MULTI-STAGE VOLUMETRIC FLUID EXPANSION DEVICE
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.
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.
GOVERNMENT LICENSE RIGHTSThis 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
TECHNICAL FIELDThis 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.
BACKGROUNDWaste 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.
SUMMARYIn 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.
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.
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.
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.
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.
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.
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.
Referring to
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.
In one embodiment, and as shown in
Referring to
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.
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.
With reference to the example embodiment shown in
With reference to the example embodiment shown in
With reference to the example embodiment shown in
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.
In the example shown at
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
Each of the rotors 130/132, 230/232, 330/332, collectively referred to as rotors 30, 32 in this section and with reference to
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.
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.
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 GeometryIn 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.
As shown schematically at
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
Furthermore, and as shown in
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
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.
To illustrate,
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.
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.
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 EmbodimentsReferring to
With reference to
As can be seen at
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.
Referring to
With reference to
As can be seen at
As shown at
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 EmbodimentsReferring to
With reference to the example shown in
With reference to the example shown in
With reference to the example shown in
With reference to the example shown in
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.
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.
Type: Application
Filed: Jul 28, 2015
Publication Date: Nov 19, 2015
Inventors: William Nicholas EYBERGEN (Harrison Twp, MI), Martin D. PRYOR (Canton, MI), Sheetalkumar Shamrao PATIL (Pune), Lalit Murlidhar PATIL (Pune), Matthew James FORTINI (Allen Park, MI)
Application Number: 14/810,726