09 02 17 testo

Pagina 1

POWER PRODUCTION FROM RENEWABLE ENERGY AY 2016-17 9th February 2017 Prof. Silva and Manzolini Time: 1,5 hours 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 comprehe nsive manner with exact numerical results. Numerical results correct but not accompa- nied 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 que stions. 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.). 6) Not all the provided inputs are necessary for the problem solving Exercise 1 (16 points) It is required to determine the net power output at design conditions of a solar tower plant of an ind irect type, with solar salts as Heat Transfer Fluid and a steam cycle for converting the thermal power into elec- tricity, assuming the following characteristics (5 points). The receiver is a cylinder with a diameter of 8 m and height of 12 m. Please determine the power conversion processes (2 points) Assumptions Number of heliostats 2500 Heat losses (kW/m 2) 77 Heliostats surface area [m 2] 120 Piping efficiency 0.98 Direct Normal Irradiance [W/m 2] 900 Solar Multiple 2 Diffuse irradiance [W/m 2] 100 HTF receiver inlet temperature 300°C Optical efficiency 0. 72 HTF receiver outlet temperature 565°C Ambient temperature 15°C Power block Second law efficiency 65% Determine the overall yearly energy…