An air conditioner with refrigerant 134a as the working used is used to keep a room at 23 C by rejecting waste heat to the outdoor air at 35 C. The room gains heat through the walls at a rate of 250 kJ/min and household appliances generate heat amounting to 900 W. The refrigerant enters the compressor at 400 kPa as a saturated vapor at a rate of 80 L/min and leaves at 1200 kPa and 70 C. Find the actual COP of this system. In addition, find the maximum COP possible for this system and the refrigerant volume flow rate into the compressor for this ideal COP.

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?

Aplate clutch has a single pair of mating friction surfaces 250-mm od by 175-mm id. the mean value of the coefficient of friction is 0.30, and the actuating force is 4 kn. a) find the maximum pressure and the torque capacity using the uniform-wear model. b) find the maximum pressure and the torque capacity using the uniform-pressure model.

Condition monitoring is a major component of. (clo4) a)- predictive maintenance. b)-preventive maintenance c)-proactive maintenance d)-reactive maintenance.