MEEN 315 Fall 2016 Section 501 505 Professor Strzelec Homework 11 60 pts Due Monday November 21st 2016 at the START of class NO late homework will be accepted You are encouraged to use the problem solving steps and show all of your work Please use this page as a cover sheet Student Name Section 1 2pts An ideal gas at a given state expands to a fixed final volume first at constant pressure and a second separate time at constant temperature For which case is the work done by the system larger 2 2pts A steam turbine inlet is at 1200 kPa and 500 C The exit is at 200 kPa What is the lowest possible exit temperature What is the highest possible exit temperature What are the corresponding efficiencies 3 2pts Describe the Rankine cycle in terms of the unit operations it includes and what is happening to the working fluid as it goes through each 4 3pts 50 lbm of air is isothermally and reversibly compressed from its initial state of 90 F and 13 psia to a final pressure of 80 psia How much work is required for the compression 5 3pts A compressor receives air at 290 K 100 kPa and 5 5 kW of shaft work from a gasoline engine It should deliver a mass flow rate of 0 01 kg s air to a pipeline Find the maximum possible exit pressure of the compressor 6 3pts A compressor is surrounded by cold R 134a so that it works as an isothermal compressor The inlet state is 0 C 100 kPa and the exit state is saturated vapor Find the specific heat transfer and specific work 7 5pts 250 lbm of steam at 650 F and 100 psia is adiabatically expanded to 10 psia in a piston cylinder device How much work is produced if the isentropic expansion efficiency is 80 8 5pts A steam power plant operating a Rankine cycle has saturated vapor leaving the boiler at 600 lbf in2 The turbine exhausts to the condenser operating at 2 23 psi Find a 2 pts The specific work in each component b 2 pts The heat transfer in each component c 1 pts The cycle efficiency 9 5pts A supply of geothermal hot water is to be used as the energy source for an ideal Rankine cycle with R134a as the cycle working fluid Saturated vapor R134a leaves the boiler at 180 F and the condenser temperature is 100 F a 3pts What is the thermal efficiency of this cycle b 2pts What is the percent difference in thermal efficiency if you ignore the pump work 10 10pts Steam enters an adiabatic utility class power turbine at 1000 psia and 1100 F At a pressure of 120 psia and 550 F 20 of the mass flow rate of the steam is extracted from the turbine for use in an industrial process heat exchanger The remainder of the steam expands through the turbine and exhausts with a quality of 90 The turbine output is 4000hp a 3pts Determine the mass flow rate of the steam entering at 1000 psia and 1100 F b 3pts Determine the entropy at the entrance extraction and exit conditions and c 4pts Sketch the process on a T s diagram MEEN 315 Fall 2016 Section 501 505 Professor Strzelec 11 10pts A solar bank of collectors with an area of 8000 ft 2 supplies energy to the boiler of a Rankine cycle power plant using R 134a as the working fluid At peak load the collectors provide 200 Btu ft 2 hr to the working fluid The R134a leaves the boiler at 300 psia and 240 F and enters the pump at 100 F Determine a 2pts The pump work b 4pts The cycle efficiency c 2pts The mass flux of the R134a d 2pts The maximum power output 4 12 10pts A steam power plant that operates on Turbine the ideal regenerative Rankine cycle with a closed feedwater heater as shown in the 5 diagram The plant maintains the turbine inlet 6 Boiler at 3MPa and 350 C and operates the condenser at 20 kPa Steam is extracted at Condenser 1000 kPa for the feed water heater which discharges into the condenser after being 8 7 throttled to the proper pressure Calculate Closed 1 a 4pts The turbine and pump work FWH Pump b 2pts The heat supplied to the 2 3 boiler c 4pts Find the thermal efficiency of the cycle if the isentropic efficiency of the turbine is 90 before and after the steam extraction
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