Liquid water at 200 kPa and 15°C is heated in a chamber by mixing it with superheated steam at 200 kPa and 150°C. Liquid water enters the mixing chamber at a rate of 4.3 kg/s, and the chamber is estimated to lose heat to the surrounding air at 20°C at a rate of 1200 kJ/min. If the mixture leaves the mixing chamber at 200 kPa and 80°C, determine (a) the mass flow rate of the superheated steam and (b) the rate of entropy generation during this mixing process.
FIGURE P7–154
a)
The mass flow rate of the superheated steam.
Answer to Problem 154P
The mass flow rate of the superheated steam is
Explanation of Solution
Write the expression for the energy balance equation for closed system.
Here, rate of net energy transfer in to the control volume is
Write the expression to calculate the mass balance of the system.
Here, inlet mass flow rate is
Conclusion:
Substitute 0 for
Here, mass flow rate at entry 1 is
Substitute
Rewrite the Equation (IV) to calculate the mass flow rate at entry 2.
From Table A-4, “the saturated water table”, select the initial enthalpy at entry 1
From Table A-6, “Superheated water”, select the initial enthalpy at entry 2
From Table A-4, “the saturated water table”, select the enthalpy at exit
Substitute
Thus, the mass flow rate of the superheated steam is
b)
The rate of heat entropy generation during the process.
Answer to Problem 154P
The rate of heat entropy generation during the process is
Explanation of Solution
Write the expression for the entropy balance during the process.
Here, rate of net input entropy is
Conclusion:
Substitute
Here, entropy at entry 1 is
Substitute
Substitute
Substitute
Thus, the rate of heat entropy generation during the process is
Want to see more full solutions like this?
Chapter 7 Solutions
THERMODYNAMICS (LL)-W/ACCESS >IP<
- Argon gas enters an adiabatic compressor at 14 psia and 75°F with a velocity of 60 ft/s, and it exits at 200 psia and 240 ft/s. If the isentropic efficiency of the compressor is 87 percent, determine the exit temperature of the argon.arrow_forwardAir enters the compressor of a gas-turbine plant at ambient conditions of 100 kPa and 25°C with a low velocity and exits at 1 MPa and 347°C with a velocity of 90 m/s. The compressor is cooled at a rate of 1500 kJ/min, and the power input to the compressor is 250 kW. Determine the mass flow rate of air through the compressor.arrow_forwardAir enters the compressor of a gas-turbine plant at ambient conditions of 100 kPa and 30°C with a low velocity and exits at 1 MPa and 367 °C with a velocity of 6×103 m/min. The compressor is cooled at a rate of 1800 kJ/min, and the power input to the compressor is 250 kW. Determine the mass flow rate of air through the compressor.arrow_forward
- Steam at 1000 kPa, a temperature of 300°C, and a velocity of 50 m/s. The steam leaves the turbine at a pressure of 150 kPa and a velocity of 200 m/s. Determine the work per kg of steam flowing through the turbine, assuming the process to be reversible and adiabatic.arrow_forwardAir enters an adiabatic nozzle at 45 psia and 940°F with low velocity and exits at 650 ft/s. If the isentropic efficiency of the nozzle is 85 percent, determine the exit temperature and pressure of the air.arrow_forwardIn a gas turbine plant, air enters the compressor at ambient conditions of 100 kPa and 25°C with a low velocity and exits at 1 MPa and 382°C with a velocity of 80 m/s. The compressor is cooled at a rate of 1500 kJ/min, and the power input to the compressor is 230 kW. (i) Identify the enthalpy of air (units: kJ/kg) at the compressor inlet, (ii) Identify the enthalpy of air (units: kJ/kg) at the compressor exit, and (iii) Determine the mass flow rate of air (units: kg/s) through the compressor.arrow_forward
- Steam enters a turbine steadily at 7 MPa and 600°C with a velocity of 60 m/s and leaves at 25 kPa with a quality of 95 percent. A heat loss of 20 kJ/kg occurs during the process. The inlet area of the turbine is 150 cm2 , and the exit area is 1400 cm2. Determine the mass flow rate of the steam.arrow_forwardSteam enters an adiabatic turbine steadily at 7 MPa, 500°C, and 45 m/s and leaves at 100 kPa and 75 m/s. If the power output of the turbine is 5 MW and the isentropic efficiency is 77 percent, determine the mass flow rate of steam through the turbine.arrow_forwardWater at 80°F and 20 psia is heated in a chamber by mixing it with saturated water vapor at 20 psia. If both streams enter the mixing chamber at the same mass flow rate, determine the temperature and the quality of the exiting stream.arrow_forward
- A 5-ft3 rigid tank initially contains refrigerant-134a at 60 psia and 100 percent quality. The tank is connected by a valve to a supply line that carries refrigerant-134a at 140 psia and 80F. The valve is now opened, allowing the refrigerant to enter the tank, and is closed when it is observed that the tank contains only saturated liquid at 100 psia. Determine (a) the mass of the refrigerant that entered the tank, (b) the amount of heat transfer with the surroundings at 708F, and (c) the entropy generated during this process.arrow_forwardRefrigerant-134a enters an adiabatic compressor as saturated vapor at 30 psia at a rate of 20 ft3 /min and exits at 70 psia pressure. If the isentropic efficiency of the compressor is 80 percent, determine the second-law efficiency of the compressor. Assume the surroundings to be at 75°F.arrow_forwardDetermine the final temperature when air is expanded isentropically from 1000 kPa and 477°C to 100 kPa in a piston–cylinder devicearrow_forward
- Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University PressMechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSONThermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
- Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEYMechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage LearningEngineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY