by silviliril; September 13, 2023 at 02:32. Reason: typing correction

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September 13, 2023, 00:33		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,676 Rep Power: 66	Bulk temperature is defined as mass averaged

September 13, 2023, 00:41		#3
silviliril Member L S Join Date: Apr 2016 Posts: 63 Rep Power: 10	okay. Till now I have understood that mass flow averaged has to be considered. But, that can be found for single phase flow. what about two phase flow at cross section? How mass flow averaged temperature formula works for two-phase?

September 13, 2023, 01:33		#4
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,676 Rep Power: 66	What happens if you have a glass of water with ice? Bulk temperature was invented exactly to deal with these kinds of scenarios and yet you are questioning how bulk temperature would work as it was intended.