U.S. patent application number 15/810374 was filed with the patent office on 2019-05-16 for exhaust channel of microturbine engine.
The applicant listed for this patent is NATIONAL CHUNG SHAN INSTITUTE OF SCIENCE AND TECHNOLOGY. Invention is credited to CHIH-CHUAN LEE, YUNG-MAO TSUEI, SING-MAW WU.
Application Number | 20190145284 15/810374 |
Document ID | / |
Family ID | 66433312 |
Filed Date | 2019-05-16 |
United States Patent
Application |
20190145284 |
Kind Code |
A1 |
LEE; CHIH-CHUAN ; et
al. |
May 16, 2019 |
EXHAUST CHANNEL OF MICROTURBINE ENGINE
Abstract
An exhaust channel of a microturbine engine, characterized by a
tapering pipe for reducing the speed at which a high-temperature
gas is discharged from the turbine and ensuring that the
high-temperature gas induced into a recuperator produces a uniform,
low-speed flow field, with a view to preventing any noticeable
vortex region from developing in the channel, minimizing the
pressure loss in the channel, and enhancing the heat exchange
efficiency of the recuperator.
Inventors: |
LEE; CHIH-CHUAN; (TAICHUNG
CITY, TW) ; TSUEI; YUNG-MAO; (TAICHUNG CITY, TW)
; WU; SING-MAW; (TAICHUNG CITY, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NATIONAL CHUNG SHAN INSTITUTE OF SCIENCE AND TECHNOLOGY |
TAOYUAN CITY |
|
TW |
|
|
Family ID: |
66433312 |
Appl. No.: |
15/810374 |
Filed: |
November 13, 2017 |
Current U.S.
Class: |
165/52 |
Current CPC
Class: |
F28F 2009/029 20130101;
F05D 2220/76 20130101; F28D 21/0003 20130101; F05D 2250/82
20130101; F28D 2021/0026 20130101; F28F 13/08 20130101; F01D 25/30
20130101; F05D 2250/324 20130101; F02C 6/18 20130101; F28D 9/0062
20130101 |
International
Class: |
F01D 25/30 20060101
F01D025/30; F28F 13/08 20060101 F28F013/08 |
Claims
1. An exhaust channel of a microturbine engine, comprising: an
expanding segment being a tapering pipe and having an expanding
segment outlet and an expanding segment inlet of a smaller diameter
than the expanding segment outlet; A bending segment being a
U-shaped curved tube and having a bending segment outlet and a
bending segment inlet in communication with the expanding segment
outlet; a heat exchange segment being a pipe and having a heat
exchange segment outlet and a heat exchange segment inlet in
communication with the bending segment outlet, wherein the heat
exchange segment contains cooling fins; and A rear exhaust segment
being a pipe, being in communication with the heat exchange segment
outlet, and being of a larger diameter than the heat exchange
segment.
2. The exhaust channel of a microturbine engine of claim 1, wherein
the expanding segment has a tapering angle no greater than
7.degree..
3. The exhaust channel of a microturbine engine of claim 1, wherein
a rate of change in cross-sectional area of the bending segment is
expressed by 0.1<(.DELTA.A/.DELTA.L)<0.2, where
cross-sectional area and length of the bending segment are denoted
by .DELTA.A and .DELTA.L, respectively.
4. The exhaust channel of a microturbine engine of claim 1, wherein
an included angle between the bending segment outlet and the heat
exchange segment inlet is no greater than 5.degree..
5. The exhaust channel of a microturbine engine of claim 1, wherein
the rear exhaust segment has a larger internal volume than the heat
exchange segment.
6. The exhaust channel of a microturbine engine of claim 1, wherein
the expanding segment, the bending segment, the heat exchange
segment and the rear exhaust segment are each made of sheet metal
and then welded together.
7. The exhaust channel of a microturbine engine of claim 1, wherein
the expanding segment, the bending segment, the heat exchange
segment and the rear exhaust segment are integrated.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to turbine engine exhaust pipe
design technologies and, more particularly, to an exhaust channel
of a microturbine engine for use in microturbine power generation
systems.
BACKGROUND OF THE INVENTION
[0002] A microturbine generator is a device which uses a gas
turbine to drive an electrical generator to generate electrical
power. However, its operation principle differs from a typical gas
turbine's as follows: air compressed by a centrifugal compressor is
introduced into a recuperator to undergo heat exchange with gas
discharged from the turbine to thereby increase internal energy of
the air and reduce fuel consumption; then the air enters a
combustion chamber to undergo combustion; and, finally, a large
amount of fuel is injected to produce the work required for driving
the electrical generator to generate electrical power. Therefore,
the recuperator is a main component of the microturbine generator.
The compressed air and the high temperature gas have to undergo
heat exchange by the recuperator. As a result, channel design
regarding the introduction of the high-temperature gas from the
outlet of the turbine into the recuperator must take the position
of the recuperator into consideration, ensure that the
high-temperature gas enters the recuperator at a low flow rate and
uniformly, and reduce pressure loss to therefore enhance the heat
exchange efficiency of the recuperator. Therefore, channel design
is a crucial technology.
[0003] The recuperator of any type of conventional microturbine
generator is either an annular recuperator or an independent
recuperator. The annular recuperator encloses the combustion
chamber to reduce the length of the microturbine. The independent
recuperator is placed outside or behind the microturbine. The
compressed air must enter the recuperator at a reduced low flow
rate in order to stay in the recuperator longer, because the
compressed air has to undergo high-efficiency heat exchange during
a short flow path in the recuperator. The area of the outlet of the
turbine is 20 times less than the area of the inlet of the
recuperator, expander channel design difficult and important.
Furthermore, its space is limited because of the short distance
between the channel of the turbine outlet and the recuperator
inlet. Moreover, its diffusion area is large, and thus a flow
separation and a vortex are likely to develop in the channel, that
will decrease the kinetic energy of the fluid and increase the
pressure loss at the channel. The above drawbacks of the prior art
add to the difficulties in channel design.
SUMMARY OF THE INVENTION
[0004] To overcome the aforesaid drawbacks of the prior art, the
present invention provides an exhaust channel of a microturbine
engine, characterized by a tapering channel for reducing the speed
at which a high-temperature gas is exit from the turbine and
ensuring that the high-temperature gas introduced into the
recuperator produces a uniform, low-speed flow field, with a view
to preventing any noticeable return region from developing in the
channel, minimizing the pressure loss in the channel, and enhancing
the heat exchange efficiency of the recuperator.
[0005] The present invention provides an exhaust channel of
microturbine engine, comprising: an expanding segment being a
tapering pipe and having an expanding segment outlet and an
expanding segment inlet of a smaller diameter than the expanding
segment outlet; a bending segment being a U-shaped curved tube and
having a bending segment outlet and a bending segment inlet in
communication with the expanding segment outlet; a heat exchange
segment being a pipe and having a heat exchange segment outlet and
a heat exchange segment inlet in communication with the bending
segment outlet, wherein the heat exchange segment contains cooling
fins; and a rear exhaust segment being a pipe, being in
communication with the heat exchange segment outlet, and being of a
larger internal volume than the heat exchange segment.
[0006] In an embodiment of the present invention, the expanding
segment has a tapering angle no greater than 7.degree..
[0007] In an embodiment of the present invention, the rate of
change in cross-sectional area of the bending segment is expressed
by 0.1<(.DELTA.A/.DELTA.L)<0.2, where cross-sectional area
and length of the bending segment are denoted by .DELTA.A and
.DELTA.L, respectively.
[0008] In an embodiment of the present invention, the included
angle between the bending segment outlet and the heat exchange
segment inlet is no greater than 5.degree..
[0009] In an embodiment of the present invention, the expanding
segment, the bending segment, the heat exchange segment and the
rear exhaust segment are each made of sheet metal and then welded
together.
[0010] In an embodiment of the present invention, the expanding
segment, the bending segment, the heat exchange segment and the
rear exhaust segment are integrated.
[0011] The above summary, the detailed description below, and the
accompanying drawings further explain the technical means and
measures taken to achieve predetermined objectives of the present
invention and the effects thereof. The other objectives and
advantages of the present invention are explained below and
illustrated with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic view of an exhaust channel of a
microturbine engine according to an embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] Implementation of the present invention is hereunder
illustrated by a specific embodiment. Improved in the art can
easily understand other advantages and effects of the present
invention by referring to the disclosure contained in the
specification.
[0014] Referring to FIG. 1, there is shown a schematic view of an
exhaust channel 1 of a microturbine engine according to an
embodiment of the present invention. As shown in the diagram, the
exhaust channel 1 of a microturbine engine comprises: an expanding
segment 11 being a tapering pipe and having an expanding segment
outlet 11B and an expanding segment inlet 11A of a smaller diameter
than the expanding segment outlet 11B; a bending segment 12 being a
U-shaped curved tube and having a bending segment outlet 12B and a
bending segment inlet 12A in communication with the expanding
segment outlet 11B; a heat exchange segment 13 being a pipe and
having a heat exchange segment outlet 13B and a heat exchange
segment inlet 13A in communication with the bending segment outlet
12B, wherein the heat exchange segment 13 contains cooling fins
131; and a rear exhaust segment 14 being a pipe or hollow-cored
casing, being in communication with the heat exchange segment
outlet 13B, and being of a larger internal volume than the heat
exchange segment 13.
[0015] To reduce the speed at which a high-temperature gas is
discharged from the microturbine engine, the present invention has
technical features as follows: the expanding segment is a tapering
pipe such that the flow rate of the gas passing the expanding
segment is reduced but not to an overly low level, otherwise the
heat exchange efficiency of subsequent segments will deteriorate.
In a preferred embodiment of the present invention, the expanding
segment has a tapering angle no greater than 7.degree..
[0016] To enhance its heat exchange efficiency, a recuperator of an
exhaust channel of a microturbine generator must be positioned as
close to an exhaust pipe of a microturbine engine as possible to
transfer the heat from the high-temperature gas and the heat from
the exhaust pipe to the recuperator and thus enhance the heat
exchange efficiency. Hence, the engine exhaust pipe and the
recuperator segment are parallel, near each other, and in
communication with each other by a curved tube. Distribution of
streamlines and speed of the gas in the channel depends on the
cross-sectional area and angle of the curved tube. In an embodiment
of the present invention, the rate of change in cross-sectional
area of the bending segment is expressed by
0.1<(.DELTA.A/.DELTA.L)<0.2, where .DELTA.A denotes
cross-sectional area of the bending segment, and .DELTA.L denotes
length of the bending segment, with a view to preventing an overly
large rate of change in cross-sectional area from affecting the
streamlines of the gas. The included angle between the bending
segment outlet and the heat exchange segment inlet is no greater
than 5.degree..
[0017] In an embodiment of the present invention, the rear exhaust
segment is of a larger internal volume than the heat exchange
segment to prevent generation of exhaust rear pressure and thus
reduction in working efficiency of the microturbine engine, and
reduce exhaust resistance confronting the outgoing gas, which may
even return to cause a reflow in the channel.
[0018] In an embodiment of the present invention, to enhance
production efficiency and reduce difficulties in the manufacturing
process, the expanding segment, the bending segment, the heat
exchange segment and the rear exhaust segment are each made of
sheet metal and then welded together to form an exhaust channel of
a microturbine engine according to the present invention.
Furthermore, owing to rapid development of laminated manufacturing
technologies, theoretically speaking, laminated manufacturing
(commonly known as 3D printing) can be employed to make an
integrally-formed exhaust channel of a microturbine engine, but it
has some unsolved drawbacks in terms of processing precision and
costs. If its production efficiency and yield is enhanced, it can
produce exhaust channels of high structural strength and low
weight.
[0019] In conclusion, the present invention provides an exhaust
channel of a microturbine engine, characterized by a tapering
channel for reducing the speed at which a high-temperature gas is
discharged from the microturbine engine and ensuring that the
high-temperature gas introduced into the recuperator produces a
uniform, low-speed flow field, with a view to preventing any
noticeable return region from developing in the channel, minimizing
the pressure loss in the channel, and enhancing the heat exchange
efficiency of the recuperator.
[0020] In an embodiment of the present invention, the expanding
segment, the bending segment, the heat exchange segment and the
rear exhaust segment are integrated.
[0021] The embodiments described above are intended only to
illustrate the features and advantages of the present invention
rather than limit the substantial technical contents of the present
invention. Persons skilled in the art can make modifications and
variations to the aforesaid embodiments without departing from the
spirit and scope of the present invention. Accordingly, the legal
protection for the present invention should be defined by the
appended claims.
* * * * *