ES 08 07 2024 practical test

Pagina 1

POWER PRODUCTION FROM RENEWABLE ENERGY AY 2023-24 8th July 2024 Prof. Andrea Giostri Time: 1.5 hours NAME and SURNAME:.................................................................................................................................................. COURSE and CFU:......................................................................................................................................................... Instructions for the examination: 1) Clearly indicate your name on all the sheets you will deliver. 2) The score refers to exercises done in a comprehensive manner with exact numerical results. Numerical results correct but not accompanied by explanations will not be taken into account. The final score can be normalized according to the average results. 3) Answer briefly and clearly only to the asked questions. Calculations and explanations which do not respond to the questions will not be considered for evaluation even if correct. 4) Talking with colleagues and / or cheating will cause the cancellation of the exam. 5) All the needed data for the resolution of exercises lies on this paper. It is NOT ALLOWED to use material other than this (e.g. books, clipboard etc.). Exercise 1 (15 points) A wind turbine is characterized by a nominal size of 2 MW and a yearly capacity factor of 28%. The wind turbine diameter is 85 m and the mechanical electric efficiency is 0.96 (considered independent of the wind speed). Tip speed ratio in nominal conditions is equal to 7.1. The average air conditions are temperature equal to 12 °C and pressure equal to 101325 Pa (air treated as ideal gas with molar mass equal to 28.9 kg/kmol). The cut-in and cut-off velocities are 3 and 24 m/s, respectively, and the probability density function f(v) of the wind velocity can…