Concept explainers
Helium gas is compressed from 16 psia and 85°F to 120 psia at a rate of 10 ft3/s. Determine the power input to the compressor, assuming the compression process to be (a) isentropic, (b) polytropic with n = 1.2, (c) isothermal, and (d) ideal two-stage polytropic with n = 1.2.
a)
The power input of the compressor for isentropic compression process
Answer to Problem 110P
The power input of the compressor for isentropic compression process is
Explanation of Solution
Write the expression to calculate the mass flow rate
Here, initial pressure is
Write the expression for the power input of the compressor for isentropic compression process.
Here, power input of the compressor is
Conclusion:
From Table A-2E, “Ideal-gas specific heats of various common gases”, the value of gas constant
Substitute
Substitute
Thus, the power input of the compressor for isentropic compression process is
b)
The power input of the compressor for polytropic compression process.
Answer to Problem 110P
The power input of the compressor for polytropic compression process is
Explanation of Solution
Write the expression for the the power input of the compressor for polytropic compression process.
Here, power input of the compressor is
Conclusion:
Substitute
Thus, the power input of the compressor for polytropic compression process is
c)
The power input of the compressor for isothermal compression process.
Answer to Problem 110P
The power input of the compressor for isothermal compression process is
Explanation of Solution
Write the expression to calculate the power input of the compressor for isothermal compression process.
Here, power input of the compressor is
Conclusion:
Substitute
Thus, the power input of the compressor for isothermal compression process is
d)
The expression to calculate the power input of the compressor for two stage compression process
Answer to Problem 110P
The expression to calculate the power input of the compressor for two stage compression process is
Explanation of Solution
Write the expression to calculate the even pressure or pressure ratio
Write the expression to calculate the power input of the compressor for two stage compression process.
Here, power input of the compressor is
Conclusion:
Substitute
Substitute
Thus, the expression to calculate the power input of the compressor for two stage compression process is
Want to see more full solutions like this?
Chapter 7 Solutions
Thermodynamics: An Engineering Approach
- Helium gas is compressed from 16 psia and 85°F to 120 psia at a rate of 10 ft3 /s. Determine the power input to the compressor, assuming the compression process to be ideal two-stage polytropic with n = 1.2.arrow_forwardAir is expanded isentropically from 100 psia and 500°F to 20 psia in a closed system. Determine its final temperaturearrow_forwardIs it possible for an idiabatic turbine to take steam at 3500kPa and expand it to a saturated vapor at a pressure of 1000kPa? Why?arrow_forward
- Argon gas enters an adiabatic compressor at 14 psia and 75F 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 (a) the exit temperature of the argon and (b) the work input to the compressor.arrow_forwardAir enters an adiabatic nozzle at 45 psia and 940Fwith low velocity and exits at 650 ft/s. If the isentropic efficiencyof the nozzle is 85 percent, determine the exit temperatureand pressure of the air.arrow_forward10 kg/s of air enters the turbine at a pressure of 120 MPa and 910 K. The air expands Isentropically to a pressure of 25 MPa, determine the Hp of this turbine. Also draw and label the P-V and T-S diagram.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_forwardThree kg of helium gas at 100 kPa and 27°C are adiabatically compressed to 900 kPa. If the isentropic compression efficiency is 80 percent, determine the required work input and the final temperature of helium.arrow_forwardHelium gas is compressed from 16 psia and 85°F to 120 psia at a rate of 10 ft3 /s. Determine the power input to the compressor, assuming the compression process to be polytropic with n = 1.2.arrow_forward
- Air at 200 kPa and 950 K enters an adiabatic nozzle at low velocity and is discharged at a pressure of 110 kPa. If the isentropic efficiency of the nozzle is 92 percent, determine the exit temperature.arrow_forwardA 0.8-m3 rigid tank contains carbon dioxide (CO2) gas at 250 K and 100 kPa. A 500-W electric resistance heater placed in the tank is now turned on and kept on for 40 min, after which the pressure of CO2 is measured to be 175 kPa. Assuming the surroundings to be at 300 K and using constant specific heats, determine the entropy generation during this process.arrow_forwardRefrigerant-134a enters an adiabatic compressor as saturated vapor at 160 kPa at a rate of 2 m3 /min and is compressed to a pressure of 900 kPa. Determine the minimum power that must be supplied to the compressor.arrow_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