A steam-heated single-pass tubular preheater is designed to raise 45,000 lb/h of air from 70 to 170?F,

Question:

A steam-heated single-pass tubular preheater is designed to raise 45,000 lb/h of air from 70 to 170?F, using saturated steam at 375 psia. It is proposed to double the flow rate of air and, in order to be able to use the same heat exchanger and achieve the desired temperature rise, it is proposed to increase the steam pressure. Calculate the steam pressure necessary for the new conditions and comment on the design characteristics of the new arrangement.GIVENSteam-heated single-pass tubular preheated heating airAir flow rate (ma) = 45,000 lb/hAir temperatureTa,in = 70?FTa,out = 170?FSaturated steam pressure (ps) = 375 psia = 2.59 x 106N/m2