U.S. patent application number 14/811276 was filed with the patent office on 2015-12-31 for organic rankine cycle system with lubrication circuit.
The applicant listed for this patent is EATON CORPORATION. Invention is credited to William Nicholas EYBERGEN, Matthew FORTINI, Lalit Murlidhar PATIL, Sheetalkumar Shamrao PATIL, Tapan Vasant PONKSHE, Martin D. PRYOR, Bradley WRIGHT.
Application Number | 20150377080 14/811276 |
Document ID | / |
Family ID | 54929984 |
Filed Date | 2015-12-31 |
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United States Patent
Application |
20150377080 |
Kind Code |
A1 |
FORTINI; Matthew ; et
al. |
December 31, 2015 |
ORGANIC RANKINE CYCLE SYSTEM WITH LUBRICATION CIRCUIT
Abstract
A Rankine cycle system including a Rankine cycle working circuit
and a lubrication circuit is disclosed. The lubrication circuit and
the Rankine cycle working circuit include a shared segment
including a mixture of Rankine cycle working fluid from the Rankine
cycle working circuit and lubricant from the lubrication circuit. A
separator receives the mixture of Rankine cycle working fluid and
lubricant from the shared segment and separates the Rankine cycle
working fluid from the lubricant. The separated Rankine cycle
working fluid is directed along the Rankine cycle working circuit
from the separator to the heating zone and the separated lubricant
is directed along the lubrication circuit from the separator to a
mechanical expander. The working fluid and lubricant are recombined
after passing separately through the expander and are then
introduced to the condensing zone.
Inventors: |
FORTINI; Matthew; (Livonia,
MI) ; EYBERGEN; William Nicholas; (Harrison Twp.,
MI) ; PATIL; Lalit Murlidhar; (Pune, IN) ;
PONKSHE; Tapan Vasant; (Pune, IN) ; WRIGHT;
Bradley; (Livonia, MI) ; PRYOR; Martin D.;
(Canton, MI) ; PATIL; Sheetalkumar Shamrao; (Pune,
IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EATON CORPORATION |
Cleveland |
OH |
US |
|
|
Family ID: |
54929984 |
Appl. No.: |
14/811276 |
Filed: |
July 28, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/US2014/013397 |
Jan 28, 2014 |
|
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14811276 |
|
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61757533 |
Jan 28, 2013 |
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Current U.S.
Class: |
60/657 ;
60/671 |
Current CPC
Class: |
F01K 25/10 20130101;
F01D 25/18 20130101; F01K 23/065 20130101; F01K 21/005 20130101;
F01K 25/06 20130101 |
International
Class: |
F01K 25/10 20060101
F01K025/10 |
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.
Foreign Application Data
Date |
Code |
Application Number |
Dec 9, 2014 |
IN |
3611/DEL/2014 |
Claims
1. A Rankine cycle system comprising: a. a separator for separating
a working fluid from a lubricant, the separator having a first
inlet for receiving a working fluid and lubricant mixture, a first
outlet for discharging the working fluid, and a second outlet for
discharging the lubricant; b. a mechanical expander having a
working fluid inlet in fluid communication with the separator first
outlet, a lubricant circuit inlet in fluid communication with the
separator second outlet, a working fluid outlet, and a lubricant
circuit outlet in direct fluid communication with the working fluid
outlet; c. a mixing location at which the lubricant from the
lubricant circuit outlet is mixed with the working fluid from the
working fluid outlet to form the working fluid and lubricant
mixture; d. a condenser in direct fluid communication with the
mixing location; and e. a fluid pump in fluid communication with
the condenser and the separator, the fluid pump being for receiving
the working fluid and lubricant mixture from the condenser and
discharging the working fluid and lubricant mixture to the
separator.
2. The Rankine cycle system of claim 1, wherein: a. the system is
configured such that the mechanical separator lubricant inlet is
above the first outlet of the separator.
3. The Rankine cycle system of claim 1, wherein the separator
includes a pipe directing the working fluid and lubricant mixture
around an inside surface of the separator.
4. The Rankine cycle system of claim 1, wherein the separator
includes a diverter plate.
5. The Rankine cycle system of claim 4, wherein the diverter plate
includes an open center.
6. The Ranking cycle system of claim 1, wherein the separator
includes a plurality of converging inlet branches extending from an
interior volume of the separator to the separator first outlet.
7. The Rankine cycle system of claim 1, further including a control
valve located between the separator second outlet and the
mechanical expander lubricant circuit inlet, the control valve
being configured to regulate a flow rate of lubricant through the
mechanical expander.
8. The Rankine cycle system of claim 1, wherein the Rankine cycle
working circuit is an organic Rankine cycle working circuit.
9. The Rankine cycle system of claim 1, wherein the Rankine cycle
working fluid is an organic solvent.
10. The Rankine cycle system of claim 9, wherein the Rankine cycle
working fluid is selected from the group consisting of ethanol,
n-pentane, and toluene.
11. The Rankine cycle system of claim 1, wherein the lubricant is
an oil.
12. The Rankine cycle system of claim 1, wherein the Rankine cycle
working fluid is heated at a heating zone by waste heat from a
prime mover.
13. The Rankine cycle system of claim 12, wherein the prime mover
is selected from the group consisting of an internal combustion
engine and a fuel cell.
14. The Rankine cycle system of claim 1, wherein the mechanical
expander includes a fixed displacement expander.
15. The Rankine cycle system of claim 14, wherein the mechanical
expander is a three stage volumetric expander.
16. A Rankine cycle system comprising: a. an organic working fluid;
b. a condenser for condensing the organic working fluid to form
condensed organic working fluid; c. a heat exchanger for heating
the organic working fluid to form heated organic working fluid; d.
a fixed displacement mechanical expansion device for extracting
energy from the organic working fluid, the mechanical expansion
device including first and second interleaved non-contacting rotors
each having an equal number of a plurality of lobes mounted on a
shaft, the mechanical expansion device including intermeshing
timing gears that coordinate rotation of the rotors and prevent the
lobes of the first and second interleaved rotors from contacting
each other, the mechanical expansion device including a housing
having an inlet, an outlet, and an interior region that provides
fluid communication between the inlet and the outlet, the interior
region including first and second rotor bores in which the first
and second rotors are respectively positioned, the first and second
rotors defining fluid transfer volumes between the lobes that
transfer the working fluid circumferentially about the bores from
the inlet to the outlet, and at least one of the shafts defining an
output shaft; e. a pump positioned between the condenser and the
heat exchanger for pumping the condensed organic working fluid
received from the condenser to the heat exchanger, wherein the
heated organic working fluid flows from the heat exchanger to the
inlet of the mechanical expansion device, and wherein expanded
working fluid flows from the outlet of the mechanical expansion
device to the condenser; f. the condenser, the heat exchanger, and
the fixed displacement mechanical expansion device being part of a
Rankine cycle working circuit through which the organic working
fluid is circulated; g. a lubrication circuit for lubricating the
fixed displacement mechanical expansion device; h. the lubrication
circuit and the Rankine cycle working circuit including a shared
segment including a mixture of the organic working fluid from the
Rankine cycle working circuit and lubricant from the lubrication
circuit; and i. a separator that receives the mixture of organic
working fluid and lubricant from the shared segment and separates
the organic working fluid from the lubricant, wherein the separated
organic working fluid is directed along the Rankine cycle working
circuit from the separator to the heat exchanger and the separated
lubricant is directed along the lubrication circuit from the
separator to the fixed displacement mechanical expansion
device.
17. The Rankine cycle system of claim 16, wherein the pump drives
flow of the organic working fluid through the Rankine cycle working
circuit and also drives flow of the lubricant through the
lubrication circuit.
18. The Rankine cycle system of claim 16, wherein the pump is
positioned along the shared segment.
19. The Rankine cycle system of claim 16, wherein the lubricant
leaving the expansion device is combined with the organic working
fluid leaving the expansion device at a location between the
condenser and the pump.
20. The Rankine cycle system of claim 1, further including a
control valve located between the separator second outlet and the
mechanical expander lubricant circuit inlet, the control valve
being configured to regulate a flow rate of lubricant through the
mechanical expander.
Description
RELATED APPLICATIONS
[0001] This application is a continuation-in-part of and claims
priority to Patent Cooperation Treaty International Application
Number PCT/US2014/013397, filed on Jan. 28, 2014. This application
also claims priority to U.S. Provisional patent application No.
61/757,533, filed on Jan. 28, 2013 and to India Provisional patent
application number 3611/DEL/2014, filed on Sep. 12, 2014. The
entireties of U.S. 61/757,533, India 3611/DEL/2014 and
PCT/US2014/013397 are incorporated by reference herein.
TECHNICAL FIELD
[0003] The present disclosure relates to systems for recovering
waste heat. More particularly, the present disclosure relates to
organic Rankine cycle systems.
BACKGROUND
[0004] The Rankine cycle is a power generation cycle that converts
thermal energy to mechanical work. The Rankine cycle is typically
used in heat engines, and accomplishes the above conversion by
bringing a working substance from a higher temperature state to a
lower temperature state. The classical Rankine cycle is the
fundamental thermodynamic process underlying the operation of a
steam engine.
[0005] The Rankine cycle typically employs individual subsystems,
such as a condenser, a fluid pump, a heat exchanger such as a
boiler, and an expander turbine. The pump is frequently used to
pressurize the working fluid that is received from the condenser as
a liquid rather than a gas. The pressurized liquid from the pump is
heated at the heat exchanger and used to drive the expander turbine
so as to convert thermal energy into mechanical work. Upon exiting
the expander turbine, the working fluid returns to the condenser
where any remaining vapor is condensed. Thereafter, the condensed
working fluid returns to the pump and the cycle is repeated.
[0006] A variation of the classical Rankine cycle is the Organic
Rankine cycle (ORC), which is named for its use of an organic, high
molecular mass fluid, with a liquid-vapor phase change, or boiling
point, occurring at a lower temperature than the water-steam phase
change. As such, in place of water and steam of the classical
Rankine cycle, the working fluid in the ORC may be a solvent, such
as n-pentane or toluene. The ORC working fluid allows Rankine cycle
heat recovery from lower temperature sources such as biomass
combustion, industrial waste heat, geothermal heat, solar ponds,
etc. The low-temperature heat may then be converted into useful
work, which may in turn be converted into electricity.
[0007] Further development in such Rankine cycle systems is
desired.
SUMMARY
[0008] One aspect of the present disclosure relates to a
closed-loop organic Rankine cycle system including a Rankine cycle
working circuit and a lubrication circuit. In certain examples, the
Rankine cycle working circuit and the lubrication circuit have
portions that coincide with one another. In certain examples, the
Rankine cycle working circuit and the lubrication circuit share a
common hydraulic pump. In certain examples, lubricant from the
lubrication circuit and working fluid from the Rankine cycle
working circuit are allowed to mix with each other. In certain
examples, the lubrication circuit is a cooling circuit that cools
lubricant used to lubricate and cool components (e.g. bearings,
timing gears, etc.) of a mechanical expander that extracts
energy/work from the Rankine cycle working circuit. In certain
examples, lubricant from the lubrication circuit mixes with working
fluid of the Rankine cycle working circuit and provides lubrication
to a hydraulic pump that drives flow through both the Rankine cycle
working circuit and the lubrication circuit.
[0009] Aspects of the present disclosure allow for a simplified
Rankine cycle system having reduced sealing considerations and
reduced pumping components. In certain examples, a separator is
used to separate lubricant from the Rankine cycle working fluid
before the Rankine cycle working fluid is delivered to a heat
exchanger. In certain examples, the Rankine cycle system is used to
re-capture energy from waste heat from a prime mover such as an
internal combustion engine, a fuel cell, or a similar component. In
certain examples, Rankine cycle system is used to re-capture energy
from waste heat from the prime mover of a vehicle.
[0010] A variety of additional aspects will be set forth in the
description that follows. These aspects can relate to individual
features and to combinations of features. It is to be understood
that both the foregoing general description and the following
detailed description are exemplary and explanatory only and are not
restrictive of the broad concepts upon which the embodiments
disclosed herein are based.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic depiction of a Rankine cycle system
employing a Rankine cycle working circuit and a lubrication circuit
having features that are examples of inventive aspects in
accordance with the principles of the present disclosure;
[0012] FIG. 1A is a schematic depiction of a simplified Rankine
cycle working circuit and lubrication circuit having shared
features with the circuits shown in FIG. 1.
[0013] FIG. 2 is a perspective view of an example configuration for
a separator that can be used in the Rankine cycle systems of FIGS.
1 and 2;
[0014] FIG. 2A is a perspective view of an example configuration
for a separator that can be used in the Rankine cycle systems of
FIGS. 1 and 2;
[0015] FIG. 3 is a top view of the separator shown in FIG. 2;
[0016] FIG. 4 is a bottom view of the separator shown in FIG.
2;
[0017] FIG. 5 is a first side view of the separator shown in FIG.
2;
[0018] FIG. 6 is a second side view of the separator shown in FIG.
2;
[0019] FIG. 7 is a cross-sectional side view of the separator shown
in FIG. 2;
[0020] FIG. 8 is a cross-sectional side view of a portion of the
separator shown in FIG. 2;
[0021] FIG. 9 is a perspective cross-sectional view of the
separator shown in FIG. 2;
[0022] FIG. 10 is a diagram depicting the Rankine cycle employed by
the system shown in FIG. 1;
[0023] FIG. 11 is a cross-sectional schematic view of a single
stage Roots-style expander suitable for use in extracting
mechanical energy from the system of FIG. 1;
[0024] FIG. 12 is a schematic depiction of the Roots-style expander
of FIG. 11;
[0025] FIG. 13 is a cross-sectional view showing timing gears of
the Roots-style expander of FIG. 11; and
[0026] FIG. 14 schematically depicts a vehicle including a Rankine
cycle system in accordance with the principles of the present
disclosure.
DETAILED DESCRIPTION
[0027] Referring to the drawings wherein like reference numbers
correspond to like or similar components throughout the several
figures.
[0028] The present disclosure relates generally to a Rankine cycle
system (e.g., an organic Rankine cycle system) that utilizes heat
from a heat source to generate useful work. In one example, the
heat source is waste heat from a device such as a prime mover
(e.g., an internal combustion engine such as a diesel engine or
spark ignition engine, a fuel cell, etc.). In one example, a
mechanical device, such as a rotary expander, is used to extract
mechanical energy from the Rankine cycle system. In one example,
the Rankine cycle system is an organic Rankine cycle system that
heats and vaporizes the Rankine cycle working fluid (e.g., a
solvent such as ethanol, n-pentane, toluene or other solvents) to
temperatures that can equal or exceed 250 degrees Celsius (C).
[0029] Such high temperatures can deteriorate the lubricating oil
used to lubricate moving components (e.g., bearings, gears, etc.)
of mechanical devices (e.g., rotary expanders) used to extract
energy from the Rankine cycle circuit. In this regard, with respect
to flowable lubricating oils, it is desirable to use a lubrication
cooling circuit that maintains the lubricant at acceptable
temperatures. Grease typically is not effective because the solvent
forming the Rankine cycle working fluid can cause de-greasing.
Furthermore, grease will deteriorate at high temperatures.
Lubricating oils can present issues when ineffective sealing (e.g.,
at mechanical components such as expanders, pumps or other
components with moving parts that require lubrication) allows such
oils to mix with the Rankine cycle working fluid. For example,
lubricant within the Rankine cycle working fluid can be detrimental
to the evaporation process by fouling the evaporator coils.
[0030] Aspects of the present disclosure relate to a closed-loop
organic Rankine cycle system including a Rankine cycle working
circuit and a lubrication circuit. In certain examples, the Rankine
cycle working circuit and the lubrication circuit are configured
such that lubricant from the lubrication circuit intentionally
mixes with the Rankine cycle working fluid. In this way, the
Rankine cycle working circuit and the lubrication circuit have
portions that coincide with one another. In certain examples, the
Rankine cycle working circuit and the lubrication circuit share a
common hydraulic pump. In certain examples, the lubricant and the
Rankine cycle working fluid mix at a location upstream from a low
pressure side of the pump, and a separator separates the Rankine
cycle working fluid from the lubricant at a location between a high
pressure side of the pump and an evaporator. In certain examples,
the lubrication circuit is a cooling circuit that cools lubricant
used to lubricate components (e.g. bearings, timing gears, etc.) of
a mechanical expander that extracts energy/work from the Rankine
cycle working circuit, and lubricant from the lubrication circuit
mixes with working fluid of the Rankine cycle working circuit and
provides lubrication to a hydraulic pump that drives flow through
both the Rankine cycle working circuit and the lubrication circuit.
Patent Cooperation Treaty patent application publication WO
2014/117156 shows such a system, wherein the lubricant is mixed
with the working fluid after being condensed to remove heat energy
from the lubricant which was captured during expander component
lubrication. WO '156 is incorporated herein by reference in its
entirety. In certain examples, the Rankine cycle system is used to
capture energy from waste heat.
[0031] FIGS. 1 and 1A illustrate an organic Rankine cycle system
100 in accordance with the principles of the present disclosure.
The organic Rankine cycle system 100 is configured to convert heat
energy from a heat source, such as an engine 116, into mechanical
energy. The organic Rankine cycle system 100 is configured to cycle
a Rankine cycle working fluid (e.g., a solvent such as ethanol,
n-pentane, toluene or other solvents) repeatedly through a
closed-loop organic Rankine cycle. As depicted at FIG. 1, the
organic Rankine cycle system 100 includes a Rankine cycle working
circuit 102 having a condensing zone 104, a heating zone 106, and a
mechanical energy extracting zone 108. A hydraulic pump 110 is used
to move the working fluid through the Rankine cycle circuit 102.
The pump 110 includes a low pressure side 112 in fluid
communication with the condensing zone 104, via a reservoir 160,
and a high pressure side 114 in fluid communication with the
heating zone 106. The mechanical energy extracting zone 108 has an
inlet side 117 in fluid communication with the heating zone 106 and
an outlet side 118 in fluid communication with the condensing zone
104.
[0032] The Rankine cycle system 100 also includes a lubrication
circuit 113 for cycling/circulating and cooling lubricant (e.g.,
castor oil, synthetic oil, other oils or lubricating material) used
to lubricate moving parts associated with a mechanical component
(e.g., a rotary expander) of the mechanical energy extracting zone
108. The Rankine cycle working circuit 102 and the lubrication
circuit 113 include a shared segment 115 in which the Rankine cycle
working fluid and the lubricant are mixed with each other. The
Rankine cycle working circuit 102 and the lubrication circuit 113
are co-extensive along the shared segment 115 which feeds into the
inlet 172 of a condenser 170. The condensed fluid is delivered from
an outlet 174 of the condenser 170 to an inlet 162 of a fluid
reservoir 160. The condenser 170 is preferably constructed such
that lubricant cannot pool or become otherwise trapped within the
condenser and can freely flow to the reservoir 160.
[0033] The pump 110 is positioned in fluid communication with the
fluid reservoir 160 such that the mixture of Rankine cycle working
fluid and lubricant flows from an outlet 164 of the reservoir 160
and through the pump 110 from the low pressure side 112 to the high
pressure side 114. The lubricant within the mixture assists in
lubricating the pump 110. The pump 110 provides positive pressure
for cycling flow through both the Rankine cycle working circuit 102
and the lubrication circuit 113.
[0034] In the configuration shown at FIG. 1A, the shared segment
115 starts at a primary mixing location 111 located between the
condensing zone 104 and the low pressure side 112 of the pump 110,
and extends from the primary mixing location 111, through the pump
110 to a fluid separator 119. Lubricant can be metered into the
Rankine cycle working fluid at the primary mixing location 111. In
this configuration, the separated lubricant bypasses the condenser
104 such that the relatively cool working fluid leaving the
condenser can aid in cooling the separated lubricant leaving the
energy extracting zone 108.
[0035] In the configuration shown at FIG. 1A, the shared segment
115 starts at a primary mixing location 111 located between the
energy extracting zone 108 and the condensing zone 104, and extends
from the primary mixing location 111, through the condensing zone
104, the reservoir 160, the pump 112 to the fluid separator 119. In
this configuration, the working fluid and lubricant are mixed
upstream of the condensing zone 104 such that the condensing zone
104 acts to simultaneously cool the working fluid and the
lubricant.
[0036] The fluid separator 119 is configured to separate the
lubricant from the Rankine cycle working fluid. The Rankine cycle
working circuit 102 includes a non-shared segment 121 that includes
Rankine cycle working fluid without lubricant. The non-shared
segment 121 extends from the separator 119, through the heating
zone 106, and the mechanical energy extracting zone 108. The
lubrication circuit 113 includes a non-shared segment 123 that
extends from the separator 119 to the mechanical energy extracting
zone 108. In one example, the non-shared segment 123 is provided
with a control valve 155, such as a needle valve, for controlling
the flow rate and/or pressure of the lubricant as it is introduced
into the mechanical expander 127 at an inlet 190. Such control is
desirable as the introduction of excess lubricant will increase
and/or introduce parasitic losses by increases friction at the
gears and/or bearings of the expander 127. As shown, the system 100
is configured such that the expander lubrication inlet 190 is above
the lubrication outlet 526 of the separator 119 to prevent
lubricant from completely draining from the separator 119 to the
expander 127 when the system 100 is shut down. In one example, the
lubrication outlet 526 is above the lubrication inlet 190 by a
height, hl. In one example, the system 100 is configured such that
the lowest part of the expander 127 is above the lubrication outlet
526. In one example, the non-shared segment 123 includes lubricant
without Rankine cycle working fluid. At the mechanical energy
extracting zone 108, the lubricant can flow through lubricant
containing structures 125 such as bearings, bearing chambers, and
gear chambers of a rotary mechanical expander 127. From the
lubricant containment structures 125 (125a, 125b, 125c, 125d) of
the mechanical energy extracting zone 108, the lubricant can flow
to the primary mixing location 111 via segment 129.
[0037] In certain examples, Rankine cycle working fluid can leak
past the shaft seals of expander 127 into the lubricant containment
structures 125 such that the segment 129 carries a mixture of
lubricant and Rankine cycle working fluid. In this example, the
leakage of Rankine cycle working fluid into the lubrication circuit
113 at the mechanical expander 127 does not pose an issue for the
system because of the ability to subsequently separate the
lubricant from the Rankine cycle working fluid. Likewise, some of
the Rankine cycle working fluid may migrate through seals in the
expander 127 such that segment 131 carries a mixture of lubricant
and Rankine cycle working fluid. Thus, special sealing used to
absolutely prevent leakage is not needed thereby reducing the
quantity and/or expense of the seals in the system.
[0038] In one example, the fluid separator 119 separates the
Rankine cycle working fluid from the lubricant and directs the
Rankine cycle working fluid to the non-shared segment 121 and the
lubricant to the non-shared segment 123. Pressure from the pump 110
drives flow of the Rankine cycle working fluid through the
non-shared segment 121 and also drives flow of lubricant through
the non-shared segment 123. The mechanical expander 127 can include
one or more rotor chambers 128 (128a, 128b, 128c) containing one or
more rotors. In use, the heated Rankine cycle working fluid from
the heating zone 106 flows through the rotor chambers 128 of the
mechanical expander 127 causing rotation of the rotors such that
useful work is extracted from the Rankine cycle circuit 102. For
example, work can be extracted via an output shaft 400. At the
rotary mechanical expander 127, some Rankine cycle working fluid
may flow across seals from rotor chamber 128 to the lubricant
containment structures 125. Thus, in some examples, a mixture of
Rankine cycle working fluid and lubricant flows from the lubricant
containment structures 125 through segment 129 to the primary
mixing location 111. At the primary mixing zone 111, primary mixing
between the lubricant and the Rankine cycle working fluid occurs.
The mixed lubricant and Rankine cycle working fluid then flow from
the mechanical primary mixing zone 111 through the condensing zone
104 and then to the reservoir where the mixture is stored. The
mixture of Rankine cycle working fluid and lubricant flows through
the pump 110 to the separator 119 from the reservoir outlet 164,
which is located at a lower part of the reservoir 160 below a
liquid level line 165 to ensure that only fully condensed fluid is
introduced to the pump 110. Moreover, locating the reservoir outlet
164 at or near the bottom of the reservoir 160 ensures that any
available lubricant is introduced back into the circuit. In some
applications, the lubricant is only about 10% to about 20% of the
total volume of the combined lubricant and the condensed Rankine
cycle working fluid. The lubricant mixed with the Rankine cycle
working fluid can assist in lubricating the pump 110.
[0039] By configuring the system 100 to mix the Rankine cycle
working fluid and the lubricant upstream of the condenser 170,
separate outlet pipes for each chamber 128 do not need to be tied
together and routed to feed into the pump 110. Rather, the
lubricant outlet ports simply need to be routed to the nearby
expander outlet. This results in fewer leak paths and simplified
packaging. Moreover, it is fully ensured that any working fluid
that enters in the lubrication chambers 125 through the seals (e.g.
turbo rings) is easily drained and returned back to the liquid
state since both segments 129 and 131 feed into the condenser 170
after being mixed together at the primary mixing location 111.
[0040] In the depicted example, the Rankine cycle system 100 is
configured to recapture waste energy from a prime mover, such as an
engine 116 (e.g., an internal combustion engine such as a diesel or
spark ignition engine or a fuel cell), by drawing waste heat from
the engine (e.g., by drawing heat from the engine exhaust such as
from a main exhaust line and/or from exhaust in an exhaust gas
recirculation line). As depicted at FIG. 1, the heating zone 106 of
the organic Rankine cycle system 100 includes at least one heat
exchanger 150 for drawing waste heat from the engine 116. The heat
exchanger 150 transfers heat from the engine 116 to the Rankine
cycle working fluid of the Rankine cycle circuit 102 as the working
fluid passes through the heating zone 106 thereby heating and
evaporating the working fluid. In certain examples, the working
fluid is super-heated. In other examples, the working fluid is not
super-heated.
[0041] It will be appreciated that the engine 116 can be used to
power a vehicle 300 (see FIG. 14). The vehicle 300 can include a
torque transfer arrangement 302 (e.g., a drive train, drive shaft,
transmission, differential, etc.) for transferring torque from the
engine crankshaft to one or more axles 304 of the vehicle 300. The
axles 304 can be coupled to wheels 308, or to tracks or other
structures adapted to contact the ground. In such examples, the
organic Rankine cycle system 100 and the engine 116 are carried
with a vehicle chassis/frame 306 (shown schematically). In certain
examples, prime movers such as fuel cells diesel engines or spark
ignition engines can be used to power the vehicle.
Separator
[0042] FIGS. 2-9 show an example separator 500 suitable for use as
the separator 119 of the Rankine cycle systems of FIGS. 1 and 1A.
The separator 500 includes a separator housing 520 defining an
inlet 522, a first outlet 524, and a second outlet 526. As shown,
the inlet 522 and first outlet 524 are located in a top plate 530
of the housing 520 while the second outlet 526 is located in a
bottom plate 532 of the housing 520. When incorporated into the
Rankine cycle system 100 of FIG. 1, the inlet 522 is coupled in
fluid communication with the high pressure side of the pump 110 so
as to receive the mixture of lubricant and Rankine cycle working
fluid from the pump 110. Also, the first outlet 524 is coupled to
the first non-shared segment 121 and the second outlet 526 is
coupled to the second non-shared segment 123.
[0043] The separator inlet 522 can be provided with a conduit 528
that extends into the interior volume 521 of the separator 520 and
directs the pumped fluid around the internal diameter of the
separator to reduce the velocity of the mixture which accelerates
the separation process. In one example, the conduit 528 is provided
with a bent portion 528a for directing the fluid spray. The
separator working fluid first outlet 524 can be provided with a
plurality of converging inlet branches that extend from the outlet
524 into the interior volume 521 of the separator 500 to increase
the velocity of the separated working fluid. As shown, two
converging inlet branches 524a, 524b are provided. The separator
lubricant second outlet 526 can be placed in fluid communication
with the bottom of a funneled collection structure 534 which
collects all lubricant to ensure that the outlet 526 is always
subjected to a volume of lubricant. The separator 500 may also be
provided with a diverter plate 536 within the interior volume 1
configured to minimize lubricant spray and to accelerate the
separation process. In the example shown, the diverter plate 536 is
provided with a toroid or doughnut shape with an open center. In
one example, and as described in WO '156, the separator 500 can
further include a filter or porous media to accelerate the
separation process.
[0044] In this example, the mixture of lubricant (e.g., oil) and
Rankine cycle working fluid (e.g., ethanol) can enter the oil
separator 500 at the inlet 522 and flows into the interior volume
521 via conduit 528. In certain examples, the lubricant is heavier
than the Rankine cycle working fluid and this weight difference
allows the separator 500 to separate the lubricant from the Rankine
cycle working fluid via gravity. For example within the housing
520, the lubricant sinks relative to the Rankine cycle working
fluid. Thus, the Rankine cycle working fluid collects towards the
top plate 530 of the housing 520 and the lubricant collects
proximate the bottom plate 532 of the housing 520. The first outlet
524 is positioned at the top 528 of the housing 520 so as to
receive the separated Rankine cycle working fluid while the second
outlet 526 is positioned at a bottom 530 of the housing 520 so as
to receive the separated lubricant. It is noted that the inlet and
outlet positions can be relocated as necessary where the working
fluid is more dense than the lubricant without departing from the
concepts presented herein. The Rankine cycle working fluid exits
the housing 520 through the first outlet 524 and flows through the
first non-shared segment 121 to the heat exchanger 150. The
lubricant exits the housing 520 through the second outlet 526 and
flows through the second non-shared segment 123 to the lubricant
containment structure 125 of the mechanical expander 127.
[0045] FIG. 2A shows a second embodiment of a separator 500 usable
with either of the configurations shown in FIGS. 1 and 1A. In
contrast to the separator 500 shown at FIGS. 2-9, the separator 500
of FIG. 2A is provided with a porous media 527 (e.g., a filtering
media, a separating media, a precipitating media) contained within
the housing 520 and is provided with a differently located inlet
522 and outlets 524, 526. The porous media 27 can include substance
that contains pores or spaces between solid material through which
liquid or gas can pass. Examples of naturally occurring porous
media include sand, soil, and some types of stone, such as pumice
and sandstone. Sponges, ceramics, and reticulated foam are also
manufactured for use as porous media. It is to be understood that
the type of porous media may vary with other examples. In some
examples, the porous media can be made from wire mesh or knitted
wire mesh, such as stainless steel wire mesh with a coiled
construction, which is well suited for separating out the
lubricating oil droplets. In one example, the density of the porous
media can be on the order of about nine pounds per cubic foot. In
other examples, the porous media can be made from a combined or
co-knit metal wire and fiberglass mesh, such as a 304 stainless
steel mesh co-knitted with fiberglass. These materials are found to
be well-suited for filtering the lubricating oil and the porous
media can have a density of about twelve pounds per cubic foot.
[0046] In the configuration shown at FIG. 2A, the mixture of
lubricant (e.g., oil) and Rankine cycle working fluid (e.g.,
ethanol) can enter the oil separator 500 at the inlet 522 and flow
through the porous media 527. The porous media 527 can slow the
flow of the mixture, which encourages separation. In certain
examples, the lubricant is heavier than the Rankine cycle working
fluid and this weight difference allows the separator 500 to
separate the lubricant from the Rankine cycle working fluid via
gravity. For example within the housing 520, the lubricant sinks
relative to the Rankine cycle working fluid. Thus, the Rankine
cycle working fluid collects at a top 528 of the housing 520 and
the lubricant collects at a bottom 530 of the housing 520. The
first outlet 524 is positioned at the top 528 of the housing 520 so
as to receive the separated Rankine cycle working fluid while the
second outlet 526 is positioned at a bottom 530 of the housing 520
so as to receive the separated lubricant. The Rankine cycle working
fluid exits the housing 520 through the first outlet 524 and flows
through the first non-shared segment 121 to the heat exchanger 150.
The lubricant exits the housing 520 through the second outlet 526
and flows through the second non-shared segment 123 to the
lubricant containment structure 125 of the mechanical expander
127.
Mechanical Energy Extraction/Recovery Device
[0047] As described above, the organic Rankine cycle system 100 of
FIGS. 1 and 1A includes a mechanical energy extraction zone 108
including at least one mechanical device (e.g., a reaction turbine,
a piston engine, a scroll expander, a screw-type expander, a Roots
expanders, etc.) capable of outputting mechanical energy from the
Rankine cycle working circuit 102. In certain examples, the
mechanical device relies upon the kinetic energy, temperature/heat
and pressure of the working fluid to rotate the output shaft 400
(see FIG. 1). Where the mechanical device is used in an expansion
application, such as with a Rankine cycle, energy is extracted from
the working fluid via fluid expansion. In such instances, the
mechanical device may be referred to as an expander or expansion
device. However, it is to be understood that the mechanical device
is not limited to applications where a working fluid is expanded
across the device. In certain examples, the mechanical device
includes one or more rotary elements (e.g., turbines, blades,
rotors, etc.) that are rotated by the working fluid of the Rankine
cycle so as to drive rotation of the output shaft 400 of the
mechanical device. In certain examples, the output shaft 400 can be
coupled to an alternator used to generate electricity, used to
power active components, or used to charge a battery suitable for
providing electrical power on demand. In other examples, the output
shaft 400 can be coupled to a hydraulic pump used to generate
hydraulic pressure, used to power active hydraulic components, or
used to charge a hydraulic accumulator suitable for providing
hydraulic pressure on demand. In still other examples, the output
shaft 400 can be mechanically coupled (e.g., by gears, belts,
chains or other structures) to other active components or back to a
prime mover that is the source of waste heat for the Rankine cycle
system.
[0048] In one example, the mechanical device used at the mechanical
energy extracting zone 108 can include a Roots-style rotary device
referred to herein as a Roots-style expander. Patent Cooperation
Treaty patent application publication WO 2014/117159 discloses
multi-stage expanders suitable for such use herein. The entirety of
WO '159 is incorporated by reference herein. The pressure at the
inlet side of the device is greater than the pressure at the outlet
side of the device. The pressure drop between the inlet and outlet
drives rotation within the device. Typically, except for
decompression related to fluid leakage and device inefficiencies,
expansion/decompression does not occur within the device itself,
but instead occurs as the working fluid exits the device at the
outlet. The device can be referred to a volumetric device since the
device has a fixed displacement for each rotation of a rotor within
the device.
[0049] As shown at FIG. 1, extraction device 127 includes a first
stage 180, a second stage 182, and a third stage 184, wherein
working fluid enters the inlet 117, then passes through the rotors
of the first stage 180, then passes through the rotors of the
second stage 182, and then passes through the rotors of the third
stage 184 before existing through outlet 118. As there are gear
sets and bearing points at the ends of each stage 180, 182, 184,
lubrication containment chambers or structures 125a, 125b, 125c,
and 125d are provided and placed in fluid communication with a
lubrication fluid inlet 190. In one example, the chambers 125a-125d
are placed in fluid communication with each other via an fluid
delivery circuit 192 including internal and/or external branch
lines, for example, branch line 192a, 192b, 192c, 192d, 192e, and
192f. To ensure that the appropriate lubricant flow reaches each of
the chambers 125a-125d, flow control orifices may be provided in
one or more of the individual branch lines 192a-192e. After passing
through the chambers 125a-125d, the lubricant can be discharged
through outlets in the device 127, for example, outlets 194, 196,
and 198. As shown, outlets 194, 196, and 198 are placed in fluid
communication with branch line 129. As outlets 194-198 are in close
proximity to outlet 118, very little piping is required to
reconnect the respective lines at primary mixing location 111. As
stated previously, this approach minimizes costs and results in a
more compact construction.
[0050] FIGS. 11-13 depict a generic, single stage Roots-style
expander 200 also suitable for use at the mechanical energy
extraction zone 108 of the Rankine cycle system 100. Expander 200
relies on the same general operating principles as extraction
device 127 and the descriptions of each are therefore largely
applicable for the other. The expander 200 includes a housing 202
having an inlet 204 and an outlet 206. In use, the inlet 204 is in
fluid communication with the heating zone 106 of the Rankine cycle
system 100 and the outlet 206 is in fluid communication with the
condensing zone 104 of the Rankine cycle system 100.
[0051] The expander housing 202 defines an internal cavity 208
(i.e., a rotor chamber) that provides fluid communication between
the inlet 204 and the outlet 206. The internal cavity 208 is formed
by first and second parallel rotor bores 210 (see FIG. 4) defined
by cylindrical bore-defining surfaces 222. The expander 200 also
includes first and second rotors 212 respectively mounted in the
first and second rotor bores 210. Each of the rotors 212 includes a
plurality of lobes 214 mounted on a shaft 216. The shafts 216 are
parallel to one another and are rotatably mounted relative to the
expander housing 202 by bearings 217 (FIG. 3). The shafts 216 are
free to rotate relative to the housing 202 about parallel axes of
rotation 213. The lobes 214 of the first and second rotors 212
intermesh/interleave with one another. Intermeshing timing gears
218 (see FIG. 5) are provided on the shafts 216 so as to
synchronize the rotation of the first and second rotors 212 such
that the lobes 214 of the first and second rotors 212 do not
contact one another in use. In certain examples, the lobes 214 can
be twisted or helically disposed along the lengths of the shafts
216. The rotors 212 define fluid transfer volumes 219 (FIG. 4)
between the lobes 214. The lobes 214 can include outer tips 220
(FIG. 4) that pass in close proximity to the bore-defining surfaces
222 of the housing 202 as the rotors 212 rotate about their
respective axes 213. In certain embodiments, the outer tips 220 do
not contact the bore-defining surfaces 222.
[0052] In use of the expander 200, working fluid (e.g., vaporized
working fluid or two-phase working fluid) from the heating zone 106
enters the expander housing 202 through the inlet 204. Upon passing
through the inlet 204, the vaporized working fluid enters one of
the fluid transfer volumes 219 defined between the lobes 214 of one
of the rotors 212. The pressure differential across the expander
200 causes the working fluid to turn the rotor 212 about its axis
of rotation 213 such that the fluid transfer volume 219 containing
the vaporized working fluid moves circumferentially around the
bore-defining surface 222 from the inlet 204 to the outlet 206. As
the rotors 212 are rotated by the working fluid, mechanical energy
is transferred out from the expander 200 through the output shaft
400 which coincides with one of the shafts 216. The output shaft
400 (FIG. 3) extends outwardly beyond an outer boundary of the
expander housing 202 so as to be accessible for transferring
torque/energy from the expander 200.
[0053] It will be appreciated that working fluid from the inlet 204
enters the internal cavity 208 of the housing 202 (see arrows 228
at FIG. 4) at a central region CR of the internal cavity 208 that
is between parallel planes P, which include the axes 213 and which
extend between inlet and outlet sides of the expander housing 202.
The working fluid from the inlet 204 enters fluid transfer volumes
219 of the rotors 212 at the central region CR and causes the
rotors 212 to rotate in opposite directions about their respective
axes 213. The rotors 212 are rotated about their respective axes
213 such that the fluid transfer volumes 219 containing the working
fluid move away from the central region CR along their respective
circumferential bore-defining surface 222 of the housing 202 to
outer regions OR (i.e., regions outside the planes P) of the
internal cavity 208 as indicated by arrows 230 (see FIG. 4). The
rotors 212 continue to rotate about their respective axes 213
thereby moving the fluid transfer volumes 219 from the outer
regions OR back to the central region CR adjacent the outlet 206 as
indicated by arrows 232. The working fluid from the fluid transfer
volumes 219 exits the expander housing 202 through the outlet 206
as indicated by arrows 234 (see FIG. 4).
[0054] The intermeshing gears 218 and bearings 217 can be
positioned within a lubrication chamber 402 containing lubricant
for lubricating the gears 218 and the bearings 217 (see FIG. 3).
The lubrication chamber 402 is an example of the lubricant
containing structure 125 of FIG. 1. The temperature in the rotor
cavity can be as high as 300.degree. C. to 350.degree. C. and thus
bearings and timing gears in the expander are exposed to relatively
high temperatures. The high temperature can deteriorate the
lubricating oil for the bearings and timing gears and reduce the
life of the bearings and timing gears. To prevent this from
occurring, the lubrication circuit 113 can be used to circulate the
lubricant through the lubrication chamber 402 so the lubricant is
exposed to the high temperatures for only a limited amount of time.
The lubricant of the lubrication circuit 113 is cooled by the
Rankine cycle working fluid as both fluids pass through the
condenser 170. In the circuit shown at FIG. 1A, the lubricant is
cooled when the lubricant mixes with the relatively cool Ranking
cycle working fluid that exits the condensing zone 104. Inside the
condenser 170, the Rankine cycle working fluid condenses and cools
as it undergoes a phase change within the condensing zone 104. The
condensed Rankine cycle working fluid is then able to absorb heat
from the lubricant. It will be appreciated that the lubrication
chamber 402 is one example of a lubricant containment structure 125
and that other lubricant containing structures 125 (e.g., other
lubricant chambers) can also be provided as part of the lubrication
circuit 113.
Rankine Cycle Operation
[0055] FIG. 2 shows a general diagram depicting a representative
Rankine cycle applicable to the system 100, as described with
respect to FIGS. 1 and 1A. The diagram depicts different stages of
the Rankine cycle showing temperature in Celsius plotted against
entropy "S", wherein entropy is defined as energy in kilojoules
divided by temperature in Kelvin and further divided by a kilogram
of mass (kJ/kg*K). The Rankine cycle shown in FIG. 2 is
specifically a closed-loop Organic Rankine Cycle (ORC) that may use
an organic, high molecular mass working fluid with a liquid-vapor
phase change or boiling point occurring at a lower temperature than
the water-steam phase change of the classical Rankine cycle.
Accordingly, in the system 100, the working fluid may be a solvent,
such as ethanol, n-pentane or toluene.
[0056] In the diagram of FIG. 2, the term "Q" represents the heat
flow to or from the system 100, and is typically expressed in
energy per unit time. The term "W" represents mechanical power
consumed by or provided to the system 100, and is also typically
expressed in energy per unit time. As may be additionally seen from
FIG. 2, there are four distinct processes or stages 142-1, 142-2,
142-3, and 142-4 in the ORC. During stage 142-1, the Rankine cycle
working fluid in the form of a wet vapor enters and passes through
at least one condenser 170 at the condensing zone 104, in which the
Rankine cycle working fluid is condensed at a constant temperature
to become a saturated liquid. Following stage 142-1, the Rankine
cycle working fluid is pumped from low to high pressure by the pump
106 during the stage 142-2. During stage 142-2, the Rankine cycle
working fluid is in a liquid state.
[0057] From stage 142-2 the Rankine cycle working fluid is
transferred to stage 142-3. During stage 142-3, the pressurized
Rankine cycle working fluid enters and passes through the heat
exchanger 150 where it is heated at constant pressure by an
external heat source to become a vapor or a two-phase fluid, (i.e.,
liquid together with vapor). During stage 142-4, the Rankine cycle
working fluid, in the form of a fully vaporized fluid or a
two-phase fluid, passes through the mechanical energy extracting
zone 108, thereby generating useful work or power. The working
fluid may expand at the outlet of the mechanical energy extracting
zone 108 thereby decreasing the temperature and pressure of the
working fluid such that some additional condensation of the working
fluid may occur. Following stage 142-4, the working fluid is
returned to the condensing zone 104, at which point the cycle
completes and will typically restart at stage 142-1.
[0058] From the forgoing detailed description, it will be evident
that modifications and variations can be made without departing
from the spirit and scope of the disclosure.
* * * * *