Question

Refrigerant-134a enters the compressor of a refrigeration system as saturated vapor at 0.14 MPa and leaves as superheated vapor at 0.8 MPa and 60°C at a rate of 0.058 kg/s. Determine the rates of energy transfers by mass into and out of the compressor. Assume the kinetic and potential energies to be negligible. The enthalpies of refrigerant-134a at the inlet and the exit are 239.19 kJ/kg and 296.82 kJ/kg, respectively.

Answer 1

Answer:

17.21kW and 13.97kW

Explanation:

To solve this question we have two data that are provided to us and correspond to the Enthalpy.

$h1=239.16kJ/kg\\h2=296.81kJ/kg$

The energy in mass and enthalpy terms is given by.

$E_{mass,in}=mh_1$

Where the variables are,

• m=mass flow rate
• h= Enthalpy of refrigerant at the compressor

We only proceed to replace the values.

$E_{mass,in}=(0.058Kg/s)(239.16kJ/kg)\\E_{mass,in}=12.91kW$

Energy transfer rate by mass in the compressor is 13.97kW

Being analogs for the other part of the cycle,

$E_{mass,out}=mh_2$

Substituing,

$E_{mass,out}=(0.058Kg/s)(296.81kJ/kg)\\E_{mass,out}=16.02kW$

Energy transfer rate by mass out of the compressor is 17.21 kW