A wastewater bar screen is constructed using 6.5-mm wide bars spaced $.0-cm. apart centre to centre. The wastewater flow velocity in the channel immediately upstream of the se from 0.4 to 0.9 m/s. Assume that the discharge coefficient is 0.84 a) What are the design head losses for the screens at the two extremes of flow (0.4 and 0.9 m/s) if the screen is mechanically-cleaned? b) What are the design head losses for the screens at the two extremes of flow (0.4 and 0.9 m/s) if the screen is manually-cleaned?

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.