THERMODYNAMICS (LL)-W/ACCESS >CUSTOM<
9th Edition
ISBN: 9781266657610
Author: CENGEL
Publisher: MCG CUSTOM
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Chapter 7.13, Problem 157P
To determine
The amount of energy and money saved by reducing the final pressure of compressed air.
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A 3 m' tank initially contains air at 100 kPa and 25°C. The tank is connected to a
supply line at 550 kPa and 25°C. The valve is opened, and air is allowed to enter the
tank until the pressure in the tank reaches the line pressure, at which point the valve is
closed. A thermometer placed in the tank indicates that the air temperature at the final
state is 65°C, Treating air as a perfect gas, determine (a) the mass of air that has entered
the tank, (b) the heat transfer (Q) and (c) the entropy generated (Spen).
Supply line
Air
The compressors of a production facility maintain the compressed-air lines at a (gage) pressure of 700 kPa at 1400-m elevation, where the atmospheric pressure is 85.6 kPa. The average temperature of air is 15°C at the compressor inlet and 25°C in the compressed-air lines. The facility operates 4200 h/yr, and the average price of electricity is $0.10/kWh.
The compressors of a production facility maintain the compressed-air lines at a (gauge) pressure of 700 kPa at sea level where the atmospheric pressure is 101 kPa. The average temperature of air is 20°C at the compressor inlet and 24°C in the compressed-air lines. The facility operates 4200 hours a year, and the average price of electricity is $0.078/kWh. Taking the compressor efficiency to be 0.8, the motor efficiency to be 0.92, and the discharge coefficient to be 0.65, determine the energy and money saved per year by sealing a leak equivalent to a 3-mm-diameter hole on the compressed-air line.
Chapter 7 Solutions
THERMODYNAMICS (LL)-W/ACCESS >CUSTOM<
Ch. 7.13 - Does a cycle for which Q 0 violate the Clausius...Ch. 7.13 - Does the cyclic integral of heat have to be zero...Ch. 7.13 - Is a quantity whose cyclic integral is zero...Ch. 7.13 - Prob. 4PCh. 7.13 - Prob. 5PCh. 7.13 - How do the values of the integral 12Q/T compare...Ch. 7.13 - Prob. 7PCh. 7.13 - The entropy of a hot baked potato decreases as it...Ch. 7.13 - When a system is adiabatic, what can be said about...Ch. 7.13 - Prob. 10P
Ch. 7.13 - A pistoncylinder device contains helium gas....Ch. 7.13 - A pistoncylinder device contains nitrogen gas....Ch. 7.13 - A pistoncylinder device contains superheated...Ch. 7.13 - The entropy of steam will (increase, decrease,...Ch. 7.13 - During a heat transfer process, the entropy of a...Ch. 7.13 - Steam is accelerated as it flows through an actual...Ch. 7.13 - Heat is transferred at a rate of 2 kW from a hot...Ch. 7.13 - A completely reversible air conditioner provides...Ch. 7.13 - Heat in the amount of 100 kJ is transferred...Ch. 7.13 - In Prob. 719, assume that the heat is transferred...Ch. 7.13 - During the isothermal heat addition process of a...Ch. 7.13 - Prob. 22PCh. 7.13 - During the isothermal heat rejection process of a...Ch. 7.13 - Air is compressed by a 40-kW compressor from P1 to...Ch. 7.13 - Refrigerant-134a enters the coils of the...Ch. 7.13 - A rigid tank contains an ideal gas at 40C that is...Ch. 7.13 - A rigid vessel is filled with a fluid from a...Ch. 7.13 - A rigid vessel filled with a fluid is allowed to...Ch. 7.13 - Prob. 29PCh. 7.13 - One lbm of R-134a is expanded isentropically in a...Ch. 7.13 - Two lbm of water at 300 psia fill a weighted...Ch. 7.13 - A well-insulated rigid tank contains 3 kg of a...Ch. 7.13 - Using the relation ds = (Q/T)int rev for the...Ch. 7.13 - The radiator of a steam heating system has a...Ch. 7.13 - A rigid tank is divided into two equal parts by a...Ch. 7.13 - Prob. 36PCh. 7.13 - An insulated pistoncylinder device contains 5 L of...Ch. 7.13 - Onekg of R-134a initially at 600 kPa and 25C...Ch. 7.13 - Refrigerant-134a is expanded isentropically from...Ch. 7.13 - Refrigerant-134a at 320 kPa and 40C undergoes an...Ch. 7.13 - A rigid tank contains 5 kg of saturated vapor...Ch. 7.13 - A 0.5-m3 rigid tank contains refrigerant-134a...Ch. 7.13 - Steam enters a steady-flow adiabatic nozzle with a...Ch. 7.13 - Steam enters an adiabatic diffuser at 150 kPa and...Ch. 7.13 - R-134a vapor enters into a turbine at 250 psia and...Ch. 7.13 - Refrigerant-134a enters an adiabatic compressor as...Ch. 7.13 - The compressor in a refrigerator compresses...Ch. 7.13 - An isentropic steam turbine processes 2 kg/s of...Ch. 7.13 - Prob. 52PCh. 7.13 - Twokg of saturated water vapor at 600 kPa are...Ch. 7.13 - A pistoncylinder device contains 5 kg of steam at...Ch. 7.13 - Prob. 55PCh. 7.13 - In Prob. 755, the water is stirred at the same...Ch. 7.13 - Prob. 57PCh. 7.13 - Prob. 58PCh. 7.13 - Determine the total heat transfer for the...Ch. 7.13 - Calculate the heat transfer, in kJ/kg. for the...Ch. 7.13 - Prob. 61PCh. 7.13 - An adiabatic pump is to be used to compress...Ch. 7.13 - Prob. 63PCh. 7.13 - Prob. 64PCh. 7.13 - A 30-kg aluminum block initially at 140C is...Ch. 7.13 - A 50-kg copper block initially at 140C is dropped...Ch. 7.13 - A 30-kg iron block and a 40-kg copper block, both...Ch. 7.13 - Prob. 69PCh. 7.13 - Prob. 70PCh. 7.13 - Can the entropy of an ideal gas change during an...Ch. 7.13 - An ideal gas undergoes a process between two...Ch. 7.13 - Prob. 73PCh. 7.13 - Air is expanded from 200 psia and 500F to 100 psia...Ch. 7.13 - Prob. 75PCh. 7.13 - Air is expanded isentropically from 100 psia and...Ch. 7.13 - Which of the two gaseshelium or nitrogenhas the...Ch. 7.13 - Which of the two gasesneon or airhas the lower...Ch. 7.13 - A 1.5-m3 insulated rigid tank contains 2.7 kg of...Ch. 7.13 - An insulated pistoncylinder device initially...Ch. 7.13 - A pistoncylinder device contains 0.75 kg of...Ch. 7.13 - A mass of 25 lbm of helium undergoes a process...Ch. 7.13 - One kg of air at 200 kPa and 127C is contained in...Ch. 7.13 - An insulated rigid tank is divided into two equal...Ch. 7.13 - Air at 27C and 100 kPa is contained in a...Ch. 7.13 - Air at 3.5 MPa and 500C is expanded in an...Ch. 7.13 - Air is compressed in a pistoncylinder device from...Ch. 7.13 - Helium gas is compressed from 90 kPa and 30C to...Ch. 7.13 - Nitrogen at 120 kPa and 30C is compressed to 600...Ch. 7.13 - Five kg of air at 427C and 600 kPa are contained...Ch. 7.13 - Prob. 92PCh. 7.13 - Prob. 93PCh. 7.13 - Prob. 94PCh. 7.13 - The well-insulated container shown in Fig. P 795E...Ch. 7.13 - An insulated rigid tank contains 4 kg of argon gas...Ch. 7.13 - Prob. 97PCh. 7.13 - Prob. 98PCh. 7.13 - Prob. 99PCh. 7.13 - It is well known that the power consumed by a...Ch. 7.13 - Calculate the work produced, in kJ/kg, for the...Ch. 7.13 - Prob. 102PCh. 7.13 - Prob. 103PCh. 7.13 - Saturated water vapor at 150C is compressed in a...Ch. 7.13 - Liquid water at 120 kPa enters a 7-kW pump where...Ch. 7.13 - Water enters the pump of a steam power plant as...Ch. 7.13 - Consider a steam power plant that operates between...Ch. 7.13 - Saturated refrigerant-134a vapor at 15 psia is...Ch. 7.13 - Helium gas is compressed from 16 psia and 85F to...Ch. 7.13 - Nitrogen gas is compressed from 80 kPa and 27C to...Ch. 7.13 - Describe the ideal process for an (a) adiabatic...Ch. 7.13 - Is the isentropic process a suitable model for...Ch. 7.13 - On a T-s diagram, does the actual exit state...Ch. 7.13 - Argon gas enters an adiabatic turbine at 800C and...Ch. 7.13 - Steam at 100 psia and 650F is expanded...Ch. 7.13 - Combustion gases enter an adiabatic gas turbine at...Ch. 7.13 - Steam at 4 MPa and 350C is expanded in an...Ch. 7.13 - Prob. 120PCh. 7.13 - Prob. 121PCh. 7.13 - Refrigerant-134a enters an adiabatic compressor as...Ch. 7.13 - The adiabatic compressor of a refrigeration system...Ch. 7.13 - Prob. 125PCh. 7.13 - Argon gas enters an adiabatic compressor at 14...Ch. 7.13 - Prob. 127PCh. 7.13 - Air enters an adiabatic nozzle at 45 psia and 940F...Ch. 7.13 - An adiabatic diffuser at the inlet of a jet engine...Ch. 7.13 - Hot combustion gases enter the nozzle of a...Ch. 7.13 - The exhaust nozzle of a jet engine expands air at...Ch. 7.13 - Prob. 133PCh. 7.13 - Refrigerant-134a is expanded adiabatically from...Ch. 7.13 - A frictionless pistoncylinder device contains...Ch. 7.13 - Prob. 136PCh. 7.13 - Steam enters an adiabatic turbine steadily at 7...Ch. 7.13 - Prob. 138PCh. 7.13 - Oxygen enters an insulated 12-cm-diameter pipe...Ch. 7.13 - Water at 20 psia and 50F enters a mixing chamber...Ch. 7.13 - Prob. 141PCh. 7.13 - Prob. 142PCh. 7.13 - In a dairy plant, milk at 4C is pasteurized...Ch. 7.13 - Steam is to be condensed in the condenser of a...Ch. 7.13 - An ordinary egg can be approximated as a...Ch. 7.13 - Prob. 146PCh. 7.13 - In a production facility, 1.2-in-thick, 2-ft 2-ft...Ch. 7.13 - Prob. 148PCh. 7.13 - Prob. 149PCh. 7.13 - Prob. 150PCh. 7.13 - Prob. 151PCh. 7.13 - Prob. 152PCh. 7.13 - Prob. 153PCh. 7.13 - Liquid water at 200 kPa and 15C is heated in a...Ch. 7.13 - Prob. 155PCh. 7.13 - Prob. 157PCh. 7.13 - Prob. 158PCh. 7.13 - Prob. 159PCh. 7.13 - Prob. 160PCh. 7.13 - The compressed-air requirements of a plant are met...Ch. 7.13 - Prob. 162PCh. 7.13 - The space heating of a facility is accomplished by...Ch. 7.13 - Prob. 164PCh. 7.13 - Prob. 165PCh. 7.13 - Prob. 166PCh. 7.13 - Prob. 167RPCh. 7.13 - A refrigerator with a coefficient of performance...Ch. 7.13 - What is the minimum internal energy that steam can...Ch. 7.13 - Prob. 170RPCh. 7.13 - What is the maximum volume that 3 kg of oxygen at...Ch. 7.13 - A 100-lbm block of a solid material whose specific...Ch. 7.13 - Prob. 173RPCh. 7.13 - A pistoncylinder device initially contains 15 ft3...Ch. 7.13 - A pistoncylinder device contains steam that...Ch. 7.13 - Prob. 176RPCh. 7.13 - Prob. 177RPCh. 7.13 - Prob. 178RPCh. 7.13 - A 0.8-m3 rigid tank contains carbon dioxide (CO2)...Ch. 7.13 - Air enters the evaporator section of a window air...Ch. 7.13 - Prob. 181RPCh. 7.13 - Prob. 182RPCh. 7.13 - Prob. 183RPCh. 7.13 - Prob. 184RPCh. 7.13 - Helium gas is throttled steadily from 400 kPa and...Ch. 7.13 - Determine the work input and entropy generation...Ch. 7.13 - Prob. 187RPCh. 7.13 - Reconsider Prob. 7187. Determine the change in the...Ch. 7.13 - Prob. 189RPCh. 7.13 - Air enters a two-stage compressor at 100 kPa and...Ch. 7.13 - Three kg of helium gas at 100 kPa and 27C are...Ch. 7.13 - Steam at 6 MPa and 500C enters a two-stage...Ch. 7.13 - Prob. 193RPCh. 7.13 - Prob. 194RPCh. 7.13 - Refrigerant-134a enters a compressor as a...Ch. 7.13 - Prob. 196RPCh. 7.13 - Prob. 197RPCh. 7.13 - Prob. 198RPCh. 7.13 - Prob. 199RPCh. 7.13 - Prob. 200RPCh. 7.13 - Prob. 201RPCh. 7.13 - Prob. 202RPCh. 7.13 - Prob. 203RPCh. 7.13 - Prob. 204RPCh. 7.13 - Prob. 205RPCh. 7.13 - Prob. 206RPCh. 7.13 - Prob. 207RPCh. 7.13 - Prob. 208RPCh. 7.13 - (a) Water flows through a shower head steadily at...Ch. 7.13 - Prob. 211RPCh. 7.13 - Prob. 212RPCh. 7.13 - Prob. 213RPCh. 7.13 - Consider the turbocharger of an internal...Ch. 7.13 - Prob. 215RPCh. 7.13 - Prob. 216RPCh. 7.13 - A 5-ft3 rigid tank initially contains...Ch. 7.13 - Prob. 218RPCh. 7.13 - Show that the difference between the reversible...Ch. 7.13 - Demonstrate the validity of the Clausius...Ch. 7.13 - Consider two bodies of identical mass m and...Ch. 7.13 - Consider a three-stage isentropic compressor with...Ch. 7.13 - Prob. 223RPCh. 7.13 - Prob. 224RPCh. 7.13 - Prob. 225RPCh. 7.13 - The polytropic or small stage efficiency of a...Ch. 7.13 - Steam is condensed at a constant temperature of...Ch. 7.13 - Steam is compressed from 6 MPa and 300C to 10 MPa...Ch. 7.13 - An apple with a mass of 0.12 kg and average...Ch. 7.13 - A pistoncylinder device contains 5 kg of saturated...Ch. 7.13 - Argon gas expands in an adiabatic turbine from 3...Ch. 7.13 - A unit mass of a substance undergoes an...Ch. 7.13 - A unit mass of an ideal gas at temperature T...Ch. 7.13 - Heat is lost through a plane wall steadily at a...Ch. 7.13 - Air is compressed steadily and adiabatically from...Ch. 7.13 - Argon gas expands in an adiabatic turbine steadily...Ch. 7.13 - Water enters a pump steadily at 100 kPa at a rate...Ch. 7.13 - Air is to be compressed steadily and...Ch. 7.13 - Helium gas enters an adiabatic nozzle steadily at...Ch. 7.13 - Combustion gases with a specific heat ratio of 1.3...Ch. 7.13 - Steam enters an adiabatic turbine steadily at 400C...Ch. 7.13 - Liquid water enters an adiabatic piping system at...Ch. 7.13 - Liquid water is to be compressed by a pump whose...Ch. 7.13 - Steam enters an adiabatic turbine at 8 MPa and...Ch. 7.13 - Helium gas is compressed steadily from 90 kPa and...Ch. 7.13 - Helium gas is compressed from 1 atm and 25C to a...
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