Water at 20 bar, 400oC enters a turbine operating at steady state and exits at 1.5 bar. Neglect heat transfer, kinetic energy and potential energy effects. Someone states that the vapor quality at the turbine exit is 98%. (a) (35%) Find the entropy generation based on this statement. (b) (5%) Is this statement possible?

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?