Heat rejection from air compressor
Heat rejection from air compressor
(OP)
Hello everyone,
How much heat does air compressor produce with inter and after coolers per 1 HP.
Any rules? Formulas? Help please.
Thanks.
How much heat does air compressor produce with inter and after coolers per 1 HP.
Any rules? Formulas? Help please.
Thanks.





RE: Heat rejection from air compressor
RE: Heat rejection from air compressor
RE: Heat rejection from air compressor
That is an interesting calculation. 17,200 BTU/hr is 6.76 hp. To get a temperature rise from 80F (assuming the cooler above has a 20F approach to ambient) to 250F in air at sea level requires 2.6 compression ratios.
To raise 100 CFM (0.144 MMCF/d) 2.6 ratios requires 7.1 hp.
Based on this arithmetic (that looks fine to me), it takes almost as much energy to cool the air as it takes to compress the gas in the first place.
Does this say that only 5% of the energy input to a compressor is useful for raising pressure and 95% is just waste heat? What does that say about thermodynamic efficiency?
David
RE: Heat rejection from air compressor
RE: Heat rejection from air compressor
Consider isothermal compression and neglecting KE and elevation ---- energy equation is
WHin + energy of compression - heat transfer = WHout
But for Hin=Hout
enery per unit mass compression = heat transfer
Doesn't this agree with your conclusion?
RE: Heat rejection from air compressor
Probably, it was just so foreign to my expectations that I was having a problem visualizing it. I didn't have any basis for my expectations, but the heat transfer number just looked BIG.
David
RE: Heat rejection from air compressor