Problem 3: Refrigerant-134a is throttled from 10 bar and 36 o C to 240 kPa. Heat is lost from the refrigerant in the amount of 1 kJ/kg to the surroundings. Determine the exit temperature of the refrigerant. Assume steady state and ignore kinetic and potential energy effects.

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?

Compute the pressure drop of 30°c air flowing with a mean velocity of 8 m/s in a circular sheet-metal duct 300 mm in diameter and 15 m long. use a friction factor, f 0.02, and pair = 1.1644 kg/m a. 37.26 pa b. 25.27 pa n c. 29.34 pa d. 30.52 pa

Have a greater impact on maintenance productivity than any other support group. (clo5) a)-the top management b)-inventory and purchasing c)-sub-contracting d)-cmms