22 11 16

Pagina 1

Politecnico di Milano Department of Energy School of Industrial and Information Engineering Course Energy Systems LM proff. E. MARTELLI, M. ROMANO - Academic Year 2015/16 Energy Systems LM - written test of November 22nd 2016 page 1 of 1 Written Exam, November 22nd 2016 - QUESTIONS - Time: 1 hour PLEASE NOTICE 1) This part of the exam is closed book. Computers and cell phones are NOT allowed. Talking with colleagues and/or copying will lead to the immediate cancellation of the exam. 2) The final grade is the sum of the points assigned to the answer of each question (max. 15 points each) plus a bonus of max 3 points. The bonus will be given based on whether the answer to each question is complete, as well as the clarity and the details of the explanations. 3) Wherever possible, support your statements with clear drawings and/or graphical representations ANSWER JUST TO THE QUESTIONS asked. CONSIDERATIONS THAT DO NOT ADDRESS THE QUESTIONS MAY LEAD TO THE SUBTRACTION OF POINTS Indicate the name of the professor of the classes that you attended: _____________________ Question 1 (15 points) Describe the effects of regeneration (“feedwater preheating”) on the following types of steam cycles: - Fuel-fired steam cycle (with boiler) - Heat recovery steam cycles Consider the effects on plant efficiency and investment costs and provide a complete and concise motivation of such effects. Question 2 (15 points) a) Provide a complete definition of Cogeneration power plant (also called Combined Heat and Power plant) highlighting the differences with respect to a conventional power plant. b) Motivate the thermodynamic advantage of cogeneration plants with respect to sepa rate generation. c) Draw the scheme of a cogeneration gas turbine and draw the T-s diagram of the thermodynamic cycle…