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Politecnico di Milano Department of Energy - School of Industrial Engineering Course Energy Systems LM prof. S. Consonni, E. Martelli, M. Romano - Academic Year 2017/18 Written Exam – Energy systems LM pag. 1 di 1 Written Exam 22 January 2018 Theoretical Questions: Time 1.00 h 1) Books, lecture notes, cell phones are forbidden. Using them or talking with colleagues and/or copying will lead to the immediate invalidation of the exam. 2) Answer clearly ONLY to the questions posed by the problem sets. Even if correct, additional considerations will NOT contribute to the final grade – and you have NOT enough time to do this ! 3) Fill this sheet with your name and return it. 4) MARK EACH SHEET with YOUR NAME AND PAGE/SHEET NUMBER. 5) WRITING AND SHEET/PAGE SEQUENCE MUST BE LEFT TO RIGHT AS USED IN WESTERN COUNTRIES. 6) The final grade is the sum of the points assigned to the answer of each question plus a bonus of max 3 points. The bonus will be given based on completeness, clarity and details of the explanations. 7) Wherever possible, support your statements with clear drawings and/or graphical representations FIRST NAME………………………......……………..…FAMILY NAME…………………………………….……………….. Question 1 (16 points): HEAT EXCHANGERS A) Write the energy balance equation for a generic heat exchanger in steady‐flow condition. B) Write the heat transfer rate equation used to calculate the area of the heat exchanger, explaining under which assumptions such equation can be used. C) Assume that the hot stream is a gas and the cold stream is subcooled liquid at the inlet and super‐heated steam at the outlet.  How would you estimate the total heat transfer area? D) Write the reversible power loss of a generic heat exchanger (in steady‐flow condition) and the simplified expression for heat…