ES210617 practical test

Page 1

POWER PRODUCTION FROM RENEWABLE ENERGY AY 2020-21 17th June 2021 Prof. Silva Time: 1,5 hours Instructions for the examination: 1) Clearly indicate your name on all the files 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) Talking with colleagues and / or cheating will cause the cancellation of the exam. 4) 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 (17 points) CASE A Consider a binary cogenerative geothermal plant fed by a geothermal brine that provides a flow rate of 800 t/h at a temperature of 175°C. The geothermal plant works with a saturated iso-pentane Rankine cycle described by the thermodynamic points in the table and relative graph below. Point 2 corresponds to the outlet of the feed pump, Point 5 corresponds to the turbine outlet in real conditions and Point 6 is saturated vapor. Point T [°C] P [bar] h [kJ/kg] 1 35,0 1,286 221,40 2 35,0 8,214 222,17 3 109,0 8,719 409,6 4 109,0 8,719 675,99 5 is 60,0 1,286 604,9 5 65,7 1,286 615,6 6 35,0 1,286 559,8 The following data are given:  Geothermal water average heat capacity 4,4 kJ/kgK  Sub-cooling ∆T at the economizer outlet 3°C  Pinch point at the evaporator 4°C  Organic-electric efficiency of the generator 95.5%  Auxiliary power consumption (including feed pump) 585 kW  Minimum re-injection temperature 50°C The thermal power is recovered by cooling down the geothermal fluid from the economizer outlet temperature to the minimum reinjection temperature. It is requested…