A200-l tank (see fig. p4.107) initially contains water at 100 kpa and a quality of 1%. heat is transferred to the water, thereby raising its pressure and temperature. at a pressure of 2 mpa, a safety valve opens and saturated vapor at 2 mpa flows out. the process continues, maintaining 2 mpa inside until the quality in the tank is 90%, then stops. determine the total mass of water that flowed out and the total heat transfer.

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?