Consider a gas turbine with air entering the compressor at 0.25 mpa and 30 c. it exits the compressor at 2000 kpa. the maximum temperature is 1800 °c. assume a compressor efficiency of 85% and a turbine efficiency of 90%, and a pressure drop of 20 kpa between the compressor and the turbine. a) determine the compressor work, the turbine work and cycle efficiency. b) repeat the same problem for a compressor efficiency of 60% and a turbine efficiency of 85% with a boiler efficiency of 65% c) repeat part b if the gas of operation is argon, and again for oxygen.

Acommercial grade cubical freezer, 4 m on a side, has a composite wall consisting of an exterior sheet of 5.0-mm thick plain carbon steel (kst= 60.5 w/m k), an intermediate layer of 100-mm thick polyurethane insulation (kins 0.02 w/m k), and an inner sheet of 5.0- mm thick aluminium alloy (kal polyurethane insulation and both metallic sheets are each characterized by a thermal contact resistance of r 2.5 x 104 m2 k/w. (a) what is the steady-state cooling load that must be maintained by the refrigerator under conditions for which the outer and inner surface temperatures are 25°c and -5°c, respectively? (b) for power saving purpose, which wall material should be increased/reduced in. thickness in order to reduce 50% of the cooling load found in part (a)? redesign the thickness of the proposed material. 177 w/m-k). adhesive interfaces between the q=575.93 w