Patent Grant
11047381
With respect to conventional compressors, the lubrication of the moving compressor parts is achieved by separated oil drawn from the oil-vapor mixture that exits the compressor. The oil can be separated from the oil vapor mixture by an oil separator and collected into an oil sump that supplies the compressor with oil for proper operation. On the compressor exhaust, after compression, the exhausted fluid consists of an oil-vapor mixture. Prior to sending the oil-vapor mixture to further components in the vapor compression system, the oil drops out of the flow inside the oil separator and is separated from the vapor and can be fed to an oil sump through gravity acting on the oil. The vapor only is then exited to the further components in the system. The separated oil is then directed back to the compressor inlet without traveling through the remainder of the vapor compression system. In addition to oil separators with gravity oil-fed oil sumps to separate the oil from the vapor, other components such as accumulators and some evaporator types with oil bleed ports can be used to separate the oil from the vapor. Thus, with conventional compressors, the vast majority of the oil contained in the vapor compression system is kept inside the compressor and oil separation mechanism alone (stored in the oil sump or other device such as an accumulator), as it is in continuous recirculation between the compressor and oil separation mechanism.
Therefore, conventional compressors, requiring some form of an oil separation mechanism either through the use of oil separators or other means such as through the use of oil bleed lines from some evaporator types or accumulators, are commonly orientation dependent, meaning dependent on the orientation of the compressor and oil separation mechanism with respect to the surrounding gravitational field, due to the gravity dependence of the oil-sump requirement and the gravity dependent location of any oil bleed lines drawn from other devices such as accumulators. The movement of oil from the exhaust of the compressor to the oil separation mechanism and back to the compressor is gravity dependent. Accordingly, with conventional compressors, there exists certain compressor orientations that restrict or completely cut off the gravity driven flow of oil to the compressor due to improper oil levels or no oil at all being located in the designated areas of the supplied oil sump or other oil storage device. With inadequate or no oil lubrication, the compressor performance can be significantly reduced. Short term operation effects without adequate oil lubrication can include an increase in the compressor power required due to increase frictional effects from the sliding components, a reduction in the flow output per compressor stroke due to a reduction in gas sealing, and an increase in frictional heat resulting in an increase of the compressor temperature. Both higher compressor power and reduced flow output can adversely affect vapor compression cycle system performance. Long term compressor operation without adequate oil lubrication can damage vital compressor components thus causing the compressor to fail.
Therefore, there is a need in the art for an orientation independent compressor and an orientation independent vapor compression cycle system.
Embodiments of the subject invention pertain to a method and apparatus for an orientation independent compressor. Embodiments of the subject invention also relate to a method and apparatus for an orientation independent vapor compression cycle system. The subject compressor can be part of a vapor compression cycle system. Embodiments of the subject compressor can use one or more of a variety of working fluids, including, but not limited to, one or more gases, such as nitrogen, oxygen, hydrogen, and air, gas mixtures, and/or refrigerants such as r-134a, r-22, CO2, and NH3. Embodiments of the compressor can utilize positive displacement means to compress the vapor. In a specific embodiment, the compressor can incorporate an oil-lubricated rotary lobed type positive displacement compressor. In alternate embodiments, the compressor can operate on a different principle, such as a rotary compressor, a piston compressor, a screw compressor, a scroll compressor, or a centrifugal compressor. In a specific embodiment, the working fluid can be a refrigerant incorporating entrained oil. In a further specific embodiment, the working fluid can be a hydrogen fluorocarbon (HFC) refrigerant, such as r-134a, incorporating entrained oil, such as miscible lubricating oils. Examples of such miscible lubricating oils that can be used are mineral oils, Polyalkylene Glycol (PAG) oil, Alkylbenzene oil, and Polyol Ester (POE) oil.
In accordance with embodiments of the subject invention, proper compressor lubrication and operation is achieved by the oil-entrained working fluid vapor entering the compressor. Preferred embodiments can achieve proper compression lubrication without an oil separation mechanism and without the need for an oil sump to collect the separated oil. In accordance with embodiments of the subject invention, the oil-vapor mixture remains as a mixture upon entering and exiting the compressor within a flow path that does not allow significant amounts of, if any, oil to collect, so as to reduce the mass flow rate of oil entrained in the oil-entrained working fluid entering the compressor in a way so as to not adequately lubricate the compressor independent of the orientation of the compressor, with respect to the surrounding gravitational field.
The oil-vapor flow path can be achieved by actively minimizing the internal volumes of the compressor that can potentially fill with separated oil. When oil fills into such internal volumes, the oil loses contact with the working fluid due to the localized reduction in vapor velocity through the internal volume of flow path such that the oil in such internal volumes does not remain entrained with the working fluid vapor. By reducing the amount of internal volume that oil can reside so as to avoid the forces of the moving working fluid vapor, enough of the oil by volume is circulated in the working fluid though the vapor compression cycle and entrained in the flow path for the working fluid vapor and oil mixture at the compressor inlet and outlet, such that proper compressor lubrication can be achieved. In specific embodiments, more than 70%, more than 80%, and more than 90%, respectively, of the oil by volume is circulated in the working fluid through the vapor compression cycle and entrained in the flow path for the working fluid vapor, independent of the orientation of the compressor with respect to the surrounding gravitational field. In further embodiments, the amount of the lubricating oil entrained in the working fluid vapor, or oil mass flow rate, at any orientation of the compressor with respect to the surrounding gravitational field is at least 80%, at least 90%, and at least 95%, respectively, of the maximum amount of the lubricating oil entrained in the working fluid vapor, or maximum oil mass flow rate, where the maximum amount of the lubricating oil entrained in the working fluid, or maximum oil mass flow rate vapor is achieved at one or more orientations of the compressor, or vapor compression cycle system, that results in a maximum mass flow rate of lubricating oil being entrained in the working fluid vapor. In this way, the mass flow rate of oil entrained remains within a certain range of a maximum mass flow rate of oil, based on the mass flow rate of oil in the compressor, or vapor compression cycle system, and the design of the compressor, or vapor compression cycle system, respectively.
Achieving sufficient velocity for the working fluid vapor can ensure the movement of the working fluid vapor keeps the oil entrained in the working fluid vapor through the compressor from the compressor inlet (or suction side) to the compressor outlet (or discharge side). Sufficient fluid velocities also ensure proper oil propagation in the flow path connecting the compressor to the components incorporated in the vapor compression cycle. The relationship of the pressure differential between the input to the compressor and the output of the compressor, the volume of the flow path from the input of the compressor to the output of the compressor, the length of the flow path from the input of the compressor to the output of the compressor and the cross-sectional area of the flow path can assure the adequacy of the velocity of the working fluid vapor through the flow path through the compressor. In a specific embodiment using r-134a as a working fluid, the compressor and compressor flow path is designed to achieve a working fluid vapor velocity of 0.1 m/sec to 5 m/sec, so as to entrain the lubricating oil in the flowing working fluid vapor. In specific embodiments, using r-134a as a working fluid, an oil-entrained working fluid vapor velocity of at least 2 m/sec; of at least 3 m/sec; and in a range of 5-7 m/sec, is achieved. In addition, the structure of the vapor fluid flow path can be designed to maintain the velocity of the oil-entrained working fluid vapor above the minimum vapor velocity to maintain oil entrainment in the oil-vapor mixture. Straight sections of the internal flow path are preferred and smooth surfaces are preferred. The typical operating surface Roughness Average (Ra) range varies from 16 micro-inch Ra (ground) to 250 micro-inch Ra (milled), with a typical value of 63 micro-inch Ra (milled). If a bend in the vapor flow path cannot be avoided, slower curving angles, such as less than 60 degrees, are preferred to sharper angles, which include those angles greater than 60 degrees from the fluid direction. In specific embodiments, the operating flow path angles remain in the range 20-45 degrees. Fluid vapor flow path angles can incorporate radii of curvature that keep the working fluid flowing smoothly. In specific embodiments, the radii of curvature is greater than 0.025″, and greater than 0.050″.
In order to maintain an adequate oil-vapor mixture velocity, compressor internal volumes, often unavoidable during manufacture and compressor assembly, can be partially, or completely, filled. Internal volumes that can cause oil to be removed from the flow can be minimized, when possible, prior to manufacture. Empty volumes inside the compressor can be avoided during construction of the compressor and flow path, or can be filled with various filler materials, such as metals, epoxies, plastics, and rubbers once construction is complete. With few, if any, empty volumes or pockets for the oil to collect, the oil remains mixed with the refrigerant vapor as it travels to and from the compressor, and results in an oil mass flow balance across the compressor and the entire vapor compression cycle. The mass flow rate of oil that enters the compressor is equivalent to the mass flow rate of oil that exits the compressor and requires no oil separation mechanism.
In further embodiments, the flow path of the working fluid and oil outputted from the compressor into a vapor compression cycle system can be designed using the same techniques previously mentioned to reduce or eliminate empty spaces that can gather oil in a way that would impact the oil entrained in the working fluid entering the compressor. Preferably, the mass flow rate of oil that exits the compressor flows through the flow path and enters the compressor independent of the orientation to the surrounding gravitational field. In a specific embodiment, the mass flow rate of oil that enters the rest of the vapor compression system from the output port of the compressor is equal to the mass flow rate of oil that enters the input port of the compressor from the vapor compression system and the vapor compression system does not include any means of active oil separation, thus enabling gravitational independence. In this way, oil does not build up in internal volumes connected to the flow path when the vapor compression cycle system is in a first orientation, so as to be removed from the flow through the flow path, and then release back into the flow path when the orientation of the vapor compression cycle system is changed to a second orientation. After compression, the oil-vapor mixture is then directed to the next component in the vapor compression cycle. Components of a vapor compression cycle system can include, for example, a condenser, an expansion device, an evaporator, one or more filters, one or more receivers, one or more accumulators, one or more by-pass valves, and one or more interconnection tubes or other interconnection apparatus. In a specific embodiment, the working fluid and oil are outputted by the compressor, pass through a condenser, then pass through an expansion device, and finally pass through an evaporator before being inputted back into the compressor.
Embodiments of the subject invention can enable proper compressor operation largely, or completely, independent of compressor orientation with respect to the gravitation field. Orientation independence is accomplished by maintaining adequate oil lubrication in many, if not all, possible geometric orientations by removing the oil separation mechanisms, oil sumps, oil bypass and bleed lines, and other means of oil separation incorporated in conventional compressors. With embodiments of the subject invention, the oil and vapor remain mixed through the implementation of a clearly defined oil-vapor flow path by filling in, reducing, and/or eliminating, empty volumes for oil collection to occur. Removing the oil separation mechanisms that are gravity dependent allows proper compressor operation independent of the compressors orientation, whether vertical, horizontal, or in any other orientation angle.
Embodiments of the subject invention pertains to a method and apparatus for an orientation independent compressor. Embodiments of the subject invention also relate to a method and apparatus for an orientation independent vapor compression cycle system. The subject compressor can be part of a basic vapor compression cycle system using one or more of a variety of working fluids including, but not limited to, one or more gases, such as nitrogen, oxygen, hydrogen, and air, gas mixtures, and/or refrigerants such as hydrogen fluorocarbon (HFC) refrigerant, r-134a, r-22, CO2, or NH3. The compressor can utilize positive displacement means to compress the vapor. In a specific embodiment, the compressor can incorporate an oil-lubricated rotary lobed type positive displacement compression. In a specific embodiment, the working fluid can be a refrigerant incorporating entrained oil. In a further specific embodiment, the working fluid can be a refrigerant, specifically r-134a, containing entrained oil, such as miscible lubricating oils. Examples of such miscible lubricating oils that can be used are mineral oils, Polyalkylene Glycol (PAG) oil, Alkylbenzene oil, and Polyol Ester (POE) oil. The compressor requires oil for adequate lubrication so as to properly perform. A properly performing compressor is one in which required power and oil-vapor flow output are within acceptable levels needed for overall vapor compression cycle system operation. Inadequate lubrication can lead to higher required power, in addition to reduced flow output, both of which are unacceptable to proper performance. If a compressor is continued to operate with inadequate oil lubrication, compressor component accelerated wear and ultimately component failure can occur.
With respect to specific embodiments of the subject invention, proper compressor lubrication and operation is achieved without any oil separation mechanism and without an oil sump to collect the separated oil. This is in contrast to conventional compressors in which oil is contained and re-circulated between the compressor 50 and the oil separation mechanism after being separated and collected into an orientation dependent, gravity-fed oil sump or other gravity dependent oil storage vapor compression cycle component or device. By removing the oil separation mechanism needed to lubricate the compressor, orientation independence is achieved. While maintaining the oil-vapor mixture in the compressor as a mixture without any active oil separation mechanism either in the flow path first segment 30 leading to the inlet or the flow path second segment 35 leading to the outlet of the compressor in a clearly defined flow path, embodiments of the subject compressor is able to properly perform in any position, such as vertical, horizontal, or any other angled orientation. Specific embodiments can allow proper performance independent of angular rotation of the subject compressor as well as independent of the angle the compressor makes to the gravitational field.
In an embodiment, the oil-vapor mixture is kept as a mixture and is constrained within a clearly defined flow path by filling in empty volumes in the flow path after construction and actively minimizing the internal volumes in the design of the flow path prior to construction of the compressor, which can potentially fill with separated oil, such as when the localized vapor velocity falls below the minimum requirement to maintain oil entrainment. In an embodiment, this minimum is 2-3 m/s. In an embodiment, after filling in and minimizing empty internal volumes within the flow path, the sum of all the empty volumes in the flow path where the velocity is not enough to entrain the oil is less than 20 percent of the total value of the volume of the oil charge.
Empty volumes inside the compressor can be filled with various filler materials, such as metals, epoxies, plastics, rubbers, or any other filler material that is compatible with the mixture that is used in the particular vapor compression system 80. During the design phase, the internal structure of the flow path is preferably designed to avoid vapor velocities below the acceptable minimum, by, for example, including but not limited to, minimizing the number of sharp directional changes, such as directional changes greater than 70 degrees; incorporating radii of curvature for any flow path angles i with a radii of 0.050 in. or greater; and yielding operating surfaces 19 having finishes on internal parts, with an operating surface 19 having a finish value or Roughness Average (Ra) in the range of 16 (ground) to 250 micro-inch Ra (milled). With few, or no, empty volumes or pockets for the oil to collect by actively and properly designing the internal flow path and filling in any empty volumes remaining after construction, the oil remains mixed with the refrigerant vapor as it travels to and from the compressor 50 and results in an oil mass flow balance across the compressor, preferably without an oil separation mechanism. The mass flow rate of oil that enters the compressor is equivalent to the mass flow rate of oil that exits the compressor, which is equivalent to the mass flow rate of oil that enters the rest of the vapor compression system 80 from the oil-flow balanced compressor and the mass flow rate of oil that returns to the compressor from the vapor compression system.
After compression, the oil-vapor mixture can then be directed to the next component in the vapor compression system. In specific embodiments, the same techniques of filling in and minimizing the internal volumes in the compressor flow path are applied to the components of the vapor compression system as well, such that the vapor compression system becomes gravity and orientation independent in the same manner as the orientation independent compressor. Further, in addition to being orientation independent with respect to the surrounding gravitational field, embodiments of the subject compressor and/or vapor compression cycle system can be orientation independent with respect to acceleration of the compressor and/or vapor compression cycle system. Specific embodiments can be orientation independent with respect to accelerations up to 2 times gravity, 3 times gravity, and 5 times gravity, respectively.
By minimizing empty volumes for oil to accumulate, the oil charge becomes critical as there is no oil separation mechanism and no sump or other extra spaces to collect any excess oil added to the vapor compression system. In a specific embodiment, the oil mass flow rate can range from 0.1-10% of the vapor mass flow rate, with the range for a further specific embodiment of approximately 1-2% of the vapor mass flow rate. An adequate oil quantity present in the oil-vapor mixture allows proper compressor performance, and can ensure proper operation of other components in the vapor compression system. A shortage of oil can result in improper compressor performance due to inadequate lubrication. However, excess oil, as a percentage of the vapor mass flow rate, can lead to performance degradation on other components in the vapor compression cycle system, such as a heat transfer reduction in the evaporator and/or condenser.
The oil-entrained working fluid vapor is input into a compressor head input port 12, is compressed within the compressor head, and is output from the compressor head output port. In this way, in specific embodiments, the oil-entrained working fluid vapor can have an input pressure in the range of 20 to 100 psi upon entry of the compressor head and in the range of 150 to 350 psi upon exiting the compressor head. Other ranges can also be achieved for the input and output pressures. In specific embodiments, the output pressure to input pressure ratio can vary from 1.5 to 17.5. In specific embodiments, the differential between output pressure and input pressure can vary from 50 psi to 330 psi.
An embodiment of a compressor 50 in accordance with the subject invention is shown in
After the oil-vapor mixture travels through the inlet manifold 7, the oil-vapor mixture can enter into the compression housing 8, through a compressor head input port 12, and can be subsequently compressed by the compressor rotary lobe 9. The compressed oil-vapor mixture can then be outputted out of the compressor head output port 18 and passed through the outlet manifold 10. In the specific embodiment, the oil-vapor mixture is guided through a flow path in the outlet manifold 10 by filling in any extra volume with aluminum. The compressed oil-vapor mixture can then be exited through the outlet 11, or output port, of the compressor and can be directed to further vapor compression system 80 components without any oil separation or accumulation having taken place within the compressor. The mass flow rate of oil that was entrained in the vapor at the inlet of the compressor 1 is equivalent to the mass flow rate of oil that is entrained in the vapor at the outlet 11 of the compressor 50. This oil mass balance then enables orientation independent operation, as many, if not all, empty spaces in 3, 7, and 10 were actively filled in with material to clearly define the non-separated, oil-vapor mixture flow path.
In the embodiment shown in
Empty volumes for oil to gather can also be reduced or eliminated in other components of the vapor compression cycle system, such as a condenser, an expansion device, an evaporator, and/or interconnecting tubes or other interconnection apparatus, such that these additional components and the flow path, having at least a first segment 30 and a second segment 35, connecting the components to the compressor head do not gather oil in a way that makes the vapor compression cycle system's performance dependent on the orientation of the system with respect to the surrounding gravitational field.
Various embodiments of the subject invention can incorporate one or more of the following taught by U.S. Pat. No. 7,010,936: an evaporator, a compressor, a condenser, and a vapor compression cycle system, where the one or more components allow orientation independent operation of the vapor compression cycle system in accordance with the subject invention. In a particular embodiment, any of the compressors of
Evaporator 700, shown in
In an embodiment, referring to
To reduce the vibrations caused by the mass of the rotor spinning eccentrically in the compressor, a counter balance 635 can be placed on the main shaft. A second rotor can be used to balance the compressor. In embodiment the second rotor can be positioned 180° out of phase with the first rotor so as to counter balance the rotating force. The addition of the second rotor adds complexity to the compressor, but can double the mass flow rate for a given RPM speed. Shaft seals and bearings can be used along the shaft to assist in sealing and to absorb the loads caused by the rotating parts. External sealing can be achieved by the shaft seals and gaskets 614 and 628 while internal sealing of the compression chambers can be accomplished using, for example, a sealing gasket 622 or o-ring.
In an embodiment, referring to
The condenser can be, for example, a general purpose heat exchanger. On a first side of the heat exchanger the compressed hot refrigerant gas can flow and on a second side of the heat exchanger an external fluid can flow. Typically, ambient air or water can be used on the second side of the heat exchanger. The heat is transferred between the two fluids via dividing wall 870 such that an external fluid flowing on the outer surface, or heat transfer surface 880, of dividing wall 870 will remove heat from dividing wall which has absorbed from the refrigerant flowing through the condenser. The design of the subject condenser can involve optimizing the heat transfer between the two fluids flowing on either side of dividing wall 870.
All patents, patent applications, provisional applications, and publications referred to or cited herein are incorporated by reference in their entirety, including all figures and tables, to the extent they are not inconsistent with the explicit teachings of this specification.
It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application.
The present application claims the benefit of U.S. Provisional Application Ser. No. 61/115,429, filed Nov. 17, 2008, which is hereby incorporated by reference herein in its entirety, including any figures, tables, or drawings.
| Number | Name | Date | Kind |
|---|---|---|---|
| 1569499 | Emil | Jan 1926 | A |
| 1896081 | Hampson | Feb 1933 | A |
| 1896953 | Hassell | Feb 1933 | A |
| 1974317 | Steenstrup | Sep 1934 | A |
| 2566865 | Wingerter | Sep 1951 | A |
| 2768508 | Guyton | Oct 1956 | A |
| 2920463 | Gould | Jan 1960 | A |
| 3152455 | Ware | Oct 1964 | A |
| 3200480 | Heuer | Aug 1965 | A |
| 3214087 | Luck | Oct 1965 | A |
| 3248020 | Spalding | Apr 1966 | A |
| 3529432 | Nussbaum | Sep 1970 | A |
| 3555848 | Johnson | Jan 1971 | A |
| 3558248 | Parker | Jan 1971 | A |
| 3877247 | Le Couturier | Apr 1975 | A |
| 3926008 | Webber | Dec 1975 | A |
| 4287724 | Clark | Sep 1981 | A |
| 4300630 | Trojani | Nov 1981 | A |
| 4555915 | Dasher | Dec 1985 | A |
| 4630669 | Kessler et al. | Dec 1986 | A |
| 5097897 | Watanabe et al. | Mar 1992 | A |
| 5452585 | Pincus et al. | Sep 1995 | A |
| 5502983 | Dasher | Apr 1996 | A |
| 5511384 | Likitcheva | Apr 1996 | A |
| 5570583 | Boehde et al. | Nov 1996 | A |
| 5660050 | Wilson et al. | Aug 1997 | A |
| 5950445 | Wang | Sep 1999 | A |
| 5974828 | Guerand | Nov 1999 | A |
| 6056891 | Goble | May 2000 | A |
| 6370775 | Reagen et al. | Apr 2002 | B1 |
| 6499534 | Tawney et al. | Dec 2002 | B1 |
| 7010936 | Rini et al. | Mar 2006 | B2 |
| 20060267600 | Beatty | Nov 2006 | A1 |
| 20070086904 | Gray | Apr 2007 | A1 |
| 20080245127 | Staffend | Oct 2008 | A1 |
| 20100043631 | Hamlin | Feb 2010 | A1 |
| 20100132382 | Rini | Jun 2010 | A1 |
| Number | Date | Country |
|---|---|---|
| 131220 | Mar 1947 | AU |
| 106312 | Jan 1925 | CH |
| 160351 | May 1905 | DE |
| 848656 | Sep 1952 | DE |
| 0438922 | Jul 1991 | EP |
| 971287 | Jan 1951 | FR |
| 1158943 | Jun 1958 | FR |
| 1590923 | Jun 1981 | GB |
| 2107852 | May 1983 | GB |
| Entry |
|---|
| Li, Q. et. al. “Heat Transfer and Pressure Drop Characteristics in Rectangular Channels with Elliptic Pin Fins,” International Journal of Heat and Fluid Flow, 1998, pp. 245-250, vol. 19. |
| Ogura, I., “The Ogura-Wankel compressor-Application of Wankel Rotary Concept as Automotive Air Conditioning Compressor,” International Congress & Exposition, Feb. 22-26, 1982, Detroit, Michigan. |
| XP001187086, “Advanced Lightweight Microclimate Cooling System (ALMCS),” Natick Soldier Center, Dec. 19, 2001. |
| XP001187087, “Portable Vapor-Compression Cooling System (PVCS),” Natick Soldier Center, Dec. 19, 2001. |
| International Search Report for International Application No. PCT/US2003/030113, dated Jul. 15, 2004. |
| Number | Date | Country | |
|---|---|---|---|
| 20100132382 A1 | Jun 2010 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61115429 | Nov 2008 | US |
