
#1
Aug2410, 12:07 PM

P: 153

please can someone help me with the equations to use for Cp and h(convection coefficient) because i am doing a finite difference problem over time, of a gas being heated, and i need these two constants to be variable as temperature changes, which at the moment they are just constants.
I think its to do with nusselt, prandtl, reynolds (of which i also dont know how to calculate, and whether they vary with temperature), and whether the convection is forced or natural. I am looking for dCp/dt and dh/dt If anyone can help that would be greatly appreciated 



#2
Aug2710, 05:25 AM


#3
Aug2710, 05:40 AM

P: 153

ok so just to clear up, none of these have straight forward equations relating them to temperature, i have to interpolate for the values between values at known temperatures?




#4
Aug2710, 06:19 AM

P: 30

heat constant change with temperature
just h have to be interpolated , but you might find empirical equation describe behavior of h with respect of T if you search through internet (difficult and time consuming).
Pr,Nu,Re , vescosity and Cp have a specific equation. 



#5
Aug2710, 06:37 AM

P: 153

In terms of Cp, I cant use the equation that relates it to Cv and I cant use the equation that relates it to heat transfer Q =mCpDT
Is there another one that relates it to the current temperature? 


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