Moist air at 15°C, 1.3 atm, 63% relative humidity, and a volumetric flow rate of 770 m3/h enters a control volume at steady state and flows along a surface maintained at 187°C through which heat transfer occurs. Liquid water at 15°C is injected at a rate of 7 kg/h and evaporates into the flowing stream. For the control volume, cv = 0, and kinetic and potential energy effects are negligible. If moist air exits at 45°C, 1.3 atm, determine: the rate of heat transfer, in kW. the rate of entropy production, in kW/K.

Refrigerant 134a enters an insulated compressor operating at steady state as saturated vapor at -26°c with a volumetric flow rate of 0.18 m3/s. refrigerant exits at 9 bar, 70°c. changes in kinetic and potential energy from inlet to exit can be ignored. determine the volumetric flow rate at the exit, in m3/s, and the compressor power, in kw.

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?

Thermal stresses are developed in a metal when its a) initial temperature is changed b) final temperature is changed c) density is changed d) thermal deformation is prevented e) expansion is prevented f) contraction is prevented