Aclosed system consisting of 4 lb of a gas undergoes a process during which the relation between pressure and volume is pvn 5 constant. the process begins with p1 5 15 lbf/in.2, 1 5 1.25 ft3/lb and ends with p2 5 53 lbf/in.2, 2 5 0.5 ft3/lb. determine (a) the volume, in ft3, occupied by the gas at states 1 and 2 and (b) the value of n. (c) sketch process 1–2 on pressure–volume coordinates.

The catalogue for a refrigerant 22, four-cylinder, hermetic compressor operating at 29 r/s. a condensing temperature of 40°c and an evaporating temperature of -4°c shows a refrigeration capacity of 115 kw. at this operating point, the motor (its efficiency is 90 percent) draws 34.5 kw. the bore of the cylinders is 87 mm and the piston stroke is 70 mm. the performance data are based on 8°c of sub-cooling of the liquid leaving the condenser. compute (a) the actual volumetric efficiency and (b) the compression efficiency.