MEEN 315 SECTION 503 PRINCIPLES OF THERMODYNAMICS Spring 2013 Homework 11 DUE April 25 2013 1 A steam power plant has a high pressure of 3 MPa and it maintains 60 C in the condenser A condensing turbine is used but the quality should not be lower than 90 at any state in the turbine Find the specific work and heat transfer in all components and the cycle efficiency 2 Consider an ideal steam reheat cycle in which the steam enters the high pressure turbine at 600 psia 700 F and then expands to 120 psia It is then reheated to 700F and expands to 2 226 psia in the lowpressure turbine Calculate the thermal efficiency of the cycle and the moisture content i e quality of the steam leaving the low pressure turbine Why should we be concerned about the moisture content in the steam leaving the low pressure turbine HINT Example 10 4 in your textbook might help you on this problem 3 Consider an air standard Otto cycle that has a heat addition of 800 Btu lbm of air a compression ratio of 7 and a pressure and temperature at the beginning of the compression process of 13 psia 50 F Assuming constant specific heat with the value from Table A 2E a determine the maximum pressure and temperature of the cycle the thermal efficiency of the cycle and the mean effective pressure 4 An ideal diesel engine has a compressio ratio of 20 and uses air as the working fluid The state of air at the beginning of the compression process is 95 kPa and 20 C If the maximum temperature in the cycle is not to exceed 2200K determine a the thermal efficiency and b the mean effective pressure 5 A kitchen freezer uses 500 W of power to hold the freezer temperature to 10F With R 134a as the refrigerant it rejects high temperature thermal energy to the kitchen at 100 F i e the temperature of the R 134a after the condenser is 100F Assuming the vapor refrigeration cycle calculate the COP of this refrigerator FINAL EXAM DETAILS Here are some details for you to know about the final exam 1 There are two times available to take the final exam an early alternate time or the later originallyscheduled time You can choose whichever time you feel is best for your success in the class and your schedule Once you sit for the exam however you cannot sit for it a second time The two times are a Friday May 3 6 8pm 104B Zachary alternate early time b Wednesday May 8 1 3pm 104B Zachary originally scheduled time 2 The final exam is comprehensive with emphasis on material that we ve covered since Exam 2 Exam format is similar to Exams 1 and 2 10 multiple choice 2 points each and 4 work out problems 20 points each 3 You are allowed to fashion one 1 8 5 x 11 both sides crib sheet of formulae You are welcome to put whatever you wish on this sheet In addition to your self generated formula sheet the usual end of page formula sheet will be included on the final exam 4 A sample final exam will be posted on the e learning website at least one week prior to the final exam 5 A review session will be held on Thursday May 2 from 2 20 to 3 35pm in 104B Zachary Bring good questions
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