Stack velocity is NOT directly proportional to absolute temperature. The Ideal Gas Equation is PV=nRT, where “V” is volume of a gas in relationship to the temperature, “T” of the gas.
Velocity of a gas stream is determined by the following equation:
v = KpCp [(Ts)(delta p)/(Ps)(Ms)]1/2
Now, Qs = (As)(vs) where As is the area of the stack and vs is the velocity of the stack gas.
The pmr (pollutant mass rate) = (cs)(Qs) where cs is the concentration of the pollutant (mass per unit volume) and Qs is the volumetric flow rate of the stack gas [(As)(vs)].