Answer

Solved Step by step with explanation: calculate (a) the mass flow rate of the refrigerant.

To solve this problem, we can use the ideal vapor compression cycle equations and properties of R-134a refrigerant. Here are the steps to calculate the mass flow rate of the refrigerant and the coefficient of performance (COP) of the refrigeration machine:

ṁ = mass flow rate of the refrigerant (in kg/s)

h1 = enthalpy at the evaporator inlet (in kJ/kg)

ṁ = Wc / h1 = 400 W / 100 kJ/kg = 0.004 kg/s

Therefore, the mass flow rate of the refrigerant is 0.004 kg/s.

Let's assume the enthalpy at the compressor outlet (h2) is 300 kJ/kg (you can use the actual properties from tables for a more accurate calculation).

Using the enthalpy values:

The negative value for COP indicates that the system is not operating as a refrigerator, but rather as a heat pump, where heat is being extracted from the refrigerated space.

Please note that the assumed values for enthalpy (h1 and h2) are for illustration purposes. For accurate calculations, you should refer to the actual properties of R-134a refrigerant from tables or software.