Abstract:
A conditioner for conditioning fuel passing therethrough includes a deoxygenator having a body in which oxygen is removed from the fuel, and a heat exchanger attaching directly to the body for moderating a temperature of the fuel.

Description:
BACKGROUND 
       [0001]    The present invention relates to stabilizing fuel by deoxygenation, and more particularly to a heat exchanger fuel stabilization unit. 
         [0002]    Fuel is often utilized in aircraft as a coolant for various aircraft systems. The presence of dissolved oxygen in hydrocarbon jet fuels may be objectionable because the oxygen supports oxidation reactions that yield undesirable by-products. Dissolution of air in jet fuel results in an approximately 70 ppm oxygen concentration. When aerated fuel is heated between 350 degrees F. (or 177 degrees C.) and 850 degrees F. (or 454 degrees C.), the oxygen initiates free radical reactions of the fuel resulting in deposits commonly referred to as “coke” or “coking”. Coke may be detrimental to the fuel lines and may inhibit combustion. The formation of such deposits may impair the normal functioning of a fuel system, either with respect to an intended heat exchange function or the efficient injection of fuel. 
         [0003]    Various conventional fuel deoxygenation techniques are currently utilized to deoxygenate fuel. Typically, lowering the oxygen concentration to 2 ppm is sufficient to minimize coking problems. 
         [0004]    One conventional Fuel Stabilization Unit (FSU) utilized in aircraft removes oxygen from jet fuel by producing an oxygen pressure gradient across a membrane permeable to oxygen. The FSU includes a plurality of fuel plates sandwiched between permeable membranes and porous substrate plates disposed within a housing. Each fuel plate defines a portion of the fuel passage and the porous plate backed permeable membranes define the remaining portions of the fuel passages. The permeable membrane includes Teflon or other type of amorphous glassy polymer coating in contact with fuel within the fuel passages for preventing the bulk of liquid fuel from migrating through the permeable membrane and the porous plate. 
         [0005]    The use of a plurality of similarly configured flat plates increases manufacturing efficiency and reduces overall cost. Further, the size and weight of the FSU is substantially reduced while increasing the capacity for removing dissolved oxygen from fuel. Moreover, the planar design is easily scalable compared to previous tubular designs. 
       SUMMARY 
       [0006]    According to an embodiment disclosed herein a conditioner for conditioning fuel passing therethrough includes a deoxygenator having a body in which oxygen is removed from the fuel and a surface, and a heat exchanger attaching directly to the body and conforming to the surface for moderating a temperature of the fuel. 
         [0007]    According to a further embodiment disclosed herein, a fuel system for an energy conversion device includes a deoxygenator having a body in which oxygen is removed from the fuel and a surface; a heat exchanger attaching directly to the body and conforming to the surface for moderating a temperature of the fuel; no upstream heat exchanger attaching to the heat exchanger attaching directly to the body; and, no downstream heat exchanger attaching directly to the heat exchanger attaching directly to the body. 
         [0008]    According to an embodiment disclosed herein, a method for conditioning fuel in a fuel system includes the steps of providing a deoxygenator having a body in which oxygen is removed from the fuel and a surface; attaching a heat exchanger directly to the body and conforming to the surface for providing a first temperature of the fuel; not attaching an upstream heat exchanger to the heat exchanger attaching directly to the body; and, not attaching a downstream heat exchanger to the heat exchanger attaching directly to the body. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
           [0010]      FIG. 1  is a schematic, prior art block diagram of an energy conversion device (ECD) and an associated fuel system employing a fuel deoxygenator; 
           [0011]      FIG. 2  is a schematic sectional view of a portion of the prior art deoxygenator system illustrating a single fuel plate and a single oxygen permeable membrane; 
           [0012]      FIG. 3  is an schematic view of the deoxygenator system illustrating a multiple of fuel plates and oxygen permeable membranes in conjunction with a heat exchanger therefor; 
           [0013]      FIG. 3A  is a cut-away schematic view of the deoxygenator system taken along the line  3 A- 3 A of  FIG. 3 ; 
           [0014]      FIG. 4  is a schematic view of a deoxygenator system with a laminated heat exchanger; and, 
           [0015]      FIG. 5  a general schematic block diagram of an associated fuel system employing a fuel deoxygenator in accordance with the embodiments disclosed herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]      FIG. 1  illustrates a general schematic view of a prior art fuel system  10  for an energy conversion device (ECD)  12 . A plate-type deoxygenator system  14  receives liquid fuel F from a reservoir  16  such as a fuel tank. The fuel F is typically a hydrocarbon such as jet fuel. The ECD  12  may exist in a variety of forms in which the fuel, at some point prior to eventual use for processing, for combustion or for some form of energy release, acquires sufficient heat to support autoxidation reactions and coking if dissolved oxygen is present to any significant extent in the fuel. 
         [0017]    One form of the ECD  12  is a gas turbine engine, and particularly such engines in high performance aircraft. Typically, the fuel also serves as a coolant for one or more sub-systems in the aircraft and becomes heated as it is delivered to fuel injectors immediately prior to combustion. 
         [0018]    A heat exchange section  18  represents a system through which the fuel passes in a heat exchange relationship. It should be understood that the heat exchange section  18  may be directly associated with the ECD  12  and/or distributed elsewhere in the larger system  10 . The heat exchange system  18  may alternatively or additionally include a multiple of heat exchangers distributed throughout the system. For instance a heat exchange unit  19  may be distributed upstream of the deoxygenator system  14 . 
         [0019]    As generally understood, fuel F stored in the reservoir  16  normally contains an unacceptable level of dissolved oxygen therein, possibly at a saturation level as high as 70 ppm. A fuel pump  20  draws the fuel F from the reservoir  16 . The fuel pump  20  communicates with the reservoir  16  via a fuel reservoir conduit  22  and a valve  24  to a fuel inlet  26  of the deoxygenator system  14 . The pressure applied by the fuel pump  20  assists in circulating the fuel F through the deoxygenator system  14  and to other portions of the fuel system  10  including the upstream heat exchanger  19 . As the fuel F passes through the deoxygenator system  14 , oxygen is selectively removed into a sweep gas/vacuum system  28 . 
         [0020]    The deoxygenated fuel Fd flows from a fuel outlet  30  of the deoxygenation system  14  via a deoxygenated fuel conduit  32 , to the heat exchange system  18  and to the ECD  12  such as the fuel injectors of a gas turbine engine (not shown). A portion of the deoxygenated fuel may be recirculated, as represented by recirculation conduit  33  to either the deoxygenation system  14  and/or the reservoir  16 . It should be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit from the instant invention. 
         [0021]    Referring to  FIG. 2 , the prior art deoxygenator system  14  can include a multiple of gas/fuel micro-channel assemblies  34  which may include an oxygen permeable membrane (not shown) between a fuel channel (not shown) and an oxygen receiving channel including either a vacuum or a sweep gas (not shown). It should be understood that the channels may be of various shapes and arrangements to provide a pressure differential, which maintains an oxygen concentration differential across the membrane to deoxygenate the fuel. The deoxygenator system  14  includes a top plate  45  and a bottom plate  50  that are connected via bolts or other connectors  55  to the gas/fuel micro-channel assemblies  34  to maintain the rigidity of the gas/fuel micro-channel assemblies  34 . The top plate  45  includes a conduit  57  that connects to the sweep gas/vacuum system  28 . Though the deoxygenator system  14  shown herein is of a plate type, one of ordinary skill in the art will recognize that other types of deoxygenator systems may benefit from the teachings herein. 
         [0022]    Referring now to  FIGS. 3 and 3A , an embodiment of a novel deoxygenator/heat exchanger  65  is shown herein. The novel deoxygenator/heat exchanger  65  includes a heat exchanger  70  having a generally rectangular-shaped body that includes a plurality of fins  75  extending outwardly therefrom disposed atop the gas/fuel micro-channel assemblies  34  after the top plate  45  of the deoxygenator system  14  is removed. The heat exchanger  70  body conforms to a shape of the gas/fuel micro-channel assemblies  34 . Referring to  FIG. 3A , the fuel flows along path  80 , which may be sinuous, within the heat exchanger  70  under the fins  75  before entering a manifold  85  and conduits  90  that feed the gas/fuel micro-channel assemblies  34  where oxygen is removed. Though one path  80  is shown, one of ordinary skill in the art will recognized that other shaped paths may be utilized. The path  80  may be bored into the heat exchanger  70  be within an open space and finned, or be distributed across the heat exchanger  70  in every other of a series of multiple plates (see  FIG. 4 ) etc. 
         [0023]    Fuel flowing from the fuel pump  20  flows into the fuel inlet  26  and along the sinuous path  80  and absorbs heat collected by the heat exchanger surface  65  to raise the temperature of the fuel, in one example, to about 180° F. This temperature assists in the removal of oxygen via the gas/fuel micro-channel assemblies  34  without significantly raising a probability of created coke. The fuel is then sent to the upstream heat exchanger  18  and/or the ECD. This deoxygenator/heat exchanger  65  is designed to extract heat from ambient. One of ordinary skill in the art will recognize that the heat exchanger surface  70  may be placed on any portion of the deoxygenator system  14  where fuel flows before entering the gas/fuel micro-channel assemblies  34 . 
         [0024]    Referring to  FIG. 4 , another embodiment of a novel heat exchanger  95  for use with the gas/fuel micro-channel assemblies  34 , or other oxygen removal module is shown. In this embodiment, more heat, or heat from a different source than ambient, may be required before entering the fuel micro-channel assemblies  34 . In this example, top plate  45  is replaced with a heat exchanger body  100  that has an additional heat source, such as oil or heated air, input  105  and an output  110  through paths  115  that interact with path(s)  80  (see  FIG. 3A ) in plates  120  that carry fuel to transfer heat to the fuel in the plates  120 . The air or oil may be distributed into input  105  that attaches to multiple paths through multiple plates  120  or otherwise interact with the path  80  to efficiently transfer heat to the fuel. 
         [0025]    Referring now to  FIG. 5  an embodiment of a fuel system  10  is shown. Many commercial airliners operate their fuel systems at about 250 degrees F. or 121 degrees C. to minimize coking. By attaching the heat exchangers  65 / 95  or the like to the deoxygenator system  14 , several advantages accrue: the fuel F captures low grade heat from ambient via fins  75  to improve the efficiency of the deoxygenator system  65 / 95 ; the heat exchanger and the deoxygenator system  65 / 95  are one unit and space is recovered and the amount of connections are minimized, rigidity necessary to retain the gas/fuel micro-channel assemblies  34  is maintained; installation is simplified; and the size of the downstream heat exchanger  18  may be minimized or eliminated, particularly if the heat exchanger body  100  is utilized in the deoxygenator system  65 / 95 . 
         [0026]    The heat exchangers  65 / 95  may be placed near heat sources  120  such as an auxiliary power unit or the like to take advantage of waste heat emanating from the auxiliary power unit. 
         [0027]    In military or other operations where higher temperature fuel is required, the requirement to minimize coking is minimized because more maintenance is generally performed in which coke is removed routinely. The heat exchangers  65 / 95  may be required to add much more heat to the fuel (e.g. up to 400 degrees F. or 204 degrees C. more heat) in conjunction with or instead of the heat exchangers  18  and  19 . 
         [0028]    Though a system for use with an ECD  12  such as a gas turbine engine (not shown) is described herein, one of ordinary skill in the art will recognize that the teachings herein are applicable to other ECDs. 
         [0029]    The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. Thus, the scope of legal protection given to this disclosure can only be determined by studying the following claims.