Exam test 1

Page 1

Wind, Hydro and Geothermal Power Generation AY 2021-22 Example of Test - 1 Prof. Paolo Silva Time: 90 minutes Instructions for the exam: 1) Clearly indicate your name on all the sheets you will deliver. 2) Give a synthetic and clear answer to as many questions as possible. The final score will be normalized according to the average results. 3) Talk with colleagues and / or cheating will cause the cancellation of the exam. 1. Consider a three-bladed, horizontal-axis wind turbine with a rotor diameter of 110 m coupled to a full scale converter. Analyze the behavior of the turbine in the following conditions: cut-in, a wind speed between the cut-in and nominal condition, nominal condition, cut-off. For each point indicate the wind speed and the expected/calculated values of C p, λtip, rotational speed and electrical power output (assume reasonable values for the main parameters). Qualitatively plot the points on a graph with respect to the wind speed. (5 points) 2. Plot the lay -out of a geothermal direct steam cycle with 2 pressure laminations and draw the corresponding T-s diagram. Please highlight the main technical issues related to the plant op- eration. (5 points) 3. Considering a run-of-river plant based on a diversion channel, define the flow duration curve and show how it can be used to obtain an optimal preliminary design of the turbine. Please show how it is possible to graphically evaluate the annual flow rate elaborated by the turbine (it is not necessary to give a numerical example, just provide a qualitative evaluation). (5 points) 4. Explain the concept and the calculating method of the Levelized Cost of Electricity (LCOE) for renewable energy sources (RES). Comparing different power plants/RES with the same invest- ment cost (€/kW), what are the most…