Well, I had. The total calculate pressure drop is 395 mmWG, including free discharge. I was considering reducing the final stack diameter, but this will increase the free discharge pressure drop. Thats why I would like to know if I must consider the free discharge in the 400mmWG back pressure...
Thanks Latexman. You are right, the answer is in the manufacturer, but I was hoping someone would have experience in that. Taking into account the free discharge, it would add +20mmWG pressure drop (no little thing).
The maximun back pressure of a reciprocating CHP engine exhaust gas is 400 mmWG. To calculate the pressure drop of the whole exhaust system, I have taken into account: elbows,straight sections, dampers, diverter,tee, branches, silencers, heat exchanger, gradual expansion, free discharge.
But do...
