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 6 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 Homework Assignment 6 Due Mar 07 2017 At the beginning of the class Problem 1 Refrigerant 134a enters a well insulated compressor as a saturated vapor at 32 C with a volumetric flow rate of 0 5 m3 s The R134a exits the compressor at a pressure of 10 bar and a temperature of 75 C a Determine the mass flow rate through the compressor in kg s b Determine the volumetric flow rate at the compressor exit in m3 s c Calculate the compressor power in kW Problem 2 Steam enters an adiabatic turbine at a mass flow rate of 12 kg s and at 4 MPa and 500 C The exit pressure is 60 kPa and the turbine produces 7 MW of mechanical power on the output shaft Neglecting kinetic and potential energy of the steam determine a the temperature C at the outlet b the volumetric flow rate at the outlet m3 s repeat a and b assuming the mechanical power of the turbine is 5 MW For each case draw the process on a P v diagram Inlet H2O 12 kg s 500 C 4 MPa Wout 7MW or 5MW Turbine Outlet 60 kPa Problem 3 A gas turbine accepts gas air at a mass flow rate of 10 lbm s and at 200 psia and 2800 R The combustion products leave the turbine at 14 psia and 1500 R Due to insufficient insulation of the turbine heat is lost from the turbine at a rate of 420 Btu s The power produced by the gas turbine is used to drive an R 134a compressor by a rotating shaft connecting the two devices R134a enters the compressor as a saturated vapor at 25 psia and leaves at 200 psia and 280 F Neglecting kinetic and potential energy determine a the power produced by the turbine hp b the mass flow rate of the R134a lbm s c the increase in mass flow rate of R134a that could be achieved if the turbine were adiabatic lbm s MEEN 315 PRINCIPLES OF THERMODYNAMICS Inlet Air 10 lbm s 2800 R 200 psia SPRING 2017 Outlet 200 psia 280 F W Gas Turbine 420 Btu s Outlet 1500 R 14 psia R 134a Compressor Inlet Sat vap 25 psia Problem 4 A pump accepts liquid water at 25 C and 100 kPa and compresses it isothermally to 10 MPa The pump has a constant power input of 12 kW and may be assumed to be adiabatic Neglecting changes in potential and kinetic energy of the water determine the volumetric flow rate in Liters min at the outlet of the pump assuming a incompressible liquid assumption i e approximate properties at the saturated liquid phase at given temperature and use h hf T vf T P Pf T for enthalpy b the properties of water at the outlet determined from the compressed liquid table A 7 Pump Power 12 kW Outlet 10 MPa Inlet Liquid H2O 25 C 100 kPa Problem 5 Refrigerant R 134a and air streams enter a steady state heat exchanger The R 134a stream enters with a pressure of 6 bar and a temperature of 4 C and exits at a pressure of 4 0 bar and a temperature of 20 C At the inlet the air stream has a volumetric flow rate of 50 m3 s the temperature of the air stream is 50 C and the pressure is 1 01 bar The air stream exits with a temperature of 20 C and a pressure of 0 99 bar Calculate the mass flow rate of R 134a in kg s
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