Thermodynamics: An Engineering Approach
8th Edition
ISBN: 9780073398174
Author: Yunus A. Cengel Dr., Michael A. Boles
Publisher: McGraw-Hill Education
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Chapter 7.13, Problem 200RP
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A 50-L electrical radiator containing heating oil is placed in a 50-m³ room. Both the room and the oil in the
radiator are initially at 5°C. The radiator with a rating of 3 kW is now turned on. At the same time, heat
is lost from the room at an average rate of 0.3 kJ/s. After some time, the average temperature is measured
to be 20°C for the air in the room, and 60°C for the oil in the radiator. Taking the density and the specific
heat of the oil to be 950 kg/m³ and 2.2kJ/(kg °C), respectively, determine how long the heater is kept on.
Assume the room is well-sealed so that there are no air leaks.
Consider a well-insulated piston-cylinder assembly. The volume of the cylinder is 3.258 m3. You can assume the piston to be frictionless and that it does not occupy a significant volume in the cylinder. Initially the piston is placed such that the entire volume of the cylinder is filled with steam at 100 kPa and 200°C. The cylinder is connected to a pipeline carrying air at 500 kPa and 250°C. The valve between the pipeline and the cylinder is opened slightly allowing air to enter the cylinder very slowly until the pressure in the cylinder reaches 500 kPa. The valve is then turned off. Assume air behaves like an ideal gas with a constant heat capacity of Cp=7R/2.
a) What will be the final temperature of the air if the piston is nonconducting?
(Note: steam is being compressed adiabatically and very slowly by means of a frictionless piston)
b) Suppose the insulation pad at the bottom of the cylinder is removed and heat is
transferred to the steam side to keep its temperature constant at…
3
A 40-L electrical radiator containing heating oil is placed in a 50-m³ room. Both the room and the oil in the radiator are initially at 10°C.
The radiator with a rating of 2.4 kW is now turned on. At the same time, heat is lost from the room at an average rate of 0.35 kJ/s. After
some time, the average temperature is measured to be 20°C for the air in the room, and 50°C for the oil in the radiator. Taking the
density and the specific heat of the oil to be 950 kg/m3 and 2.2 kJ/kg-°C, respectively, determine how long the heater is kept on.
Assume the room is well sealed so that there are no air leaks. The gas constant of air is R = 0.287 kPa-m³/kg-K (Table A-1). Also, c =
0.718 kJ/kg-K for air at room temperature (Table A-2). Oil properties are given to be p = 950 kg/m³ and
Cp = 2.2 kJ/kg.°C.
3
10°C
Room
Radiator
The heater is kept on for
Q
min.
4
Chapter 7 Solutions
Thermodynamics: An Engineering Approach
Ch. 7.13 - Prob. 1PCh. 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 - 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. 9PCh. 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 - Prob. 14PCh. 7.13 - Prob. 15PCh. 7.13 - Prob. 16PCh. 7.13 - Steam is accelerated as it flows through an actual...Ch. 7.13 - Prob. 18PCh. 7.13 - Prob. 19PCh. 7.13 - Prob. 20PCh. 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 - 7–23 A completely reversible heat pump produces...Ch. 7.13 - During the isothermal heat addition process of a...Ch. 7.13 - Prob. 25PCh. 7.13 - During the isothermal heat rejection process of a...Ch. 7.13 - Prob. 27PCh. 7.13 - Prob. 28PCh. 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 - 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 - 7–33 An insulated piston–cylinder device contains...Ch. 7.13 - Prob. 34PCh. 7.13 - Prob. 35PCh. 7.13 - Onekg of R-134a initially at 600 kPa and 25C...Ch. 7.13 - Refrigerant-134a is expanded isentropically from...Ch. 7.13 - Prob. 38PCh. 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 - Prob. 44PCh. 7.13 - Prob. 45PCh. 7.13 - Steam enters an adiabatic diffuser at 150 kPa and...Ch. 7.13 - Prob. 47PCh. 7.13 - An isentropic steam turbine processes 2 kg/s of...Ch. 7.13 - Prob. 50PCh. 7.13 -
7–51 0.7-kg of R-134a is expanded isentropically...Ch. 7.13 - Twokg of saturated water vapor at 600 kPa are...Ch. 7.13 - Steam enters a steady-flow adiabatic nozzle with a...Ch. 7.13 - Prob. 54PCh. 7.13 - In Prob. 755, the water is stirred at the same...Ch. 7.13 - A pistoncylinder device contains 5 kg of steam at...Ch. 7.13 - Prob. 57PCh. 7.13 - Prob. 59PCh. 7.13 - A 50-kg copper block initially at 140C is dropped...Ch. 7.13 - Prob. 61PCh. 7.13 - Prob. 62PCh. 7.13 - A 30-kg aluminum block initially at 140C is...Ch. 7.13 - A 30-kg iron block and a 40-kg copper block, both...Ch. 7.13 - An adiabatic pump is to be used to compress...Ch. 7.13 - Prob. 67PCh. 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. 72PCh. 7.13 - Prob. 73PCh. 7.13 - Prob. 74PCh. 7.13 - Prob. 75PCh. 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 - Prob. 80PCh. 7.13 - 7–81 Air enters a nozzle steadily at 280 kPa and...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 - Prob. 85PCh. 7.13 - Air at 3.5 MPa and 500C is expanded in an...Ch. 7.13 -
7–87E Air is compressed in an isentropic...Ch. 7.13 - An insulated rigid tank is divided into two equal...Ch. 7.13 - An insulated rigid tank contains 4 kg of argon gas...Ch. 7.13 - Prob. 90PCh. 7.13 - Prob. 91PCh. 7.13 - Prob. 92PCh. 7.13 - Air at 27C and 100 kPa is contained in a...Ch. 7.13 - Prob. 94PCh. 7.13 - Helium gas is compressed from 90 kPa and 30C to...Ch. 7.13 - Five kg of air at 427C and 600 kPa are contained...Ch. 7.13 - Prob. 97PCh. 7.13 - The well-insulated container shown in Fig. P 795E...Ch. 7.13 - Prob. 99PCh. 7.13 - Prob. 100PCh. 7.13 - It is well known that the power consumed by a...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 - Prob. 106PCh. 7.13 - Consider a steam power plant that operates between...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 - Saturated refrigerant-134a vapor at 15 psia is...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 - Steam at 100 psia and 650F is expanded...Ch. 7.13 - Prob. 117PCh. 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. 122PCh. 7.13 - Prob. 123PCh. 7.13 - Refrigerant-134a enters an adiabatic compressor as...Ch. 7.13 - Prob. 126PCh. 7.13 - Argon gas enters an adiabatic compressor at 14...Ch. 7.13 - Air enters an adiabatic nozzle at 45 psia and 940F...Ch. 7.13 - Prob. 130PCh. 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 - Refrigerant-134a is expanded adiabatically from...Ch. 7.13 - Oxygen enters an insulated 12-cm-diameter pipe...Ch. 7.13 - Prob. 135PCh. 7.13 - Prob. 136PCh. 7.13 - Steam enters an adiabatic turbine steadily at 7...Ch. 7.13 - 7–138 In an ice-making plant, water at 0°C is...Ch. 7.13 - Water at 20 psia and 50F enters a mixing chamber...Ch. 7.13 - Prob. 140PCh. 7.13 - Prob. 141PCh. 7.13 - Prob. 142PCh. 7.13 - Prob. 143PCh. 7.13 - In a dairy plant, milk at 4C is pasteurized...Ch. 7.13 - An ordinary egg can be approximated as a...Ch. 7.13 - Prob. 146PCh. 7.13 - Prob. 147PCh. 7.13 - In a production facility, 1.2-in-thick, 2-ft 2-ft...Ch. 7.13 - Prob. 149PCh. 7.13 - Prob. 150PCh. 7.13 - A frictionless pistoncylinder device contains...Ch. 7.13 - Prob. 152PCh. 7.13 - Prob. 153PCh. 7.13 - Prob. 154PCh. 7.13 - Prob. 155PCh. 7.13 - Liquid water at 200 kPa and 15C is heated in a...Ch. 7.13 - Prob. 157PCh. 7.13 - Prob. 158PCh. 7.13 - Prob. 159PCh. 7.13 - Prob. 160PCh. 7.13 - Prob. 161PCh. 7.13 - Prob. 162PCh. 7.13 - Prob. 163PCh. 7.13 - Prob. 164PCh. 7.13 - Prob. 165PCh. 7.13 - The space heating of a facility is accomplished by...Ch. 7.13 - Prob. 167PCh. 7.13 - Prob. 168PCh. 7.13 - Prob. 169RPCh. 7.13 - A refrigerator with a coefficient of performance...Ch. 7.13 - Prob. 171RPCh. 7.13 - Prob. 172RPCh. 7.13 - Prob. 173RPCh. 7.13 - A 100-lbm block of a solid material whose specific...Ch. 7.13 - Prob. 175RPCh. 7.13 - Prob. 176RPCh. 7.13 - A pistoncylinder device initially contains 15 ft3...Ch. 7.13 - Prob. 178RPCh. 7.13 - A 0.8-m3 rigid tank contains carbon dioxide (CO2)...Ch. 7.13 - Helium gas is throttled steadily from 400 kPa and...Ch. 7.13 - Air enters the evaporator section of a window air...Ch. 7.13 - Refrigerant-134a enters a compressor as a...Ch. 7.13 - Prob. 183RPCh. 7.13 - Three kg of helium gas at 100 kPa and 27C are...Ch. 7.13 - Prob. 185RPCh. 7.13 -
7–186 You are to expand a gas adiabatically from...Ch. 7.13 - Prob. 187RPCh. 7.13 - Determine the work input and entropy generation...Ch. 7.13 - Prob. 189RPCh. 7.13 - Prob. 190RPCh. 7.13 - Air enters a two-stage compressor at 100 kPa and...Ch. 7.13 - Steam at 6 MPa and 500C enters a two-stage...Ch. 7.13 - Prob. 193RPCh. 7.13 - Prob. 194RPCh. 7.13 - Prob. 196RPCh. 7.13 - Prob. 197RPCh. 7.13 - 7–198 To control the power output of an isentropic...Ch. 7.13 - Prob. 199RPCh. 7.13 - Prob. 200RPCh. 7.13 - A 5-ft3 rigid tank initially contains...Ch. 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 - Prob. 217RPCh. 7.13 - Consider two bodies of identical mass m and...Ch. 7.13 - Prob. 220RPCh. 7.13 - Prob. 222RPCh. 7.13 - Prob. 224RPCh. 7.13 - The polytropic or small stage efficiency of a...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 - Prob. 229FEPCh. 7.13 - Prob. 230FEPCh. 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 - Prob. 233FEPCh. 7.13 - Prob. 234FEPCh. 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 - Prob. 243FEPCh. 7.13 - Steam enters an adiabatic turbine at 8 MPa and...Ch. 7.13 - Helium gas is compressed steadily from 90 kPa and...
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