TEST_3_F95 - ME326:THERMODYNAMICS I Test3,Dec.1,1995...

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ME 326: THERMODYNAMICS I Test 3, Dec. 1, 1995 1) (33%) An inventor  brings you a heat engine that she claims takes  thermal energy from a solar collector at 227°C at a rate of 300 kW, converts  200 kW to mechanical power  and  rejects the rest to a cooling pond  at 27°C. a) What is the thermal efficiency of this heat engine if it operates as  claimed? b) Does this heat engine violate the first law of thermodynamics? c) Does this heat engine violate the second  law of thermodynamics? (Provide  some mathematical justification for your answers.) SOLUTION: a)   η =W net /Q h =200/300=0.67 or 67% b)  Write First Law around  complete cycle:  W net =Q h -Q c   or Q c  = Q h  - W net  =300-200 = 100 kW; As long as rejected  rate of heat   transfer is 100 kW, the device obeys the First Law . c) Can 1) Check whether  efficiency of real device (0.67 from part a) is less 
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This note was uploaded on 04/20/2010 for the course M E 320 taught by Professor Deinert during the Spring '08 term at University of Texas.

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TEST_3_F95 - ME326:THERMODYNAMICS I Test3,Dec.1,1995...

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