practical test 20200826

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SOLAR AND BIOMASS POWER PRODUCTION AY 2019-20 26th August 2020 Prof. Giampaolo Manzolini Time: 2 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.). 6) Not all the provided inputs are necessary for the problem solving Exercise 1 (16 points) Calculate the LHV, HHV and the energy density of the biomass reported below on a “dry” and “as received” basis at the boiler inlet (∆hevaporation = 2.44 MJ/kg) (3 points). Determine the biomass mass flowrate assuming that the net power output of the boiler is 30 MW, thermal losses from boiler walls are equal to 1% of the fuel LHV dry thermal input, un- burned carbon is 2% (of carbon content, dry basis, LHV = 32.8 MJ/kg), stac k temperature equal to 150°C (cp exhaust gases 1.1 kJ/kg K) and ashes melt at 900°C can be accounted as losses (equivalent heat capacity 2 kJ/kg K), ambient temperature is 15°C and the ( 𝑚𝑚𝑎𝑎𝑎𝑎𝑎𝑎 𝑚𝑚̇ 𝑑𝑑𝑎𝑎𝑑𝑑 )̇ is equal to 10. (7 points) Determine the storage per iod of the biomass considering that the storage can be approxi- mated as a greenhouse with 1500 m2 surface, overall heat transfer…