U.S. patent application number 14/810726 was filed with the patent office on 2015-11-19 for multi-stage volumetric fluid expansion device.
The applicant listed for this patent is EATON CORPORATION. Invention is credited to William Nicholas EYBERGEN, Matthew James FORTINI, Lalit Murlidhar PATIL, Sheetalkumar Shamrao PATIL, Martin D. PRYOR.
Application Number | 20150330257 14/810726 |
Document ID | / |
Family ID | 50070725 |
Filed Date | 2015-11-19 |
United States Patent
Application |
20150330257 |
Kind Code |
A1 |
EYBERGEN; William Nicholas ;
et al. |
November 19, 2015 |
MULTI-STAGE VOLUMETRIC FLUID EXPANSION DEVICE
Abstract
A multi-stage expansion device is disclosed. In one embodiment,
the multi-stage expansion device has a housing within which a first
stage, a second stage, and a third stage are housed. The housing
may also be configured with internal working fluid passageways to
direct a working fluid from the first stage to the second stage
and/or from the second stage to the third stage. Each of the stages
may include a pair of non-contacting rotors that are mechanically
connected to each other and to a power output device such that
energy extracted from the working fluid is converted to mechanical
work at the output device. In one embodiment, a step up gear
arrangement is provided between the rotors of the first and second
stages. A step up gear arrangement may also be provided between the
rotors of the second and third stage.
Inventors: |
EYBERGEN; William Nicholas;
(Harrison Twp, MI) ; PRYOR; Martin D.; (Canton,
MI) ; PATIL; Sheetalkumar Shamrao; (Pune, IN)
; PATIL; Lalit Murlidhar; (Pune, IN) ; FORTINI;
Matthew James; (Allen Park, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EATON CORPORATION |
Cleveland |
OH |
US |
|
|
Family ID: |
50070725 |
Appl. No.: |
14/810726 |
Filed: |
July 28, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/US2014/013401 |
Jan 28, 2014 |
|
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14810726 |
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61757533 |
Jan 28, 2013 |
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61810579 |
Apr 10, 2013 |
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61816143 |
Apr 25, 2013 |
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Current U.S.
Class: |
60/670 ; 415/123;
415/124.1; 415/61; 415/68; 60/692 |
Current CPC
Class: |
F01K 23/10 20130101;
F01K 7/16 20130101; F01K 7/02 20130101; F01K 7/36 20130101; F01K
23/16 20130101; F01D 25/00 20130101; F01K 9/02 20130101; F01D
13/003 20130101; F01K 7/22 20130101 |
International
Class: |
F01K 7/16 20060101
F01K007/16; F01D 25/00 20060101 F01D025/00; F01D 13/00 20060101
F01D013/00; F01K 9/02 20060101 F01K009/02; F01K 23/16 20060101
F01K023/16 |
Goverment Interests
GOVERNMENT LICENSE RIGHTS
[0002] This invention was made with government support under
Contract No. DE-EE0005650 awarded by the National Energy Technology
Laboratory funded by the Office of Energy Efficiency &
Renewable Energy of the United States Department of Energy. The
government has certain rights in the invention
Claims
1. A multi-stage volumetric fluid expansion device comprising: a. a
first fluid expansion stage having a first pair of non-contacting
rotors disposed between a first inlet and a first outlet, the first
fluid expansion stage being configured to generate useful work at
the first pair of rotors by expanding a working fluid from a first
pressure to a second pressure that is lower than the first
pressure; b. a second fluid expansion stage having a second pair of
non-contacting rotors disposed between a second inlet and a second
outlet, the second fluid expansion stage being configured to
generate useful work at the second pair of rotors by receiving the
working fluid from the first fluid expansion stage outlet and
expanding the working fluid to a third pressure that is lower than
the second pressure; and c. a power output device rotated by the
first and second pair of rotors.
2. The multi-stage volumetric fluid expansion device of claim 1,
further comprising: a. a housing within which the first and second
pairs of rotors is disposed, wherein the first outlet and the
second inlet are joined within the housing to form a continuous
working fluid passageway extending between the first inlet and the
second outlet .
3. The multi-stage volumetric fluid expansion device of claim 1,
wherein: a. one of the first pair of rotors and one of the second
pair of rotors are mounted to a first common rotor shaft and the
other of the first pair of rotors and the other of the second pair
of rotors are mounted to a second common rotor shaft; b. wherein
the power output device is rotated by the first rotor shaft.
4. The multi-stage volumetric fluid expansion device of claim 3,
wherein: a. the first shaft is provided with a drive gear and the
power output device is provided with an input gear that is driven
by the drive gear.
5. The multi-stage volumetric fluid expansion device of claim 4,
wherein: a. the drive gear and input gear are configured in a step
down arrangement such that the first and second pair of rotors
rotates at a higher rotational speed than the power output
device.
6. The multi-stage volumetric fluid expansion device of claim 5,
wherein: a. the power output device is provided with a clutch to
selectively engage and disengage the first rotor shaft from the
power output device.
7. The multi-stage volumetric fluid expansion device of claim 2,
wherein: a. one of the first pair of rotors is mounted to a first
rotor shaft and the other of the first pair of rotors is mounted to
a second rotor shaft; and b. one of the second pair of rotors is
mounted to a third rotor shaft and the other of the second pair of
rotors is mounted to a fourth shaft; c. wherein the power output
device is rotated by the fourth rotor shaft.
8. The multi-stage volumetric fluid expansion device of claim 4,
wherein: a. the first shaft is provided with a first drive gear and
the fourth shaft is provided with a first input gear that is driven
by the first drive gear.
9. The multi-stage volumetric fluid expansion device of claim 5,
wherein: a. the first drive gear and first input gear are
configured in a step up arrangement such that the first pair of
rotors rotates at a lower rotational speed than the second pair of
rotors.
10. The multi-stage volumetric fluid expansion device of claim 9,
wherein: a. the fourth shaft is provided with a second drive gear
and the power output device is provided with an second input gear
that is driven by the second drive gear.
11. The multi-stage volumetric fluid expansion device of claim 10,
wherein: a. The second drive gear and the second input gear are
configured in a step down arrangement such that the second pair of
rotors rotates at a higher rotational speed than the power output
device.
12. The multi-stage volumetric fluid expansion device of claim 11,
wherein: a. the power output device is provided with a clutch to
selectively engage and disengage the fourth rotor shaft from the
power output device.
13. The multi-stage volumetric fluid expansion device of claim 1,
wherein: a. the second pair of rotors have twisted non-contacting
lobes, wherein one of the second pair of rotors has a number of
twisted lobes that equals a number of twisted lobes of the other of
the second pair of rotors.
14. A multi-stage volumetric fluid expansion device comprising: a.
a first fluid expansion stage having a first pair of non-contacting
rotors disposed between a first inlet and a first outlet, the first
fluid expansion stage being configured to generate useful work at
the first pair of rotors by expanding a working fluid from a first
pressure to a second pressure that is lower than the first
pressure; b. a second fluid expansion stage having a second pair of
non-contacting rotors disposed between a second inlet and a second
outlet, the second fluid expansion stage being configured to
generate useful work at the second pair of rotors by receiving the
working fluid from the first fluid expansion stage outlet and
expanding the working fluid to a third pressure that is lower than
the second pressure; c. a third fluid expansion stage having a
third pair of non-contacting rotors disposed between a third inlet
and a third outlet, the third fluid expansion stage being
configured to generate useful work at third pair of rotors by
receiving the working fluid from the second fluid expansion stage
outlet and expanding the working fluid to a fourth pressure that is
lower than the third pressure; d. a power output device rotated by
the first, second, and second third of rotors.
15. The multi-stage volumetric fluid expansion device of claim 14,
further comprising: a. a housing within which the first, second,
and third pairs of rotors is disposed, wherein the second outlet
and third inlet are joined within the housing to form a continuous
working fluid passageway extending between the second inlet and the
third outlet.
16. The multi-stage volumetric fluid expansion device of claim 15,
wherein: a. the first outlet and the second inlet are joined within
the housing to form a continuous working fluid passageway extending
between the first inlet and the third outlet.
17. The multi-stage volumetric fluid expansion device of claim 14,
wherein: a. one of the first pair of rotors, one of the second pair
of rotors, and one of the third pair of rotors are mounted to a
first common rotor shaft and the other of the first pair of rotors,
the other of the second pair of rotors, and the other pair of
rotors are mounted to a second common rotor shaft; b. wherein the
power output device is rotated by the first rotor shaft.
18. The multi-stage volumetric fluid expansion device of claim 15,
wherein: a. one of the first pair of rotors and one of the second
pair of rotors is mounted to a first common rotor shaft and the
other of the first pair of rotors and the other of the second pair
of rotors is mounted to a second common rotor shaft; and b. one of
the third pair of rotors is mounted to a third rotor shaft and the
other of the third pair of rotors are mounted to a fourth rotor
shaft; c. wherein the power output device is rotated by the fourth
rotor shaft.
19. The multi-stage volumetric fluid expansion device of claim 16,
wherein: a. one of the first pair of rotors is mounted to a first
rotor shaft and the other of the first pair of rotors is mounted to
a second rotor shaft; b. one of the second pair of rotors is
mounted to a third rotor shaft and the other of the second pair of
rotors is mounted to a fourth rotor shaft; and c. one of the third
pair of rotors is mounted to a fifth rotor shaft and the other of
the third pair of rotors is mounted to a sixth rotor shaft; d.
wherein the power output device is rotated by the sixth rotor
shaft.
20. The multi-stage volumetric fluid expansion device of claim 17,
wherein: a. the first rotor shaft is provided with a drive gear and
the power output device is provided with an input gear that is
driven by the drive gear; b. the drive gear and input gear being
configured in a step down arrangement such that the first, second,
and third pairs of rotors rotate at a higher rotational speed than
the power output device.
21. The multi-stage volumetric fluid expansion device of claim 20,
wherein: a. the power output device is provided with a clutch to
selectively engage and disengage the first rotor shaft from the
power output device.
22. The multi-stage volumetric fluid expansion device of claim 17,
wherein: a. the first rotor shaft is provided with a first drive
gear and the third rotor shaft device is provided with an input
gear that is driven by the drive gear; b. the drive gear and input
gear being configured in a step down arrangement such that the
first, second, and third pairs of rotors rotate at a higher
rotational speed than the power output device.
23. The multi-stage volumetric fluid expansion device of claim 20,
wherein: a. the power output device is provided with a clutch to
selectively engage and disengage the first rotor shaft from the
power output device.
24. The multi-stage volumetric fluid expansion device of claim 18,
wherein: a. the first shaft is provided with a first drive gear and
the fourth shaft is provided with a first input gear that is driven
by the first drive gear; b. the first drive gear and first input
gear being configured in a step up arrangement such that the first
and second pair of rotors rotates at a lower rotational speed than
the third pair of rotors.
25. The multi-stage volumetric fluid expansion device of claim 24,
wherein: a. the fourth shaft is provided with a second drive gear
and the power output device is provided with a second input gear
that is driven by the second drive gear; b. the second drive gear
and the second input gear being configured in a step down
arrangement such that the third pair of rotors rotates at a higher
rotational speed than the power output device.
26. The multi-stage volumetric fluid expansion device of claim 25,
wherein: a. the power output device is provided with a clutch to
selectively engage and disengage the fourth rotor shaft from the
power output device.
27. The multi-stage volumetric fluid expansion device of claim 19,
wherein: a. the first shaft is provided with a first drive gear and
the third shaft is provided with a first input gear that is driven
by the first drive gear; b. the first drive gear and first input
gear being configured in a step up arrangement such that the first
pair of rotors rotates at a lower rotational speed than the second
pair of rotors.
28. The multi-stage volumetric fluid expansion device of claim 27,
wherein: a. the fourth shaft is provided with a second drive gear
and the sixth shaft is provided with a second input gear that is
driven by the second drive gear; b. the first drive gear and first
input gear being configured in a step up arrangement such that the
second pair of rotors rotates at a lower rotational speed than the
third pair of rotors.
29. The multi-stage volumetric fluid expansion device of claim 28,
wherein: a. The sixth shaft is provided with a third drive gear and
the power output device is provided with a third input gear that is
driven by the third drive gear; b. the third drive gear and the
third input gear being configured in a step down arrangement such
that the third pair of rotors rotates at a higher rotational speed
than the power output device.
30. The multi-stage volumetric fluid expansion device of claim 29,
wherein: a. the power output device is provided with a clutch to
selectively engage and disengage the sixth rotor shaft from the
power output device.
31. The multi-stage volumetric fluid expansion device of claim 14,
wherein: a. the first pair of rotors have twisted non-contacting
lobes, wherein one of the first pair of rotors has a number of
twisted lobes that equals a number of twisted lobes of the other of
the first pair of rotors; b. the second pair of rotors have twisted
non-contacting lobes, wherein one of the second pair of rotors has
a number of twisted lobes that equals a number of twisted lobes of
the other of the second pair of rotors; and c. the third pair of
rotors have twisted non-contacting lobes, wherein one of the third
pair of rotors has a number of twisted lobes that equals a number
of twisted lobes of the other of the third pair of rotors.
32. A system for generating mechanical work via a closed-loop
Rankine cycle, the system comprising: a. a power plant that
produces a waste heat stream, wherein the power plant has a waste
heat outlet through which the waste heat stream exits; b. at least
one heat exchanger in fluid communication with the waste heat
stream, the heat exchanger being configured to heat a working
fluid; c. a multi-stage fluid expansion device configured to
generate mechanical work at an output device from the working
fluid, the expansion device having a housing within which a first
stage and a second stage are disposed, the first stage being
configured to expand the working fluid, the second stage being
configured to receive the working fluid from the first stage and to
expand the working fluid; d. a condenser constructed and arranged
to condense the working fluid; e. a pump constructed and arranged
to pump the condensed working fluid to the at least one heat
exchanger.
33. The system for generating mechanical work of claim 32, wherein:
a. the multi-stage fluid expansion device housing further includes
a third stage disposed within the housing that is configured to
receive the working fluid from the second stage and to expand the
working.
34. The system for generating mechanical work of claim 33, further
comprising: a. a second heat exchanger located between the first
and second stages.
35. The system for generating mechanical work of claim 33, wherein:
a. The housing defines an internal working fluid pathway within
which the working fluid can pass internally from the first stage to
the second stage and from the second stage to the third stage.
36. The system for generating mechanical work of claim 35, wherein:
a. the output device is mechanically coupled to the third stage,
the second stage is mechanically coupled to the third stage, and
the first stage is mechanically coupled to the second stage such
that power developed by each of the first, second, and third stages
is transmitted to the power output device.
37. The system for generating mechanical work of claim 35, further
comprising: a. a first step up gear arrangement provided between
the first and second stages such that a first pair of rotors
associated with the first stage rotate at a lower speed than a
second pair of rotors associated with the second stage; and b. a
second step up gear arrangement provided between the second and
third stages such that the second pair of rotors rotate at a lower
speed than a third pair of rotors associated with the third
stage.
38. The system for generating mechanical work of claim 37, further
comprising: a. a step down gear arrangement provided between the
third stage and the power output device such that third pair of
rotors rotate at a lower speed than the power output device.
39. The multi-stage volumetric fluid expansion device of claim 38,
wherein: a. the power output device is provided with a clutch to
selectively engage and disengage the third stage from the power
output device.
40. The multi-stage volumetric fluid expansion device of claim 38,
wherein: a. the first pair of rotors have twisted non-contacting
lobes, wherein one of the first pair of rotors has a number of
twisted lobes that equals a number of twisted lobes of the other of
the first pair of rotors; b. the second pair of rotors have twisted
non-contacting lobes, wherein one of the second pair of rotors has
a number of twisted lobes that equals a number of twisted lobes of
the other of the second pair of rotors; and c. the third pair of
rotors have twisted non-contacting lobes, wherein one of the third
pair of rotors has a number of twisted lobes that equals a number
of twisted lobes of the other of the third pair of rotors.
41. A multi-stage volumetric fluid expansion device comprising: a.
a first fluid expansion stage having a first pair of non-contacting
rotors disposed between a first inlet and a first outlet, the first
fluid expansion stage being configured to generate useful work at a
first output shaft by expanding a working fluid from a first
pressure to a second pressure that is lower than the first
pressure; b. a second fluid expansion stage having a second pair of
non-contacting rotors disposed between a second inlet and a second
outlet, the second fluid expansion stage being configured to
generate useful work at a second output shaft by receiving the
working fluid from the first fluid expansion stage outlet and
expanding the working fluid to a third pressure that is lower than
the second pressure; and c. a power output device having an input
gear that is rotated by the first and second output shafts.
42. The multi-stage volumetric fluid expansion device of claim 41
wherein: a. the first output shaft acts on the power output device
input gear via a first gear train and the second output shaft acts
on the power output device input gear via a second gear train in
parallel to the first gear train.
43. A multi-stage volumetric fluid expansion device comprising: a.
a first fluid expansion stage having a first pair of non-contacting
rotors disposed between a first inlet and a first outlet, the first
fluid expansion stage being configured to generate useful work at a
first output shaft by expanding a working fluid from a first
pressure to a second pressure that is lower than the first
pressure; b. a second fluid expansion stage having a second pair of
non-contacting rotors disposed between a second inlet and a second
outlet, the second fluid expansion stage being configured to
generate useful work at a second output shaft by receiving the
working fluid from the first fluid expansion stage outlet and
expanding the working fluid to a third pressure that is lower than
the second pressure; and c. a third fluid expansion stage having a
third pair of non-contacting rotors disposed between a second inlet
and a second outlet, the second fluid expansion stage being
configured to generate useful work at a third output shaft by
receiving the working fluid from the first fluid expansion stage
outlet and expanding the working fluid to a third pressure that is
lower than the second pressure; d. wherein at least two of the
first, second, and third output shafts are arranged in parallel to
act on an input gear of the fluid expansion device.
44. The multi-stage volumetric fluid expansion device of claim 43
wherein: a. the input gear of the fluid expansion device is a power
output device input gear; b. the first output shaft acts on the
power output device input gear via a first gear train; c. the
second output shaft acts on the power output device input gear via
a second gear train; and d. the third output shaft acts on the
power output device input gear via a third gear train.
45. The multi-stage volumetric fluid expansion device of claim 43
wherein: a. the input gear of the fluid expansion device is a first
stage input gear; b. the first output shaft acts on a power output
device input gear via a first gear train; c. the second output
shaft acts on the first stage input gear via a second gear train;
and d. the third output shaft acts on the first stage input gear
via a third gear train.
46. The multi-stage volumetric fluid expansion device of claim 43
wherein: a. the input gear of the fluid expansion device is a power
output device input gear; b. the first output shaft acts on the
power output device input gear via a first gear train; c. the
second output shaft acts on the power output device input gear via
a second gear train; and d. the third output shaft acts on a second
stage input gear via a third gear train.
47. The multi-stage volumetric fluid expansion device of claim 46
wherein: a. the working fluid is directed through an internal
passageway in a housing of the volumetric fluid expansion device
from the second stage to the third stage.
48. The multi-stage volumetric fluid expansion device of claim 47
wherein: a. the second pair of rotors and the third pair of rotors
are mounted to a common pair of shafts.
49. The multi-stage volumetric fluid expansion device of claim 43
wherein: a. the input gear of the fluid expansion device is a power
output device input gear; b. the first output shaft acts on the
power output device input gear via a first gear train; c. the
second output shaft acts on a first stage input gear via a second
gear train; and d. the third output shaft acts on the power output
device input gear via a third gear train.
50. The multi-stage volumetric fluid expansion device of claim 49
wherein: a. the working fluid is directed through an internal
passageway in a housing of the volumetric fluid expansion device
from the first stage to the second stage.
51. The multi-stage volumetric fluid expansion device of claim 50
wherein: a. the first pair of rotors and the second pair of rotors
are mounted to a common pair of shafts.
Description
RELATED APPLICATIONS
[0001] This application is a Continuation of PCT/US2014/013401,
filed 28 Jan. 2014, which claims benefit of U.S. Patent Application
Ser. No. 61/757,533 filed on 28 Jan. 2013, claims benefit of U.S.
Patent Application Ser. No. 61/810,579 filed on 10 Apr. 2013, and
claims benefit of U.S. Patent Application Ser. No. 61/816,143 filed
on 25 Apr. 2013 and which applications are incorporated herein by
reference. To the extent appropriate, a claim of priority is made
to each of the above disclosed applications.
TECHNICAL FIELD
[0003] This present disclosure relates to volumetric fluid
expansion devices that convert waste energy from a power plant to
useful work for the purposes of increasing power plant
efficiency.
BACKGROUND
[0004] Waste heat energy is necessarily produced in many processes
that generate energy or convert energy into useful work, such as a
power plant. Typically, such waste heat energy is released into the
ambient environment. In one application, waste heat energy is
generated from an internal combustion engine. Exhaust gases from
the engine have a high temperature and pressure and are typically
discharged into the ambient environment without any energy recovery
process. Alternatively, some approaches have been introduced to
recover waste energy and re-use the recovered energy in the same
process or in separate processes. However, there is still demand
for enhancing the efficiency of energy recovery.
SUMMARY
[0005] In one aspect of the disclosure, a multi-stage volumetric
fluid expansion device is provided to generate useful work by
expanding a working fluid. In one application, the volumetric fluid
expansion device can be utilized to recover waste energy from a
power plant, such as waste heat energy from a fuel cell or an
internal combustion engine. The power plant may be provided in a
vehicle or may be provided in a stationary application, such as a
generator application.
[0006] The multi-stage volumetric fluid expansion device may be
provides as part of a system for generating mechanical work via a
closed-loop Rankine cycle. Such a system may also include a power
plant that produces a waste heat stream, wherein the power plant
has a waste heat outlet through which the waste heat stream exits
and at least one heat exchanger in fluid communication with the
waste heat stream. In operation, the heat exchanger heats the
working fluid. The multi-stage fluid expansion device can be
configured to generate mechanical work at an output device from the
working fluid and be provided with a housing within which a first
stage, a second stage, and a third stage are disposed. The first,
second, and third stages can be configured to sequentially expand
the working fluid and product mechanical work at the output device.
A condenser may also be provided to partially or fully condense the
working fluid while a pump may be provided to pump the condensed
working fluid back to the heat exchanger.
[0007] The multi-stage expansion device first stage may include a
first pair of non-contacting rotors disposed between a first inlet
and a first outlet while the second stage may include a second pair
of non-contacting rotors disposed between a second inlet and a
second outlet. The third fluid expansion stage may include a third
pair of non-contacting rotors disposed between a third inlet and a
third outlet. In one aspect, the power output device is rotated by
the first, second, and second third of rotors. In one embodiment,
the second outlet and third inlet are joined within the housing to
form a continuous working fluid passageway extending between the
second inlet and the third outlet. In one embodiment, the first
outlet and the second inlet are joined within the housing to form a
continuous working fluid passageway extending between the first
inlet and the third outlet.
[0008] In one aspect, the output device is mechanically coupled to
the third stage, the second stage is mechanically coupled to the
third stage, and the first stage is mechanically coupled to the
second stage such that power developed by each of the first,
second, and third stages is transmitted to the power output device.
In one embodiment, a first step up gear arrangement provided
between the first and second stages such that a first pair of
rotors associated with the first stage rotate at a lower speed than
a second pair of rotors associated with the second stage.
Alternatively, the first and second pair of rotors can be mounted
to a pair of common shafts. In one embodiment, a second step up
gear arrangement is provided between the second and third stages
such that the second pair of rotors rotate at a lower speed than a
third pair of rotors associated with the third stage.
Alternatively, the second and third pair of rotors can be mounted
to a pair of common shafts. A step down gear arrangement may also
be provided between the third stage and the power output device
such that third pair of rotors rotate at a greater speed than the
power output device. In one embodiment, the power output device is
provided with a clutch to selectively engage and disengage the
third stage from the power output device.
[0009] In one embodiment, the first pair of rotors have twisted
non-contacting lobes, wherein one of the first pair of rotors has a
number of twisted lobes that equals a number of twisted lobes of
the other of the first pair of rotors. The second and third pairs
of rotors may be similarly configured.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a cross-sectional side view of a vehicle having a
volumetric fluid expansion device having features that are examples
of aspects in accordance with the principles of the present
disclosure.
[0011] FIG. 2 is a schematic view of a first example of the
volumetric fluid expansion device shown in FIG. 1.
[0012] FIG. 3 is a schematic view of a second example of the
volumetric fluid expansion device shown in FIG. 1.
[0013] FIG. 4 is a schematic view of a third example of the
volumetric fluid expansion device shown in FIG. 1.
[0014] FIG. 5 is a schematic view of a first example of a
drivetrain arrangement suitable for use in the volumetric fluid
expansion device shown in FIG. 1.
[0015] FIG. 6 is a schematic view of a second example of a
drivetrain arrangement suitable for use in the volumetric fluid
expansion device shown in FIG. 1.
[0016] FIG. 7 is a schematic view of a third example of a
drivetrain arrangement suitable for use in the volumetric fluid
expansion device shown in FIG. 1.
[0017] FIG. 8 is a perspective view of a rotor suitable for use in
the volumetric fluid expansion device shown in FIG. 1.
[0018] FIG. 9 is a schematic end view of a stage inlet of the fluid
expansion device shown in FIG. 1.
[0019] FIG. 10 is a schematic side view of a stage inlet of the
fluid expansion device shown in FIG. 1.
[0020] FIG. 11 is a schematic showing geometric parameters of the
rotors of the fluid expansion device shown in FIG. 1.
[0021] FIG. 12 is a schematic showing an example fluid expansion
device in an organic Rankine cycle system having features that are
examples of aspects in accordance with the principles of the
present disclosure.
[0022] FIG. 13 is a perspective view of the fluid expansion device
shown in FIG. 12.
[0023] FIG. 14 is a perspective view of the drivetrain of the fluid
expansion device shown in FIG. 12.
[0024] FIG. 15 is a cross-sectional side view of the fluid
expansion device shown in FIG. 12.
[0025] FIG. 16 is a cross-sectional top view of the fluid expansion
device shown in FIG. 12.
[0026] FIG. 17 is an end view of the first expansion stage of the
fluid expansion device shown in FIG. 12.
[0027] FIG. 18 is an end view of the second expansion stage of the
fluid expansion device shown in FIG. 12.
[0028] FIG. 19 is a schematic showing an example fluid expansion
device in an organic Rankine cycle system having features that are
examples of aspects in accordance with the principles of the
present disclosure.
[0029] FIG. 20 is a perspective view of the fluid expansion device
shown in FIG. 19.
[0030] FIG. 21 is a perspective view of the drivetrain of the fluid
expansion device shown in FIG. 19.
[0031] FIG. 22 is a cross-sectional side view of the fluid
expansion device shown in FIG. 19.
[0032] FIG. 23 is a cross-sectional top view of the fluid expansion
device shown in FIG. 19.
[0033] FIG. 24 is an end view of the second expansion stage of the
fluid expansion device shown in FIG. 19.
[0034] FIG. 25 is an end view of the first expansion stage of the
fluid expansion device shown in FIG. 19.
[0035] FIG. 26 is a perspective view of an example fluid expansion
device having features that are examples of aspects in accordance
with the principles of the present disclosure.
[0036] FIG. 27 is a perspective view of the drivetrain of the fluid
expansion device shown in FIG. 23.
[0037] FIG. 28 is a schematic view of a first example of a parallel
drive volumetric fluid expansion device usable in the system shown
in FIG. 1.
[0038] FIG. 29 is a schematic view of a second example of a
parallel drive volumetric fluid expansion device usable in the
system shown in FIG. 1.
[0039] FIG. 30 is a schematic view of a third example of a parallel
drive volumetric fluid expansion device usable in the system shown
in FIG. 1.
[0040] FIG. 31 is a schematic view of a fourth example of a
parallel drive volumetric fluid expansion device usable in the
system shown in FIG. 1.
DETAILED DESCRIPTION
[0041] Various embodiments will be described in detail with
reference to the drawings, wherein like reference numerals
represent like parts and assemblies throughout the several views.
Reference to various embodiments does not limit the scope of the
claims attached hereto. Additionally, any examples set forth in
this specification are not intended to be limiting and merely set
forth some of the many possible embodiments for the appended
claims. Referring to the drawings wherein like reference numbers
correspond to like or similar components throughout the several
figures.
[0042] Modern demands for fuel efficient vehicles and power plants
have led to development of hybrid power-generation and propulsion
systems. Generally, such systems combine a power-plant, such as an
internal combustion engine or a fuel cell, and an electric motor to
drive the vehicle. Each of the internal combustion engine and fuel
cell emits high temperature exhaust as a byproduct of the
power-generation cycle employed therein. The high temperature
exhaust constitutes energy that is lost from the power-generation
cycle, which, if recaptured, could be employed to improve
efficiency of the cycle, and, therefore, of the propulsion system
employing the same. Improvements in other applications are also
desired, for example in marine agricultural and industries. Another
example is stationary generator sets.
[0043] Referring to FIG. 1, a vehicle 10 is shown having wheels 12
for movement along an appropriate road surface. The vehicle 10
includes a power-generation system 14. The system 14 includes a
power-plant 16 employing a power-generation cycle. The power-plant
16 uses a specified amount of oxygen, which may be part of a stream
of intake air, to generate power. The power-plant 16 also generates
waste heat such in the form of a high-temperature exhaust gas in
exhaust line 17 a byproduct of the power-generation cycle. In one
embodiment, the power-plant 16 is an internal combustion (IC)
engine, such as a spark-ignition or compression-ignition type which
combusts a mixture of fuel and air to generate power. In one
embodiment, the power-plant 16 may be or a fuel cell which converts
chemical energy from a fuel into electricity through a chemical
reaction with oxygen or another oxidizing agent.
[0044] The vehicle 10 may also include an energy recovery device,
for example volumetric fluid expansion device 20, which recovers
waste heat from the power-plant 16 to improve the efficiency of the
power-plant 16. In one aspect, the volumetric fluid expansion
device 20 is a multi-stage fluid expansion device 20.
[0045] In one embodiment, and as shown in FIG. 1, an organic
Rankine cycle (ORC) is used to power the fluid expansion device 20.
In such an embodiment, a piping system 1000 including a heat
exchanger 18 is provided that transfers heat from the exhaust gas
line 17 to a working fluid 12 that is then delivered to the
volumetric fluid expansion device 20. The working fluid 12 may be a
solvent such as ethanol, n-pentane, or toluene. A condenser 19 is
also provided which creates a low pressure zone for the working
fluid 12 and thereby provides a location for the working fluid 12
to condense. Once condensed, the working fluid 12 can be delivered
to the heat exchanger 18 via a pump 17. A more detailed description
of an ORC system being utilized to drive an energy recovery device
20 is provided in Patent Cooperation Treaty (PCT) International
Application Publication Number WO 2013/130774 entitled VOLUMETRIC
ENERGY RECOVERY DEVICE AND SYSTEMS. WO 2013/130774 is hereby
incorporated herein by reference in its entirety. Additional ORC
systems are disclosed in this application, as well as in a PCT
Application (serial number unknown) entitled VOLUMETRIC ENERGY
RECOVERY SYSTEM WITH THREE STAGE EXPANSION (Attorney Docket
15720.0275WOU1/13-rSPR-222 VTI) being filed concurrently with this
application, the entirety of which is incorporated by reference
herein. The volumetric fluid expansion device 20 may also be
utilized in a direct exhaust gas heat recovery process wherein the
exhaust gas is the working fluid 12, as disclosed in Patent
Cooperation Treaty (PCT) International Application Number
PCT/US2013/078037 entitled EXHAUST GAS ENERGY RECOVERY SYSTEM.
PCT/US2013/078037 is herein incorporated by reference in its
entirety.
Housing and Working Fluid Passageway Configurations
[0046] Referring to FIGS. 2-4, schematic representations of
examples of multi-stage volumetric fluid expansion device 20 in
accordance with the disclosure are presented. As shown, the
multi-stage volumetric fluid expansion device 20 includes a first
stage 20-1, a second stage 20-2, and a third stage 20-3. It should
be understood that although three stages is shown, the device could
be provided with fewer stages, such as two stages, or more stages,
such as four, five, six, or more stages. In generalized terms, each
of the stages 20-1, 20-2, 20-3 is or can be placed in fluid
communication with the other such that the working fluid 12 passes
sequentially through the stages 20-1, 20-2, 20-3 where energy from
the fluid is transferred to useful work. The fluid expansion device
20 may also include a power output device 400 configured to
transfer useful work from the stages 20-1, 20-2, 20-3 to a power
input location of the vehicle 10 or power plant 16.
[0047] As shown, the first stage 20-1 includes a main housing 102
that defines a first working fluid passageway 106 extending between
a first inlet 108 and a first outlet 110. Similarly, the second
stage 20-2 includes a main housing 202 defining a working fluid
passageway 206 extending between a second inlet 208 and a second
outlet 210 while the third stage 20-3 has a main housing 302
defining a working fluid passageway 306 extending between a third
inlet 308 and a third outlet 306. The fluid expansion device 20 can
also be provided with compartments 150, 152, 154, and 156 to house
bearings, timing gears, and/or step gears, as discussed later. The
compartments 152 and 154 are configured to provide a boundary
between the working fluid pathways 106/206 and 206/306 so as to
prevent the working fluid 12 from bypassing from the first stage
20-1 to the second stage 20-2 and from the second stage 20-2 to the
third stage 20-3 outside of the defined working fluid pathways 106,
206, 306.
[0048] Disposed within each of the working fluid passageways 106,
206, 306 is a pair of meshed rotors 130/132, 230/232, and 330/332,
respectively. Each pair of meshed rotors 130/132, 230/232, and
330/332 is configured such that the rotors are overlapping and
rotate synchronously in opposite directions. As the working fluid
12 passes through the inlet 108, 208, 308, across the meshed rotors
130/132, 230/232, 330/332, and to the respective outlet 110, 210,
310, the working fluid 12 undergoes a pressure drop which imparts
rotational movement onto the rotors, thus creating mechanical work
that can be input back into the power plant 16. Accordingly, each
inlet port 108, 208, 308 is configured to admit the working fluid
12 at an entering pressure whereas the corresponding outlet port
110, 210, 310 is configured to discharge the working fluid 12 at a
leaving pressure lower than the entering pressure. In such a
configuration, the working fluid 12 enters inlet 108 at a first
pressure and leaves outlet 110 and enters inlet 208 at a second
pressure lower than the first. The working fluid then exits outlet
210 and enters inlet 308 at a third pressure lower than the second
and subsequently exits outlet 310 at a fourth pressure lower than
the third. In one embodiment, the pressure drop from the first
inlet 108 to the third outlet 310 is about 10 bar wherein the
pressure drop between the first inlet and the first outlet is about
5 bar, the pressure drop between the second inlet 208 and the
second outlet 210 is about 3 bar, and the pressure drop between the
third inlet 308 and the third outlet 310 is about 2 bar.
[0049] With reference to the example embodiment shown in FIG. 2,
each of the inlets 108, 208, 308 and each of the outlets 110, 210,
310 are shown as being completely separated. In this configuration,
the second inlet 208 can be placed in fluid communication with the
first outlet 110 while the third inlet 308 can be placed in fluid
communication with the second outlet 210 via external piping 3, 5
to define a continuous internal working fluid passageway 106, 206,
306 extending through the housings 102, 202, 203. In such a
configuration, the external flow paths provided by piping 3, 5
allow for the opportunity to route the working fluid 12 leaving the
first stage 20-1 and/or the working fluid 12 leaving the second
stage 20-2 through one or more heat exchangers 102 (or other
equipment) before being directed into the inlet 208 of the second
stage 20-2 or the inlet 308 of the third stage 20-3.
[0050] With reference to the example embodiment shown in FIG. 3,
and similar to the configuration shown at FIG. 2, the first stage
108 is provided with a separated inlet 108 and a separated outlet
110. However, the housings 202, 302 of the second and third stages
20-2, 20-3 in this example are combined such that the outlet 210 of
the second stage 20-2 is internally connected with the inlet 308 of
the third stage 20-3. In this configuration, the second inlet 208
can be placed in fluid communication with the first outlet 110 via
external piping 3 to define a continuous internal working fluid
passageway 106, 206, 306 extending through the housings 102, 202,
203. In such a configuration, the external flow path provided by
piping 3 allows for the opportunity to route the working fluid 12
leaving the first stage 20-1 through one or more heat exchangers
102 (or other equipment) before being directed into the inlet 208
of the second stage 20-2. As the working fluid 12 enters the second
stage 20-2, at the second inlet 208, the working fluid 12 stays
internal to the fluid expansion device 20 until reaching the third
outlet 310. By creating an internal working fluid passageway
206/306 between the second outlet 210 and third inlet 308,
potential leak paths for working fluid steam are reduced, packaging
complexity is reduced, and pressure drop losses are minimized.
[0051] With reference to the example embodiment shown in FIG. 4,
and similar to the configuration shown at FIG. 3, the second outlet
210 and the third inlet 208 are configured as a common internal
working fluid passageway. However, the housings 102, 202 of the
first and second stages 20-2, 20-3 in this example are also
configured such that the outlet 110 of the first stage 20-1 is
internally connected with the inlet 208 of the second stage 20-2 to
form an internal passageway. In this configuration, as the working
fluid 12 enters the first stage 20-1, at the first inlet 108, the
working fluid 12 stays entirely internal to the fluid expansion
device 20 until reaching the third outlet 310. By creating an
entirely internal working fluid passageway 106/206/306 between the
first inlet 108 and the third outlet 310, the potential leak paths
for working fluid are even further reduced, which in turn also
reduces pressure drop losses and packaging complexity.
Drivetrain Configurations
[0052] As shown, each of the rotors 130, 132, 230, 232, 330, and
332 (collectively referred to as rotors 30, 32), is attached to a
respective rotor shaft 138, 140, 238, 240, 338, and 340
(collectively referred to as rotor shafts 38, 40). The rotor shafts
38, 40 are rigidly connected to the rotors 30, 32 and thus rotate
as the rotors are rotated. The rotor shafts 138, 238, 338 can be
individual separate shafts or form part of a common shaft 38.
Likewise, rotor shafts 140, 240, and 340 can be individual separate
shafts or form part of a common shaft 38.
[0053] FIG. 5 shows an example drivetrain configuration for a three
stage fluid expansion device 20 in which shafts 138, 238, 338 are
portions of a common singular shaft 38 such that rotors 130, 230,
and 330 are mounted to the same shaft 38 and all rotate together in
the same direction. Similarly, shafts 140, 240, 340 are portions of
a common singular shaft 40 such that rotors 130, 230, and 330 are
mounted to the same shaft 40 and all rotate together in the same
direction that is the opposite direction of rotation for shaft 38.
In this arrangement, rotational energy from the working fluid 12 is
imparted onto the same shafts 38, 40 (via the rotors) as the
working fluid 12 passes through each stage 20-1, 20-2, 20-3.
[0054] In the example shown at FIG. 5, bearings 260, 262 are
provided in compartment 152 while bearings 360, 362 are provided in
compartment 156. The bearings 260, 360 are configured to
rotationally support shaft 38 while bearings 262, 362 are
configured to rotationally support shaft 40. If desired, additional
bearings may be provided in compartment 150 and/or compartment
154.
[0055] The compartment 156 is also provided with a pair of timing
gears 348 and 342, wherein the timing gear 348 is fixed for
rotation with the shaft portion 338 and the timing gear 342 is
fixed for rotation with the shaft portion 340. This configuration
allows the rotors 30 and 32 to rotate in opposite directions in an
overlapping and synchronized manner. The timing gears 348, 342 are
also configured to precisely maintain the relative position of the
rotors 30, 32 such that contact between the rotors is entirely
prevented between the rotors 30, 32 which could cause extensive
damage to the rotors 30, 32. Rather, a close tolerance between the
rotors 30, 32 is maintained during rotation by the timing gears
348, 342. As the rotors 30, 32 are non-contacting, a lubricant in
the fluid 12 is not required for operation of the expansion device
20, in contrast to typical rotary screw devices and other similarly
configured rotating equipment having rotor lobes that contact each
other. As the rotors are all connected to a common shaft, it is
noted that timing gears 348, 342 could be alternatively mounted to
the shaft in any of the compartments 150, 152, 154, and 156 with
the same effect. The timing gears 348, 342 also operate such that
rotational energy developed at shaft portion 338 can be transferred
to shaft portion 340 and vice-versa. Accordingly, either shaft
portion 338 or 340 may serve as an output shaft for the fluid
expansion device 20.
[0056] As shown, a power output device 400 is provided to receive
shaft portion 340 such that all rotational energy from the fluid
expansion device 20 can be transferred to the power output device
400. As constructed, the power output device 400 is provided with
an input gear 402 that is intermeshed with and is driven by a drive
gear 344 fixed onto the shaft portion 340. In the embodiment shown,
the drive gear 344 has a smaller diameter (i.e. fewer teeth) than
the input gear 402. This configuration results in the drive gear
344 acting as a step down gear in which the input gear 402 is
rotating at a lower speed than the drive gear 344. In one
embodiment, the gear ratio is between about 0.25:1 and about 3:1,
and more preferably between about 0.5:1 and about 2:1. The drive
gear 344 and input gear 402 can be configured for a step up
operation as well. It is also noted that the rotational direction
of the output shaft 404 and output device 412 is opposite to the
rotational direction of the shaft portion 340. Although not shown,
it should be understood that bearings can be provided in power
output device 400 to support output shafts 404 and 410, in addition
to shaft 340, if desired.
[0057] The input gear 402 is fixed to an output shaft 404 that is
in turn connected to a clutch assembly 406. The clutch assembly 406
is also connected to an output shaft 410 onto which an output
device 412, for example a belt pulley, is mounted. The output
device 412 (or the shaft portion 340) may be connected to the
drivetrain of the power plant 16, for example by a belt, such that
power developed by the fluid expansion device 20 can be input
directly back into the power plant 16. Alternatively, the output
device 412 (or the shaft portion 340) can be connected to a
hydraulic pump or a generator such that energy can be respectively
stored in an accumulator or battery. In operation, the clutch
assembly 406 allows for output shafts 404 and 410 to be coupled and
decoupled such that developed power from the fluid expansion device
20 is selectively allowed or prevented from being transmitted to
the output device 412. When the clutch assembly 408 decouples the
output device 412 from the output shaft 404, the fluid expansion
device 20 is prevented from becoming a parasitic drag on the power
plant 16 when the fluid expansion device 20 is not developing
sufficient power, as may be the case at low engine idling speeds.
In one embodiment, the clutch assembly 408 is an electromagnetic
clutch assembly of the type disclosed in U.S. Pat. 8,464,697
granted on Jun. 18, 2013, the entirety of which is incorporated by
reference herein.
[0058] In another embodiment, shafts 238 and 338 are portions of a
common singular shaft 38 while shaft 138 is a separate shaft,
wherein the shafts 38 and 138 are coupled by a gear set. The gear
set can be configured to allow the shafts 38a, 138 to rotate at the
same speed, at different speeds (with a step up or step down gear),
and/or in opposite directions. In another embodiment, all three
shafts 138, 238, and 338 are separate shafts that are coupled
together by intermediate gear sets that allow for each shaft to be
rotated at the same or different speeds and/or in an opposite
direction. These variations apply equally for the shafts 140, 240,
and 340. The shafts 38, 40 may also be supported by bearings at
their ends and/or at intermediate points along the shafts 38,
40.
[0059] FIG. 6 shows an example drivetrain that is similar in many
respects to that shown in FIG. 5. However, the example of FIG. 6 is
different in that the third stage is provided with independent
shafts 338, 340 and in that the first and second stages 20-1, 20-2
share common shafts 38, 40. In this example, the common shaft 38 is
formed by shaft portions 138 and 238 and is supported by bearings
160, 260 in compartments 152, 154, respectively. Similarly, the
common shaft 40 is formed by shaft portions 140, 240 and is
supported by bearings 162, 262. As shafts 338, 340 are independent
shafts in this example; shaft 338 is supported by bearings 360, 364
while shaft 340 is supported by bearings 362, 366. With respect to
compartment 154, timing gears 248, 242 are mounted to shaft
portions 238, 240 respectively to fix the rotational relationship
between the rotors 130/230 and the rotors 132/232, and operate in
the same manner as already described for timing gears 348, 342. It
is noted that bearings could be provided in compartment 152 in
addition to or instead of bearings be provided in one of
compartments 150, 154.
[0060] Also connected to the shaft portion 238 is a drive gear 244
that is intermeshed with and drives an input gear 346 fixed onto
the shaft portion 338. In operation, the drive gear 244 and input
gear 346 allow the power developed by the rotors of the first and
second stages 20-1, 20-2 to be transferred to the third stage 20-3
of the fluid expansion device 20, and ultimately to the output
device 412. Alternatively, the drive gear 244 could be mounted to
shaft portion 240 and the input gear 346 could be mounted to the
shaft portion 340.
[0061] In the embodiment shown, the drive gear 244 has a larger
diameter (i.e. more teeth) than the input gear 346. This
configuration results in the drive gear 244 acting as a step up
gear in which the input gear 346 is rotating at a higher speed than
the drive gear 244. In one embodiment, the gear ratio is between
about 0.25:1 and about 3:1, and more preferably between about 0.5:1
and about 2:1. The drive gear 244 and input gear 346 can be
alternatively configured for a step down operation as well. It is
also noted that the rotational direction of the shaft portion 338
is opposite to the rotational direction of the shaft portion 238
which causes the rotor 330 to rotate in the opposite direction of
rotors 130, 230 and likewise causes the rotor 332 to rotate in the
opposite direction of rotors 132, 232. However, it is to be
understood that the gearing could be set up such that the rotors
330, 332 rotate in the same direction as compared to rotors 130,
230 and 132, 232, respectively, such as by mounting drive gear 244
onto shaft portion 240 or by mounting input gear 346 onto shaft
portion 340.
[0062] FIG. 7 shows an example drivetrain that is similar in many
respects to that shown in FIG. 6. However, the example of FIG. 7 is
different in that each of the stages 20-1 and 20-2 are additionally
provided with independent shafts such that all three stages 20-1,
20-2, and 20-3 are provided with independent shafts. Accordingly,
the shaft 138 is supported by bearings 160 and 164, the shaft 140
is supported by bearings 162 and 166, the shaft 238 is supported by
bearings 260 and 264, and the shaft 240 is supported by bearings
262 and 266. Additionally, a pair of timing gears 148, 142 is also
provided to fix the rotational relationship between rotor 130 and
rotor 132.
[0063] With respect to compartment 152, timing gears 148, 142 are
respectively mounted to shafts 138, 140 to fix the rotational
relationship between the rotor 130 and the rotor 132, and operate
in the same manner as already described for timing gears 248/242
and 348/342. Also connected to the shaft portion 138 is a drive
gear 144 that is intermeshed with and drives an input gear 246
fixed onto the shaft 240. In operation, the drive gear 144 and
input gear 246 allow the power developed by the rotor of the first
stage 20-1 to be transferred to the second stage 20-2 while the
drive and input gears 244, 346 allow the power developed by the
first and second stages 20-1, 20-2 to be transferred to the third
stage 20-3 of the fluid expansion device 20, and ultimately to the
output device 412 via input and drive gears 344, 402.
[0064] In the embodiment shown, the drive gear 144 has a larger
diameter (i.e. more teeth) than the input gear 246. This
configuration results in the drive gear 144 acting as a step up
gear in which the input gear 246 is rotating at a higher speed than
the drive gear 144. In one embodiment, the gear ratio is between
about 0.25:1 and about 3:1, and more preferably between about 0.5:1
and about 2:1. Accordingly, it will be appreciated that, in
relative terms, the rotors 130, 132 of the first stage 20-1 rotate
at a lower speed than the rotors 230, 232 of the second stage 20-2,
which in turn are rotating at a lower speed than the rotors 330,
332 of the third stage 20-3. As the gears 344/402 are configured in
a step down arrangement, the rotors 330, 332 are rotating at a
higher speed than the output device 412.
[0065] The drive gear 144 and input gear 246 can be alternatively
configured for a step down operation as well. It is also noted that
the rotational direction of the shaft portion 238 is opposite to
the rotational direction of the shaft portion 140 which causes the
rotor 230 to rotate in the same direction as rotor 130 and likewise
causes the rotor 232 to rotate in the same direction as rotors 132.
However, it is to be understood that the gearing could be set up
such that the rotors 230, 232 rotate in an opposite direction as
compared to rotors 132, 232, respectively.
[0066] A step up configuration between the first and second stage
20-1, 20-2 and between the second and third stage 20-2, 20-3 can be
advantageous in embodiments where the volume of the working fluid
12 is expanding rapidly as the working fluid 12 is passing through
each successive expansion stage. The volumetric flow rate can be
different through each stage because the working fluid 12 has a
greater volume when being introduced into rotors 230, 232 of the
second stage 20-2 due to the fluid expansion caused by the first
stage 20-1, and an even greater volume when being introduced into
the rotors 330, 332 of the third stage 20-3 due to the fluid
expansion caused by the second stage 20-2. Such a condition could
easily exist in the housing and working fluid flow path
configuration shown at FIG. 4 and with respect to the working fluid
flow path through the second and third stages 20-2, 20-3 of the
configuration shown at FIG. 3. Accordingly, the drivetrain
configuration shown in FIG. 5 can be particularly useful with the
housing and working fluid flow path configuration shown in FIG. 3
while the drivetrain configuration shown in FIG. 7 can be
particularly useful with the housing and working fluid flow path
configuration shown in FIG. 4. Likewise, the common shaft
drivetrain configuration of FIG. 5 may be suitable for the housing
and working fluid flow path configuration of FIG. 2 where it may be
easier to mitigate changes in the volumetric flow rate between
stages 20-1 and 20-2 and between 20-2 and 20-3. The volumetric flow
rate may also be accommodated by configuring the second stage 20-2
to have larger rotors 230, 232 as compared to the rotors 130, 132
of the first stage 20-1 and by configuring the rotors 330, 332 of
the third stage 20-3 to be larger than the rotors 230, 232 of the
second stage 20-1.
Rotor Design
[0067] Each of the rotors 130/132, 230/232, 330/332, collectively
referred to as rotors 30, 32 in this section and with reference to
FIGS. 8-11, is provided with a plurality of lobes. As shown in
FIGS. 8 and 9, each rotor 30, 32 can be provided with three lobes,
30-1, 30-2, 30-3 in the case of the rotor 30, and 32-1, 32-2, 32-3
in the case of the rotor 32. Although three lobes are shown for
each rotor 30 and 32, each of the two rotors may have any number of
lobes that is equal to or greater than two. For example, PCT
Publication WO 2013/130774 shows a suitable rotor having four
lobes. Additionally, the rotors of one or more of the stages 20-1,
20-2, 20-3 may have a different number of lobes than the rotors of
the other stages 20-1, 20-2, 20-3 in the device 20.
[0068] As presented, the number of lobes is the same for each rotor
30 and 32. This is in contrast to the construction of typical
rotary screw devices and other similarly configured rotating
equipment which have a dissimilar number of lobes (e.g. a male
rotor with "n" lobes and a female rotor with "n+1" lobes).
Furthermore, one of the distinguishing features of the expansion
device 20 is that the rotors 30 and 32 are identical, wherein the
rotors 30, 32 are oppositely arranged so that, as viewed from one
axial end, the lobes of one rotor are twisted clockwise while the
lobes of the meshing rotor are twisted counter-clockwise.
Accordingly, when one lobe of the rotor 30, such as the lobe 30-1
is leading with respect to the inlet port 24, a lobe of the rotor
32, such as the lobe 30-2, is trailing with respect to the inlet
port 24, and, therefore with respect to a stream of the
high-pressure fluid 12.
[0069] As previously mentioned, the first and second rotors 30 and
32 are interleaved and continuously meshed for unitary rotation
with each other. In one embodiment, the lobes of each rotor 30, 32
are twisted or helically disposed along the length L of the rotors
30, 32. Upon rotation of the rotors 30, 32, the lobes at least
partially seal the fluid 12 against an interior side of the housing
at which point expansion of the fluid 12 only occurs to the extent
allowed by leakage which represents and inefficiency in the system.
In contrast to some expansion devices that change the volume of the
fluid when the fluid is sealed, the volume defined between the
lobes and the interior side 33 of the housing is constant as the
fluid 12 traverses the length of the rotors 30, 32. Accordingly,
the expansion device 20 is referred to as a "volumetric device" as
the sealed or partially sealed fluid volume does not change wherein
the working fluid 12 is generally not reduced or compressed.
[0070] The rotor shafts 38, 40 are rotated by the working fluid 12
as the fluid undergoes expansion from the higher first pressure
working fluid 12 to the lower second pressure working fluid 12.
Accordingly, the shafts 38, 40 are configured to capture the work
or power generated by the expansion device 20 during the expansion
of the fluid 12 that takes place between the inlet port 108, 208,
308 and the respective outlet port 110, 210, 310. As discussed
previously, the work is transferred from the shafts 38, 40 as
output torque from the expansion device 20 via output device
412.
Inlet and Outlet Geometry
[0071] In one aspect of the geometry of the expansion device 20,
each of the rotor lobes 30-1 to 30-3 and 32-1 to 32-3 has a lobe
geometry in which the twist of each of the first and second rotors
30 and 32 is constant along their substantially matching length L.
Alternatively, the lobes 130, 132, 230, 232, 330, 332 can be
provided without a twist although a drop in efficiency would be
expected to occur. In one embodiment, lobes 130, 132 are provided
as straight lobes while lobes 230, 232, 330, 332 are provided as
twisted lobes. In one embodiment, the length L of all rotors 130,
132, 230, 232, 330, 332 is the same. In one embodiment, the length
L of the rotors 130, 132 is less than a length L of the rotors 230,
232, which is in turn less than a Length L of the rotors 330,
332.
[0072] As shown schematically at FIG. 11, one parameter of the lobe
geometry is the helix angle HA. By way of definition, it should be
understood that references hereinafter to "helix angle" of the
rotor lobes is meant to refer to the helix angle at the pitch
diameter PD (or pitch circle) of the rotors 30 and 32. The term
pitch diameter and its identification are well understood to those
skilled in the gear and rotor art and will not be further discussed
herein. As used herein, the helix angle HA can be calculated as
follows: Helix Angle (HA)=(180/.pi.*arctan (PD/Lead)), wherein:
PD=pitch diameter of the rotor lobes; and Lead=the lobe length
required for the lobe to complete 360 degrees of twist. It is noted
that the Lead is a function of the twist angle and the length L of
the lobes 30, 32, respectively. The twist angle is known to those
skilled in the art to be the angular displacement of the lobe, in
degrees, which occurs in "traveling" the length L of the lobe from
the rearward end of the rotor to the forward end of the rotor. In
one embodiment, the twist angle is about 120 degrees, although the
twist angle may be fewer or more degrees, such as 160 degrees.
[0073] In another aspect of the expansion device geometry, the
inlet ports 108, 208 and/or 308 can include an inlet angle 24-1, as
can be seen schematically at FIG. 10. In one example, the inlet
angle 24-1 is defined as the general or average angle of an inner
surface 24 of the inlet port 108, 208, 308, for example an anterior
inner surface. In one example, the inlet angle 24-1 is defined as
the angle of the general centerline of the inlet port 108, 208,
308. In one example, the inlet angle 24-1 is defined as the general
resulting direction of the fluid 12 entering the rotors 30, 32 due
to contact with the anterior inner surface 24, as can be seen at
FIG. 10. As shown, the inlet angle 24-1 is neither perpendicular
nor parallel to the rotational axes X1, X2 of the rotors 30, 32.
Accordingly, the anterior inner surface 24 of the inlet port 24
causes a substantial portion of the fluid 12 to be shaped in a
direction that is at an oblique angle with respect to the
rotational axes X1, X2 of the rotors 30, 32, and thus generally
parallel to the inlet angle 24-1.
[0074] Furthermore, and as shown in FIG. 10, the inlet port 108,
208, 308 may be shaped such that the fluid 12 is directed to the
first axial ends 30a, 30b of the rotors 30, 32 and directed to the
rotor lobe leading and trailing surfaces (discussed below) from a
lateral direction. However, it is to be understood that the inlet
angle 24-1 may be generally parallel or generally perpendicular to
axes X1, X2, although an efficiency loss may be anticipated for
certain rotor configurations. Furthermore, it is noted that the
inlet port 24 may be shaped to narrow towards the inlet opening
adjacent the rotor 30, 32.
[0075] In another aspect of the expansion device geometry, the
outlet ports 110, 210, and/or 310 include an outlet angle 26-1, as
can be seen schematically at FIG. 10. In one example, the outlet
angle 26-1 is defined as the general or average angle of an inner
surface 26 of the outlet port 110, 210, and/or 310. In one example,
the outlet angle 26-1 is defined as the angle of the general
centerline of the outlet port 110, 210, 310. In one example, the
outlet angle 26-1 is defined as the general resulting direction of
the fluid 12 leaving the rotors 30, 32 due to contact with the
inner surface 26a, as can be seen at FIG. 10. As shown, the outlet
angle 26-1 is neither perpendicular nor parallel to the rotational
axes X1, X2 of the rotors 30, 32. Accordingly, the inner surface 26
of the outlet port 110, 210, 310 receives the leaving fluid 12 from
the rotors 30, 32 at an oblique angle which can reduce backpressure
at the outlet port 26. In one example, the inlet angle 24-1 and the
outlet angle 26-1 are generally equal or parallel, as shown in FIG.
10. In one example, the inlet angle 24-1 and the outlet angle 26-1
are oblique with respect to each other. It is to be understood that
the outlet angle 26-1 may be generally perpendicular to axes X1,
X2, although an efficiency loss may be anticipated for certain
rotor configurations. It is further noted that the outlet angle
26-1 may be perpendicular to the axes X1, X2. As configured, the
orientation and size of the outlet port 26-1 are established such
that the leaving fluid 12 can evacuate each rotor cavity 28 as
easily and rapidly as possible so that backpressure is reduced as
much as possible. The output power of the fluid expansion device 20
is maximized to the extent that backpressure caused by the outlet
110, 210, 310 can be minimized such that the fluid can be rapidly
discharged into the lower pressure fluid at the condenser.
[0076] The efficiency of the expansion device 20 can be optimized
by coordinating the geometry of the inlet angle 24-1 and the
geometry of the rotors 30, 32. For example, the helix angle HA of
the rotors 30, 32 and the inlet angle 24-1 can be configured
together in a complementary fashion. Because the inlet port 108,
208, 309 introduces the fluid 12 to both the leading and trailing
faces of each rotor 30, 32, the fluid 12 performs both positive and
negative work on the expansion device 20.
[0077] To illustrate, FIG. 9 shows that lobes 30-2, 30-3, 32-2, and
32-3 are each exposed to the fluid 12 through the inlet port
opening 24b. Each of the lobes has a leading surface and a trailing
surface, both of which are exposed to the fluid at various points
of rotation of the associated rotor. The leading surface is the
side of the lobe that is forward most as the rotor is rotating in a
direction R1, R2 while the trailing surface is the side of the lobe
opposite the leading surface. For example, rotor 30 rotates in
direction R1 thereby resulting in side 30-la as being the leading
surface of lobe 30-1 and side 30-1b being the trailing surface. As
rotor 32 rotates in a direction R2 which is opposite direction R1,
the leading and trailing surfaces are mirrored such that side 32-1a
is the leading surface of lobe 32-1 while side 32-1b is the
trailing surface.
[0078] In generalized terms, the fluid 12 impinges on the trailing
surfaces of the lobes as they pass through the inlet port opening
24b and positive work is performed on each rotor 30, 32. By use of
the term positive work, it is meant that the fluid 12 causes the
rotors to rotate in the desired direction: direction R1 for rotor
30 and direction R2 for rotor 32. As shown, fluid 12 will operate
to impart positive work on the trailing surface 30-1b of rotor
30-1. The fluid 12 is also imparting positive work on the trailing
surface 32-2b of rotor 32-2. However, the fluid 12 also impinges on
the leading surfaces of the lobes, for example surfaces 30-3a and
32-1a, as they pass through the inlet port opening thereby causing
negative work to be performed on each rotor 30, 32. By use of the
term negative work, it is meant that the working fluid 12 causes
the rotors to rotate opposite to the desired direction, R1, R2.
[0079] Accordingly, it is desirable to shape and orient the rotors
30, 32 and to shape and orient the inlet ports 108, 208, 308 such
that as much of the fluid 12 as possible impinges on the trailing
surfaces of the lobes with as little of the fluid 12 impinging on
the on the leading lobes such that the highest net positive work
can be performed by the fluid expansion device 20.
[0080] One advantageous configuration for optimizing the efficiency
and net positive work of the expansion device 20 is a rotor lobe
helix angle HA of about 35 degrees and an inlet angle 24-1 of about
30 degrees. Such a configuration operates to maximize the
impingement area of the trailing surfaces on the lobes while
minimizing the impingement area of the leading surfaces of the
lobes. In one example, the helix angle is between about 25 degrees
and about 40 degrees. In one example, the inlet angle 24-1 is set
to be within (plus or minus) 15 degrees of the helix angle. In one
example, the helix angle is between about 25 degrees and about 40
degrees. In one example, the inlet angle 24-1 is set to be within
(plus or minus) 15 degrees of the helix angle HA. In one example,
the inlet angle is within (plus or minus) 10 degrees of the helix
angle. In one example, the inlet angle 24-1 is set to be within
(plus or minus) 5 degrees of the helix angle HA. In one example,
the inlet angle 24-1 is set to be within (plus or minus) fifteen
percent of the helix angle HA while in one example, the inlet angle
24-1 is within ten percent of the helix angle. Other inlet angle
and helix angle values are possible without departing from the
concepts presented herein. However, it has been found that where
the values for the inlet angle and the helix angle are not
sufficiently close, a significant drop in efficiency (e.g. 10-15%
drop) can occur.
Example Embodiments
[0081] Referring to FIGS. 12-18, an example embodiment of a fluid
expansion device 20 in accordance with the present disclosure is
shown. In this example, the overall configuration is generally
similar to the housing and working fluid passageway arrangement of
FIG. 3 and the drivetrain arrangement presented in FIG. 6.
Therefore, the similarities between the systems will not be
discussed further here. Accordingly, the fluid expansion device 20
shown in FIGS. 12-18 has an inlet 108 and an outlet 310, and
further includes a first stage outlet 110 that is separated from a
second stage inlet 208.
[0082] FIG. 12 shows the fluid expansion device 20 being used in an
organic Rankine cycle in which a working fluid is sequentially
heated at heat exchangers 18-1, 18-2, and 18-3 and introduced to
the first stage 20-1 of the fluid expansion device. As shown, the
working fluid leaves the first stage 20-1 and is again heated by a
heat exchanger 15 and then introduced back into the fluid expansion
device 20 where the working fluid passes internally from the second
stage 20-2 to the third stage 20-3. After passing through the third
stage 20-3, the working fluid is transported to heat exchanger 18-1
and then to condenser 19. A pump 17 is provided to pump the working
fluid back to the heat exchanger 18-1. Heat exchanger 18-1 operates
as a recuperator to simultaneously cool the working fluid before
reaching the condenser 19 and preheating the working fluid after
the condenser 19. The heat exchangers 15 and 18-2 are sequentially
heated by exhaust directly from the power plant 16 while the heat
exchanger 18-3 is heated by exhaust gas downstream from a
turbocharger 13.
[0083] With reference to FIGS. 14-18, the internal components of
the volumetric fluid expansion device 20 are shown in greater
detail. As shown, the rotors 130, 132 of the first expansion stage
are each provided with four straight lobes. The rotors 230, 232,
which are mounted to the same common shafts 38, 40 as the rotors
130, 132, are shown as each being provided with three twisted
lobes. Additionally, the rotors 230, 232 are shown as having a
greater overall length than that of the rotors 130, 132. The rotors
330, 332 are provided with an even greater length than that of the
rotors 230, 232, but with the same helix angle. Accordingly, the
rotors 330, 332 extend through a greater twist angle than rotors
230, 232.
[0084] As can be seen at FIGS. 15-18, the compartment 154 is formed
by the third housing 302 and an internal housing part 203
associated with the second housing 102. The internal housing part
203 also forms a portion of the working fluid passageway 206/306
between the rotors 230, 232 and the rotors 330, 332. As shown, the
second housing 202 is secured to the third housing 302, and the
internal housing part 203 sandwiched there between, via a plurality
of mechanical fasteners 207. The first housing 102 is also secured
to the second housing 202 via a plurality of mechanical fasteners
107.
[0085] As shown, the compartment 156 is formed by a housing part
303 and a portion of the power output device 400. The housing part
303 also forms a portion of the working fluid passageway 306 near
the outlet 310. The housing part 303 is secured to the third
housing 103 via a plurality of mechanical fasteners 307 and is
secured to the power output device 400 via a plurality of
mechanical fasteners 407. It is noted that gaskets may be provided
at the interfaces between the power output device and the housing
part 303, between the housing part 303 and the third housing 302,
between the third housing 302 and the internal housing part 203,
between the third housing 302 and the second housing 202, and
between the second housing 202 and the first housing 102.
[0086] Referring to FIGS. 19-22, another example embodiment of a
fluid expansion device 20 in accordance with the present disclosure
is shown. In this example, the overall configuration is generally
similar to the housing and working fluid passageway arrangement of
FIG. 4 and the drivetrain arrangement presented in FIG. 7.
Additionally, the construction of the housing components is
generally similar to that shown in FIGS. 12-18. Therefore, the
similarities between the systems will not be discussed further
here.
[0087] FIG. 19 shows the fluid expansion device 20 being used in an
organic Rankine cycle 1000 in which a working fluid is sequentially
heated at heat exchangers 18-1, 18-2, and 18-3 and introduced to
the first stage 20-1 of the fluid expansion device. As shown, the
working fluid passes from the inlet 108 and internally through all
three stages 20-1, 20-2, 20-3 before reaching the outlet 310. After
passing through the third stage 20-3, the working fluid is
transported to heat exchanger 18-1 and then to condenser 19. A pump
17 is provided to pump the working fluid back to the heat exchanger
18-1. Heat exchanger 18-1 operates as a recuperator to
simultaneously cool the working fluid before reaching the condenser
19 and preheating the working fluid after the condenser 19. The
heat exchanger 18-2 is heated by exhaust directly from the power
plant 16 while the heat exchanger 18-3 is heated by exhaust gas
downstream from a turbocharger 13.
[0088] With reference to FIGS. 14-18, the internal components of
the volumetric fluid expansion device 20 are shown in greater
detail. As shown, each of the rotors 130, 132, 230, 232, 330, 332
are mounted to an independent shaft and are provided with four
twisted lobes having a matching helix angle. As with the previous
example, the rotors 230, 232 are shown as having a greater overall
length than that of the rotors 130, 132 while the rotors 330, 332
are provided with an even greater length than that of the rotors
230, 232. Accordingly, the rotors 330, 332 extend through a greater
twist angle than rotors 230, 232 which in turn extend through a
greater twist angle than rotors 130, 132.
[0089] As can be seen at FIGS. 15-18, the compartment 152 is formed
by the second housing 202 and an internal housing part 103
associated with the first housing 102. The internal housing part
103 also forms a portion of the working fluid passageway 106/206
between the rotors 130, 132 and the rotors 230, 232. As shown, the
second housing 202 is secured to the first housing 102, and the
internal housing part 103 sandwiched there between, via a plurality
of mechanical fasteners. It is noted that gaskets may be provided
at the interfaces between the second housing 202 and the housing
part 103. The compartment 150 is formed by a cavity in the first
housing 102 and a cover plate 105 extending over the cavity. The
cover plate 105 is secured to the first housing 102 by a plurality
of fasteners 109.
[0090] FIGS. 23-24 show an embodiment of a fluid expansion device
in which each of rotors 130, 230, and 330 are mounted to a common
shaft 38 and each of rotors 132, 232, and 332 are mounted to a
common shaft 340. Additionally, each stage 20-1, 20-2, and 20-3 is
provided with its own independent inlet and outlet 108/110,
208/210, and 308/310, respectively. Accordingly, the embodiment
shown at FIGS. 23-24 is similar to the drivetrain arrangement shown
in FIG. 5 and the housing and fluid pathway configuration of FIG.
2. Therefore, the similarities between the systems will not be
discussed further here.
[0091] As shown at FIG. 23, and most easily seen at FIG. 24 for the
components relating to shaft 40, the rotors 130, 132 of the first
expansion stage are each provided with four straight lobes. The
rotors 130, 132, 230, and 232 are shown as each being provided with
three twisted lobes. Additionally, the rotors 230, 232 are shown as
having a greater overall length than that of the rotors 130, 132.
The rotors 330, 332 are provided with an even greater length than
that of the rotors 230, 232, but with the same helix angle.
Accordingly, the rotors 330, 332 extend through a greater twist
angle than rotors 230, 232. In the example shown in FIG. 23, the
power output device 400 is directly mounted to the third housing
302 without the use of housing part 303 and is also provided
without a clutch mechanism 408. Additionally, the first housing 102
is mounted to the second housing directly via fasteners 107.
[0092] The various embodiments described above are provided by way
of illustration only and should not be construed to limit the
claims attached hereto. Those skilled in the art will readily
recognize various modifications and changes that may be made
without following the example embodiments and applications
illustrated and described herein, and without departing from the
true spirit and scope of the disclosure.
Example Parallel Drive Embodiments
[0093] Referring to FIGS. 28-21, examples a fluid expansion device
20 in accordance with the present disclosure is shown. In these
examples, the overall configurations of the expanders are generally
similar to the housing and working fluid passageway arrangements
previously described at least in that the rotor and housing designs
are similar, and in that a working fluid 12 flows from the first
stage 20-1, through the second stage 20-2, and then through the
third stage 20-3. Additionally, the drivetrain configurations
between the stages are also generally the same as previously
described. Therefore, the similarities between the systems in this
regard will not be discussed further here. However, the examples
shown in FIGS. 28-31 differ from the previously discussed
embodiments in that the output gears (144, 244, 344) of at least
two of the three stages 20-1, 20-2, 20-3 are in placed in a
parallel arrangement to drive either the power output device 400 or
the third expander stage, as described below.
[0094] With reference to the example shown in FIG. 28, each of the
output gears (144, 244, 344) of the three stages 20-1, 20-2, 20-3
are placed in a parallel arrangement such that each of the drive
gears 144, 244, and 344 acts on the input gear 402 of the power
output device 400. In the embodiment shown, drive gear 144 drives
the input gear 402 via a gear train 420 while drive gear 244 drives
the input gear via a gear train 422. Additionally, drive gear 344
outputs to a gear train 424 that acts on drive gear 244. However,
it is to be understood that gear trains 420, 422, and 424 can be
configured to each act directly on input gear 402 and/or act on
each other via one or more of the drive gears, as desired. By use
of the term "gear train" it is meant to include any gear assembly
including one or more gears that act on each other. As with the
other gearing mechanisms disclosed, the gear trains 420, 422, and
422 may be configured to accomplish either a step down gear ratio
function or a step up gear ratio function.
[0095] With reference to the example shown in FIG. 29, the output
gears 244 and 344 of the second and third stages 20-2 and 20-3 are
placed in a parallel arrangement such that each of the drive gears
244 and 344 acts on the input gear 146 of the first expander stage
20-1. In the embodiment shown, drive gear 244 drives the input gear
146 via a gear train 245 while drive gear 344 drives the input gear
146 via a gear train 345. As shown, the drive gear 144 of the first
stage acts on the input gear 402 of the output device 400.
[0096] With reference to the example shown in FIG. 30, the first
stage 20-1 has an independently formed housing while the second and
third stages 20-2, 20-3 are coupled together in a similar fashion
to the drivetrain arrangement shown in FIG. 7 and the housing
arrangement shown in FIG. 3. In this example, the drive gears 144
and 244 act on the input gear 402 via respective gear trains 420,
422. However, it is to be understood that the gear trains 420, 422
could be configured to act on each other such that only one of the
gear trains 420, 422 acts directly on the input gear 402. It is
also noted that the device 20 could be configured such that rotors
230 and 330 are on a common shaft 38 and such that rotors 232 and
332 are on a common shaft 40, as is shown for the second and third
stages 20-2, 20-3 at FIG. 5.
[0097] With reference to the example shown in FIG. 31, the third
stage 20-3 has an independently formed housing while the first and
second stages 20-2, 20-3 are coupled together with an internal
working fluid flow path and a drivetrain having a similar
arrangement to that shown in FIG. 7, but in a reverse
configuration. In this example, the drive gears 144 and 344 act on
the input gear 402 via respective gear trains 420, 424. However, it
is to be understood that the gear trains 420, 424 could be
configured to act on each other such that only one of the gear
trains 420, 424 acts directly on the input gear 402. It is also
noted that the device 20 could be configured such that rotors 130
and 230 are on a common shaft 38 and such that rotors 132 and 132
are on a common shaft 40, as is shown for the first and second
stages 20-1, 20-2 at FIGS. 5 and 6.
[0098] With respect to above described parallel drive examples, it
should be appreciated that fewer or more than three stages can be
arranged in such a configuration, for example, two stages, four
stages, six stages, and/or eight stages. In one example, two three
stage expanders 20 are provided to simultaneously drive the input
gear 402.
* * * * *