240205 theoretical test

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POWER PRODUCTION FROM RENEWABLE ENERGY AY 2022-23 5th February 2024 Prof. Andrea Giostri Time: 1 hour NAME and SURNAME:.................................................................................................................................................. COURSE and CFU:......................................................................................................................................................... MARK IN THE PRACTICAL PART (if you have done it in previous exam calls):……................ ...................... Instructions for the examination: 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. OPEN QUESTIONS (points 18) 1. Derive the efficiency of a solar thermal module and i llustrate the analytic expression to evaluate its stagnation temperature. Give an example of its value for a plain module and a vacuum module and motivate the difference. 2 Consider a binary ORC cycle powered by a liquid- dominant geothermal source. Draw the plant layout and discuss the effect of evaporation temperature on plant efficiency. Analyze the opportunity to insert a regenerator downstream of the turbine. MULTIPLE-CHOICE QUESTIONS (points 12) Answer to the following 15 questions. Select the box with correct answer (0.8 points if correct, -0.3 points if wrong). Consider a closed OTEC plant for power production (based in NH3 Rankine cycle) operating in a specific location : CW Cold seawater The highest investment cost is related to the ammonia turbine Ideally can have a high capacity factor (i.e. 80%) For sure, an increase…