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PRODUZIONE DI POTENZA DA FONTI RINNOVABILI for Energy engineering students 14 Febbraio 2014 Examination time: 1,5 ore 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 accompa- nied by explanations will not be taken into account. The final score will be normalized according to the average results. 3) Answer briefly but clearly only to the asked questions. Calculations and explanations - though correct in itself - that do not respond to the questions will not be considered for evaluation. 4) Talk with colleagues and / or cheating will cause the cancellation of the exam. Quesito 1 (16 punti) An OTEC cycle, open circuit type, is integrated with a solar thermal plant to produce electricity and 15 t/h of desalinated water. The seawater is heated by solar panels up to a temperature of 75°C (enthalpy = 314.1 kJ/kg), and is subsequently flashed to a pressure of 0.26 bar (sea water specific heat = 3.98 kJ/kgK). The steam cycle expands the fluid from the flash pressure down to the condensing pressure of 0.04 bar and the condensation is obtained by means of seawater at a temperature of 11°C. The seawater is first ly used to cool the condenser, then the same flow is preheated through a r e- generator with an efficiency of 95 %, which is positioned on the liquid outlet of the flash separator, and finally is sent to the solar panels. Draw (i) the system plant scheme. Neglecting the presence of non-condensable gases, please calculate (ii) the seawater flow-rate to be collected by the pumps, (iii) the electric power obtainable from the steam turbine, given the isentropic efficiency of the turbine (79%), and…