Exercise 4 Offdesign operation of power cycle

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ENERGY CONVERSION A 2019-20 1 Exercises Off-design operation of power cycles Exercise 1 Consider a gas turbines in four off-design conditions with the following common parameters: • ambient temperature and pressure: 15°C and 1.01325 bar; • compression pressure ratio: 40; • TIT: 1400°C; • breathed air mass flow rate: 100 kg/s. The four conditions differ by a localized pressure drop of 0.1 bar alternatively located at: 1. compressor suction; 2. compressor discharge; 3. turbine suction; 4. turbine discharge. For the reference case without pressure drops as well as all alternative cases, please: i. plot a realistic cycle on the T-s diagram, for all alternative cases, highlighting the differences; ii. compute and compare the second-law efficiency losses due to only the pressure drop; iii. comment without computing how all other losses change from case to case. Note: see exercise 1 of the second-law analysis of power cycles. Exercise 2 Consider an aeroderivative gas turbine characterized by the following parameters: • compression pressure ratio: 35, • TIT: 1400°C, • net electric power and specific work (without filter and silencer): 50 MW, 385 kJ/kg. Moreover, consider the following alternative conditions: 1. pressure drop null at the compressor inlet; 2. pressure drop of 150 mm of column head at the compressor inlet (assume controlling the turbine at constant TIT without operating the Inlet Guide Vanes). Please: i. plot the cycles on the same T-s diagram, showing the differences due to the pressure drop; ii. calculate the new temperatures at the compressor outlet and at the turbine outlet (TOT); iii. compute the variation of the net power due to the pressure drop. Exercise 3 Consider a natural-gas fired gas turbine in a single-shaft and simple-cycle architecture,…