total btu/h formula broken down
total btu/h formula broken down
(OP)
hello i have just a general question....
the formula Q=4.5 x CFM x (delta h) i know this is standard formula at sea level but my question that i havent determuned is where does the 4.5 constant get derived from..what are the specifics of that constant and does it change upon ones change in elevation.
the formula Q=4.5 x CFM x (delta h) i know this is standard formula at sea level but my question that i havent determuned is where does the 4.5 constant get derived from..what are the specifics of that constant and does it change upon ones change in elevation.





RE: total btu/h formula broken down
Things like density, specific heat and 60 are in there.
RE: total btu/h formula broken down
mass flow (lb/hr) = volume flow (cf/hr) x density (lb/cf)
60 mins = 1 hour
air density at standard conditions = 0.075 lb/cf
so...
q (btu/hr) = volume flow (cf/min) x 60 (min/hr) x 0.075 (lb/cf) x enthalpy change
or
q = 4.5 x CFM x enthalpy change
altitude, moisture content, and temperature will all affect the 4.5 constant because they all affect density.