SpecialProblems19-21

SpecialProblems19-21 - SP 21 Answer the following a Does a...

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Special Problems for ME 200 - Spring 2011 Special Problems 19, 20, 21 Due March 4, 2011 SP19: Answer the following: A) Would you expect the temperature of air to drop as it undergoes a steady-flow throttling process? Explain. B) A well-insulated valve is used to throttle steam from 8 MPa and 500°C to 6 MPa. Determine the final temperature of the steam. SP 20 : A steam turbine is used to drive a nitrogen compressor, as shown in the figure. The states of the steam and nitrogen are given in the diagram, and the mass flow rate is 0.125 kg/s and 0.02 kg/s through the turbine and compressor, respectively. Heat transfer from the turbine is small and can be neglected. The turbine delivers 12 kW to the compressor and the balance to an electric power generator. a) Determine the power available from the turbine for driving the electric power generator. b) Determine the rate of heat transfer from the nitrogen as it flows through the compressor and aftercooler.
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Unformatted text preview: SP 21 : Answer the following: a) Does a heat engine that has a thermal efficiency of 100 percent necessarily violate (i) the first law and (ii) the second law of thermodynamics? Explain. b) In the absence of any friction and other irreversibilities, can a heat engine have an efficiency of 100 percent? Explain. c) Are the efficiencies of all the work-producing devices, including the hydroelectric power plants, limited by the Kelvin–Planck statement of the second law? Explain. d) Solar energy stored in large bodies of water, called solar ponds, is being used to generate electricity. If such a solar power plant has an efficiency of 4 percent and a net power output of 350 kW, determine the average value of the required solar energy collection rate, in Btu/h. sink HE Solar pond Source 350 kW 4%...
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This note was uploaded on 04/23/2011 for the course ME 200 taught by Professor Gal during the Spring '08 term at Purdue.

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