Another alternative refrigerant (see preceding problem) is 1,1,1,2- tetrafluoroethane (refrigerant HFC-134a). Tillner-Roth and Baehr published a compendium of thermo physical properties of this substance (R. Tillner-Roth and H.D. Baehr,]. Phys. Chem. Ref Data 23,657 (1994)), from which properties such as the Joule- Thomson coefficient μ can be computed.
(a) Compute μ at 0.100 MPa and 300 K from the following data (all referring to 300 K):
P/MPa 0.080 0.100 0.12
Specific enthalpy/Ikl kg-1) 426.48 426.12 425.76
(The specific constant-pressure heat capacity is 0.7649 kl K-I kg-I)
(b) Compute μ at 1.00 MPa and 350 K from the following data (all referring to 350 K):
P/MPa 0.80 1.00 1.2
Specific enthalpy/Ikl kg-1) 461.93 459.12 456.15
(The specific constant-pressure heat capacity is 1.0392 k] K-1 kg-1)