A new and relatively unstudied compound is being investigated for its potential use as a refrigerant in a vapor compression cycle that operates with T = 25°C in the boiler and T = 35°C in the condenser. The properties of the compound at these two conditions have been measured as follows:

∎ At T = 25°C, the vapor pressure is P^sat = 0.6 bar, the enthalpy of vaporization is 35 kJ/mol.

∎ At T = 35°C, the vapor pressure is P^sat = 4.2 bar and the enthalpy of vaporization is 30 kJ/mol.

However, there is very little data for the compound at other temperatures and pressures. Best estimates are the ideal gas heat capacity is C_P* = 110 J/mol · K and the van der Waals parameters are a = 1.5 × 10⁷ bar · cm⁶/mol² and b = 40 cm³/mol.

Give your best estimate of the coefficient of performance of a refrigeration cycle using this compound, if the efficiency of the compressor is 80%. State any assumptions that you make.