A Freon -12 refrigerator producing a cooling effect of 20 kJ/s operates on a simple cycle with pressure limits of 1.509 bar and 9.607 bar. The vapour leaves the evaporator dry saturated and there is no under cooling. Determine the power required by the machine. If the compressor operates at 3000 rpm and has a clearance volume of 3% of stroke volume determine the piston displacement of the compressor. For compressor assume that the expansion follows the law pv1.13 = constant.
|
Temperature
(oC)
|
ps
(bar )
|
vg
m3/kg
|
Enthalpy kJ/kg
|
Entropy kJ/kg K
|
Specific heat
|
|
|
|
|
hf
|
hg
|
sf
|
sg
|
|
|
–20
|
1.509
|
0.1088
|
17.8
|
178.61
|
0.073
|
0.7082
|
|
|
40
|
9.607
|
|
74.53
|
203.05
|
0.2716
|
0.682
|
0.747
|