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January 31, 2011, 07:13 
area weighted or mass weighted average

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Amit Chauhan
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thank you sir... thank you very much.


May 3, 2013, 17:10 

#22  
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Ehsan
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what do you mean by a conserved variable exactly? is a scalar transport variable conserved?I have mixed up with a conserved variable and a conserved equation. thank you.
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March 4, 2014, 06:19 

#23  
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adnan
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Quote:
I interested to find temperature. Thanks in advance 

March 4, 2014, 13:37 

#24 
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adnan
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Dear friends, I have in my project mixing chamber CO2 with air (with different temperature ) but mass fraction for CO2 very small when try to find static temperature or total temp. by mass  averaging different if I find it by area  averaging, and my project incompressible flow
I interested to find temperature. Thanks in advance 

July 8, 2015, 07:15 

#25  
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Shane
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April 26, 2018, 02:12 
asking reference of the statements

#26  
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teguh hady
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Actually, I want to use massaveraging in calculating bulk tempertature. But, my supervisor ask me to use basic equation in calculating bulk temperature in pipe. I see some papers use mass averaging to calculate bulk temperature. Why they do not use basic equation to calculate bulk temperature? I would like to know the reference of your statement written in which book or paper. Can you tell me your references? Thank you for your help. Best Regards Teguh
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April 26, 2018, 09:10 

#27 
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The averaging discussed here is how to average over a whole inlet or outlet boundary in a CFD simulations. Your problem of "calculating bulk temperature" sounds like a different problem. Do you have a CFD simulation available? Do you want to average over a known boundary and what property to you want to average? What will the averaged result be used for?


April 29, 2018, 21:02 

#28  
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Lucky
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So when is the bulk temperature not the mass averaged temperature? When there are variable specific heats or you consider the bulk temperature as the temperature associated with the bulk enthalpy. 

April 29, 2018, 22:40 

#29  
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teguh hady
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I am sorry maybe my understanding is wrong. I think the bulk temperature is similar to mean temperature so I ask about it. Yes, I have CFD simulation. I need the bulk temperature in inlet and outlet to calculate the Heat transfer coefficient and also Nusselt number. Actually for the property (density, viscosity, conductivity and heat capacity) is constant. Thank you for your help
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April 29, 2018, 22:50 

#30  
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teguh hady
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I use the attached equation (It is taken from Fundamental of Heat and Mass Transfer Incropera). Actually, I have tried to calculate the bulk temperature by using that equation and massweighted average temperature. But there is a difference in each result. I don't know which one is the correct. Thank you for your help
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April 30, 2018, 03:16 

#31 
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Lucky
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The rho u sitting in the integral is what makes it a mass average integral. So you see that is a mass weighted average integral of Cp*T. Obviously the integral of rho*U is the mass flow rate mdot. So if Cp is a constant and you can bring it out of the integral (which is implied in this formula by comparing with the denominator), then the bulk temperature is the mass averaged temperature. If cp was not constant, then there would be an integral of rho*U*cp in the denominator or something equivalent. Maybe you missed that you are staring at the formula for the massaverage? The reason it makes sense to call this integral a massweigted average (vs the more precise massflowrate weighted average) is that there's no mass on a plane, only massflux or massflows.


April 30, 2018, 05:12 

#32  
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teguh hady
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Thank you for your explanation. Now, I have a clear understanding of the equations. Thank you so much. Thank you best regards Teguh
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