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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 12 February 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): COMBUSTION BOILERS A) Provide the definition of thermal efficiency of a boiler. B) Derive the relation between boiler efficiency and boiler operating parameters. C) Describe how the excess of air should be set to maximize the boiler efficiency. D) Discuss the differences between premixed and diffusive flame and explain the effect on NOx formation. E) Give typical maximum pressure and maximum temperatures of the steam generated in a boiler of a large state-of-the-art steam cycle power plant. Question 2 (16 points): COMBINED CYCLE A) Draw the scheme of a combined cycle featuring…