Saturated refrigerant-134a vapor is expanded reversibly in an insulated piston- cylinder device from an initial state of 0.6 mpa and 0.03 m^3 to a final state of 0.16 mpa. determine a) the reversible work, b) the change in the exergy of the refrigerant during this isentropic process. assume the surroundings to be at 25c and 100 kpa.

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?

Journeyman training is usually related (clo2) a)-to specific tasks b)-to cost analysis of maintenance task c)-to control process to ensure quality d)-to installation of machinery

Select any two (2) areas of applications of chain-drive. (clo4) a)-permanent lubrication necessary b)-hydraulic forklift truck operation c)-rigging and heavy moving materials d)-relatively high maintenance costs e)-costlier than belt drives