Abstract:
One embodiment of the present invention is a unique method for operating an engine. Another embodiment is a unique engine system. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for engines and engine systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to engines, and more particularly engines that are supplied with reformed fuel, and methods for operating such engines. 
       BACKGROUND 
       [0002]    Engine systems that effectively use reformed fuel remain an area of interest. Some existing systems have various shortcomings, drawbacks, and disadvantages relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology. 
       SUMMARY 
       [0003]    One embodiment of the present invention is a unique method for operating an engine. Another embodiment is a unique engine system. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for engines and engine systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
           [0005]      FIG. 1  schematically illustrates some aspects of a non-limiting example of an engine system in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0006]    For purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nonetheless be understood that no limitation of the scope of the invention is intended by the illustration and description of certain embodiments of the invention. In addition, any alterations and/or modifications of the illustrated and/or described embodiment(s) are contemplated as being within the scope of the present invention. Further, any other applications of the principles of the invention, as illustrated and/or described herein, as would normally occur to one skilled in the art to which the invention pertains, are contemplated as being within the scope of the present invention. 
         [0007]    Referring to  FIG. 1 , some aspects of a nonlimiting example of an engine system  10  in accordance with an embodiment of the present invention are schematically illustrated. Engine system  10  is configured for reduced NO x  emissions by employing a reformer to generate hydrogen (H 2 ) as part of a hydrogen assisted lean operation scheme. Engine system  10  includes an engine  12  and a fuel delivery system  14 . In one form, engine  12  is an internal combustion engine, e.g., a spark-ignition piston engine. In other embodiments, engine  12  may take other forms, e.g., a gas turbine engine, or another type of reciprocating engine. Engine  12  includes, among other things, an air intake  16  and a combustion chamber  18 . In various embodiments, air intake system  16  may be pressurized by a compressor (not shown), e.g., a turbocharger, a supercharger and/or any other type of compressor. In one form, combustion chamber  18  is a pre-combustion chamber positioned upstream of and in fluid communication with one or more main combustion chambers, e.g., piston combustion chambers or, e.g., a precombustion zone in or coupled to gas turbine engine combustion chambers. In other embodiments, combustion chamber  18  may be or include one or more main combustion chambers, e.g., a main piston engine combustion chamber or a main gas turbine engine combustion chamber. 
         [0008]    In one form, fuel delivery system  14  is an auxiliary fuel delivery system that delivers to engine  12  only a portion of the fuel consumed by engine  12  during engine  12  operations, whereas the balance of fuel is supplied by a main fuel system (not shown). In other embodiments, fuel delivery system  14  may supply most or all of the fuel consumed by engine  12  during engine  12  operations. In one form, fuel delivery system  14  includes a compressor  20  operative to receive an oxidant from an oxidant source  22 ; a fuel flow control valve  24  operative to receive and regulate a flow of fuel from a fuel source  26 , a merging chamber  32  and a reformer  34 . In one form, oxidant source  22  is air pressurized by an engine  12  compressor (not shown), e.g., a compressor used to pressurize engine air intake  16 . Compressor  20  is configured to increase the pressure of the oxidant to above the pressure at the engine air intake. In other embodiments, oxidant source  22  may be, for example and without limitation, ambient air or oxygen-enriched air or nitrogen enriched air. In one form, fuel source  26  is a source of pressurized fuel, for example and without limitation, compressed natural gas (CNG). In other embodiments, other fuels may be employed, e.g., other hydrocarbon fuels, pressurized or not. Where fuel source  26  is not pressurized, a pump or compressor may be included to pressurize the fuel received from fuel source  26 . Fuel flow control valve  24  is configured to control the amount of fuel supplied to fuel delivery system  14 , or more particularly, to reformer  34 . In embodiments, where fuel source  26  is not pressurized, fuel flow control valve  24  may include a pump or compressor or may be a pump or compressor. 
         [0009]    Merging chamber  32  is in fluid communication with the output of compressor  20  and fuel flow control valve  24 , and is configured to receive and combine the fuel and oxidant and discharge a feed mixture containing both the fuel and the oxidant. The oxygen to carbon molar ratio (substantially the same as the volume ratio under anticipated operating conditions) supplied to reformer  34  may vary with the needs of the application, and may be, for example and without limitation, in the range of 0.5 to 2. The corresponding oxygen content of the oxidant may be, for example and without limitation, 5% to 50% by molar ratio (e.g., volume ratio). Reformer  34  is configured to receive the feed mixture and to reform the feed mixture into a reformed fuel having flammables, including primarily hydrogen (H 2 ) and carbon monoxide (CO), and methane slip, e.g., 0.25%-3%, and trace amounts of higher hydrocarbon slip, such as ethane. The total flammables content of the reformed fuel, associated with the corresponding ranges immediately above, may be, for example and without limitation, in the range from near 0% to approximately 80%. In various embodiments, other gases in various proportions may be included in the reformed fuel in varying amounts, e.g., depending on the oxidant/fuel ratio of the feed stream supplied to reformer  34 , including, for example and without limitation, nitrogen (N 2 ), carbon dioxide (CO 2 ), also small amounts of steam. The form of merging chamber  32  may vary with the needs of the application. For example, in one form, merging chamber  32  is a simple plumbing connection joining the oxidant stream with the fuel stream. In various embodiments, any arrangement that is structured to combine an oxidant stream with a fuel stream, with or without mixing, may be employed. In some embodiments, a mixing chamber, e.g., having swirler vanes to mix the streams, may be employed, e.g., as part of merging chamber  32  or disposed downstream of merging chamber  32 . 
         [0010]    Reformer  34  is in fluid communication with merging chamber  32 , and is operative to receive the fuel and oxidant from merging chamber  32 . In one form, reformer  34  is a catalytic reactor having a catalyst  36 . Catalyst  36  may be any catalyst suitable for reforming a gaseous hydrocarbon fuel with an oxidant. Some suitable catalysts include, for example and without limitation, an active material including group VIII noble metals, such as Pd, Pt, Rh, Ir, Os and Ru. A carrier may be employed in conjunction with the catalyst, e.g., a high surface area carrier, including, for example and without limitation, stabilized alumina, zirconia and/or silica-alumina. A catalyst support may also be employed, for example and without limitation, pellets in a fixed bed arrangement, or a coated monolith or honey comb support, e.g., formed of a metallic or refractory. One suitable refractory is cordierite. In a particular form, reformer  34  is a catalytic partial oxidation (CPOX) reformer configured to reform the fuel with the oxidant using catalyst  36 . In other embodiments, other types of reformers may be employed. Combustion chamber  18  is in fluid communication with reformer  34 . Disposed downstream of reformer  34  is a temperature sensor  38 . Temperature sensor  38  is configured to sense the temperature of the reformed fuel after it exits reformer  34 . A sense line  40  electrically couples temperature sensor  38  to fuel flow control valve  24 . In other embodiments, sense line  40  may be an optical or wireless link. Fuel flow control valve  24  is configured to control the amount of fuel supplied to reformer  34  based on the temperature of the gases, e.g., the reformed fuel, exiting the reformer  34 . 
         [0011]    In various embodiments, fuel delivery system  14  includes one or more additional components, which may include one or more of a cooler  42 , a junction  44 , a check valve  46 , a junction  48 , a check valve  50 , a valve  52 , a valve  54 , a startup heating system  67  and one or more heaters  80 . Cooler  42  is configured to reduce the temperature of the reformed fuel output by reformer  34 . In one form, cooler  42  is a heat exchanger that is cooled by engine  12  coolant. In other embodiments, cooler  42  may be an air cooled heat exchanger, or may be one or more of other types of cooling systems. In embodiments so equipped, combustion chamber  18  is in fluid communication with cooler  42 , and is configured to receive the cooled reformed fuel from cooler  42 . 
         [0012]    Engine air intake  16  is in fluid communication with valve  52 , which is in fluid communication with reformer  34  and cooler  42  via junction  44 . In one form, valve  52  is a back-pressure regulating valve. In other embodiments, valve  52  may be one or more of any type of valve. Junction  44  is operative to allow the venting of some or all of the reformed fuel discharged by reformer  34  from combustion chamber  18  and direct the vented amount of the reformed fuel to another location via valve  52 , such as to engine air intake  16 , to an engine exhaust (not shown), to atmosphere, or to another venting location, including a device or application. 
         [0013]    Valve  54  is in fluid communication with fuel supply  26  and junction  48 . Junction  48  is in fluid communication with combustion chamber  18  via check valve  50 . Valve  54  is configured to selectively provide unreformed fuel to combustion chamber  18 . Check valve  46  is configured to prevent the backflow of unreformed fuel toward junction  44 , hence preventing the backflow of unreformed fuel toward reformer  34  and valve  52 . Check valve  50  is configured to prevent backflow from combustion chamber  18  into fuel delivery system  14 . 
         [0014]    Startup heating system  67  is in fluid communication with merge chamber  32 , and is configured to heat the feed mixture received from merge chamber  32  to a sufficient temperature to achieve catalytic auto-ignition of the fuel and oxidant upon its exposure to catalyst  36  in reformer  34  in order to start up reformer  34 . Startup heating system  67  includes a start control valve  69  having a valve element  70  and a valve element  72 ; and a feed mixture heater  74 . In one form, valve elements  70  and  72  are part of a combined valving element or system. The inlets of valve elements  70  and  72  are downstream of and fluidly coupled to merging chamber  32 . The outlet of valve element  70  is fluidly coupled to reformer  34  for providing the feed mixture to catalyst  36  of reformer  34 . The outlet of valve element  72  is fluidly coupled to the inlet of feed mixture heater  74 . In one form, start control valve  69  is a three-way valve that operates valve elements  70  and  72  to direct flow entering valve  69  into catalytic reactor  34  directly from merge chamber  32  and/or via feed mixture heater  74 . It is alternatively considered that other valve arrangements may be employed, such as a pair of individual start control valves in place of start control valve  69  with valve elements  70  and  72 . 
         [0015]    Feed mixture heater  74  includes a heating body  76  and a flow coil  78  disposed adjacent to heating body  76 . The outlet of feed mixture heater  74  is fluidly coupled to reformer  34  for providing heated feed mixture to catalyst  36 . In the normal operating mode, valve elements  70  and  72  direct all of the feed mixture directly to reformer  34 . In the startup mode, feed mixture is directed through feed mixture heater  74  via flow coil  78 , which is then heated by heating body  76 . In one form, all of the feed mixture is directed through feed mixture heater  74 , although in other embodiments, lesser amounts may be heated, and some of the feed mixture may be passed directly to reformer  34  from merge chamber  32 . 
         [0016]    Feed mixture heater  74  is configured to “light” the catalyst  36  of catalytic reactor  34  (initiate the catalytic reaction of fuel and oxidant) by heating the feed mixture, which is supplied to catalytic reactor  34  from feed mixture heater  74 . In one form, the feed mixture is heated by feed mixture heater  74  to a preheat temperature above the catalytic auto-ignition temperature of the feed mixture (the catalytic auto-ignition temperature is the temperature at which reactions are initiated over the catalyst, e.g., catalyst  36 ). Once catalyst  36  is lit, the exothermic reactions taking place at catalyst  36  maintain the temperature of catalytic reactor  34  at a controlled level, based on the amount of fuel and oxidant supplied to catalyst  36 . Also, once catalyst  36  is lit it may no longer be necessary to heat the feed mixture, in which case valve elements  70  and  72  are positioned to direct all of the feed mixture directly to the catalytic reactor  34 , bypassing feed mixture hearer  74 . In some embodiments, feed mixture heater  74  may be maintained in the “on” position when engine  12  is not operating, but is required to start quickly. 
         [0017]    Heaters  80  are disposed adjacent to catalytic reactor  34  and configured to heat catalyst  36 . In one form, heaters  80  are also configured to maintain catalyst  36  at a preheat temperature that is at or above the catalytic auto-ignition temperature for the feed mixture supplied to reactor  34 . This preheat temperature may be maintained during times when engine  12  is not operating, but is required to start quickly. Some embodiments may employ either or both of startup heating system  67  and heater(s)  80 . In other embodiments, it is alternatively considered that another heater  82  may be used in place of or in addition to startup heating system and heater(s)  80 , e.g., a heater  82  positioned adjacent to catalytic reactor  34  on the upstream side. Such an arrangement may be employed to supply heat more directly to catalyst  36  in order to initiate catalytic reaction of the feed mixture in an upstream portion of catalytic reactor  34 . 
         [0018]    In one form, heaters  74 ,  80  and  82  are electrical heaters, although it is alternatively considered that in other embodiments, indirect or direct combustion heaters may be employed in addition to or in place of electrical heaters. Also, although the present embodiment employs both feed mixture heater  74  and heaters  80  to rapidly light the feed mixture on the catalyst, it is alternatively considered that in other embodiments, only one such heater may be employed, or a greater number of hearers may be employed. 
         [0019]    During operation, the oxidant, e.g., air, is pressurized by compressor  20  and discharged therefrom toward merge chamber  32 . Fuel is delivered to merge point from fuel supply  26  via valve  24 , which controls the rate of flow of the fuel. The oxidant and fuel combine at merge chamber  32 , and are directed to reformer  34 . During a start cycle of engine system  10 , heating body  76  is activated, and valve elements  70  and  72  are activated by a control system (not shown) to direct fuel and oxidant through feed mixture heater  74 . In various embodiments, some or all of the fuel and oxidant feed stream may be directed through feed mixture heater  74 . Heating body  76  adds heat to the feed stream to raise its temperature to the catalytic auto-ignition temperature, i.e., a temperature sufficient for catalytic auto-ignition of the feed stream upon contact with catalyst  36 . The catalytic auto-ignition temperature may vary with the type of catalyst used and the life of the catalyst. For example, with some catalysts, such as at least some of those mentioned herein, the catalytic auto-ignition temperature may be 300° C. at the start of the catalyst&#39;s life, but may be 450° C. near the end of the catalyst&#39;s life. In various embodiments, one or more of heaters  80  and  82  may be employed to heat the catalyst and/or feed stream to a temperature sufficient for catalytic auto-ignition of the feed stream. 
         [0020]    The fuel and oxidant are reformed in reformer  34  using catalyst  36 . Temperature sensor  38  senses the temperature of the reformed fuel exiting reformer  36 . The temperature data from temperature sensor  38  is transmitted to flow control valve  24  via sense line  40 . Valve  24  controls the flow of fuel, and hence the oxidant/fuel mixture based on the sensed temperature, thus maintaining catalyst  36  at a desired temperature. The reformed fuel exiting reformer  34  is then cooled by cooler  42  and discharged into combustion chamber  18  via junctions  44  and  48  and check valves  46  and  50 . 
         [0021]    In some circumstances, such as a cold start of engine system  10 , it may be desirable to start engine  12  by supplying unreformed fuel to combustion chamber  18 , and then transition from unreformed fuel to reformed fuel as reformer  34  reaches the ability to reform the fuel. For example, in some situations, fuel is supplied to combustion chamber from fuel supply  26  via flow control valve  54 . Reformer  34  may be started before, during or after engine  12  is started, using one or more of startup heating system  67 , and heater(s)  80  and  82 , e.g., depending upon the embodiment and the needs of the particular application, and the needs of the particular start cycle, e.g., cold start vs. hot restart. Valves  24 ,  52  and  54  form a valve system that is configured to transition between 100% unreformed fuel and 0% reformed fuel being supplied to combustion chamber  18  and 0% unreformed fuel and 100% reformed fuel being supplied to the combustion chamber  18 . When reformer  34  is started, e.g., is capable of catalytic auto-ignition of the feed mixture, valves  24 ,  52  and  54 , controlled by a control system (not shown), transition from supplying 100% of the fuel being delivered to combustion chamber  18  in the form of unreformed fuel with 0% reformed fuel, to supplying 100% reformed fuel and 0% unreformed fuel to combustion chamber  18 . In one form, the transition is a gradual continuous process. In other embodiments, the transition may be a sudden transition or otherwise stepwise transition. In either case, during the transition, in some embodiments, excess reformed fuel may be vented, e.g., to engine air intake  16 , bypassing combustion chamber  18 , e.g., until the complete transition to 100% reformed fuel being supplied to the combustion chamber is made. In other embodiments, valves  24 ,  52  and  54  may modulate the flow of reformed and unreformed fuel without producing an excess of reformed fuel during the start cycle. During the start cycle, the output of compressor  20  may be varied in order to control the rate of flow of oxidant before, during and after the transition to supplying combustion chamber  18  with reformed fuel. The output of compressor  20  may also be varied during normal engine  12  operations in response to demand for reformed fuel. 
         [0022]    In one form, during normal operations of engine  12 , e.g., after engine  12  has been started and has achieved steady state operation, combustion chamber  18  is supplied with 100% reformed fuel. In other embodiments, a mixture of reformed fuel and unreformed fuel may be supplied to combustion chamber  18 . 
         [0023]    In various embodiments, fuel delivery system  14  controls the output of reformed fuel by varying the output of compressor  20  and by varying the amount of fuel delivered by valve  24  via a control system (not shown). In some embodiments, a valve (not shown) downstream of compressor  20  may be employed to be able to respond more quickly to a demand for higher or lower flow. In some embodiments, the valve may vent excess flow at lower engine  12  operating points, e.g., to intake  16 , to atmosphere, or to engine  12  exhaust. In such embodiments, upon a demand for more output from fuel delivery system  14 , the valve may be closed in order to reduce or eliminate venting. Upon a demand for decreased output from fuel delivery system  14 , the valve would increase the amount of vented oxidant. 
         [0024]    In some embodiments, it may be desirable for engine  12  to change operating points quickly, e.g., to switch from low power to high power or from high power to low power fairly quickly. In the event the particular engine  12  configuration is able to change operating points more quickly than the particular fuel delivery system  14  maximum response rate, some embodiments of fuel delivery system  14  may be configured to produce an excess of reformed fuel at a particular operating point or range of operating points in order to provide operating margin. In such embodiments and situations, the excess reformed fuel may be vented, e.g., to air intake  16  via valve  52 , bypassing combustion chamber  18 . In such embodiments, valve  52 , which is in fluid communication between reformer  34  and air intake  16 , is configured to control the amount of flow of the reformed fuel to combustion chamber  18  by bypassing a portion of the reformed fuel to air intake  16 , thereby diverting that portion of reformed fuel flow from combustion chamber  18 . 
         [0025]    In some embodiments, valve  52  is configured to increase the vented amount of the reformed fuel in response to a decrease in engine power output; and is configured to decrease the vented amount of the reformed fuel in response to an increase in engine power output. Thus, for example, if an increase in engine  12  output were commanded, the amount of flow of reformed fuel vented to air intake  16  would be reduced by valve  52  under the direction of a control system (not shown), thus increasing the amount of reformed fuel delivered to combustion chamber  18 . On the other hand, if a reduction in engine  12  output were commanded, the amount of flow of reformed fuel vented to air intake  16  would be increased by valve  52  under the direction of the control system, thus decreasing the amount of reformed fuel delivered to combustion chamber  18 . Hence, the ratio of the portion of reformed fuel supplied to combustion chamber  18  relative to the portion of reformed fuel supplied to air intake  16  may be changed so that fuel delivery system  14  may be able to respond more quickly to changes the operating point (e.g., power output) of engine  12 , and in some embodiments, without adversely affecting catalyst  36 , for example, by otherwise creating an off-design transient condition by attempting to follow demand for reformed fuel more quickly than fuel delivery system  14  can readily respond. In some embodiments, by avoiding off-design transient conditions, the adverse effects of operation at off-design transient conditions on the life of catalyst  36  may be reduced or eliminated. In addition, in some embodiments, the ability to more quickly respond to changing demand by controlling the venting of reformed fuel flow, e.g., to air intake  16 , may increase the ability of fuel delivery system  14  to respond to other changing conditions, such as a change in fuel composition, humidity or an engine or engine system component output. 
         [0026]    In some embodiments, it may be desirable to limit the amount of reformed fuel provided to air intake  16 , in which case fuel delivery system  14  may be configured to supply no reformed fuel to air intake  16  at or above a selected engine  12  operating point. In some embodiments, this may be the maximum power operating point of engine, below which reformed fuel is provided via valve  52  to air intake  16 , e.g., in proportion to the output of engine  12 , with greater amounts of reformed fuel being provided to air intake  16  at lower power points. In other embodiments, fuel delivery system  14  may be configured to supply no reformed fuel to air intake  16  at or above a other selected engine  12  operating points. In some embodiments, fuel delivery system may be configured to reduce or terminate the flow of reformed fuel to air intake  16 , e.g., once stable engine operation has been achieved. 
         [0027]    Embodiments of the present invention include a method for operating an engine, comprising: providing a combustion chamber of the engine with a fuel; starting the engine using the fuel; starting a reformer, wherein the reformer is configured to reform at least some of the fuel; transitioning from the provision of fuel to the combustion chamber to a provision of reformed fuel; and providing only reformed fuel to the combustion chamber. 
         [0028]    In a refinement, the combustion chamber is a pre-combustion chamber. 
         [0029]    In another refinement, the transitioning is performed after the reformer has reached a catalytic auto-ignition temperature. 
         [0030]    In yet another refinement, the engine is an internal combustion engine. 
         [0031]    In a further refinement, the fuel is natural gas. 
         [0032]    In a yet further refinement, the reformer is a catalytic partial oxidation (CPOX) reformer. 
         [0033]    Embodiments of the present invention include a method for operating an engine, comprising: operating a reformer to reform a fuel; supplying a first portion of the reformed fuel to a combustion chamber of the engine during engine operation; venting a second portion of the reformed fuel; wherein the first portion and the second portion are supplied to the respective combustion chamber and venting location at a first ratio; changing an engine operating condition; and supplying the first portion and the second portion to the respective combustion chamber and venting location at a second ratio in response to the change in the engine operating condition. 
         [0034]    In a refinement, the combustion chamber is a pre-combustion chamber. 
         [0035]    In another refinement, the engine is an internal combustion engine. 
         [0036]    In yet another refinement, the fuel is natural gas. 
         [0037]    In still another refinement, no reformed fuel is supplied to the venting location at or above a selected engine operating point. 
         [0038]    In yet still another refinement, the selected engine operating point is a maximum power operating point. 
         [0039]    In a further refinement, the reformer is a catalytic partial oxidation (CPOX) reformer. 
         [0040]    Embodiments of the present in engine system, comprising: an engine; a compressor operative to pressurize an oxidant; a reformer in fluid communication with the compressor and a source of fuel, wherein the reformer is configured to receive the oxidant and fuel received from the source of fuel, and to reform the fuel; a cooler in fluid communication with the reformer and configured to reduce the temperature of the reformed fuel output by the reformer; and a combustion chamber of the engine in fluid communication with the cooler, wherein the combustion chamber is configured to receive the cooled reformed fuel from the cooler. 
         [0041]    In a refinement, the reformer is a catalytic partial oxidation (CPOX) reformer. 
         [0042]    In another refinement, the combustion chamber is a pre-combustion chamber. 
         [0043]    In yet another refinement, the engine is a piston engine. 
         [0044]    In still another refinement, the engine system further comprises an engine air intake, wherein the compressor is configured to increase the pressure of the oxidant to above the pressure at the engine air intake. 
         [0045]    In yet still another refinement, the engine system further comprises an engine air intake and a valve in fluid communication between the reformer and the air intake, wherein the valve is configured to control an amount of flow of the reformed fuel to the combustion chamber by venting a portion of the reformed fuel to the air intake. 
         [0046]    In a further refinement, the valve is configured to increase a vented amount of the reformed fuel in response to a decrease in engine power output; and wherein the valve is configured to decrease a vented amount of the reformed fuel in response to an increase in engine power output. 
         [0047]    In a yet further refinement, the engine system further comprises a valve configured to control an amount of fuel supplied to the reformer. 
         [0048]    In a still further refinement, the engine system further comprises a temperature sensor configured to sense the temperature of the reformed fuel exiting the reformer, wherein the valve is configured to control the amount of fuel supplied based on the temperature of the reformed fuel exiting the reformer. 
         [0049]    In a yet still further refinement, the engine system further comprises a valve system configured to transition between 100% unreformed fuel and 0% reformed fuel supplied to the combustion chamber and 0% unreformed fuel and 100% reformed fuel supplied to the combustion chamber. 
         [0050]    In an additional further refinement, the reformer includes a catalyst, further comprising a heating system configured to heat the catalyst to a catalytic auto-ignition temperature prior to, during or after startup of the engine. 
         [0051]    Embodiments of the present invention include an engine system, comprising: an engine; a reformer configured to receive an oxidant and a fuel and to reform the fuel using the oxidant; a combustion chamber of the engine in fluid communication with the reformer, wherein reformed fuel is received into the combustion chamber; and a valve system configured to transition between 100% unreformed fuel and 0% reformed fuel supplied to the combustion chamber and 0% unreformed fuel and 100% reformed fuel supplied to the combustion chamber. 
         [0052]    Embodiments of the present invention include an engine system, comprising: an engine; a reformer configured to receive an oxidant and a fuel and to reform the fuel using the oxidant; a combustion chamber of the engine in fluid communication with the reformer, wherein reformed fuel is received into the combustion chamber; an engine air intake; and a valve in fluid communication between the reformer and the air intake, wherein the valve is configured to control an amount of flow of the reformed fuel to the combustion chamber by venting a portion of the reformed fuel. 
         [0053]    In a refinement, the valve is configured to increase a vented amount of the reformed fuel in response to a decrease in engine power output; and wherein the valve is configured to decrease a vented amount of the reformed fuel in response to an increase in engine power output. 
         [0054]    While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as “a,” “an,” “at least one” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and/or “a portion” is used the item may include a portion and/or the entire item unless specifically stated to the contrary.