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 7 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 Problem 1 A steam generator is the name given to the compound boiler apparatus used in many power plants A steam generator consists of two separate heating devices a boiler which converts compressed liquid water to saturated vapor and a super heater which adds additional thermal energy to the steam In the example shown below both the boiler and super heater are isobaric at a pressure of 1000 psia and are heated by combustion of coal Water enters the boiler at a mass flow rate of 12 lbm s and at 100 F and exits the super heater at 1200 F For this system determine a the total heating rate of the steam generator Btu s b the fraction of total heat input that is used for the boiler alone c explain why it is necessary to split the steam generator into two separate devices to produce superheated steam Superheat vapor 1200 F Sat Super heater vapor 1000 psia H2O Boiler 12 lbm s 1000 psia 100 F Coal combustion Qin Coal combustion Qin MEEN 315 PRINCIPLES OF THERMODYNAMICS SPRING 2017 Problem 2 A condenser accepts saturated x 1 steam at 10 kPa and at a mass flow rate of 10kg s The steam is entirely converted to saturated liquid in an isobaric cooling process The steam is cooled by pumping liquid water from the nearby Gibbons Creek Reservoir through a pipe that passes through the condenser The cooling water enters the condenser at 10 C and leaves the condenser at the same temperature as the condensed steam notice the pipe fully submerged in pool of saturated liquid Assuming the condenser is adiabatic to the surroundings determine a the rate of heat loss from the condensed steam kW b the minimum mass flow rate of lake water required to operate the condenser kg s c the temperature of the water returned to the reservoir C Steam 10 kg s 10 kPa Sat vap Liquid H2 O 10 C From lake mmin Liquid H2O returned to river Sat Liquid shaded area Sat Liquid 10 kPa Gibbon s Creek Reservoir
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