Arankine cycle which uses water as the working fluid operates its condenser at 50 f and its boiler at 600 f. calculate the specific work (btu/lbm) produced by the turbine, the specific heat (btu/lbm) added in the boiler, and the net thermal efficiency of this cycle when the steam enters the turbine without any superheating

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?