Refrigerant-134a enters an adiabatic compressor as saturated vapor at -24°c and leaves at 0.8 mpa and 60°c. the mass flow rate of the refrigerant is 1.2 kg/s. determine: (a) the power input to the compressor, and (b) the volume flow rate of the refrigerant at the compressor inlet.

(a) The power input to the compressor:

(b) The volume flow rate of the refrigerant at the compressor inlet:

Explanation:

(a)

We need to check the values of enthalpy (as we have an open system) for both states, being the inlet, state 1 and the outlet, state 2. We will know these values by checking the vapor charts of R134a, I used the ones found in Thermodynamics of Cengel, 7th edition.

Then, our values are:

Now we proceed to know the work with the following expression:

Now we replace values and our result is:

(b)

To know the volume rate at the compressor inlet, we need to know the specific volume in that phase, as we have that is saturated and at -24°C, we can read our table:

With our specific volume and the mass rate, we can calculate the volume rate:

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