Cengel ch08

CHAPTER
8

Gas Power Cycles

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

FIGURE 8-1
Modeling is a
powerful
engineering tool
that provides
great insight and
simplicity at the
expense of some
loss in accuracy.

8-1


FIGURE 8-2
The analysis of
many complex
processes can be
reduced to a
manageable level
by utilizing some
idealizations.

8-2


FIGURE 8-6
P-v and T-s diagrams of a
Carnot cycle.

8-3


FIGURE 8-7
A steady-flow Carnot
engine.

8-4


FIGURE 8-8
T-s diagram for
Example 8–1.

8-5


FIGURE 8-10
Nomenclature for
reciprocating engines.

8-6


FIGURE 8-11
Displacement and
clearance volumes
of a reciprocating
engine.

8-7


FIGURE 8-12
The net work
output of a cycle is
equivalent to the
product of the
mean effective
pressure and the
displacement
volume.

8-8


FIGURE 8-13
Actual and ideal cycles in
spark-ignition engines and
their P-v diagrams.

8-9


FIGURE 8-14
Schematic of a two-
stroke reciprocating
engine.

8-10


FIGURE 8-16
Thermal efficiency
of the ideal Otto
cycle as a function
of compression ratio
(k = 1.4).

8-11


FIGURE 8-18
The thermal
efficiency of the
Otto cycle increases
with the specific
heat ratio k of the
working fluid.

8-12


FIGURE 8-21
T-s and P-v
diagrams for the
ideal Diesel cycle.

8-13


FIGURE 8-22
Thermal efficiency of the
ideal Diesel cycle as a
function of compression
and cutoff ratios (k = 1.4).

8-14


FIGURE 8-23
P-v diagram of an
ideal dual cycle.

8-15


FIGURE 8-26
T-s and P-v diagrams of Carnot,
Stirling, and Ericsson cycles.

8-16


FIGURE 8-27
The execution of the
Stirling cycle.

8-17


FIGURE 8-28
A steady-flow Ericsson
engine.

8-18


FIGURE 8-29
An open-cycle gas-turbine engine.

8-19


FIGURE 8-30
A closed-cycle
gas-turbine engine.

8-20


FIGURE 8-31
T-s and P-v
diagrams for the
ideal Brayton cycle.

8-21


FIGURE 8-32
Thermal efficiency
of the ideal Brayton
cycle as a function
of the pressure
ratio.

8-22


FIGURE 8-33
For fixed values of
Tmin and Tmax , the
net work of the
Brayton cycle first
increases with the
pressure ratio, then
reaches a maximum
at rp = (Tmax /Tmin) k/
[2(k – 1)],
and finally
decreases.

8-23


FIGURE 8-36
The deviation of an
actual gas-turbine
cycle from the ideal
Brayton cycle as a
result of
irreversibilities.

8-24


FIGURE 8-38
A gas-turbine
engine with
regenerator.

8-25


FIGURE 8-39
T-s diagram of a
Brayton cycle with
regeneration.

8-26


FIGURE 8-40
Thermal efficiency of
the ideal Brayton
cycle with and
without
regeneration.

8-27


FIGURE 8-42
Comparison of
work inputs to a
single-stage
compressor (1AC)
and a two-stage
compressor with
intercooling
(1ABD).

8-28


FIGURE 8-43
A gas-turbine
engine with two-
stage compression
with intercooling,
two-stage
expansion with
reheating, and
regeneration.

8-29


FIGURE 8-44
T-s diagram of an
ideal gas-turbine
cycle with
intercooling,
reheating, and
regeneration.

8-30


FIGURE 8-45
As the number of
compression and
expansion stages
increases, the gas-
turbine cycle with
intercooling,
reheating, and
regeneration
approaches the
Ericsson cycle.

8-31


FIGURE 8-48
Basic components of a
turbojet engine and the
T-s diagram for the ideal
turbojet cycle.

[Source: The Aircraft Gas Turbine Engine and Its Operation. © United Aircraft Corporation (now United Technologies Corp.), 1951, 1974.]
8-32


FIGURE 8-51
Energy supplied to an
aircraft (from the
burning of a fuel)
manifests itself in various
forms.

8-33


FIGURE 8-52
A turbofan engine.

8-34 [Source: The Aircraft Gas Turbine and Its Operation. © United Aircraft Corporation (now United Technologies Corp.), 1951, 1974.]


FIGURE 8-53
A modern jet
engine used to
power Boeing 777
aircraft. This is a
Pratt & Whitney
PW4084 turbofan
capable of
producing 84,000
pounds of thrust.
It is 4.87 m (192
in.) long, has a
2.84 m (112 in.)
diameter fan, and
it weighs 6800 kg
(15,000 lbm).

8-35 Photo Courtesy of Pratt&Whitney Corp.


FIGURE 8-54
A turboprop engine.

8-36 [Source: The Aircraft Gas Turbine Engine and Its Operation. © United Aircraft Corporation (now United Technologies Corp.), 1951, 1974.]


FIGURE 8-55
A ramjet engine.

8-37 [Source: The Aircraft Gas Turbine Engine and Its Operation. © United Aircraft Corporation (now United Technologies Corp.), 1951, 1974.]


FIGURE 8-57
Under average
driving conditions,
the owner of a 30-
mpg vehicle will
spend $300 less each
year on gasoline
than the owner of a
20-mpg vehicle
(assuming $1.50/gal
and 12,000
miles/yr).

8-38


FIGURE 8-62
Aerodynamic drag
increases and thus
fuel economy
decreases rapidly
at speeds above
55 mph.

8-39 (Source: EPA and U.S. Dept. of Energy.)

Cengel ch08

More Related Content

What's hot (19)

Viewers also liked (17)

Similar to Cengel ch08 (20)

More from Mete Cantekin (7)

Cengel ch08