MEEN 315 PRINCIPLES OF THERMODYNAMICS SPRING 2017 Homework Cover page Student Last Name Student First Name UIN Section Select 204 OR 504 HW Date Submitted 8 Grading Completion All problems attempted Quality Neatness clarity legible Accuracy Accuracy of selected problem s Cover page this page attached on the top and all pages stapled together Total 10 points Max Score 4 1 4 1 Your Score 10 This cover page should be completed and stapled to the top of your homework solution MEEN 315 PRINCIPLES OF THERMODYNAMICS SPRING 2017 Question 1 For each part you may work out the solution in the given space 1a A heat engine has a heat input of 3 X 104 Btu h and a thermal efficiency of 40 percent Calculate the power it will produce in hp 1b An automobile engine consumes fuel at a rate of 22 L h and delivers 55 kW of power to the wheels If the fuel has a heating value of 44 000 kJ kg and a density of 0 8 g cm3 determine the efficiency of this engine MEEN 315 PRINCIPLES OF THERMODYNAMICS SPRING 2017 1c A residential heat pump has a coefficient of performance of 2 4 How much heating effect in Btu h will result when 5 hp is supplied to this heat pump 1d A heat engine operates between two thermal energy reservoirs at 1260 R and 510 R What is the maximum work the engine can produce per unit of heat that the engine receives from the source MEEN 315 PRINCIPLES OF THERMODYNAMICS SPRING 2017 1e A heat engine is operating on a Carnot cycle and has a thermal efficiency of 75 percent The waste heat from this engine is rejected to a nearby lake at 60 F at a rate of 800 Btu min Determine a the power output of the engine and b the temperature of the source 1f A refrigerator is to remove heat from the cooled space at a rate of 300 kJ min to maintain its temperature at 8 C If the air surrounding the refrigerator is at 25 C determine the minimum power input required for this refrigerator MEEN 315 PRINCIPLES OF THERMODYNAMICS 1g SPRING 2017 The performance of a heat pump degrades i e its COP decreases as the temperature of the heat source decreases This makes using heat pumps at locations with severe weather conditions unattractive Consider a house that is heated and maintained at 20 C by a heat pump during the winter What is the maximum COP for this heat pump if heat is extracted from the outdoor air at a 10 C b 5 C and c 30 C MEEN 315 PRINCIPLES OF THERMODYNAMICS SPRING 2017 Problem 2 Return to Problem 2 of Homework 6 and calculate the rate of entropy generation for the processes associated with both 7 MW and 5 MW power output described kW K Problem 3 Return to Problem 3 of Homework 6 and calculate the rate of entropy generation for the process described Btu s R with turbine heat loss of 420 Btu s Assume the surroundings temperature is 70 F
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