Abstract:
A device for separating gas and liquid from a mixture of gas and liquid phases includes a fluid guide member comprising a fluid inlet and a fluid outlet connected by a conduit configured as an elongated spiral disposed about an axis. A liquid coalescing medium is disposed on an exterior surface of the fluid guide radially outward from the elongated spiral conduit with respect to the axis. The separator also includes a plurality of radial channels providing radial flow paths for fluid from the elongated spiral conduit to the coalescing medium.

Description:
BACKGROUND 
       [0001]    The separation of gas and liquid phases from mixtures comprising gas and liquid phases is practiced across a wide variety of applications and materials. Gas-liquid phase separation is used in the oil and gas industry, various chemical manufacturing and treatment processes, heating and cooling applications, fuel management systems, and numerous other applications. For example, in many chemical manufacturing and treatment processes, liquid and gas phases are separated and directed along different paths for further individual processing or treatment. 
         [0002]    Many known gas-liquid separators utilize a coalescing medium such as a screen mesh or other porous medium to separate gas and liquid phases. During operation of such gas-liquid separators, as a gas-liquid mixture makes contact with the coalescing medium, liquid becomes engaged with the coalescing medium. The coalescing medium is typically oriented such that as liquid accumulates on the coalescing medium, liquid droplets become larger until their mass becomes sufficiently high that the force of gravity acting on the droplets causes them to migrate downward through or along the coalescing medium until they reach a collection point at the bottom of the coalescing medium. Such separators, however, are not effective in environments where gravitational forces are either not available (e.g., microgravity environments such as outer space) or are subject to interference (e.g., by changes in momentum when the separator is in motion such as on a motor vehicle or aircraft). 
       BRIEF DESCRIPTION 
       [0003]    According to some embodiments, a device for separating gas and liquid from a mixture comprising gas and liquid phases comprises a fluid guide member comprising a fluid inlet and a fluid outlet connected by a conduit configured as an elongated spiral disposed about an axis. A liquid coalescing medium is disposed on an exterior surface of the fluid guide radially outward from the elongated spiral conduit with respect to the axis. The separator also includes a plurality of radial channels providing radial flow paths for fluid from the elongated spiral conduit to the coalescing medium. 
         [0004]    In some embodiments, a method of separating gas and liquid from a mixture comprising gas and liquid phases, comprising introducing the mixture to the fluid inlet of the above-described gas-liquid separator, receiving a gas-depleted phase at a radially outer surface of the coalescing medium, and receiving a liquid-depleted phase at the fluid outlet. 
         [0005]    According to some embodiments, a heat transfer system comprises a heat transfer fluid flow loop. The heat transfer fluid flow loop comprises an evaporator heat exchanger comprising a heat absorption side comprising a fluid inlet and a fluid outlet for the heat transfer fluid. The evaporator is configured to absorb heat from a conditioned space to vaporize a liquid phase of the heat transfer fluid. A condenser heat exchanger comprising a heat rejection side includes a fluid inlet in fluid communication with the evaporator heat absorption side outlet, and a fluid outlet for the heat transfer fluid. The condenser is configured to reject heat to a heat sink to condense a gas phase of the heat transfer fluid. The heat transfer system also includes a gas-liquid separator. The gas-liquid separator comprises a fluid guide member comprising a fluid inlet in fluid communication with the condenser heat rejection side outlet, and a fluid outlet. The separator&#39;s fluid inlet and fluid outlet are connected by a conduit configured as an elongated spiral disposed about an axis. A liquid coalescing medium is disposed on an exterior surface of the fluid guide radially outward from the elongated spiral conduit with respect to the axis. The separator also includes a plurality of radial channels providing radial flow paths for fluid from the elongated spiral conduit to the coalescing medium. The heat transfer system also includes a pump comprising a fluid inlet in fluid communication with the fluid guide member fluid outlet, and a fluid outlet in fluid communication with the evaporator heat absorption side inlet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Subject matter of this disclosure is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0007]      FIG. 1  is a schematic depiction in a perspective view of an example embodiment of a gas-liquid separator; 
           [0008]      FIG. 2  is a perspective cross-section view of the gas-liquid separator of  FIG. 1 ; 
           [0009]      FIG. 3  is a magnified view of a portion of the perspective cross-section of  FIG. 2 ; 
           [0010]      FIG. 4  is a magnified view of a portion of a perspective cross-section of the gas-liquid separator of  FIG. 1 , taken on a different parting line than  FIGS. 2 and 3 , through the radial channels; 
           [0011]      FIG. 5  is a cross-section view of a schematic representation of a multilayer coalescing medium; 
           [0012]      FIG. 6  is a perspective view of an example embodiment of a gas-liquid separator that includes a liquid collection chamber; and 
           [0013]      FIG. 7  is a schematic depiction of a heat transfer system including a gas-liquid phase separator. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    With reference now to the Figures,  FIGS. 1-4  schematically depict the details of an example embodiment of a gas-liquid separator  10 . As shown in  FIGS. 1-4 , a fluid mixture  12  comprising a gas and a liquid is shown entering the inlet of a guide member  14 . Guide vanes  15  deflect the flow of the fluid mixture  12  and redirect it from an axial flow parallel to the axis  16  to a circumferential flow into conduit  18  disposed as an elongated spiral about the axis  16 . It should be noted that the guide vanes are optional, and the fluid mixture  12  can be allowed to flow into the elongated spiral conduit  18  without assistance from any guide vanes, although an abrupt 90° turn from axial flow to circumferential flow can cause unwanted turbulence and pressure drop. In some embodiments (not shown), the fluid can enter or exit the guide member  14  from a direction perpendicular to the axis so that it is flowing more or less straight into the inlet to elongated spiral conduit  18 . It should also be noted that although  FIGS. 1-4  depict only a single elongated spiral conduit  18 , a plurality of parallel elongated spiral conduits can be utilized. 
         [0015]    As the fluid flows through the elongated spiral conduit  18 , centrifugal force acts on both the gas and liquid components of the fluid, and the density difference between the gas and liquid results in the centrifugal force preferentially directing the liquid component radially outward compared to the gas. The action of the centrifugal force drives the fluid radially outward through the plurality of radial channels  20 , which direct the fluid into contact with a coalescing medium  22  disposed on the outer surface of the guide member  14 . The internal surfaces of the elongated spiral conduit  18 , the coalescing medium  22 , and other surfaces in contact with the fluid can be formed from or treated with materials that provide a surface that is wettable by liquid component of the fluid. Wettable surfaces can include cleaned metals, plastics, and polymers, any of which may be chemically and/or physically treated. A surface is considered wettable or non-wettable by a particular liquid depending on the contact angle between the liquid and the surface. A small contact angle (e.g., &lt;90°) means the surface is wettable, and a large contact angle (e.g., &gt;90°) means the surface is not wettable and vice versa. Different chemical treatments (such as low to mid concentrations acid etching and cleaning) and physical treatments (such as laser scanning and coating) can be employed to alter the contact angle to make the surface wettable or non-wettable. The treatment processes is highly dependent of the liquid and surface being used. In some embodiments, this can provide a technical effect of promoting liquid flow in a layer along the surface(s) and gas flow through open spaces away from the liquid layer. In some embodiments, the radial flow paths provided by the radial channels become narrower as the fluid flows from the elongated spiral conduit  18  to the coalescing medium  22 . In some embodiments, such a configuration can provide a technical effect of enhancing liquid phase adhesion to the porous media (coalescing medium) utilizing the surface tension of the liquid that promote phase separation. An example embodiment of such narrowing is depicted in cross-sectional view of  FIG. 4  along a parting line through a group of the radial channels  20 , where it is seen that the radial channels  20  have a relatively larger cross-sectional area at the interface with the elongated spiral conduit  18 , and a relatively smaller cross-sectional area at the interface with the coalescing medium. 
         [0016]    The coalescing medium can selected from any of a wide variety of porous media, including but not limited to mesh screens or pads made of various materials such as metal or plastic, woven or non-woven fiber pads, open-cell foams made of various materials such as metal, plastic, or composite materials. The dimensions of the coalescing medium can vary depending on the specific properties of the liquid (e.g., density, surface tension properties, etc.) and the gas, and on process design parameters including but not limited to mass flow rates and flow velocities. In some embodiments, the dimensions or materials of the coalescing medium can vary axially along the axis  16  to accommodate different conditions as the fluid flows along the elongated spiral conduit. In some embodiments, the dimensions or materials of the coalescing medium can vary radially. For example, the coalescing medium can have larger openings (e.g., coarser mesh) relatively closer to the axis  16  and smaller openings (e.g., finer mesh) relatively farther from the axis  16 . In some embodiments (e.g., as depicted in an example embodiment in  FIG. 5 ), the coalescing medium  22  can comprise a first screen mesh layer  23 , and a second screen mesh layer  25  radially outward from the first screen mesh layer and having a finer mesh size than the first screen mesh layer. In some embodiments, the coalescing medium can comprise a third screen mesh layer  27  disposed between the first and second screen mesh layers and having a finer mesh size than the first screen mesh layer  23  and a courser mesh size than the second screen mesh layer  25 . In some embodiments, the first screen mesh layer can have a mesh size of 20 μm to 50 μm, the second screen mesh layer can have a mesh size of 1 μm to 5 μm, and the third screen mesh layer can have a mesh size of 5 μm to 20 μm. 
         [0017]    As the fluid flows along through the elongated spiral conduit  18 , the liquid phase is depleted as it flows out through the radial channels  20 , resulting in a liquid-depleted phase  24  exiting from the guide member  14 . The length of the elongated spiral conduit  18 , the number and configuration of the radial channels  20 , and the configuration of the coalescing medium  22  can be specified according to design parameters to produce the desired degree of gas- and liquid-depletion in the two phases exiting the gas-liquid separator  10  at anticipated operating conditions. A gas-depleted phase can be collected from the coalescing medium  20 , for example by accumulation in axial grooves  26  disposed on the outer surface of the gas-liquid separator  10 . In some embodiments, the gas-depleted predominantly liquid phase can be allowed to accumulate in a chamber  28  surrounding the coalescing medium  20  or the gas-liquid separator  10  as shown in  FIG. 6 , with or without the use of axial grooves  26 . As shown in  FIG. 6 , a housing  30  is disposed around the gas-liquid separator  10 , providing a chamber  28  for accumulation of a liquid or gas-depleted phase, which can exit the chamber  28  as fluid stream  32 . 
         [0018]    The gas-liquid phase separator described herein can be utilized in a variety of environments and applications. In some embodiments, the gas-liquid phase separator can be disposed in a microgravity environment, where it can in some embodiments provide phase separation without moving parts and without assistance from gravity. In some embodiments, the gas-liquid phase separator can be utilized in a heat transfer system such as a two-phase heat transfer system. In some embodiments, the heat transfer system is disposed in a microgravity environment. An example embodiment of a two-phase heat transfer system  34  is schematically depicted in  FIG. 7  where fluid flow paths are indicated by arrowed lines connecting the described components. As shown in  FIG. 7 , a pump  36  pumps a heat transfer fluid in a liquid phase to the heat absorption side of an evaporator heat exchanger  38  where heat (e.g., from a conditioned space, not shown) is absorbed as the liquid heat transfer fluid is vaporized. The heat transfer fluid can be any type of fluid having target thermodynamic properties, including but not limited to water, ammonia, or organic solvents (e.g., R134A). The vaporized heat transfer fluid is transported from the evaporator heat exchanger  38  to the heat rejection side of a condenser heat exchanger  40  where the vaporized heat transfer fluid is condensed to a liquid phase and heat is rejected to a heat sink (not shown, e.g., an external space such as an outdoor space for terrestrial applications or outer space for extra-terrestrial outer space applications). Under normal operating conditions, the design parameters of the condenser heat exchanger  40  are expected to fully condense the vaporized heat transfer fluid, and the liquid phase heat transfer fluid is directed along bypass flow path  42  to the inlet of pump  36 . Under some operating conditions, however, the condenser heat exchanger  40  may not fully condense the vaporized heat transfer fluid, resulting in a two-phase flow of heat transfer fluid exiting the heat rejection side of condenser heat exchanger  40 . Such conditions can occur, for example, when the heat load applied at the evaporator heat exchanger  38  exceeds system design parameters such as during startup or other high heat load conditions, or when the heat absorbing capacities of the heat absorption side of the condenser heat exchanger  40  are reduced below design parameters such as when the heat sink temperature increases. The latter can occur, for example, in an outer space application where the spacecraft is re-oriented such that the condenser heat exchanger  40  is exposed to solar radiation. A two-phase gas-liquid fluid can cause cavitation at the pump  36 , potentially resulting in damage to the pump. Accordingly, in conditions where a two-phase heat transfer fluid exits the heat rejection side of condenser heat exchanger  40 , the flow of the heat transfer fluid can be routed to the gas-liquid phase separator  10  where the vapor phase is removed as liquid-depleted or vapor stream  24 , and a vapor-depleted or liquid stream  32  is directed to the inlet of pump  36 . The liquid-depleted or vapor stream  24  can be recirculated to the inlet of the gas-liquid phase separator  10  or can be stored in a storage vessel (not shown) until normal operating conditions resume, at which time any vapor that has not condensed in the storage vessel can be routed to the inlet of the gas-liquid phase separator  10 . 
         [0019]    While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the present disclosure. Additionally, while various embodiments of the present disclosure have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments. Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.