Example 8.11:Vaporizer Heat Duty
Fluid Flow Rate(ql, gpm):
Fluid Density(Den, lb/ft3):
Enthalpy at Inlet(H1, Btu/lb):
Enthalpy at Outlet(H2, Btu/lb):
Mass Flow(M,lb/h):
Heat Duty(UHT, MMBtu/hr):

Example 8-11;
What heat duty is required to vaporize 50 gpm of liquid propane at 60°F and 235 psig
and superheat the vapor by 20°F?

Solution Steps
Refer to Section 24 “Thermodynamics” and the P-H diagram for propane.
At 60°F and 249.7 psia the enthalpy of propane is 187 Btu/lb.
The exit enthalpy at 142°F (20°F above the dew point) and 249.7 psia is 369 Btu/lb.
The liquid density is 31.7 lb/cu ft and this corresponds to 4.24 lb/gal.

UHT=M * (H2 - H1)

1 cu ft = 7.48052 Usgal

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