Heat Iniput Required to Raise Air Temp from 70F to 1537F

[steveski]

I need to calculate the theoretical heat required to raise the temperateure of dry air from 70F to 1537F. I did it once using mean heat capacity and got 375 btu/(lb-mass). I did it again integrating the heat capacities expressed as power series and got 377 btu/(lb-mass). So, I'm feeling pretty confident, but I'm hoping someone can give me a sanity check as I haven't done this calculation in a long time. Thank you very much.

 

[25362]

I only can reach old tables in metric units for air at atmospheric pressure. Thus

70 deg F => 1.0056 kJ/(kg.K) => 0.24 Btu/(lb.^oF)
1537 deg F => 1.160 kJ/(kg.K) =>0.277 Btu/(lb.^oF)

The heat gain:

0.277[×]1537 - 0.24[×]70 ~ 409 Btu/lb​

 

[TD2K]

I have some mean heat capacities from "Material and Energy Balance" by Schmidt and List (Cp is in BTU/lbmoleF)


For air from 25C to 1292F, the Cp is 7.37
For air from 25C to 1472F, the Cp is 7.45
For air from 25C to 1652F, the Cp is 7.52

That should bracket your temperature range and provide another cross check.

 

[steveski]

Thank you both for your help.

 

[TangoCleveland]

I get 377.7 BTU/lb at atmospheric pressure using enthalpies from NIST Standard Reference Database 23,
NIST Reference Fluid Thermodynamic and Transport Properties Database (REFPROP): Version 7.0

Larry

 

[25362]

Using data from Perry, I get the same results obtained by TangoCleveland.