The Cu2MnAl alloy is ferromagnetic even though Mn itself is not. The Mn-Mn distance in this alloy is larger than for Mn metal. What effect does this have on the 3d band of Mn and therefore, why is this alloy ferromagnetic?

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.