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ENERGY CONVERSION A 2015-16 Name/Lastname:__________________________________________ Code n.___________ Exam 26/09/2016 Exercise 1 (10 points) Focusing on the low-pressure preheating line of a water-cooled coal -fired steam power plant, consider adopting alternatively for the first preheater: (case 1) an indirect heat exchanger or (case 2) a direct heat exchanger to heat the feedwater up to 60°C. All other preheaters are conventional and identical in terms of architecture and tempera- tures for the two cases. Saturated steam at 65°C and 60°C is employed respectively for the two cases (heat of con- densation of about 2360 kJ/kg for both). Please: i. highlight clearly in your the text all assumed parameters and their assumed values (1 point); ii. sketch the layout of the low-pressure preheating line for both cases (2.5 points); iii. plot the temperature-heat transfer (T-Q) diagram of the low-pressure preheating line for both cases (2.5 points); iv. knowing that the feedwater mass flow rate is 1.260 t/h, compute and compare the wasted work due to the irreversibility of heat transfer in the first preheater for both cases – for simplicity neglect here subcooling in the indirect preheater (2 point); v. qualitatively compare, without computing, the irreversibility of heat transfer in the other low-pressure pre- heaters (2 points). Exercise 2 (12 points) Consider an inter-cooled gas turbine characterized by:  overall compression ratio: 16,  combustor outlet temperature: 1300°C,  turbine outlet temperature: 560°C,  net electric power: 6 MW,  net electric specific work: 390 kJ/kg,  net electric efficiency: 32% Neglecting all pressure drops, please: i. highlight clearly in your the text all assumed parameters and their assumed values (1 point); ii. sketch the plant layout…