Chapter 1: Intro and Basic Concepts
Pressure (1-9)
3. Both a gage and a manometer are attached to a gas tank to measure its pressure. If the
reading on the pressure gage is 80 kPa, determine the distance between the two fluid
levels of the manometer if the fluid is (a) mercury (U = 13,600 kg/m3) or (b) water (U =
1000 kg/m3).
2
Chapter 1: Intro and Basic Concepts
Pressure (1-9)
4. The pressure in a natural gas pipeline is measured by the manometer shown in the
figure with one of the arms open to the atmosphere where the local atmospheric
pressure is 14.2 psia. Determine the absolute pressure in the pipeline.
3
Chapter 1: Intro and Basic Concepts
Pressure (1-9)
5. A hydraulic lift is to be used to lift a 2500 kg weight by putting a weight of 25 kg on a
piston with a diameter of 10 cm. Determine the diameter of the piston on which the
weight is to be placed.
4
Chapter 2: Energy
Forms of Energy (2-2)
1. Calculate the total kinetic energy, in Btu, of an object with a mass of 10 lbm when its
velocity is 50 ft/s.
2. Calculate the total potential energy, in Btu, of an object with a mass of 200 lbm when it
is 10 ft above a datum level at a location where standard gravitational acceleration
exists.
5
Chapter 2: Energy
Forms of Energy (2-2)
3. A river flowing steadily at a rate of 175 m3/s is considered for hydroelectric power
generation. It is determined that a dam can be built to collect water and release it from
an elevation difference of 80 m to generate power. Determine how much power can be
generated from this river water after the dam is filled.
6
Chapter 2: Energy
Mechanical Forms of
Work (2-5)
4. Determine the energy required to accelerate a 1300 kg car from 10 to 60 km/h on an
uphill road with a vertical rise of 40 m.
5. Determine the torque applied to the shaft of a car that transmits 450 hp and rotates at a
rate of 3000 rpm.
6. Determine the work required to deflect a linear spring with a spring constant of 70 kN/m
by 20 cm from its unstretched position.
7
Chapter 2: Energy
The First Law of
Thermodynamics (2-6)
7. At winter conditions, a house is projected to lose heat at a rate of 60,000 Btu/h. The
internal heat gain from people, lights, and appliances is estimated to be 6000 Btu/h. If
this house is to be heated by electric resistance heaters, determine the required rated
power of these heaters in kW to maintain the house at a constant temperature.
8. A water pump increases water pressure from 15 psia to 70 psia. Determine the power
input required, in hp, to pump 0.8 ft3/s of water.
9. Consider a room that is initially at the outdoor temperature of 20oC. The room contains a
40 W light bulb, a 110 W TV set, a 300 W refrigerator, and a 1200 W iron. Assuming no
heat transfer through the walls, determine the rate of increase of the energy content of
the room when all these electric devices are on.
8
Chapter 2: Energy
The First Law of
Thermodynamics (2-6)
10. Water is pumped from a lower reservoir to a higher reservoir by a pump that provides 20
kW of shaft power. The free surface of the upper reservoir is 45 m higher than that of the
lower reservoir. If the flow rate of water is measured to be 0.3 m3/s, determine the
mechanical power that is converted to mechanical energy during this process due to
frictional effects.
9
Chapter 2: Energy
The First Law of
Thermodynamics (2-6)
11. An oil pump is drawing 44 kW of electric power while pumping oil with U = 860 kg/m3 at a
rate of 0.1 m3/s. The inlet and outlet diameters of the pipe are 8 cm and 12 cm,
respectively. If the pressure rise of oil in the pump is measured to be 500 kPa and the
motor efficiency is 90 percent, determine the mechanical efficiency of the pump.
10
Chapter 3: Properties of Pure Substances
Property Tables (3-5)
1. A rigid tank contains 50 kg of saturated liquid water at 90 oC. Determine the pressure in
the tank and the volume of the tank.
2. A piston-cylinder device contains 2 ft3 of saturated water vapor at 50 psia pressure.
Determine the temperature and the mass of the vapor inside the cylinder.
11
Chapter 3: Properties of Pure Substances
Property Tables (3-5)
3. A mass of 200 g of saturated liquid water is completely vaporized at a constant pressure
of 100 kPa. Determine (a) the volume change and (b) the amount of energy transferred
to the water.
12
Chapter 3: Properties of Pure Substances
Property Tables (3-5)
4. A rigid tank contains 10 kg of water at 90oC. If 8 kg of the water is in the liquid form and
the rest is in the vapor form, determine (a) the pressure in the tank and (b) the volume of
the tank.
13
Chapter 3: Properties of Pure Substances
Property Tables (3-5)
5. An 80-L vessel contains 4 kg of refrigerant-134a at a pressure of 160 kPa. Determine (a)
the temperature, (b) the quality, (c) the enthalpy of the refrigerant, and (d) the volume
occupied by the vapor phase.
14
Chapter 3: Properties of Pure Substances
Property Tables (3-5)
6. Determine the internal energy of water at 20 psia and 400 oF.
7. Determine the temperature of water at a state of P = 0.5 Mpa and h = 2890 kJ/kg.
15
Chapter 3: Properties of Pure Substances
Property Tables (3-5)
8. Determine the internal energy of compressed liquid water at 80 oC and 5 MPa, using (a)
data from the compressed liquid table and (b) saturated liquid data. What is the error
involved in the second case?
16
Chapter 3: Properties of Pure Substances
Property Tables (3-5)
9. Determine the missing properties and the phase descriptions in the following table for
water.
T, oC
(a)
(b)
(e)
u, kJ/kg
200
125
(c)
(d)
P, kPa
Phase Description
0.6
1600
1000
75
x
2950
500
850
0.0
17
Chapter 3: Properties of Pure Substances
Property Tables (3-5)
11. 10-kg of R-134a at 300 kPa fills a rigid container whose volume is 14 L. Determine the
temperature and total enthalpy in the container. The container is now heated until the
pressure is 600 kPa. Determine the temperature and total enthalpy when the heating is
complete.
19
Chapter 3: Properties of Pure Substances
Property Tables (3-5)
12. A rigid tank initially contains 1.4 kg saturated liquid water at 200oC. At this state, 25
percent of the volume is occupied by water and the rest by air. Now heat is supplied to
the water until the tank contains saturated vapor only. Determine (a) the volume of the
tank, (b) the final temperature and pressure, and (c) the internal energy change of the
water.
20
Chapter 3: Properties of Pure Substances
Ideal Gas (3-6)
13. A 3 ft3 container is filled with 2 lbm of oxygen at a pressure of 80 psia. What is the
temperature of the oxygen?
24
Chapter 3: Properties of Pure Substances
Ideal Gas (3-6)
14. A 1 m3 tank containing air at 10oC and 350 kPa is connected through a valve to another
tank containing 3 kg of air at 35oC and 200 kPa. Now the valve is opened, and the entire
system is allowed to reach thermal equilibrium with the surroundings which are at 20 oC.
Determine the volume of the second tank and the final equilibrium pressure of air.
25
Chapter 3: Properties of Pure Substances
Property Tables (3-5)
15. Determine the specific volume of refrigerant-134a at 1 MPa and 50oC, using (a) the ideal
gas equation of state and (b) the generalized compressibility chart. Compare the values
obtained to the actual value of 0.021796 m3/kg and determine the error involved in each
case.
26
Chapter 3: Properties of Pure Substances
Property Tables (3-5)
16. Determine the specific volume of superheated water vapor at 3.5 MPa and 450 oC based
on (a) the ideal gas equation, (b) the generalized compressibility chart, and (c) the steam
tables. Determine the error involved in the first two cases.
27
Chapter 4: Energy Analysis of Closed Systems
Moving Boundary
Work (4-1)
1. A mass of 5 kg of saturated water vapor at 300 kPa is heated at a constant pressure until
the temperature reaches 200oC. Calculate the work done by the steam during this
process.
28
Chapter 4: Energy Analysis of Closed Systems
Moving Boundary
Work (4-1)
2. A frictionless piston-cylinder device contains 5 kg of nitrogen at 100 kPa and 250 K.
Nitrogen is now compressed slowly according to the relation PV1.4 = constant until it
reaches a final temperature of 360 K. Calculate the work input during this process.
29
Chapter 4: Energy Analysis of Closed Systems
Energy Balance (4-2)
3. A rigid tank is divided into two equal parts by a partition. Initially, one side of the tank
contains 5 kg of water at 200 kPa and 25oC, and the other side is evacuated. The partition
is then removed, and the water expands into the entire tank. The water is allowed to
exchange heat with its surroundings until the temperature in the tank returns to the
initial value of 25oC. Determine the volume of the tank, the final pressure, and the heat
transfer for this process.
30
Chapter 4: Energy Analysis of Closed Systems
Energy Balance (4-2)
4. An insulated piston-cylinder device contains 5 L of saturated liquid water at a constant
pressure of 175 kPa. Water is stirred by a paddle wheel while a current of 8 A flows for
45 min through a resistor placed in the water. If one-half of the liquid is evaporated
during this constant-pressure process and the paddle wheel work amounts to 400 kJ,
determine the voltage of the source.
31
Chapter 4: Energy Analysis of Closed Systems
Specific Heat
Ideal Gases (4-4)
5. Air at 300 K and 200 kPa is heated at constant pressure to 600 K. Determine the change
in internal energy of air per unit mass, using
(a) data from the air table (Table A-17)
(b) the functional form of the specific heat (Table A-2c)
(c) the average specific heat value (Table A-2c)
32
Chapter 4: Energy Analysis of Closed Systems
Specific Heat
Ideal Gases (4-4)
6. An insulated rigid tank initially contains 1.5 lbm of helium at 80oF and 50 psia. A paddle
wheel with a power rating of 0.02 hp is operated within the tank for 30 minutes.
Determine the:
(a) Final temperature of the helium gas
(b) Final pressure of the helium gas
33
Chapter 4: Energy Analysis of Closed Systems
Specific Heat
Ideal Gases (4-4)
7. A piston-cylinder device initially contains 0.5 m3 of nitrogen gas at 400 kPa and 27oC. An
electric heater within the device is turned on and is allowed to pass a current of 2 A for 5
minutes from a 120-V source. Nitrogen expands at constant pressure, and a heat loss of
2800 J occurs during the process. Determine the final temperature of the nitrogen.
34
Chapter 4: Energy Analysis of Closed Systems
Specific Heat
Ideal Gases (4-4)
8. A piston-cylinder device initially contains air at 150 kPa and 27oC. At this state, the piston
is resting on a pair of stops, as shown in the figure, and the enclosed volume is 400 L. The
mass of the piston is such that a 350 kPa pressure is required to move it. The air is now
heated until the volume has doubled. Determine:
(a) The final temperature
(b) The work done by the air
(c) The total heat transferred to the air
35
Chapter 4: Energy Analysis of Closed Systems
Specific Heat
Solids & Liquids (4-5)
9. Determine the enthalpy of liquid water at 100oC and 15 MPa by
(a) Using compressed liquid tables
(b) Approximating it as a saturated liquid
(c) Using the correction given by h = hf + vf(P-Psat)
36
Chapter 4: Energy Analysis of Closed Systems
Specific Heat
Solids & Liquids (4-5)
10. A 50 kg iron block at 80oC is dropped into an insulated tank that contains 0.5 m3 of liquid
water at 25oC. Determine the temperature when thermal equilibrium is reached.
37
Chapter 5: Energy Analysis of Control Volumes
Conservation of Mass (5-1)
1. A garden hose attached with a nozzle is used to fill a 10 gallon bucket. The inner
diameter of the hose is 2 cm, and it reduces to 0.8 cm at the nozzle exit. If it takes 50
seconds to fill the bucket with water, determine
(a) The volume and mass flow rates of water through the hose
(b) The average velocity of water at the nozzle exit
38
Chapter 5: Energy Analysis of Control Volumes
Conservation of Mass (5-1)
2. A 4 ft high, 3 ft diameter cylindrical water tank whose top is open to the atmosphere is
initially filled with water. Now the discharge plug near the bottom of the tank is pulled
out and a water jet whose diameter is 0.5 in. streams out. The average velocity of the jet
is approximated as V = (2gh)1/2, where h is the height of the water in the tank measured
from the hole (a variable) and g is the gravitational acceleration. Determine how long it
takes for the water level in the tank to drop to 2 ft from the bottom.
39
Chapter 5: Energy Analysis of Control Volumes
Energy of a Flowing Fluid (5-2)
3. Steam is leaving a 4 L pressure cooker whose operating pressure is 150 kPa. It is observed
that the amount of liquid in the cooker has decreased by 0.6 L in 40 minutes after the
steady operating conditions are established, and the cross sectional area of the exit
opening is 8 mm2. Determine:
(a) the mass flow rate of the steam and the exit velocity.
(b) the total and flow energies of the steam per unit mass.
(c) the rate at which energy leaves the cooker by the steam.
40
Chapter 5: Energy Analysis of Control Volumes
Energy of a Flowing Fluid (5-2)
4. Refrigerant 134a enters the compressor of a refrigeration system as a saturated vapor at
0.14 MPa, and leaves as superheated vapor at 0.8 MPa and 60oC at a rate of 0.06 kg/s.
Determine the rates of energy transfers by mass into and out of the compressor. Assume
the kinetic and potential energies to be negligible.
41
Chapter 5: Energy Analysis of Control Volumes
Steady Flow Devices (5-4)
5. Air at 10oC and 80 kPa enters the diffuser of a jet engine steadily with a velocity of 200
m/s. The inlet area of the diffuser is 0.4 m2. The air leaves the diffuser with a velocity that
is very small compared with the inlet velocity. Determine:
(a) the mass flow rate of the air.
(b) the temperature of the air leaving the diffuser.
42
Chapter 5: Energy Analysis of Control Volumes
Steady Flow Devices (5-4)
6. Steam at 250 psia and 700oF steadily enters a nozzle whose inlet area is 0.2 ft2. The mass
flow rate of steam through the nozzle is 10 lbm/s. Steam leaves the nozzle at 200 psia
with a velocity of 900 ft/s. Heat losses from the nozzle per unit mass of the steam are
estimated to be 1.2 Btu/lbm. Determine:
(a) the inlet velocity
(b) the exit temperature of the steam
43
Chapter 5: Energy Analysis of Control Volumes
Steady Flow Devices (5-4)
7. Air at 100 kPa and 280 K is compressed steadily to 600 kPa and 400 K. The mass flow rate
of the air is 0.02 kg/s, and a heat loss of 16 kJ/kg occurs during the process. Assuming the
changes in kinetic and potential energies are negligible, determine the power input
necessary to the compressor.
44
Chapter 5: Energy Analysis of Control Volumes
Steady Flow Devices (5-4)
8. The power output of an adiabatic steam turbine is 5 MW, and the inlet and exit conditions of the
steam are as indicated in the figure.
(a) compare the magnitudes of 'h, 'ke, and 'pe.
(b) determine the work done per unit mass of the steam
flowing through the turbine.
(c) calculate the mass flow rate of the steam.
45
Chapter 5: Energy Analysis of Control Volumes
Steady Flow Devices (5-4)
9. Refrigerant 134a enters the capillary tube of a refrigerator as saturated liquid at 0.8 MPa and
is throttled to a pressure of 0.12 MPa. Determine the quality of the refrigerant at the final state
and the temperature drop during this process.
46
Chapter 5: Energy Analysis of Control Volumes
Steady Flow Devices (5-4)
10. Consider an ordinary shower where hot water at 140oF is mixed with cold water at 50oF. If it
is desired that a steady stream of warm water at 110oF be supplied, determine the ratio of the
mass flow rates of the hot to cold water. Assume the heat losses from the mixing chamber to
be negligible and the mixing to take place at a pressure of 20 psia.
47
Chapter 5: Energy Analysis of Control Volumes
Steady Flow Devices (5-4)
11. Refrigerant 134a is to be cooled by water in a condenser. The refrigerant enters the
condenser with a mass flow rate of 6 kg/min at 1 MPa and 70 oC and leaves at 35oC. The cooling
water enters at 350 kPa and 15oC and leaves at 25oC. Neglecting any pressure drops,
determine:
(a) the mass flow rate of the cooling water required
(b) the heat transfer rate from the refrigerant to water
48
Chapter 5: Energy Analysis of Control Volumes
Steady Flow Devices (5-4)
12. The electric heating systems used in many houses consist of a simple duct with resistance
heaters. Air is heated as it flows over resistance wires. Consider a 15 kW electric heating
system. Air enters the heating section at 100 kPa and 17 oC with a volume flow rate of 150
m3/min. If heat is lost from the air in the duct to the surroundings at a rate of 200 W, determine
the exit temperature of air.
49
Chapter 5: Energy Analysis of Control Volumes
Unsteady Flow (5-5)
13. A rigid, insulated tank that is initially evacuated is connected through a valve to a supply
line that carries steam at 1 MPa and 300oC. Now the valve is opened, and steam is
allowed to flow slowly into the tank until the pressure reaches 1 MPa, at which the point
valve is closed. Determine the final temperature of the steam in the tank.
50
Chapter 5: Energy Analysis of Control Volumes
Unsteady Flow (5-5)
14. An insulated 8 m3 tank contains air at 600 kPa and 400 K. A valve connected to the tank is
now opened, and air is allowed to escape until the pressure inside drops to 200 kPa. The
air temperature during the process is maintained by an electric resistance heater placed
in the tank. Determine the electrical energy supplied to air during this process.
51
Chapter 6: The Second Law of Thermodynamics
Heat Engines (6-3)
1. Heat is transferred to a heat engine from a furnace at a rate of 80 MW. If the rate of
waste heat rejection to a nearby river is 50 MW, determine the net power output and
the thermal efficiency for this heat engine.
Chapter 6: The Second Law of Thermodynamics
Heat Engines (6-3)
2. A car engine with a power output of 65 hp has a thermal efficiency of 24 percent.
Determine the fuel consumption rate of this car if the fuel has a heating value of 19,000
Btu/lbm (that is, 19,000 Btu of energy is released for each lbm of fuel burned).
Chapter 6: The Second Law of Thermodynamics Refrigerators and Heat Pumps (6-4)
3. The food compartment of a refrigerator is maintained at 4oC by removing heat from it at
a rate of 360 kJ/min. If the required power input to the refrigerator is 2 kW, determine
(a) the coefficient of performance of the refrigerator
(b) the rate of heat rejection to the room that houses the refrigerator
Chapter 6: The Second Law of Thermodynamics Refrigerators and Heat Pumps (6-4)
4. A heat pump is used to meet the heating requirements of a house and maintain it at
20oC. On a day when the outdoor air temperature drops to -2oC, the house is estimated
to lose heat at a rate of 80,000 kJ/h. If the heat pump under these conditions has a COP
of 2.5, determine
(a) the power consumed by the heat pump
(b) the rate at which heat is absorbed from the cold outdoor air
Chapter 6: The Second Law of Thermodynamics Refrigerators and Heat Pumps (6-4)
5. A food department is kept at -12oC by a refrigerator in an environment at 30oC. The total
heat gain to the food department is estimated to be 3300 kJ/h and the heat rejection by
the condenser is 4800 kJ/h. Determine
(a) the power input to the compressor, in kW
(b) the COP of the refrigerator
Chapter 6: The Second Law of Thermodynamics
Carnot Heat Engine (6-10)
6. A Carnot heat engine receives 500 kJ of heat per cycle from a high-temperature source at
652oC and rejects heat to a low temperature sink at 30oC. Determine
(a) the thermal efficiency of this Carnot engine
(b) the amount of heat rejected to the sink per cycle
Chapter 6: The Second Law of Thermodynamics
Carnot Refrigerators and
Heat Pumps (6-11)
8. A Carnot refrigeration cycle is executed in a closed system in the saturated liquid-vapor
mixture region using 0.8 kg of refrigerant 134a as the working fluid. The maximum and
minimum temperatures in the cycle are 20 and -8oC, respectively. It is known that the
refrigerant is saturated liquid at the end of the heat rejection process, and the net work
of the cycle is 15 kJ. Determine
(a) the fraction of the mass of the refrigerant that vaporizes during the process
(b) the pressure at the end of the heat rejection process.
Chapter 6: The Second Law of Thermodynamics
Carnot Refrigerators and
Heat Pumps (6-11)
9. A heat pump is to be used to heat a house during the winter. The house it to be
maintained at 21oC at all times. The house is estimated to be losing heat at a rate of
135,000 kJ/h when the outside temperature drops to -5oC. Determine
(a) the minimum power required to drive this heat pump
Chapter 6: The Second Law of Thermodynamics
Carnot Refrigerators and
Heat Pumps (6-11)
10. A refrigerator is to remove heat from the cooled space at a rate of 300 kJ/min to
maintain its temperature at -8oC. If the air surrounding the refrigerator is at 25oC,
determine the minimum power input required for this refrigerator.
Chapter 6: The Second Law of Thermodynamics
Carnot Refrigerators and
Heat Pumps (6-11)
11. An air-conditioner with refrigerant 134a as the working fluid is used to keep a room at
23oC by rejecting waste heat to the outdoor air at 34oC. The room gains heat through
the walls and the windows at a rate of 250 kJ/min while the heat generated by the
computer, TV, and lights amounts to 900 W. The refrigerant enters the compressor at
400 kPa as a saturated vapor at a rate of 80 L/min and leaves at 1200 kPa and 70 oC.
Determine
(a) the actual COP
(b) the maximum COP
(c) the minimum volume flow rate of the refrigerant at the compressor inlet for the
same compressor inlet and exit conditions
Chapter 7: Entropy
Entropy (7-1)
1. A piston-cylinder device contains a liquid vapor mixture of water at 300 K. During a
constant-pressure process, 750 kJ of heat is transferred to the water. As a result, part of
the liquid in the cylinder vaporizes. Determine the entropy change of the water during
this process.
Chapter 7: Entropy
The Increase in Entropy
Principle (7-2)
2. A heat source at 800 K loses 2000 kJ of heat to a sink at (a) 500 K and (b) 750 K.
Determine which heat transfer process is more reversible.
Chapter 7: Entropy
The Increase in Entropy
Principle (7-2)
3. A completely reversible heat pump produces heat at a rate of 300 kW to warm a house
maintained at 24oC. The exterior air, which is at 7oC, serves as the source. Calculate the
rate of entropy change of the two reservoirs and determine if this heat pump satisfies
the second law according to the increase of entropy principle.
Chapter 7: Entropy
The Increase in Entropy
Principle (7-2)
4. During the isothermal heat rejection process of a Carnot cycle, the working fluid
experiences an entropy change of –0.7 Btu/R. If the temperature of the heat sink is
95oF, determine
(a) The amount of heat transfer.
(b) The entropy change of the sink.
(c) The total entropy change for this process.
Chapter 7: Entropy
Entropy Change of Pure
Substances (7-3)
5. A rigid tank contains 5 kg of refrigerant 134a initially at 20oC and 140 kPa. The
refrigerant is now cooled while being stirred until its pressure drops to 100 kPa.
Determine the entropy change of the refrigerant during this process.
Chapter 7: Entropy
Entropy Change of Pure
Substances (7-3)
6. A piston cylinder device initially contains 3 lbm of liquid water at 20 psia and 70 oF. The
water is now heated at constant pressure by the addition of 3450 Btu of heat.
Determine the entropy change of the water during this process.
Chapter 7: Entropy
Entropy Change of Pure
Substances (7-3)
7. Refrigerant 134a at 320 kPa and 40oC undergoes an isothermal process in a closed
system until its quality is 45 percent. On per unit mass basis, determine how much work
and heat transfer are required.
Chapter 7: Entropy
Isentropic Processes (7-4)
8. Steam enters an adiabatic turbine at 5 MPa and 450 oC and leaves at a pressure of 1.4
MPa. Determine the work output of the turbine per unit mass if the process is
reversible.
Chapter 7: Entropy
Isentropic Processes (7-4)
9. Steam enters an adiabatic diffuser at 150 kPa and 120oC with a velocity of 550 m/s.
Determine the minimum velocity that the steam can have at the outlet when the outlet
pressure is 300 kPa.
Chapter 7: Entropy
Entropy Change of Liquids
and Solids (7-8)
10. Liquid methane is commonly used in various cryogenic applications. The critical
temperature of methane is 191 K and thus must be maintained below 191 K to keep it in liquid
phase. The properties of liquid methane at various temperatures and pressures are given in
Table 7-1. Determine the entropy change of liquid methane as it undergoes a process from 110
K and 1 MPa to 120 K and 5 MPa
(a) using tabulated properties
(b) approximating liquid methane as an incompressible substance (and what is the error
involved in this assumption)
Chapter 7: Entropy
Entropy Change of
Ideal Gases (7-9)
11. Air is compressed from an initial state of 100 kPa and 17oC to a final state of 600 kPa and
57oC. Determine the entropy change of air during this compression process using
(a) property values from the air table
(b) average specific heats
Chapter 7: Entropy
Entropy Change of
Ideal Gases (7-9)
12. Air is compressed in a car engine from 22oC and 95 kPa in a reversible and adiabatic
manner. If the compression ratio V1/V2 of this engine is 8, determine the final temperature of
the air.
Chapter 7: Entropy
Entropy Change of
Ideal Gases (7-9)
13. Helium gas is compressed by an adiabatic compressor from an initial state of 14 psia and
50oF to a final temperature of 320oF in a reversible manner. Determine the exit pressure of
helium.
Chapter 7: Entropy
Isentropic Efficiencies of
Steady Flow Devices (7-12)
15. Steam enters an adiabatic turbine steadily at 3 MPa and 400 oC and leaves at 50 kPa and
100oC. If the power output of the turbine is 2 MW, determine
(a) the isentropic efficiency of the turbine
(b) the mass flow rate of the steam flowing through the turbine
Chapter 7: Entropy
Isentropic Efficiencies of
Steady Flow Devices (7-12)
16. Air is compressed by an adiabatic compressor from 100 kPa and 12oC to a pressure of 800
kPa at a steady rate of 0.2 kg/s. If the isentropic efficiency of the compressor is 80 percent,
determine
(a) the exit temperature of air
(b) the required power input to the compressor
Chapter 7: Entropy
Isentropic Efficiencies of
Steady Flow Devices (7-12)
17. 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 off the nozzle is 92 percent, (assuming constant
specific heats for air) determine
(a) the maximum possible exit velocity
(b) the exit temperature
(c) the actual exit velocity of the air