ES230116 practical test

Page 1

POWER PRODUCTION FROM RENEWABLE ENERGY AY 2021-22 16th January 2023 Prof. Silva 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 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 (16 points) A geothermal source has the following characteristics at the outlet of the well: pressure 12 bar, vapor fraction 80%, mass flowrate 15 kg/s. Draw the power plant lay -out in a configuration without the atmospheric vessel (1 point) and determine the net power output (4 points), considering a condensing pressure of 0.08 bar and assuming a steam turbine isentropic efficiency of 87 % and a generator organic-electric efficiency of 9 7%. Calculate the net electric efficiency considering a minimum reinjection temperature equal to the condensing temperature and an overall auxiliary consumption of 550 kW (2 points). In order to increase the power output, the geothermal fluid is further heated to 41 0°C in a biomass boiler , corresponding to an enthalpy of 3278,13 kJ/kg and an entropy of 7,303 kJ/kgK (series configuration, eliminat- ing the demister and neglecting pressure drops, biomass is oak…