Question

Refrigerant 134a enters an insulated diffuser as a saturated vapor at 80°f with a velocity of 1453.4 ft/s. at the exit, the temperature is 280°f and the velocity is negligible. the diffuser operates at steady state and potential energy effects can be neglected. determine the exit pressure in lbf/in2 .

Answer 1

Refer to the diagram shown below.

State 1: The inlet
T₁ = 80°F, the inlet temperature
v₁ = 1453 ft/s, the inlet velocity
Saturated vapor

From thermodynamic tables, obtain
h₁ = 113.94 Btu/lbm, the enthalpy
p₁ = 101.45 psia, the inlet pressure

State 2: The outlet
T₂ = 280 F, the outlet temperature
v₂ = 0, the outlet velocity

From thermodynamic tables, obtain
h₂ = 163.76 Btu/(lbm-R)
p₂ = 40 psia, the exit pressure

Answer:  40 psia