Steam flowing at 5.5 kg/min enters an adiabatic expander at 7.0 MPa and 650 C and leaves at 0.2MPa and 200 C. The expander delivers a total of 75 kW of power. A) Calculate the efficiency of theexpander. B) Use the temperature-independent heat capacity of water(found on inside of backcover) to assess whether steam is behaving ideally in this adiabatic expansion.

The temperature of air decreases as it is compressed by an adiabatic compressor. a)- true b)- false

Acompressor receives the shaft work to decrease the pressure of the fluid. a)- true b)- false

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?