Abstract:
Disclosed herein is a replaceable fuel separation unit having a permeable substrate for separating a fluid source into at least two separate fluid streams, and delivering the two separated fluid streams to separate tanks.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Ser. No. 61/502,980 filed on Jun. 30, 2011 the content of which is relied upon and incorporated herein by reference in its entirety. 
     
    
     FIELD 
       [0002]    The disclosure relates to fuel systems and fuel supply apparatus for an internal combustion engine. More particularly, the disclosure provides a fuel separation unit for containing a separation membrane. 
       BACKGROUND 
       [0003]    Fuel separation devices have been disclosed in, for example, U.S. Pat. Nos. 6,972,093 and 6,711,893. A fuel separation unit can accept a mixed feed stream, deliver the mixed feed stream to a permeable substrate, and separate the mixed feed stream into two streams, a retentate and a permeate. The feed stream can be a gas or a liquid. For example, If the separation unit is used to separate fuel such as gasoline, a mixed feed stream such as a fuel having a mixture of components can be heated and introduced to the fuel separation unit as a gas. The fuel can be separated into, for example, a relatively high Research Octane Number (RON) fuel portion and a relatively low RON fuel portion. The separated high RON fuel (the permeate) can then be cooled and delivered to a separate tank, to be used by the automobile when needed. An automobile may require high RON fuel during a high-output operation state such as at start up or upon acceleration. By providing a source of high RON fuel, the engine can perform better during high-output operation, For example, the ignition timing of the engine can be advanced, thereby increasing the output of the engine during these high-output operations. 
       SUMMARY 
       [0004]    In a first embodiment, the disclosure provides a replaceable fuel separation unit comprising: a permeable substrate having a first end face, a second end face, a plurality of parallel channels extending from the first end face to the second end face, and an outer surface; a first housing structured and arranged to contain the permeable substrate, having an internal surface, the first housing comprising a first end plate and a second end plate, the first end plate comprising a first fluid passage and a first end plate seal structured and arranged to form a seal between the first end plate and the permeable substrate at or near the first end face of the permeable substrate, the second end plate comprising a second fluid passage, a permeate outlet, and a second end plate seal structured and arranged to form a seal between the second end plate and the permeable substrate at or near the second end face of the permeable substrate and a connector seal structured and arranged to form a releasable seal with a connector plate; a permeate chamber comprising a space formed between the outer surface of the permeable substrate and the internal surface of the first housing, wherein the permeate chamber is separated from the end faces of the permeable substrate by the first end plate seal and the second end plate seal. 
         [0005]    In a second embodiment, the disclosure provides the separation unit of embodiment 1 wherein the first fluid passage is an inlet and the second fluid passage is a retentate outlet. 
         [0006]    In a third embodiment, the disclosure provides the separation unit of embodiment 1 wherein the first fluid passage is a retentate outlet and the second fluid passage is an inlet. 
         [0007]    In a fourth embodiment, the disclosure provides the fuel separation unit of any one of embodiments 1-3 wherein the connector plate comprises fittings to releasably attach the housing containing the permeable membrane to an inlet and a permeate outlet. 
         [0008]    In a fifth embodiment, the disclosure provides the fuel separation unit of embodiment 4 wherein the housing is secured to the connector plate by a compression fitting. 
         [0009]    In a sixth embodiment, the disclosure provides the fuel separation unit of embodiment 4 wherein the housing is secured to the connector plate by a screw-fitting. 
         [0010]    In a seventh embodiment, the disclosure provides the fuel separation unit of any one of embodiments 1-6 further comprising the connector plate. In an eighth embodiment, the disclosure provides the fuel separation unit of embodiment 7 wherein the connector plate comprises an inlet, a permeate outlet and a retentate outlet. 
         [0011]    In a ninth embodiment, the disclosure provides the fuel separation unit of any one of embodiments 1-8 wherein the connector plate comprises at least one groove for containing at least one seal. 
         [0012]    In a tenth embodiment, the disclosure provides the fuel separation unit of any one of embodiments 1, 2 or 3, wherein at least one of the first end plate and the second end plate of the first housing comprises a manifold and wherein the seal formed between at least one of the first end plate and the second end plate and the permeable substrate is formed between the manifold and the permeable substrate. 
         [0013]    In an eleventh embodiment, the disclosure provides the fuel separation unit of claim any one of embodiments 1, 2, 4-9, further comprising a second housing structured and arranged to provide a retentate chamber between an outer surface of first housing and an inner surface of second housing. 
         [0014]    In a twelfth embodiment, the disclosure provides the separation unit of any one of embodiments 1-11 wherein the permeable substrate comprises a porous ceramic material. 
         [0015]    In a thirteenth embodiment, the disclosure provides the separation unit of embodiment 12 wherein the permeable substrate is cylindrical. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a schematic representation of an embodiment of the replaceable separation unit as a part of an octane separation system. 
           [0017]      FIGS. 2A  and B are cross-sectional views illustrating two embodiments of a replaceable fuel separation unit. 
           [0018]      FIG. 3  is an illustration of an additional embodiment of a replaceable fuel separation unit. 
           [0019]      FIG. 4  is an exploded view of the embodiment of a replaceable fuel separation unit shown in  FIG. 3 . 
           [0020]      FIGS. 5A and 5B  are a plan view and a cross-sectional view of the placement of a replaceable fuel separation unit seated on a connector plate, in an embodiment. 
           [0021]      FIGS. 6A and 6B  are a plan view and a cross-sectional view of the placement of a replaceable fuel separation unit seated on a connector plate, in another embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    In embodiments, the disclosure provides a replaceable separation unit having a housing structured and arranged to contain a permeable substrate. The housing is structured and arranged to receive a feed stream and direct the feed stream to a permeable substrate having parallel channels extending from a first end face to the second end face of the permeable substrate. In use, a portion of the feed stream flows from one end face of the permeable substrate to the second end face of the permeable substrate through the channels of the permeable substrate. The portion of the feed stream that flows through the channels of the permeable substrate, and exits the permeable substrate through the second end face, is the retentate. The housing provides a retentate outlet to direct the retentate to a retentate tank. 
         [0023]    Another portion of the feed stream passes across a separation membrane, into the permeable substrate and is separated from the feed stream to travel through the body of the permeable substrate, to exit through the outer surface of the permeable substrate into a permeate chamber. This feed stream that flows through the permeable substrate is the permeate. The permeate chamber has a permeate outlet to direct the permeate to a separate permeate tank. In this way, a retentate fuel stream is separated from a permeate fuel stream. 
         [0024]    The housing contains the permeable substrate, and also defines a retentate and a permeate flow path. Fluid traveling through the retentate flow path begins at an inlet, travels through the permeable substrate, and exits the separation unit to flow through a retentate outlet, to be captured in a retentate tank. Fluid traveling through a permeate flow path begins at the inlet, travels through the permeable substrate through the channels of the substrate, exits the separation unit to flow through a permeate outlet, to be captured in a permeate tank. 
         [0025]    In addition, the separation unit is structured and arranged to releasably engage with a connector plate to allow for the replacement of one separation unit with another separation unit when the useful life of the permeable substrate expires. In embodiments, the inlet and the retentate outlet are fluid passages, a first fluid passage and a second fluid passage that can be interchangeable, depending upon the orientation of the separation unit with respect to the direction of fuel flow. However, in embodiments, the inlet and the retentate outlet are on opposite end plates of the housing, enabling retentate fluid to flow from one end of the housing to the other end of the housing through the channels of the permeable substrate. The permeate outlet can be on either end face of the housing. In embodiments, the permeate outlet is on the housing end face that engages with the connector plate. 
         [0026]    In embodiments, the separation unit is easily replaceable. In order to replace a separation unit, the existing unit must be removed by disengaging the separation unit from the fluid passages. There are three fluid passages, the inlet, the retentate outlet and the permeate outlet. Therefore, three fluid passage need to be disengaged and re-engaged in order to replace the separation unit. To reduce the number of steps required to replace the separation unit, the permeate outlet can be on the end face of the housing that engages with the connector plate. By locating the permeate outlet on the end face of the housing that engages with the connector plate, the number of connections that must be disengaged and re-engaged when a part is swapped is reduced from three to two, making the separation unit more easily replaceable. 
         [0027]    In embodiments, the feed stream is gasoline. In this embodiment, gasoline can be separated into a higher RON fraction (HiRON) and a lower RON fraction (LoRON) by pervaporation across a polymer membrane applied on the internal surfaces, the channel surfaces, of the permeable substrate. Higher RON fractions, pass across a pervaporation membrane, flow into the permeable substrate and then flow into the permeate chamber. From the permeate chamber, the higher RON permeate can flow through the permeate outlet, through an optional cooler, and collect in a permeate tank. Lower RON fractions flow through the channels of the permeable substrate without passing across the pervaporation membrane, and exit the permeable substrate through the retentate outlet, to be delivered to a retentate tank, or re-circulated into the gasoline tank of the automobile. 
         [0028]      FIG. 1  illustrates an embodiment of a system for separating gasoline by octane in a vehicle.  FIG. 1  illustrates a fuel tank  10  having a separate compartment  11  to contain HiRON fuel. As shown in  FIG. 1 , gasoline is pumped from the fuel tank  10 , through a fuel heater  12  to heat the fuel to a gas phase, and into the separation unit  100 . In the separation unit, fuel is separated into a LoRON stream  15  (retentate) and a HiRON stream  16  (permeate). The HiRON stream passes through an optional fuel cooler  20  and into the separate fuel tank compartment (the HiRON tank or the permeate tank)  11 . The HiRON fuel can then be pumped from the separate fuel tank compartment  11  to the engine  25  when needed. LoRON fuel exits the separation unit  100 , passes through the optional fuel cooler  20  and is recirculated back to the fuel tank  10 . Fuel from the fuel tank can be pumped to engine  25 . 
         [0029]    Embodiments of the separation unit are shown in  FIGS. 2-6 . In embodiments a permeable substrate  110 , for example a ceramic honeycomb having a polymeric membrane to separate high-octane or HiRON components from lower octane or low RON components is provided. The polymeric membrane may be applied to the interior surfaces of the channels  115  of the ceramic honeycomb substrate. In this system, fuel, which is a mixture of HiRON and LoRON fuel is provided to the polymeric membrane. HiRON fuel is separated by the polymeric membrane, passes across the polymeric membrane, and flows into the permeable ceramic material of the permeable substrate. HiRON fuel (permeate) is then directed to a permeate outlet, and sent through a separate permeate fuel line, to a separate HiRON fuel tank. LoRON fuel does not pass through the polymeric membrane, and flows through the channels of the permeable substrate to exit the separation device through a retentate outlet, to be recirculated back to the first fuel tank. 
         [0030]    The permeable substrate is contained in a housing  130 . The fuel separation system must operate in an environment of fluctuating temperatures and caustic chemicals. From time to time, over the lifetime of a gasoline powered vehicle, in order to maintain the performance of the fuel separation system, the fuel separation unit must be replaced. For example, the fuel separation unit may need to be replaced at least once, and potentially several times, over the lifetime of the vehicle. In embodiments, the permeable substrate may be removed by itself. That is, in embodiments, the housing may be opened, the permeable substrate may be removed, a new permeable substrate may be placed in the unit, and the housing may be replaced. However, because of the structure of the fuel separation unit, and because of the complexity of the housing, it may be desirable to remove and replace the permeable substrate  110  along with its housing  130 . Therefore, it is important that an easily replaceable separation unit be developed. 
         [0031]    Reference will now be made in detail to embodiments of the present invention, as illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. 
         [0032]      FIGS. 2A  and B show embodiments of the fuel separation unit  100  of the present invention. The replaceable fuel separation unit has a permeable substrate  110  and a housing  130 . In embodiments, the permeable substrate  110  has a first end face  111  and a second end face  112 , an outer surface  113 , and channels  115  running from the first end face  111  to the second end face  112 . In embodiments, the outer surface of the permeable substrate is continuous. As shown in  FIG. 1 , the permeable substrate  110  is sealed by a seal  120  at or near the first end face  111 . While seal  120  is shown seated at a peripheral edge  125  of the first end face, seal  120  can be placed around the outer surface  113  of the permeable substrate, at or near first end face  111 . Seal can be contained in a seat or groove (see, for example,  123  in  FIG. 2B ). Similarly, the permeable substrate  110  is sealed at or near the second end face  112  by seal  121 . While seal  121  is shown seated at a peripheral edge  126  of the second end face  112 , seal  121  can be placed around the outer surface  113  of the permeable substrate, at or near second end face  112 . In embodiments, the seal is placed at or near the end faces in order to ensure that a large percentage of the outer surface of the permeable substrate is available to allow for the flow of permeate from the inner surfaces of the permeable substrate to the outer surface of the permeable substrate. 
         [0033]    In embodiments, the housing of the separation unit may be made from any suitable material. In embodiments, the housing and the connector plate are resistant to temperature fluctuations and chemical environments predictable from the contemplated use of the separation unit. For example, the housing(s) and connector plate may be made from metal. 
         [0034]    The housing has a first fluid passage  150  and a second fluid passage  160 . In embodiments, fluid flows in the direction shown by arrows. As shown in  FIG. 2A , Retentate fluid flows in the second fluid passage  160  (I), through the channels of the permeable substrate to the first fluid passage  150  (the Ro passage, or the retentate outlet). Or, fluid flows in the second fluid passage (I), through the walls of the permeable substrate to the permeate chamber, and leaves the housing through the permeate outlet, Po. The retentate outlet (Ro) directs the flow of fluid exiting the channels of the permeable substrate out of the separation unit. The permeate outlet (Po) directs the flow of fluid exiting the permeate chamber out of the separation unit to a separate tank. Referring back to  FIG. 1 , the retentate outlet directs the flow of LoRON  15  (retentate) from the separation unit  100  to the optional fuel cooler  20 . First fluid passage, labeled in  FIG. 2A  as Retentate outlet Ro,  150  provides a connection between the separation unit and a fuel line. While first fluid passage  150  is shown as a nut, which indicates a compression-type fitting, this connection can be any type of releasable connection including a screw fitting, a pressure fitting, snap fitting, or any other known connection system. Second fluid passage  160 , labeled in  FIG. 2A  as inlet (I), provides fuel to the permeable substrate. Second fluid passage  160  is a structure which engages with connector plate  200 . 
         [0035]    In embodiments, as shown in  FIG. 2B , the direction of flow through a separation unit may be reversed. For example, In  FIG. 2A , fluid is illustrated as flowing into the unit at the unit&#39;s bottom end (I) through second fluid passage  160  and out of the housing through first fluid passage  150 . In  FIG. 2B , fluid is illustrated flowing into the unit at the unit&#39;s top end (I) through first fluid passage  150  and out of the unit at the unit&#39;s bottom end through second fluid passage  160 . In both embodiments, fluid flows into the unit, retentate flows through the channels of the permeable substrate and out through the Ro fluid passage, and permeate flows into the channels of the permeable substrates, passes into the permeable substrate, into the permeate chamber, and out through the Po fluid passage. The same separation unit may accommodate both directions of flow, and accomplish the task of separating fluid. The direction of flow can be determined by the placement of the unit in a fuel line. 
         [0036]    The fuel separation unit  100  has a housing  130 . In embodiments, housing  130  is a “first housing.” In embodiments (such as the embodiments shown in  FIG. 3  and  4 ), the fuel separation unit  100  may comprise more than one housing. As shown in  FIGS. 2A and 2B  housing  130  is structured and arranged to contain the permeable substrate  110 . Housing  130  has an internal surface  131 , a first end plate  132 , a second end plate  133  and a sidewall  134 . As illustrated in  FIGS. 2-6 , the housing is cylindrical, so that there is a first end plate  132 , a second end plate  133  and one sidewall forming the cylindrical body of the housing. However, in embodiments, the housing, and the permeable substrate contained within the housing, may be any shape. For example, the housing and the permeable substrate may be cube-shaped, cuboid, conical, prismatic, or any other shape. 
         [0037]    In embodiments, a seal  120  is present between the permeable substrate and the housing. In embodiments, the seal is a gasket, an o-ring, a fitting, a bead of seal material, or any other structure or material known in the art that may be useful to form a seal between the permeable substrate and the housing. Seal  120  prevents retentate from mixing with permeate. Seal  120  provides a barrier between the retentate flow path and the permeate flow path. 
         [0038]    In embodiments, housing  130  may have a manifold  140 . In embodiments, the manifold is a structure, extending into the internal space formed by the housing, to create a contained (and, together with the seal, a sealed) space between an end face of the permeable substrate and an inlet or an outlet. For example, as illustrated in  FIG. 2A , a manifold  140  forms a contained space defined by the first end face  111  of the permeable substrate  110  and the first fluid passage  150  and separated from a permeate chamber  145 . The manifold may be present (as shown in  FIG. 2A ) or absent (as shown in  FIG. 2B ).  FIG. 2A  illustrates an embodiment of the manifold  140 . In  FIG. 2A , the manifold is a structure that extends from an internal surface of the first end plate (not shown) of the housing  130 . In the embodiment illustrated in  FIG. 2A , the manifold  140  provides a structure to seat a seal  120 , formed between the permeable substrate  110  and the manifold  140  and the first fluid passage  150 , and the permeate chamber  145 . A manifold may be present at either end face of the permeable substrate, at both end faces of the permeable substrate, at one end face of the permeable substrate, or absent. 
         [0039]      FIG. 2B  illustrates an embodiment of the housing without a manifold. In this embodiment, seal  120  is provided between the permeable substrate and the internal surface (not shown) of the first end plate  132  of the housing  130 . 
         [0040]    A seal  122  is also formed between the second end face  112  of the permeable substrate  110  and the second end plate  133  of the housing  130 . In embodiments, a manifold may be present between the second end plate  133  and the permeable substrate (not shown). 
         [0041]    The second end plate has a second fluid passage  160 . Second fluid passage  160  allows fluid (fuel) to flow into the channels of the permeable substrate  110  (or out of the channels, depending upon the direction of fuel flow). In embodiments, the external surface of second fluid passage  160  has male threading to allow the inlet to releasably engage with and seal against a connector plate  200 . As shown in  FIGS. 2A and 2B , second end plate  133  may have seats or grooves  123  for containing seals or gaskets. In additional embodiments, connector plate  200  may have grooves or other structures for containing seals or gaskets (not shown). That is, the seals  122  may be part of the housing, part of the connector plate, or a separate part. 
         [0042]    When the permeable substrate is placed inside the housing and the seals are placed at or near the first and second end faces of the permeable substrate, a permeate chamber  145  is formed between the outer surface  113  of the permeable substrate  110  and the internal surface  131  of the housing  130 . The permeate chamber has a permeate chamber outlet  146 . The permeate chamber outlet  146  may be in the second end plate  133  of the housing  130  as shown in  FIG. 2A  and  FIG. 2B . There may be multiple permeate chamber outlets  146  (as shown in the exploded view of  FIG. 4 ). Permeate chamber outlets are structured and arranged to allow permeate to flow from the permeate chamber and out of the fuel separation device through the connector plate permeate outlet(s) marked Po. In embodiments, a seal  122  may be present between the housing  130  and the connector plate  200  to ensure a liquid-tight seal, and a seal to hold a vacuum between the housing  130  and the connector plate  200 . 
         [0043]    In embodiments, a pressure gradient may be formed between the permeate chamber  145  and, for example, second fluid passage  160 . In embodiments, a vacuum is applied in the permeate chamber  145 . In embodiments, vacuum may be applied through the connector plate permeate chamber outlet(s) (Po). This pressure gradient acts to pull permeate through the permeable substrate and deliver it to the permeate outlet. 
         [0044]    Also illustrated in  FIGS. 2A  and B is a connector plate  200 . The connector plate  200  is structured and arranged to releasably engage with housing  130  of separation unit  100 . The connector plate  200  has a baseplate inlet  210 . In embodiments, the baseplate inlet is internally threaded to allow the threaded housing inlet to screw into the baseplate at the inlet. Although threading is described, those of ordinary skill will understand that other methods of releasable attachment and sealing are well known in the art. These include snap fittings, pressure fittings, and other releasable attachment mechanisms. The connector plate also has a permeate outlet  220  to allow fluid that is captured in the permeate chamber of the separation unit  100  to exit the separation unit through the permeate chamber outlet, and through the connector plate permeate outlet  220 . In embodiments, the connector plate is a part of the separation unit. In additional embodiments, the connector plate is separate from the separation unit, and is a structure that is part of the automobile&#39;s fuel system. For example, in the gasoline separation system illustrated in  FIG. 1 , the connector plate could be a part of the automobile&#39;s fuel system. If a separation unit is to be installed into an automobile, the housing containing the permeable substrate could be installed or releasably sealed against the connector plate. If the separation unit is to be replaced, the old separation unit can be removed (unscrewed) from the connector plate and a new separation unit installed. If a separation unit is not intended to be used, a fuel line could be installed between the baseplate inlet  210  and outlet  150 . In addition, the connector plate is structured and arranged to engage with the permeate outlet of the housing to provide a fluid flow passage between the permeate outlet. Fuel lines or other structures can provide a fluid flow passageway between the permeate outlet (Po) and the auxiliary fuel tank (see  11 ,  FIG. 1 ). 
         [0045]      FIG. 3  illustrates an additional embodiment of the separation unit of the present invention.  FIG. 3  illustrates a separation unit having a first housing  330  and a second housing  340 . The first housing contains permeable substrate  110  having an outer surface  113 . A permeate chamber  345  is formed between the internal surface  331  of the first housing  330  and the outer surface  113  of the permeable substrate  110 . Seals  120  and  121  are present between the permeable substrate and the first housing at or near the first end face and the second end face of the permeable substrate. First housing  330  has a first fluid passage  150 . First fluid passage  150  of first housing  330  opens into a retentate chamber  350  formed between the outer surface  332  of first housing  330  and the inner surface  341  of second housing  340 . 
         [0046]    In this embodiment, fluid flows into the separation unit, as shown by the upwardly pointing arrow (“I”) in  FIG. 3 , flows through the separation unit, and exits the separation unit as retentate (through first fluid passage  150  and retentate outlet or Ro) and permeate (through Permeate outlet or Po) according to the downwardly pointing arrows of  FIG. 3 . 
         [0047]      FIG. 3  illustrates fluid flow pathways in embodiments of the separation unit  100 . Because the permeable substrate is sealed by seals  120  and  121  at or near its first end face and at or near its second end face, fluid can only flow through the separation unit in two flow paths. Fluid can flow through the inlet (I) in the second end plate  133  into the permeable substrate  110 , through the channels  115  of the permeable substrate  110 , through the first end face  111  of the permeable substrate  110 , through the optional manifold  140 , and out of the housing (or the first housing  330 ) of the separation unit through the first fluid passage  150 . In the embodiment illustrated in  FIG. 3 , retentate flows from the first fluid passage  150  of first housing  330  into a retentate chamber  350  formed between the outer surface  332  of first housing  330  and the inner surface  341  of second housing  340 . Retentate then exits the separation unit through the retentate chamber outlet  180  and the connector plate retentate outlet  221 . 
         [0048]    Or, fluid can flow into the separation unit  100  through second fluid passage  150  (“I” in  FIG. 3 ), into the permeable substrate  110  at the second end face  112  of the permeable substrate  110 , across the separation membrane, through the permeable substrate body  110 , into the permeate chamber  345  ( 145  in  FIGS. 2A and 2B ), and out of the separation unit through the permeate outlet Po ( 145  in  FIGS. 2A and 2B ). 
         [0049]      FIG. 4  is an exploded view of the embodiment of the separation unit as shown in  FIG. 3 .  FIG. 4  illustrates the second housing  340 , the first housing  330  having the first end plate  132 , the manifold  140  which sits inside the second housing, the first seal  120  which forms a seal between the permeable substrate  110  and the manifold  140  (or, in the absence of a manifold, the first seal  120  forms a seal between the permeable substrate and the interior surface of the first end plate  132 ) the permeable substrate  110 , the second seal  121  which forms a seal between the permeable substrate  110  and the second end plate  133  (or, in the presence of a second manifold, the second seal  121  forms a seal between the permeable substrate and the second manifold), the second end plate  133  having permeate or permeate chamber outlets  146  and an second fluid passage  150  which can be threaded to engage with the connector plate inlet  210 , a third seal  123  and a fourth seal  122  which form seals between the second end plate  133  and the connector plate  200  to form a defined space to separate the permeate chamber  345  from the retentate chamber  350  and to separate the permeate outlet  220  from the retentate outlet  221 . 
         [0050]    The flow of fluid is illustrated by the arrows. For example, permeate flows into the separation unit (I), into the permeable substrate  110 , out through the outer surface  113  of the permeable substrate  110 , into the permeate chamber (see  345  of  FIG. 3  or  145  of  FIGS. 2A and 2B ), and then through the permeate chamber outlets  146 , into the space formed between third seal  123  and fourth seal  122 , and then out of the connector plate (Po) through connector plate permeate outlet  220  (see Po,  FIG. 3 ). Retentate flows into the separation unit (I), through the channels of the permeable substrate  110 , through the first fluid passage  150  of the first housing  330 , into retentate chamber  350  (not shown), which is the space formed between the outer surface  332  of first housing  330  and the inner surface  341  (not shown) of second housing  340 . Retentate then exits the separation unit through the connector plate retentate outlet  221 . In this way, a single stream of fluid is separated into a retentate (which may be, for example, LoRON) and a permeate (which may be, for example, HiRON). 
         [0051]      FIGS. 5A and 5B  are a plan view and a cross-sectional view of the placement of a housing of the present invention seated on a connector plate  200 , in a seat  500 , in an embodiment. As shown in  FIGS. 5A and 5B , the housing  101  containing the permeable membrane  110  can be fitted onto the connector plate  200 , contained in a seat  500 , against seals  122  and  123 , by forming a compression seal using, for example, a bolt  400 . In embodiments (see  FIGS. 2A  and B) the housing may be threaded onto the connector plate  200  prior to seating the connector plate into the seat  500 . In additional embodiments, the housing may be separated from the connector plate, forming flow pathways for permeate and retentate, by the use of seals such as sealing rings, O-rings, gaskets or the like. In embodiments, the fuel separation unit housing is secured to the seat by a compression fitting. 
         [0052]      FIGS. 6A and 6B  are a plan view and a cross-sectional view of the placement of a housing of the present invention engaged on a connector plate, in another embodiment. As shown in  FIGS. 6A and 6B , housing  101  may have a flange  102  that extends outwardly from the connector plate-end of the housing  101 . The connector plate has screws  230 . The flange  500  has apertures to allow screws  230  to be threaded through the flange  500 , which can be tightened with nuts  501 . In this embodiment, a compression fitting can be provided between the housing and the connector plate. 
         [0053]    While the invention has been described in the accompanying figures, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the invention.