Hot combustion gases, modeled as air behaving as an ideal gas, enter a turbine at 1100 kPa, 1600 K with a mass flow rate of 0.2 kg/s and exit at 300 kPa and 1000 K. If heat transfer from the turbine to its surroundings occurs at a rate of 16 kW, determine the power output of the turbine, 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?