Q12. (a) The maximum temperature in a simple open cycle gas turbine plant is 1500°C. In normal operation, the turbine exhaust temperature (in K) may be assumed to be 0.68 times the turbine inlet temperature (in K), and the compressor delivery temperature may be assumed to be 1.89 times the suction (ambient) temperature. Calculate the specific work output when the ambient temperature is:
(i) 15°C
(ii) 35°C.
(b) During hot weather, it is proposed to improve the performance of the plant by cooling the inlet air from 35°C to 15°C using a refrigerator. Calculate the minimum required coefficient of performance of the refrigerator if it is not to use more than 20% of the work saved.
(c) Suggest (with reasons) a modification which could produce a significant improvement in the thermal efficiency of this plant.
Note: It may be assumed that C = 1.005 kJ/kg K for both air and hot gas.
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