This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Serial No. 60/660,362, entitled "Plasma Fuel Reformer" filed on March 10, 2005 by Michael Greathouse et al., the entirety of which is hereby incorporated by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to fuel reformers and systems and methods associated therewith.

BACKGROUND

A plasma fuel reformer receives one or more inputs of air and a hydrocarbon fuel (e.g., gasoline, diesel fuel) and generates an electrical arc (or "plasma") through which the air and fuel pass. The electrical arc ignites the air and fuel to initiate partial combustion of the fuel with oxygen in the air. The ignited air and fuel then advance into a reactor of the reformer where the partial combustion process is continued to generate reformate gas in the form of partial combustion product including constituents such as hydrogen (H ₂ ) and carbon monoxide (CO).

Such partial combustion product may be used for a variety of purposes. For example, the partial combustion product may be used in connection with one or more emission abatement devices (e.g., NOx trap, selective catalytic reduction device, lean NOx catalyst, particulate abatement device) to reduce emissions present in exhaust gas of an internal combustion engine. In another application, the H ₂ may be provided to a gasoline internal combustion engine to enhance the combustion process therein. The partial combustion product may also be provided to fuel cells for production of electricity.

SUMMARY

According to an aspect of the present disclosure, a plasma fuel reformer is described. The plasma fuel reformer includes an electrode assembly having a first electrode and a second electrode that is spaced apart from the first electrode to define an electrode gap. A catalyst is positioned downstream of the electrode assembly. A filter is positioned between the electrode assembly and the catalyst.

The filter may include one or more ceramic bodies. The filter may be a ceramic sponge. The filter may include an uncoated catalyst substrate. The filter may include a diesel particulate filter.

The plasma fuel reformer may include a reactor having an inlet and an outlet with the filter being positioned in the reactor at a location between the inlet and the catalyst. The catalyst may be positioned in the reactor at a location between the filter and the outlet.

According to another aspect, a method of operating a plasma fuel reformer includes generating a plasma discharge and advancing air and fuel into the plasma discharge to generate a reformate gas. The reformate gas is advanced through a filter and into a catalyst positioned downstream of the filter. Particulate matter entrained in the reformate gas is removed with the filter. The filter may also introduce turbulence in the reformate gas.

The filter may be embodied as one or more ceramic bodies, a ceramic sponge, an uncoated catalyst substrate, or a diesel particulate filter.

According to another aspect of the disclosure, a method of operating a plasma fuel reformer includes determining if a concentration level of a gas constituent of a reformate gas generated by the fuel reformer is greater than a predetermined

value and generating a first control signal in response thereto. Generation of a plasma arc is ceased in response to generation of the first control signal.

If the concentration level of the gas constituent of the reformate gas is less than the predetermined value, a second control signal is generated. The plasma arc is generated in response to generation of the second control signal.

The hydrogen concentration of the reformate gas may be sensed with a hydrogen sensor. The oxygen concentration of the reformate gas may be sensed with an oxygen sensor.

According to another aspect, a fuel reforming assembly includes a plasma fuel reformer having a plasma arc generating assembly and a catalyst. The assembly may also include a gas concentration sensor and a controller electrically coupled to both the fuel reformer and the gas concentration sensor. The controller includes a processor and a memory device electrically coupled to the processor. The memory device has stored therein a plurality of instructions which, when executed by the processor, cause the processor to monitor output from the gas concentration sensor so as to determine if a concentration level of a gas constituent of a reformate gas generated by the fuel reformer is greater than a predetermined value and generate a first control signal in response thereto and cease operation of the plasma arc generating assembly so as to cease generation of a plasma arc in response to generation of the first control signal.

If the concentration level of the gas constituent of the reformate gas is less than the predetermined temperature value a second control signal may be generated in response thereto and the plasma arc generating assembly may be operated to generate the plasma arc in response to the second control signal. According to another aspect, a plasma fuel reformer includes a reactor having an inlet and an outlet. The plasma fuel reformer also includes a lower voltage electrode and a higher voltage electrode spaced apart from the lower voltage electrode

to define an electrode gap. The higher voltage electrode is positioned between the lower voltage electrode and the inlet of the reactor.

The plasma fuel reformer may also include a catalyst positioned in the reactor at a location between the inlet and the outlet thereof. A mount may be secured to the reactor, with a high voltage pulse coil secured to the mount. A high voltage lead may be used to electrically couple the coil to the higher voltage electrode. The mount may be constructed of a ceramic material.

A cap may cover at least a portion of the higher voltage electrode. Both the cap and the lower voltage electrode may be grounded. According to another aspect, a plasma fuel reformer includes a mount and a high voltage pulse coil secured to the mount. A plasma head may be secured to the mount. The plasma head includes a first electrode and a second electrode spaced apart from the first electrode to define an electrode gap. A reactor may also be secured to the mount. A catalyst may be positioned in the reactor at a location between the inlet and the outlet thereof.

The second electrode may be positioned between the first electrode and the reactor. A high voltage lead may electrically couple the coil to the second electrode. The mount may be constructed of a ceramic material.

A cap may cover at least a portion of the second electrode, with both the cap and the first electrode being grounded.

According to another aspect, a plasma fuel reformer includes a lower body defining an expansion chamber having an inlet and an outlet. An upper body is secured to the lower body. The upper body defines an atomization chamber having an outlet aperture that is open to the inlet of the lower body. The outlet aperture is arranged along a first axis. At least one atomization passageway is arranged along a

second axis that intersects the first axis at a location between the inlet and outlet of the expansion chamber. A fuel nozzle is configured to introduce fuel into the atomization chamber of the upper body.

The lower body may include a baffle having a baffle aperture defined therein. The baffle is positioned between the inlet and the outlet of the expansion chamber. The baffle may have a number of baffle passageways defined therein which are open to the baffle aperture.

The plasma fuel reformer may also include an annular lower electrode and an annular upper electrode spaced apart from the lower electrode to define an electrode gap. The electrode gap is positioned between the lower electrode and the outlet of the expansion chamber.

The upper body may include a plurality of atomization passageways. Each of the plurality of atomization passageways is arranged along an axis that intersects the first axis at a location between the inlet and outlet of the expansion chamber. Each of the plurality of atomization passageways may extend radially inwardly and axially downwardly in a direction toward the expansion chamber of the lower body.

The lower body may have a number of lower body passageways defined therein which are open to the expansion chamber. According to another aspect, a fuel reforming assembly includes a plasma fuel reformer having a plasma arc generating assembly and a fuel nozzle configured to inject fuel in the plasma arc generating assembly. A fuel supply system is configured to supply fuel to the fuel nozzle. The fuel supply system includes a fuel pump fluidly coupled to the fuel nozzle and a bypass valve which is positionable between a first valve position in which fuel is permitted to advance from the fuel pump to the nozzle and a second valve position in which fuel is prevented from advancing from the fuel pump to the nozzle.

The plasma fuel reformer may have a check valve located upstream of the fuel nozzle. The check valve is fluidly coupled to the fuel supply system via a fuel line. Fluid pressure in the fuel line causes the check valve to move from a closed position to an open position. The bypass valve drains fuel from the fuel line when the bypass valve is positioned in its second valve position.

The fuel supply system may include a supply valve fluidly positioned between the fuel pump and the fuel line. The fuel pump is fluidly coupled to the fuel line when the supply valve is positioned in a first valve position. The fuel pump is fluidly isolated from the fuel line when the supply valve is positioned in a second valve position.

The fuel supply system may also include an electronic controller electrically coupled to the fuel pump and the bypass valve. The electronic controller is configured to control the operation of the fuel pump and the position of the bypass valve based on operation of the plasma fuel reformer. In one embodiment, the controller is configured to shutdown the fuel pump and position the bypass valve in the second valve position when the plasma fuel reformer is shutdown.

The above and other features of the present disclosure will become apparent from the following description and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a plasma fuel reformer;

FIG. 2 is a perspective view of an embodiment of a reactor for use in the plasma fuel reformer of FIG. 1;

FIG. 3 is a sectional view showing a fuel-and-heat absorber mounted in a reaction tube of a plasma fuel reformer upstream from a catalyst;

FIG. 4 is a diagrammatic view showing a first embodiment of a fiαel reformer system with a fuel supply system for supplying fuel to a plasma fuel reformer;

FIG. 5 is a diagrammatic view showing a second embodiment of a fuel reformer system with a fuel supply system for supplying fuel to a plasma fuel reformer;

FIG. 6 is a diagrammatic view showing a third embodiment of a fuel reformer system with a fuel supply system for supplying fuel to a plasma fuel reformer; FIG. 7 is a diagrammatic view showing a controller coupled to an electrical power source to vary supply of electrical power to an electrode assembly in a manner to reduce electrical power consumption;

FIG. 8 is a diagrammatic view of a plasma fuel reformer system configured to vaporize fuel and mix air and fuel before delivery of the air and fuel to a plasma fuel reformer;

FIG. 9 is a diagrammatic view of another plasma fuel reformer system configured to vaporize fuel and mix air and fuel before delivery of the air and fuel to a plasma fuel reformer;

FIG. 10 is a perspective view of a plasma head of a plasma fuel reformer;

FIG. 11 is a sectional view taken along lines 11-11 of FIG. 10;

FIG. 12 is a sectional view showing an embodiment for atomizing fuel;

FIG. 13 is a sectional view showing another embodiment for atomizing fuel; FIG. 14 is a sectional view showing yet another embodiment for atomizing fuel; and

FIG. 15 is a sectional view showing an electrode assembly and components associated therewith to remove fouling from the electrode assembly.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives following within the spirit and scope of the invention.

Referring to FIG. 1, there is shown a diagrammatic view of a plasma fuel reformer 10. The reformer 10 includes a plasma head 12 that receives one or more inputs 14 of air and hydrocarbon fuel (e.g., gasoline or diesel fuel) and has an electrode assembly 16 that generates an electrical arc through which the air and fuel pass. The electrical arc heats the air and fuel to initiate partial combustion of the fuel with oxygen in the air. The air and fuel then advance into a reactor 18 of the reformer

10 where the partial combustion process is continued to generate an output 19 of reformate gas in the form of partial combustion product including constituents such as hydrogen (H ₂ ) and carbon monoxide (CO). The partial combustion product may be used for any of the purposed discussed above.

Referring to FIG. 2, the reactor 18 may be configured as a reactor 118 to enhance the production of H ₂ and reduce formation of soot without the use of a catalyst therein. The exemplary reactor 118 does so by thoroughly mixing the air and fuel ignited by the electrical arc with an air-fuel mixer 124. The air and fuel tend to be swirling in a stratified, relatively unmixed manner upon discharge from the plasma

head 12. The air-fuel mixer 124 operates to mix the air and fuel so as to eliminate or otherwise reduce such air-fuel stratification. In this way, locally rich air-fuel mixtures having an oxygen-to-carbon ratio of around 1 are produced. This keeps the temperatures in the reactor 118 low enough to reduce or even possibly prevent soot formation while enhancing production of H ₂ by the reformer 10 without use of a catalyst.

The reactor 118 includes a reaction tube 120 having a longitudinal axis 122. The air-fuel mixer 124 is mounted in the reaction tube 120 for mixing the air and fuel received from the plasma head 12. The mixer 124 includes a plurality of baffles 126 configured, for example, as generally semi-circular perforated plates secured to a central mounting rod 134. The baffles 126 are spaced generally evenly along the rod 134 and axis 122 and extend radially outwardly from the rod 134 so that an arcuate peripheral surface of each baffle 126 mates against the inner surface 128 of the tube 120. Each baffle 126 defines a number of apertures 130 (e.g., three) to restrict flow of air and fuel therethrough. Adjacent baffles 126 are offset circumferentially from one another by 180° so as to define a serpentine flowpath for the air and fuel through the tube 120. The baffles 126 thus cooperate to de-stratify and thus mix the flow of air and fuel in the reactor 118 to promote partial combustion of the fuel into H ₂ without use of a catalyst while reducing soot formation. Referring to FIG. 3, there is shown a reactor 218 for use as the reactor

18 of the reformer 10. The reactor 218 includes a catalyst 240 mounted in a tubular housing 220 of the reactor 218 to promote production of the partial combustion product (such as promoting increase of the H ₂ yield).

The catalyst 240 may be damaged locally in certain situations. First, the catalyst 240 may be damaged locally when unburned fuel makes its way to the catalyst 240 and is then burned on the catalyst 240. For example, unburned fuel may drip from a fuel injector located in the plasma head 12 onto the catalyst 240 when the

reformer 10 is shut down. Such unburned fuel may soak up part of the catalyst 240. On start-up of the reformer 10, the unburned fuel on the catalyst 240 may then burn causing a large release of heat thereby locally damaging the catalyst 240. Second, the catalyst 240 may be damaged locally during normal operation of the reformer 12 due to high temperature regions in the flow through the reactor 218. The temperature of the flow impinging on the catalyst 240 may be non-uniform and the hotter regions may cause damage to the catalyst washcoat. Moreover, the catalyst 240 may be damaged if particulate matter, such as soot, generated by the plasma head 12 becomes entrapped in the catalyst. Under the appropriate environmental conditions, such entrapped particulate matter may combust thereby locally damaging the catalyst 240.

The reactor 218 includes a fuel-and-heat absorber, such as filter 242, positioned upstream from the catalyst 240 to prevent or otherwise reduce damage to the catalyst 240 due to the burning of unburned fuel or particulate matter thereon and high flow-impingement temperatures. The absorber 242 is mounted in the housing 220 to trap unburned fuel before it can reach the catalyst 240 during refoπner shutdown and to absorb heat and particulate matter in the flow passing through the reactor 218 during operation of the reformer 10. The absorber 242 thus promotes the longevity of the catalyst 240.

The absorber 242 is configured, for example, as one or more ceramic bodies 244 mounted in the housing 220. Illustratively, there are two such ceramic bodies 244 which are made, for example, of alumina oxide. Together, the ceramic bodies 244 provide a ceramic "sponge" which has a plurality of flow channels (not shown) extending therethrough. The absorber 242 may also be embodied as other structures such as a wire mesh, uncoated catalyst substrate, diesel particulate filter, or the like. An annular retainer ring 246 is positioned on either side of the absorber 242 and secured to the housing 220 to fix the absorber 242 in place in the housing 220.

To facilitate assembly of the reactor 218, the housing 220 has an inlet tube 223, an outlet tube 224, and a catalyst support tube 225 extending between and secured to the inlet and outlet tubes 223, 224. The tubes 223, 224, 225 extend along a longitudinal axis 222 of the housing 220. The inlet tube 223 is secured to a first mounting plate 226 for securement of the reactor 218 to the plasma head 12 and defines an inlet port 227 to receive gas from the plasma head 12. The outlet tube 224 is secured to a second mounting plate 228 for securement of the reactor 218 to a downstream structure (not shown) and defines an outlet port 229 for discharge of the partial combustion product. The absorber 242 is retained in the inlet tube 223 by the retainer rings 246. The catalyst 240 is retained in the catalyst support tube 225.

The absorber 242 also introduces turbulence into the reformate gas. m such a way, heat is disbursed evenly across the catalyst 240. If in certain designs it is not necessary to trap particulate matter or unburaed fuel, the introduction of turbulence into the reformate gas may be accomplished by use of turbine wheel in lieu of an absorber.

Referring to FIG. 4, there is shown a fuel reformer system 308a including a plasma fuel reformer 310 and a fuel supply system 348a for supplying fuel to the reformer 310. The reformer 310 is configured in a manner similar to the reformer 10. During operation of the reformer 310, pressurized fuel opens a check valve 350 of the plasma head and flows through a nozzle 352 to an electrode assembly 316 which generates an electrical arc to initiate partial combustion of the fuel with air. The ignited air-fuel mixture advances into the reactor of the reformer 310 where a catalyst 340 promotes the partial combustion process. After shutdown of the reformer 310, there may be sufficient pressure in the fuel line upstream from the check valve 350 to cause the check valve 350 to open somewhat. The fuel supply system 348a is configured to reduce the fuel pressure on the check valve 350 so that

the check valve 350 remains closed when the reformer 310 is shut down, thereby promoting the longevity of the catalyst 340.

In particular, the fuel supply system 348a includes a supply circuit

354a and a bypass circuit 356a. The supply circuit 354a is configured to supply pressurized fuel to the check valve 350. The bypass circuit 356a is configured to drain fuel from the supply circuit 354a to reduce fuel pressure on the check valve 350 during periods of reformer shutdown.

The supply circuit 354a includes a fuel tank 358, a fuel pump 360 to pump fuel from the fuel tank 358, an optional flow meter 362 to sense the flow rate of fuel pumped by the fuel pump 360, and a supply valve 364. The supply valve 364 controls flow of fuel from the fuel pump 360 to the check valve 350 and is configured, for example, as a solenoid valve under the control of a controller 366 via an electrical line 368. The controller 366 is also electrically coupled to the fuel pump

360 via an electrical line 370 and, when the flow meter 362 is present, is electrically coupled to the flow meter 362 via an electrical line 372.

The bypass circuit 356a is coupled to and configured to drain fuel from a passageway 374 of the supply circuit 354a extending from the supply valve 364 to the check valve 350. The bypass circuit 356a includes a bypass valve 376 and a return passageway 378 to conduct fuel from the bypass valve 376 to the fuel tank 358 or, optionally, to a location between the fuel tank 358 and the fuel pump 360. The bypass valve 376 is configured, for example, as a solenoid valve under the control of the controller 366 via an electrical line 380.

At reformer shutdown, the controller 366 sends signals over the lines 368 and 380 to cause the supply valve 364 to close and the bypass valve 380 to open. Fuel present in the passageway 374 is thus drained therefrom and returned via return passageway 378 to an upstream location in the supply circuit 354a.

At reformer start-up, the controller 366 sends signals over the lines 368 and 380 to cause the supply valve 364 to open and the bypass valve 380 to close. The supply circuit 354a is thus enabled to supply fuel to the reformer 310 and, in particular, to the check valve 350. The supply valve 364 and the bypass valve 376 thus cooperate to provide a fuel flow control device 382 for controlling flow of fuel to the reformer 310. In particular, the flow control device 382 is configured control supply of fuel to the reformer 310 and to remove fuel from the supply circuit 354a so as to reduce fuel pressure on the check valve 350 to avoid flow of fuel from the nozzle 352 during reformer shutdown and thus reduce catalyst degradation.

Referring to FIG. 5, there is shown another fuel reformer system 308b.

The system 308b includes the plasma fuel reformer 310 and a fuel supply system

348b for supplying fuel to the reformer 310. The fuel supply system 348b is configured in a manner similar to the fuel supply system 348a. It is different in that the supply valve 364 is omitted from its supply circuit 354b.

The fuel supply system 348b includes the bypass circuit 356a which is coupled to the passageway 374 extending between the fuel pump 360 (or optional flow meter 362) and the check valve 350 to drain fuel therefrom. At reformer shutdown, the controller 366 sends a signal over the line 380 to cause the bypass valve 380 to open. Fuel present in the passageway 374 is thus drained therefrom and returned via return passageway 378 to an upstream location in the supply circuit 354b. At reformer start-up, the controller 366 sends a signal over the line 380 to cause the bypass valve 380 to close. The supply circuit 354b is thus enabled to supply fuel to the reformer 310 and, in particular, to the check valve 350. The bypass valve 376 thus provides a fuel flow control device for controlling flow of fuel to the reformer 310. In particular, the flow control device is configured control supply of fuel to the reformer 310 and to remove fuel from the

supply circuit 354b so as to reduce fuel pressure on the check valve 350 to avoid flow of fuel from the nozzle 352 during reformer shutdown and thus reduce catalyst degradation.

Referring to FIG. 6, there is shown another fuel reformer system 308c. The system 308c includes the plasma fuel reformer 310 and a fuel supply system 348c for supplying fuel to the reformer 310. The fuel supply system 348c is configured in a manner similar to the fuel supply system 348a. It is different in that the supply valve 364 and the bypass valve 376 are replaced by a 3-way valve 384. The 3-way valve 384 forms an intersection between supply and bypass circuits 354c, 356c of the system 348c and is under the control of the controller 366 via an electrical line 386.

At reformer shutdown, the controller 366 sends a signal over the line 386 to cause the 3-way valve 384 to move to a bypass position. In the bypass position, the 3-way valve 384 drains fuel from a passageway 374c in the supply circuit 354c to cause the fuel to flow into a return passageway 378 of the bypass circuit 356c. The return passageway 378 conducts the fuel to an upstream location in the supply circuit 354c. At reformer start-up, the controller 366 sends a signal over the line 386 to cause the 3-way valve 384 to move to a supply position. In the supply position, the fuel pump 360 is allowed to pump fuel through the 3-way valve 384 to the check valve 350. The 3-way valve 384 thus provides a fuel flow control device for controlling flow of fuel to the reformer 310. In particular, the flow control device is configured control supply of fuel to the reformer 310 and to remove fuel from the supply circuit 354c so as to reduce fuel pressure on the check valve 350 to avoid flow of fuel from the nozzle 352 during reformer shutdown and thus reduce catalyst degradation.

Referring to FIG. 7, there is shown a plasma fuel reformer 410 configured in a manner similar to the reformer 10. As such, it includes a plasma head

412 that receives one or more inputs of air and fuel and has an electrode assembly 416 that initiates partial combustion of the air and fuel. The ignited air and fuel pass into a reactor 418 where the partial combustion process is continued to generate an output 419 of reformate gas in the form of partial combustion product including constituents such as H ₂ and CO.

The partial combustion reaction in the reactor 418 may become self- sustaining at least for a time when the temperature in the reactor 418 reaches a predeteπnined reaction temperature (e.g., 500° C). While the reaction is self- sustaining, the electrical power supplied to the electrode assembly 416 by an electrical power source 464 may be turned off or otherwise reduced to conserve energy. In particular, a controller 466 is coupled to the electrical power source 464 via an electrical line 468 to cause (e.g., generate control signals that cause) the power source 464 to stop or reduce provision of electrical power over an electrical line 470 to the electrode assembly 416 when the reaction is self-sustaining. A variety of control schemes may be used to determine when the partial combustion reaction in the reactor 418 is self-sustaining and thus to determine when electrical power supplied to the electrode assembly 416 is to be stopped or otherwise reduced. For example, a time-based control scheme may be used. In such a case, the controller 466 may be configured to cause (e.g., generate control signals that cause) the electrical power source 464 to operate for an initial "warm-up" time period (e.g., 40 seconds) and then to cease operating or otherwise operate in a low-power mode until the reformer 410 is shut down. Alternatively, after the initial time period, the controller 466 may cause (e.g., generate control signals that cause) the electrical power source 464 to cycle on and off or otherwise between high-power and low- power modes. Exemplarily, the on/high-power modes may last for about 100 milliseconds and the off/low-power modes may last for about 900 milliseconds.

In other examples, a sensor-based control scheme may be used in place or in conjunction with one of the time-based schemes mentioned above. In such a case, a sensor 472 may be configured to provide information to the controller 466 via a signal on electrical line 474 indicative of a parameter associated with the partial combustion reaction in the reactor 418.

According to one sensor-based control scheme, the sensor 472 is a temperature sensor coupled to the reactor 418 via a line 476 to sense the temperature of the reaction in the reactor 418. If the sensed temperature is below the predetermined reaction temperature, the controller 466 causes (e.g., generate control signals that cause) the electrical power source 464 to operate in its on/high-power mode to elevate the temperature to the predetermined reaction temperature. If the sensed temperature is at or above the predetermined reaction temperature, the controller 466 causes (e.g., generate control signals that cause) the electrical power source 464 to operate in its off/low-power mode to allow the reaction to continue while saving power.

According to another sensor-based control scheme, the sensor 472 is a hydrogen sensor coupled to the reactor 418 or the outlet 419 via lines 476, 478 to sense the concentration of H ₂ being generated. A decrease in H ₂ concentration may indicate that the reaction is becoming less self-sustaining. As such, if the H ₂ concentration is below a predetermined H ₂ level, the controller 466 causes (e.g., generate control signals that cause) the electrical power source 464 to operate in its on/high-power mode to boost H ₂ production. If the H ₂ concentration is at or above the predetermined H ₂ level, the controller 466 causes (e.g., generate control signals that cause) the electrical power source 464 to operate in its off/low-power mode to allow the reaction to continue while saving power.

According to another sensor-based control scheme, the sensor 472 is an oxygen sensor coupled to the reactor 418 or the outlet 419 via lines 476, 478 to

sense the concentration of O ₂ being generated. An increase in O ₂ concentration may indicate that the reaction is becoming less self-sustaining. As such, if the O ₂ concentration is below a predetermined O ₂ level, the controller 466 causes (e.g., generate control signals that cause) the electrical power source 464 to operate in its on/high-power mode to boost O ₂ production. If the O ₂ concentration is at or above the predetermined O ₂ level, the controller 466 causes (e.g., generate control signals that cause) the electrical power source 464 to operate in its off/low-power mode to allow the reaction to continue while saving power.

It is within the scope of this disclosure to combine any of the sensor- based control schemes with any of the other sensor-based control schemes and/or with any of the time-based control schemes.

Referring to FIG. 8, there is shown a plasma fuel reformer system 508 for "pre-vaporizing" fuel and "pre-mixing" air and fuel so as to increase the overall efficiency of generation of reformate gas in the form of partial combustion product (e.g., H ₂ , CO). The system 508 includes a plasma fuel reformer 510 having a plasma head 512 and a reactor 518. The plasma head 512 has an electrode assembly that initiates partial combustion of air and fuel supplied thereto. The ignited air and fuel pass into the reactor 518 where the partial combustion process is continued in a reaction tube 520 to generate partial combustion product. The system 508 further includes a first heat exchanger or air "pre- heater" 524. The heated flow discharged from the reactor 518 is relatively hot. It may have temperatures in the range of 800° C to 900° C. The air pre-heater 524 is arranged downstream from the reactor 518 to transfer heat from the heated flow to a supply of unheated air so as to heat the air. The air may thus be heated to a temperature in the range of 200° C to 300° C.

The heated air is delivered by a heated air passageway 526 to an air- fuel mixer 528. The mixer 528 includes a housing 530 containing a turbulence

generator 532 configured, for example, as a baffle plate having an aperture 534 defined therein to generate turbulence in the heated air. A fuel injector 536 secured to the housing 530 injects fuel into a chamber 538 formed in the housing 530 downstream from the turbulence generator 532. The heated and turbulent air vaporizes and mixes with the injected fuel to form an air-fuel mixture that flows into a supply passageway 539.

The supply passageway 539 branches into an atomization supply passageway 542 and a swirl supply passageway 544. The atomization supply passageway 542 supplies a portion of the air-fuel mixture to the plasma head 512 for delivery to the electrical arc generated by the electrode assembly of the plasma head 512. The swirl supply passageway 544 supplies the rest of the air-fuel mixture to a number of swirl ports defined in the plasma head 512 and configured to impart a swirling motion to the air-fuel mixture supplied thereto. Such swirling motion causes the electrical arc to stretch radially inwardly to promote ignition of the air-fuel mixture supplied by the passageways 542, 544.

At least a portion of the ignited air-fuel mixture is partially combusted to produce the partial combustion product upon passage through the reaction tube 520. The heated flow exiting the reaction tube 520 may then be used to further heat unheated air by use of the air pre-heater 524 to continue the process of pre- vaporizing fuel and pre-mixing air and fuel for supply to the plasma fuel reformer 510.

After passing the air pre-heater 524, the cooled flow may then pass through an optional catalyst 540 configured to further the partial combustion process of the air-fuel mixture. The catalyst 540 may be susceptible to degradation from exposure to relatively high temperatures over time. As such, cooling the flow exiting the reformer 510 by use of the air pre-heater 524 may act to prolong the useful life of the catalyst 540.

A second heat exchanger 546 may be used to further cool the flow before delivery to a downstream component such as an internal combustion engine, an emission abatement device, or fuel cell. Since the flow is already cooled somewhat by the air pre-heater 524, the second heat exchanger 546 may be configured as an air- cooled heat exchanger instead of a water-cooled heat exchanger.

In the case where the downstream component is an engine, the H ₂ of the partial combustion product is used to enhance the combustion process of the engine. The additional cooling by the exchanger 546 may help to reduce engine knocking. On the other hand, it is within the scope of this disclosure to omit or otherwise limit the cooling effect of the exchanger 546 to allow the temperature of the partial combustion product to remain elevated to promote more lean operation of the engine.

Valves 548, 550 are provided in the atomization and swirl supply passageways 542, 544 to promote pre-heating of the air and thus fuel vaporization and air-fuel mixing at start-up of the reformer 510. Initially, at start-up, the valves 548, 550 are opened to allow air and fuel to enter the plasma head 512 to provide a "stationary" air-fuel supply therein having an oxygen-to-carbon (O/C) ratio of about 1.5. After this stationary air-fuel supply is provided to the plasma head 512, the valves 548, 550 are closed for a predetermined period of time (e.g., about 20 seconds). During this time, the reformer 510 is operated to partially combust the stationary air-fuel supply to produce a heated flow exiting the reaction tube 510 for heating air in the air pre-heater 524. After the predetermined period of time has elapsed, the valves 548, 550 are re-opened to allow flow of the air-fuel mixture through the passageways 542, 544 to the reformer 510. Referring to FIG. 9, there is shown another plasma fuel reformer system 608 for "pre-vaporizing" fuel and "pre-mixing" air and fuel so as to increase the overall efficiency of generation of reformate gas in the form of partial combustion

product (e.g., H ₂ , CO). The system 608 includes a plasma fuel reformer 610 having a plasma head 612 and a reactor 618. The plasma head 612 has an electrode assembly with a pair of electrodes 613, 614 that initiate partial combustion of air and fuel supplied thereto. The ignited air and fuel pass into the reactor 618 where the partial combustion process is continued in a reaction tube 620 to generate partial combustion product.

The system 608 further includes a first heat exchanger 624 arranged downstream from the reactor 618 and positioned in thermal communication with an air-fuel mixer 628. The mixer 628 includes a housing 630 which receives an input 631 of air and fuel and an annular input 633 of air. A turbulence generator 632 mounted in the housing 630 is configured, for example, as a perforated baffle plate for generating turbulence in the air and fuel introduced into the housing 630 to thereby promote mixing of the air and fuel. The heat exchanger 624 surrounds the housing 630 to transfer heat from the heated flow discharged from the reactor 618 to the air and fuel in the air-fuel mixer 628. Such transfer of heat promotes vaporization of the fuel and mixing of the air and fuel. The heated flow discharged from the reactor 618 may have temperatures in the range of 800° C to 900° C. The air-fuel mixture exiting the mixer 628 may have a temperature in the range of 200° C to 300° C as a result of the heat transfer thereto. The air-fuel mixture exiting the mixer 628 flows through a supply passageway 639 to the plasma head 612 for partial combustion of the air-fuel mixture.

As it flows through the passageway 639, the air-fuel mixture may be heated by an engine exhaust manifold 641 to further promote fuel vaporization and air-fuel mixing.

The system 608 may also include one or both of the catalyst 540 and the second heat exchanger 546. It is within the scope of this disclosure to omit one or both of the catalyst 540 and the heat exchanger 546 from the system 608.

Referring to FIGS. 10 and 11, there is a shown a plasma fuel reformer 710. The reformer 710 includes a plasma head 712 and a reactor 718. In the plasma head 712, there is a higher voltage electrode 724 and a lower voltage electrode 726 spaced apart from the electrode 724 to define an electrode gap 728 therebetween. The electrodes 724, 726 cooperate to generate an electrical arc in the gap 728 to initiate partial combustion of fuel and air passing through the gap 728 into the reactor 718 where the partial combustion process continues to produce reformate gas in the form of partial combustion product including constituents such as H ₂ and CO.

The higher voltage electrode 724 is positioned between the lower voltage electrode 726 and the reactor 718. Such a configuration promotes minimization of electrical insulation components in the plasma head 712, simplification in the construction of the flow passageways in the plasma head 712, and compactness of the plasma head 712.

The reformer 710 includes a mount 730. The plasma head 712 and a high voltage pulse coil 732 are secured to the mount 730. The mount 730 is made, for example, of a ceramic material which acts as electrical insulation and a heat absorber.

The mount 730 has a bore 732 defined therein receiving components of the plasma head 712. In particular, the high voltage electrode 724 and an extension tube 734 underlying the high voltage electrode 724 are positioned in the bore 732. A high voltage lead 736 interconnects the high voltage electrode 724 and the coil 732 which is located outside the plasma head 712.

A cap 737 at the same electrical potential as the lower voltage electrode 726 (e.g., ground) covers internal components of the plasma head 712 including the higher voltage electrode 724. The cap 737 is secured to the mount 730 by use of fasteners (not shown) extending through apertures 735 defined in the cap

737 into the mount 730. The cap 737 and the bore 732 of the mount 730 thus

cooperate to inhibit inadvertent contact with the higher voltage electrode 724 which may at times reach an electrical potential of about 24 kilovolts.

The electrodes 724, 726 are electrically insulated and separated from one another. Electrical insulation 738 and two spacers 739, 740 located above and below the insulation 738 separate the electrodes 724, 726 from one another.

Components for supplying air to the plasma head 712 are mounted on the lower voltage electrode 726. An upper body 742 is secured to the lower voltage electrode 724 by use of fasteners (not shown) that extend through holes 743 defined in the upper body 742. A spacer 744 is positioned between the upper body 742 and the lower voltage electrode 724. A lower body 746 is received in and secured to the lower voltage electrode 724 and cooperates with the upper body 742 to define therebetween a portion of an annular "wall" air passageway 748. A first air fitting 750 is secured to the upper body 742 to supply air to the passageway 748 further defined in and between the upper body 742 and the lower voltage electrode 724. The plasma head 712 includes a nozzle 752 for spraying fuel into the head 712 and a nozzle holder 754 for holding the nozzle 752. The nozzle holder 754 is secured to the upper body 742 to position the nozzle 752 in place in the upper body 742.

Fuel discharged from the nozzle 752 is atomized by atomization air supplied to an atomization chamber 756 defined in the upper body 742. A second air fitting 758 supplies atomization air to an annular atomization air passageway 760 defined between the nozzle holder 754 and the upper body 742. The atomization air flows through the passageway 760 to the chamber 756 where it atomizes the fuel discharged from the nozzle 752. The atomized fuel and air then flow through an aperture 762 defined in the upper body 742 into an expansion chamber 764. Wall air from the wall air passageway 748 mixes with the atomized fuel and air in the expansion chamber 764

to provide the air-fuel mixture with a predetermined oxygen-to-carbon ratio and to move the air-fuel mixture through an aperture 766 defined in a baffle 768 formed in the lower body 746. The baffle 768 creates turbulence in the air-fuel mixture to further mix the air-fuel mixture. After passing the baffle 768, the air-fuel mixture passes through the electrode gap 728 where it encounters the electrical arc. The arc is stretched radially inwardly toward an axis 770 of the head 712 by swirling air introduced into the electrode gap 728 to enhance ignition of the fuel-air mixture. Such "swirl air" is delivered to the plasma head 712 by a fitting 772 which supplies the swirl air to an annular manifold 774 defined between the high voltage electrode 724 and a sleeve 776 secured thereto. Swirl ports 778 extending radially inwardly and circumferentially from the manifold 774 impart a swirling motion to the swirl air as they direct the swirl air from the manifold 774 into the electrode gap 728. Such swirling motion of the swirl air causes the electrical arc to stretch radially inwardly to facilitate ignition of the fuel-air mixture.

The ignited air-fuel mixture then advances through the extension tube 734 into the reaction tube of the reactor 718. The extension tube 734 is made of a ceramic material and thus can become relatively hot due to the temperature of the ignited air-fuel mixture. As such, the extension tube 734 acts to avoid quenching of the ignited air-fuel mixture and thus operates as an anti-quenching device located between the electrode gap 724 and the reactor 718.

An anti-leak device 780 is positioned between the extension tube 734 and a mounting plate 782 used to secure the reactor 718 to the mount 730. The anti- leak device 780 prevents leakage of the ignited air-fuel mixture between the tube 734 and the plate 782. Illustratively, the anti-leak device 780 is configured as a graphite sleeve.

Referring to FIG. 12, there is shown an embodiment for atomizing fuel discharged into the plasma head of a plasma fuel reformer. Fuel is dispensed from a nozzle 852 into an atomization chamber 856 which receives atomization air from an annular first atomization air passageway 860 defined between an upper body 842 and a nozzle holder 854 holding the nozzle 852. The upper body 842 defines a number of second atomization air passageways 880 (e.g., six) spaced circumferentially and generally evenly about an axis 870 of the reformer. The second air atomization air passageways 880 extend radially inwardly and somewhat axially downwardly to direct atomization air from an annular atomization air passageway 883 defined between an air sleeve 881 and the upper body 842 to a downstream atomization location just downstream from an aperture 862 defined in the upper body 842. The downstream atomization location is in an expansion chamber 864 defined between the upper body 842 and a baffle 868 included in a lower body 846 secured to the upper body 842 by welding, for example. The air-fuel mixture then travels through an aperture 866 defined in the baffle 868 which induces turbulence in the mixture and thus further mixing.

Referring to FIG. 13, there is shown another embodiment for atomizing fuel discharged into the plasma head of a plasma fuel reformer. In this embodiment, there are shown optional air atomization passageways defined in the lower body 846 in the region of the baffle 868 to assist with fuel atomization. In particular, the lower body 846 may include a number of third atomization air passageways 884 (e.g., six), a number of fourth atomization air passageways 885 (e.g., six), and/or a number of fifth atomization air passageways 886 (e.g., six). The passageways 884, 885, 886 are spaced circumferentially and generally evenly about the axis 870.

The third air atomization air passageways 884 extend radially inwardly and somewhat axially upwardly to direct atomization air from an annular atomization

air passageway 887 defined between an air sleeve 888 and the lower body 846 to the expansion chamber 864. The fourth air atomization air passageways 885 extend radially inwardly without an axial component through the baffle 868 to direct atomization air from the passageway 887 to the aperture 866. The fifth air atomization air passageways 886 extend radially inwardly and somewhat axially downwardly to direct atomization air from the passageway 887 into a region below the baffle 868. Each of the second, third, fourth, and fifth atomization air passageways 880, 884, 885, 886 may be used alone or in conjunction with one any one or more of the other passageways 880, 884, 885, 886. Referring to FIG. 14, there is shown yet another embodiment for atomizing fuel discharged into the plasma head of a plasma fuel reformer. In this embodiment, the upper body 842 is modified to include a baffle 889 depending from a lower wall 890 along with an annular sleeve 891 surrounding the baffle 889. A number of apertures 892 (e.g., six) are formed in the lower wall 890 around the baffle 891. The air-fuel mixture passes through the apertures 892 and is caused to follow a serpentine flow path defined between the baffle 889 and the sleeve 891.

The baffle 889 includes an axially extending central post 893, a smaller upper disk 894, and a larger lower disk 895 larger than the smaller upper disk 894. The disks 894, 895 are secured to the post and extending radially outwardly therefrom.

Referring to FIG. 15, there is shown an electrode assembly 916 for use in the plasma head of a plasma fuel reformer. The electrode assembly 916 is configured to be operated in a manner to remove fouling 917 therefrom.

The electrode assembly 916 includes an upper electrode 924 and a lower electrode 926 spaced apart from the upper electrode 924 to define an electrode gap 928 therebetween. Illustratively, the electrodes 924, 926 are shaped like a washer. The lower electrode 926 is electrically coupled to an electrical power source

964. As such, the lower electrode 926 is the higher voltage electrode. It is within the scope of this disclosure to electrically couple the upper electrode 924 to the power source 964 so that the upper electrode 924 is the higher voltage electrode.

The electrode assembly 916 further includes an annular electrical insulation body 938 positioned between the electrodes 924, 926 to establish the electrode gap 928 between the electrodes 924, 926. Exemplarily, the body 938 is made of a ceramic material. The body 938 is machined to include swirl ports 978 to deliver swirling air supplied by a swirl air supplier 979 from an annular swirl air passageway 974 to the electrode gap 928 to cause the electrical arc to stretch radially inwardly to promote ignition of the air-fuel mixture passing through the electrode gap 928.

The electrodes 924, 926 and the insulation body 938 may be encased in a casing 940. The casing 940 may be a one-piece body that is made of epoxy and cooperates with the body 938 to define the annular swirl air passageway 974 therebetween.

From time to time, regions of an inner surface 942 of the body 938 may become fouled with an enamel-like layer 917 of fuel or other substance(s). To remove the fouling 917, fuel flow is cut off from the plasma fuel reformer and a controller 966 operates the electrical power source 964 and the swirl air supplier 979 via electrical lines 968, 969. In particular, the controller 966 operates the electrical voltage source 964 so that an electrical arc is present between the electrodes 924, 926. In addition, the controller 966 causes the swirl air supplier 979 to stop supplying swirl air to the swirl ports 978 or otherwise reduce the amount of swirl air supplied thereto. In the absence or reduction of the swirl air, the electrical arc is allowed to move radially outwardly toward the inner surface 942. As such, the electrical arc impinges against the fouling 917 and burns the fouling 917 off of the inner surface 942. The controller 966 may operate the power source 964 and the swirl air supplier 979 in this

fouling-removal mode for a predetermined period of time (e.g., from about 5 seconds to about 15 minutes). In this way, the body 938 can be cleaned from time to time so as to prolong the useful life of the electrode assembly 916.

While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.

There are a plurality of advantages of the present disclosure arising from the various features of the apparatus, method, and system described herein. It will be noted that alternative embodiments of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of an apparatus, method, and system that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the present invention.