Methods and systems for start-up of ammonia burning systems

Abstract

Disclosed herein are methods and systems of operating an ammonia combustion system, including heating a first reactor of the ammonia combustion system to a first temperature value; flowing a first fuel to the first reactor, the first fuel including ammonia; reforming the first fuel into a second fuel; providing the second fuel to an intake of the ammonia combustion system; allowing the second fuel to combust in the ammonia combustion system thereby generating an exhaust gas; and flowing the exhaust gas from an exhaust along outer surfaces of a second reactor of the ammonia combustion system; wherein, when the second temperature exceeds a threshold temperature value, the flow of the first fuel to the first reactor is terminated.

Description

METHODS AND SYSTEMS FOR START-UP OF AMMONIA BURNINGSYSTEMSCLAIM OF PRIORITYThis application claims priority under 35 USC §119(e) to U.S. Patent Application Serial No. 63 / 529,080, filed on July 26, 2023, the entire contents of which are hereby incorporated by reference.FIELD OF THE DISCLOSURE

[0001] The disclosure relates to fuel reforming systems and methods, and more specifically, to fuel reforming systems and methods for ammonia-based systems.BACKGROUND

[0002] Ammonia is unsuitable as a direct replacement for current hydrocarbon fuels used in conventional internal combustion engines. The flame speed of ammonia is far lower than most hydrocarbon fuels. Therefore, the time required to propagate a flame is longer, resulting in unburned ammonia emissions and poor combustion performance. Moreover, ammonia is extremely resistant to ignition, which narrows the useful range at which it can be used as an unmodified direct replacement fuel.

[0003] In ammonia-burning systems, e.g., reciprocating engines, burners, or turbine combustors, waste heat can be utilized to heat a reforming reactor. Fuel reformation is the process of changing the chemical composition of a fuel. Reforming can be used to produce hydrogen (H2) from ammonia (NH3). The reforming reactor generates hydrogen from the ammonia for enhancing the flame characteristics of the burning ammonia. These systems, when reliant on waste heat and a stream of hydrogen, generally cannot be started from ‘cold’ (e g., ambient) temperatures using solely ammonia as the fuel.SUMMARY

[0004] Disclosed herein are various embodiments of fuel reforming reactors, systems, and methods related thereto, for ammonia fueled combustion systems.

[0005] In general, an aspect disclosed herein is a method of operating an ammonia combustion system including heating a first reactor of the ammonia combustion system to a first temperature; flowing a first fuel to the first reactor, the first fuel includes ammonia; reforming the first fuel into a second fuel; providing the second fuel to an intake of the ammonia combustion system; allowing the second fuel to combust in the ammonia combustion system thereby generating an exhaust gas; flowing the exhaust gas from an exhaust along outer surfaces of a second reactor of the ammonia combustion system; where, when the second temperature exceeds a threshold temperature, the flow of the first fuel to the first reactor is terminated.

[0006] Examples may include one or more of the following features. The method may include providing a stream of a combustion gas along with the first fuel to the first reactor; and terminating the stream of combustion gas when the second temperature exceeds a threshold temperature. The heating may include inductively heating, resistively heating, heating by combusting a portion of the second fuel, or a combination thereof. The method may include transferring heat energy between the second fuel and the first fuel before the first fuel can be provided to the reactor. The method may include, before providing the first fuel to the reactor, transitioning the first fuel from a liquid state to a gas state. The first fuel can be ammonia, and the second fuel may include hydrogen. Reforming may include catalytically decomposing the first fuel by flowing the first fuel over a structure may include a platinum group metal, a base metal, or both. Reforming may include reforming the first fuel until the second fuel may include less than 5 % ammonia. The method may include exchanging heat energy between the first fuel and the second fuel. The method may include combusting a portion of the second fuel to provide heat energy to the first reactor.

[0007] In general, an aspect disclosed herein is a fuel reformation system for ammonia combustion systems including a fuel source configured to provide a first fuel; a reactor having a first end for receiving the first fuel, a second end for exhausting a second fuel, and a wall forming an outer surface and an inner surface, the inner surface defining an interior cavity; an reactor structure within at least a portion of the interior cavity for producing the second fuel fromthe first fuel; a heater configured to heat the reactor structure; a heat exchanger configured to receive the first fuel from the fuel source and second fuel from the reactor, such that heat energy is transferred between the second fuel and the first fuel.

[0008] Examples may include one or more of the following features. The system where the second fuel has a higher percentage of hydrogen by mass than the first fuel. The heater can be an electrical resistance heater. The first end of the reactor includes one or more openings to allow the first fuel to enter and flow into the interior cavity of the reactor. The heat exchanger may include a first fluid channel through which the second fuel may flow and a second fluidic channel through which the first fuel may flow, and outer surfaces of the first fluidic channel and the second fluidic channel are connected by a heat exchange element configured to transfer heat energy between the first fluidic channel and the second fluidic channel. The heat exchange element may include a reticulated foam, a honeycomb structure, or a plurality of fins. The second end of the reactor includes one or more openings to allow the first fuel to flow out of the interior cavity of the reactor, the one or more openings fluidically connected to inlets of the heat exchanger such that the first fuel flows into the heat exchanger. The reactor structure may include a honeycomb shaped structure, reticulated foam, perforated fins, a monolithic catalyst, or combinations thereof The reactor structure may include a catalyst coating. The catalyst coating can contain a platinum group metal and the heater can be configured to heat the wall of the reactor to a temperature in a range from 100 °C to 500 °C. The platinum group metal can be ruthenium. The catalyst coating can contain a base metal catalyst may include a transition metal and the heater can be configured to heat the wall of the reactor to a temperature in a range from 100 °C to 950 °C. The base metal catalyst may include one or more of iron, nickel, cobalt, and combinations thereof. The heater can be an inductive heater configured to heat at least a portion of the base metal catalyst, or all of the base metal catalyst. The system may include insulation surrounding at least a portion of the wall of the reactor. The system may include a gas source configured to provide a combustion gas stream to one or more openings in the first end of the reactor, a first temperature sensor arranged to generate temperature data indicative of a temperature of the reactor structure, and a controller connected to the heater and configured to control the heater such that the temperature can be below a temperature threshold. The controller can be connected to and configured to control the gas source such that the temperature can be below a temperature threshold. The combustion gas stream may include air. The first fuel can beammonia. The second fuel may include ammonia and hydrogen. The second fuel may include ammonia hydrogen and hydrogen ammonia at a mass ratio in a range from 5:95 to 50:50. The reactor can be surrounded by a second heat exchange element. The first heat exchange element and the second heat exchange element may include at least one of a reticulated foam, a honeycomb structure, or a plurality of fins. The system may include a duct defining an interior space enclosing the exhaust condenser, reactor, and the fuel manifold having a first inlet opening and a second outlet opening. The heat exchanger may include the first heat exchange element and the second heat exchange element. The ammonia combustion system can be an internal combustion engine, a gas turbine, an industrial boiler, or a duct burner.

[0009] In general, an aspect disclosed herein is an engine system for internal combustion and reformation of a fuel including an engine including an intake for receiving a first fuel and an exhaust for releasing an exhaust gas; a fuel reformation system for providing a second fuel includes hydrogen to the intake of the engine, the fuel reformation system includes: a fuel source configured to provide a first fuel; a reactor having a first end for receiving the first fuel, a second end for exhausting a second fuel, and a wall forming an outer surface and an inner surface, the inner surface defining an interior cavity; an reactor structure within at least a portion of the interior cavity for producing the second fuel from the first fuel; a heater configured to heat the reactor structure; and a heat exchanger configured to receive the first fuel from the fuel source and second fuel from the reactor, such that heat energy is transferred between the second fuel and the first fuel and having an outlet connected to the intake for providing the second fuel to the intake; and a reforming reactor including a first end portion, a second end, a wall forming an outer surface and an inner surface, the inner surface defining an interior cavity for receiving the first fuel, a second fuel, reactants for the first fuel, or combinations thereof, and where the exhaust of the system is sized and shaped for receiving a portion of the reforming reactor such that the exhaust gas flows along a surface of the reforming reactor within the exhaust.

[0010] In general, an aspect disclosed herein is engine system, the system including an engine; a fuel reformation system including a ring-shaped reactor having a first end for receiving a first fuel, a second end for exhausting a second fuel, and a wall forming an outer surface and an inner surface, the inner surface defining an interior cavity, a reactor structure within at least a portion of the interior cavity for producing the second fuel from the first fuel, wherein the reactor structure has a complementary shape that aligns with the ring-shaped reactor.

[0011] Examples may include one or more of the following features. The heater can be an inductive heater including conductive coils surrounding an entire length of the wall of the reactor. The system can include an insulation surrounding at least a portion of the wall of the reactor, wherein the insulation is within an inner volume of the conductive coils. The system can include a reforming reactor comprising a first end portion, a second end, a wall forming an outer surface and an inner surface, the inner surface defining an interior cavity for receiving the first fuel, a second fuel, reactants for the first fuel, or combinations thereof, and wherein the exhaust of the system is sized and shaped for receiving a portion of the reforming reactor such that the exhaust gas flows along a surface of the reforming reactor within the exhaust wherein the insulation has a magnetic permittivity relative to free space of less than one. The engine can include an intake for receiving a first fuel and an exhaust for releasing an exhaust gas; and wherein the system includes a heater configured to heat the reactor structure; and a heat exchanger configured to receive the first fuel and second fuel from the reactor and exchange heat between the second fuel and the first fuel, the heat exchanger having an outlet connected to the intake for providing the second fuel to the intake.

[0012] Particular implementations of the subject matter described in this specification can be implemented so as to realize one or more of the following technical advantages.

[0013] The methods and systems disclosed herein facilitate the startup of one or more devices (or systems), to reach steady-state operating conditions sooner that includes the use of secondary, non-ammonia fuels and increases the fuel efficiency of the ammonia-burning device. As used herein, “steady state” operating conditions refer to the temperature of a combustion system in which the heating and cooling energy flows are balanced and are neither increasing nor decreasing. Said another way, passive (e.g., radiative) or active (e.g., heat pumps) cooling removes heat energy from the ammonia-burning device at the same rate that the ammonia combustion generates heat energy. Thus, the measured temperature at any point in the engine remains constant and does not change with time.

[0014] The methods and systems disclosed herein use inter-connected heat exchange elements to increase the energy efficiency of the reformed fuel production system.

[0015] The methods and systems disclosed herein can be implemented as add-on solutions to existing ammonia combustion devices, or integrated into the manufacturing of new ammonia combustion devices, to increase the flexibility of the proposed solution.

[0016] The methods and systems disclosed herein can be integrated with ammonia burning devices to automatically terminate or turn-down fuel flow when the ammonia burning device reaches operating conditions conducive to sustaining a reactor or other ammonia-combustion enabling device.

[0017] The methods and systems disclosed herein can be used to modify the chemical composition of the fuel source to a combustion device during steady-state operation otherwise unobtainable and limited by the waste-heat profde and primary combustion-improving mode of the ammonia combustion device.

[0018] The methods and systems disclosed herein can be integrated into and used as the primary reactor in an ammonia combustion system. The reactor is heated through direct heat application until the ammonia combustion system can be started. The heating can continue in full, at a reduced level, or halted entirely depending on the waste heat provided to the reactor.

[0019] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.DESCRIPTION OF DRAWINGS

[0020] FIG. 1 is a schematic illustration of an exemplary heated fuel reformation system for ammonia internal combustion engines;

[0021] FIG. 2 is a schematic illustration of an exemplary inductively heated fuel reformation system;

[0022] FIG. 3 is a schematic illustration of an exemplary fuel reformation system including a combustion gas source;

[0023] FIG. 4 is a schematic illustration of a portion of an exemplary reactor of a fuel reformation system in which a portion of the reactor is inductively heated;

[0024] FIG. 5 is a schematic illustration of an exemplary heated fuel reformation system using an ammonia burning fuel manifold;

[0025] FIG. 6 is a schematic illustration of another exemplary heated fuel reformation system using the ammonia burning fuel manifold;

[0026] FIG. 7 is a schematic illustration of an exemplary ammonia internal combustion engine coupled to a heated fuel reformation system; and

[0027] FIG. 8 is a flow chart diagram illustrating an exemplary method of operating an ammonia internal combustion engine.

[0028] FIG. 9 is a schematic illustration of an exemplary reactor structure heated using inductive coils.

[0029] FIG. 10 is an image depicting an exemplary reactor structure heated using inductive coils.

[0030] FIG. 11 is a schematic illustration of an exemplary inductively heated ring-shaped reactor structure.

[0031] In the figures, like references indicate like elements.DETAILED DESCRIPTION

[0032] Disclosed herein are methods and systems for producing hydrogen from ammonia fuel on demand to an ammonia-burning device, e.g., an internal combustion engine, a turbine, or a burner, at start-up. In some exemplary systems, a primary device includes a primary reformation reactor for partially reforming ammonia to hydrogen to fuel the device. Reformation reaction in the primary reformation reactor is catalyzed by waste heat generated from combustion of the ammonia fuel in the primary device. Prior to combustion, e.g., at start-up, the ammonia-burning device is not producing waste heat to heat the reformation reactor, thereby preventing the reformation reaction from occurring at a rate necessary for burning the ammonia fuel.

[0033] Some methods and systems disclosed herein provide a secondary reactor, which is heated to partially reform an ammonia fuel stream into a reformed fuel that includes both hydrogen and ammonia while the primary device is unpowered. The secondary reactor can be configured to provide hydrogen at a ratio of about 2 % to about 15 % by mass to the primary device. The secondary reactor operates to provide the reformed fuel until the primary device is “started” and generates sufficient waste heat to the primary reactor to initiate primary ammonia reformation. In some examples, the initial operation of the secondary reactor occurs from about 5 seconds to about 5 minutes prior so that the primary reactor can become sufficiently heated. Once the primary reactor has reached its operational heat conditions, the secondary reactor canbe turned off and the remaining heat energy in the secondary reactor can be recycled to the primary reactor by, for example, continuing to flow fuel through secondary reactor.

[0034] The upstream hydrogen production system allows the cold-startup of purely ammonia- fueled primary devices without a secondary fuel, such as diesel, or the need to include a source of pure hydrogen with the primary device.

[0035] References made herein to a ‘cold start’ refer to an engine system that is being initiated at ambient temperatures. Such engine system temperatures can generally include an ambient temperature below 80 °C, though this is not limiting, and are generally below the temperatures at which ammonia reforming reactors operate efficiently. In such a ‘cold’ state, heat exchange fluids, lubricating fluids, reactors, manifolds, and the engine block are at the ambient temperature of the surrounding environment. The operational range of ammonia reformation reactors can be in a range from 100 °C to 900 °C depending on the reformer’s material composition and structure and may not produce the necessary hydrogen to create efficient ammonia combustion chemistry in the combustion device itself.

[0036] As used herein, the terms ‘heat energy’ and ‘thermal energy’ are used interchangeably and are used to mean the energy related to the temperature of a system or element.

[0037] Referring to FIG. 1, a cold-start fuel reformation system 100 for providing a reformed fuel to an ammonia combustion device at ambient temperatures is shown. The fuel reformation system 100 including an optional fuel source 102, a heat exchanger 104, a reforming reactor 106, and a heater 108. The fuel reformation system 100 generates a stream of reformed fuel including ammonia and hydrogen at or near (e.g., at or within 5 %) operational temperatures and pressures to the downstream ammonia combustion device 112 for burning as fuel. The heater 108 raises the temperature of the reactor 106 to a temperature sufficient to facilitate the reformation reaction according to the reactive chemistry in the reactor 106 while the heat exchanger 104 exchanges thermal energy between the cold inlet fuel from the fuel source 102 and the heated reformed fuel from the reactor 106. In general, the reformed fuel generated by the reformation system 100 includes hydrogen and ammonia at a ratio in a range from 5:95 to 50:50. In some examples, the device receiving the reformed fuel determines the hydrogen: ammonia ratio.

[0038] The fuel reformation system 100 is operated at cold-start of the downstream ammonia combustion device 112, e.g., such as an ammonia combustion engine, a turbine, or burner. A controller 114 of the fuel reformation system 100 receives a signal from the device 112 toproduce reformed fuel. The controller 114 commands a power source 1 16 to provide power to the heater 108 to thereby increase the temperature of the reactor 106 to a pre-determined set temperature monitored by the fuel reformation system 100. The controller 114 opens a flash valve 110 to which the fuel source 102 provides compressed liquid fuel such as liquid ammonia. The flash valve 110 facilitates the phase transition of the liquid to generate gaseous fuel which is communicated to the heat exchanger 104. As an example, the gaseous fuel exiting the flash valve 110 can have a temperature in a range from -20 °C to -30 °C. In some examples, the gaseous fuel from the flash valve 110 is directed to both the exchanger 110 and the combustion device 112 and can be selectively directed, e.g., metered, or switched, between the two.

[0039] The flash valve 110 is fluidically connected to the heat exchanger 104 such that gaseous fuel flows from the flash valve 110 to the heat exchanger 104. The heat exchanger 104 includes a number of inlets and / or outlets for receiving and providing fluids to connected components. The gaseous fuel exchanges thermal energy (e.g., heat) with the heat exchanger 104 during the time in which the gaseous fuel is within the heat exchanger 104. In some examples, the heat exchanger 104 includes a channel through which the cold gaseous fuel flows which is in thermal connection to a second channel through a thermally conductive heat exchange medium, such as a reticulated foam, a honeycomb structure, or a plurality of fins.

[0040] The gaseous fuel flows from the heat exchanger 104 to a first end of the reactor 106 and through an opening into an inner reactor structure 118. The reactor structure 118 catalyzes the endothermic decomposition reactions in which the gaseous ammonia fuel is partially reformed (‘cracked’) into hydrogen, nitrogen, and remaining ammonia. At initiation, the reactor 106 is at ambient temperature which is insufficient for efficient decomposition.

[0041] In the example of FIG. 1, in which an external energy source (e.g., electricity, induction, etc.) heats the reactor 106, the reactor 106 is heated to a threshold temperature value sufficient for the reformation reaction before the system 100 initiates the gaseous fuel flow. In some examples, in which the reactor is combustion-heated (e.g., shown further herein in FIG. 5) the gaseous fuel flows at initiation. In the specific, non-limiting example of an ammonia internal combustion engine, the gaseous fuel flow is initiated when the reactor has achieved the target temperature which prevents unreacted fuel being exhausted into the atmosphere via engine exhaust.

[0042] The fuel reformation system 100 includes a heater 108 surrounding the reactor structure 118 and is electrically connected to a power source 116. The heater 108 increases the temperature of the reactor structure 118 into a temperature range that is catalytically efficient for decomposing the gaseous fuel. In general and without wishing to be bound by theory, the optimal temperature range for fuel decomposition is dependent on the structure and chemical composition of the reactor structure 118 within the reactor 106. In some examples of the heater 108 is an electric resistance heater, e.g., a resistive heater.

[0043] The reactor structure 118 includes a catalyst coating material on a supporting substrate which may be used by decomposing endothermic reactions occurring within the reforming reactor 106. Exemplary catalyst materials include a platinum group metal, such as ruthenium, rhodium, palladium, osmium, iridium, and platinum, mixtures of two or more thereof, and / or alloys of one or more thereof. Specifically, ruthenium is an efficient catalyst for an ammonia decomposition reaction.

[0044] The use of a platinum group metal in the reactor structure 118 is more catalytically efficient than the use of a base metal which reduces the overall size and volume of the reactor 106, thus reducing the energy needed to heat the thermal mass of the reactor 106 to the appropriate temperature for ammonia decomposition and achieving lower form factors for the fuel reformation system 100.

[0045] In another example, the reactor structure 118 includes a catalyst material selected from a base metal from the transition group that can include iron, nickel, cobalt, mixtures of two or more thereof, and / or alloys thereof. The use of a base metal catalyst can be cost-effective compared to platinum group metals and more thermally stable, thus, the reactor 106 can be heated to a higher temperature and increase the decomposition efficiency of the reactor structure 118.

[0046] In further examples, the reactor structure 118 includes alkali and or alkaline-earth metals from groups 1 and 2 on the periodic table in addition to the catalyst coating material, (e g., cesium (Cs), rubidium (Rb), potassium (K), sodium (Na), and / or barium (Ba), etc.)

[0047] The supporting material can be a metal, a metallic alloy, a ceramic, or combinations thereof capable of maintaining sufficient strength and rigidity in the decomposition reaction conditions. In some examples, the reactor structure 118 includes a ruthenium coating on an aluminum or aluminum-alloy support structure. The reactor structure 118 can include a pluralityof fins, metallic or ceramic foams, catalyst pellets, or monolithic catalyst supports (e.g., an extruded monolithic catalyst) having sufficiently low flow resistance to achieve a low-pressure differential between the first and second ends of the reactor 106 and the desired fraction of hydrogen to ammonia (e.g., by mass, or by volume). The reactor structure 118 has sufficiently large cross-sectional area relative to overall volume to maintain a low pressure resistance to the flow of ammonia. The volume of the reactor structure 118 determines the achieved hydrogen percentage makeup of the reformed fuel, e.g., the volume is sufficient to provide a hydrogen make up in a range from 5 % to 15 % by volume of the reformed fuel. The cross-sectional area of the reactor structure 118 determines the pressure drop. As such, a large and practical-to- manufacture cross sectional area is desirable.

[0048] As discussed herein, the optimal temperature range for fuel decomposition is dependent on the structure and chemical composition of the reactor structure 118. In an example, the fuel reformation system 100 includes a temperature sensor (not shown) arranged within the reactor 106 to monitor the temperature of the reactor structure 118 and provide temperature data to the heater 108 and / or the controller 114. In such an example, the controller 114, or the heater 108, can maintain the temperature of the reactor structure 118 via a feedback loop within a beneficial operational temperature range.

[0049] In the example in which the reactor structure 118 includes a platinum group metal, the temperature to which the heater 108 heats the reactor structure 118 can be in a range from 250 °C to 500 °C and selected based on the specific catalyst coating composition. In the example of ruthenium, an efficient catalytic temperature for the reactor structure 118 is in a range from 3500to 500 °C.

[0050] The reactor 106 includes, or can be surrounded by, insulation 120 to reduce thermal energy loss from the reactor 106 and increase the energy efficiency of the reactor 106. The insulation 120 can withstand the temperatures to which the heater 108 will elevate the reactor 106. Examples of the insulation 120 include ceramic or fiberglass fabric, mineral wool, refractory blocks or castings, compressed rigid mineral sleeves such as mica or vermiculite, metallized heat shields, or high-temperature foams (e.g., glass, metal or ceramic foams).

[0051] The reformed fuel flowing from the reactor 106 has a proportion of hydrogen in a range from 2 % to 20 % by mass (e.g., 5 % to 15 % by mass) to provide a sufficient ratio of ammonia to hydrogen to the device 112 to initiate and sustain combustion in the device 112. Said anotherway, the proportion of hydrogen in the reformed fuel is higher by mass than the proportion of hydrogen in the gaseous fuel (e.g., which may be zero). The reformed fuel enters the heat exchanger 104 and exchanges thermal energy with the unreformed gaseous fuel provided by the flash valve 110. In general, reformed fuel provides thermal energy to the heat exchanger 104 and the unreformed gaseous fuel receives thermal energy. In this manner, excess thermal energy is removed from the reformed fuel to warm the gaseous fuel beneficially increasing the energy efficiency of the fuel reformation system 100.

[0052] In general and without expressing limitation, the reformed fuel is at or near operational temperatures and pressures to the downstream ammonia combustion device 112 to increase the volumetric efficiency of the fuel provided to the device 112. The temperature of the reformed fuel entering the device 112 can be in a range from 10 °C to 50 °C and / or a pressure in a range from .9 to 2.0 bar.

[0053] In some examples, the heater 108 can be an induction heating element when coupled with a reactor structure 118 that is capable of being inductively heated. In general and without wishing to be bound by theory, materials that are electrically conducting can be heated through electromagnetic induction. In the cross-sectional example of FIG. 2, a reforming reactor 206 is shown in which a cylindrical reactor structure 218 is at least partially surrounded by insulation 220. An inductive heater 208 surrounds the insulation 220 and is electrically connected to a power source 216. The elements shown in FIG. 2 can provide the corresponding elements of FIG. 1.

[0054] The reactor structure 218 is an example of the reactor structure 118 that which can be heated by inductive heating. Examples include a reactor structure 218 having an electrically conductive support structure, a non-electrically conductive support structure coated in an electrically conductive material, an electrically conductive catalyst material, or combinations thereof. Said another way, the reactor structure 218 includes ferromagnetic and / or ferrimagnetic materials, ferromagnetic / ferrimagnetic materials (e.g., iron, cobalt, or nickel, or alloys or oxides of these three metals), or paramagnetic materials (e g., aluminum, or copper, brass, and other electrically-conductive transition metals and their alloys) which are magnetically susceptible and exhibit a magnetic hysteresis. Such effect is exploited to alternate the polarity of a magnetic field applied to the materials thereby generating heat energy through both the eddy current generationand subsequent dissipation as well as through the ordering and disordering of magnetic moments within the material.

[0055] Some electromagnetic insulator materials for the insulation 220 can include diamagnetic materials such as quartz, glass, plastics, and the like. In some embodiments, however, incorporating such material between the reactor structure 218 and the inductive heater 208 repels the magnetic field, causing a loss in heating efficiency and temperature.

[0056] The power source 216 provides power to an inverter 222 which applies an electrical signal to the heater 208 to generate the electrical field necessary to inductively heat the reactor structure 218. Parameters of the electrical signal depend on the materials of the reactor structure 218. Heating intensity is controlled by the switching frequency of the inverter 222 which in turn changes the frequency of an alternating current signal applied to the magnetically-susceptible material. In general, and without wishing to be bound by theory, higher frequency switching leads to higher heating rates in a given material, and each material responds to a different frequency based on the material class, e.g., whether the material ferromagnetic, ferrimagnetic, or paramagnetic, and electrical conductivity. In some examples of a control strategy, the frequency at which an H-bridge circuit is opened and closed to invert DC electricity to AC is changed. The rate of the H-bridge switching is the same frequency supplied to the induction heater 208. The varied frequency modulates the rate of induction heating in the target materials.

[0057] In another embodiment, the fuel reformation system includes an air introduction system which feeds a stream of oxidizer gas, e.g., air, to the reactor to beneficially aid the ammonia decomposition process in the reactor at cold-start. A cold-start fuel reformation system 300 having an air pump 302 which provides air to a valve assembly 304 is shown in FIG. 3. The fuel reformation system 300 is shown including the fuel source 102, flash valve 110, and heat exchanger 104 of FIG. 1, and the reactor 206, inductive heater 208, insulation 220, and reactor structure 218 of FIG. 2.

[0058] During an example cold-start process, the inductive heater 208 heats the reactor structure 218 to operational temperatures. The air pump 302 provides a stream of air to the valve assembly 304 which meters the air flow to a desired level. Some examples of the valve assembly 304 include a check valve and a metering device, such as a needle valve, gate valve, pressure regulator, or similar. The metered air stream is then blended with the gaseous fuel from the heat exchanger 104 before entering reactor structure 218. The blended air / fuel mix encounters theheated reactor structure 218 and at least partially combusts “autothermally” to provide additional heat energy to the reactor structure 218 at cold-start. Broadly, autothermal combustion combines energy-absorbing and energy- releasing chemical reactions to control the temperature of the reactor structure 218. The valve assembly 304 controls the air flow to the reactor structure 218 based on thermal feedback. For example, the reactor structure 218 may have one or more thermocouples or resistive temperature detectors embedded within the structure, such as along a longitudinal axis, which send information to the controller indicative of a temperature of the reactor structure 218. The flow of air is controlled using a metering valve, e.g., a multi-turn needle valve to maintain a certain reactor average temperature. The airflow can also be controlled in terms of a metered flow, e.g., using a calibrated flow element with a known pressure drop providing a specific number of grams / second of air across a specific value of the pressure drop. The flow control could also consist of a forward pressure regulator which is adjusted by the controller electronically.

[0059] The fuel reformation system 300 includes a controller 306 for controlling the inverter 222, power source 216, flash valve 110, and valve assembly 304 and receiving information from one or more sensors. The controller 306 receives temperature information from one or more temperature sensors of the reactor 206. When the temperature of the reactor structure 218 is above a threshold temperature, the controller 306 commands the valve assembly 304 to close thereby terminating the flow of air to the reactor structure 218. The reactor 206 then operates to reform the gaseous fuel as described herein. The controller 306 can be provided by controller 114 and vice versa.

[0060] Such examples of reactors including the additional air flow facilitate smaller reactor volumes and less energy use to heat the reactor. The added heat energy from combustion may increase the temperature above operational ranges of platinum group substrates (e.g., above 500 °C for ruthenium substrates). The temperature can be controlled to remain below the substratespecific maximum temperature by the controller 306 which regulates the air flow and / or fuel / air mixture entering the reactor structure 218. In such examples, base metal catalyst formulations may be preferred.

[0061] In another example, the inductive heater heats only a portion of the reactor structure. Such examples may use less energy than examples in which the inductive heater heats the entire reactor structures. Such examples may reduce the total cost of the reactor as only the inductivelyheated portion needs to include the electrically conductive materials, and the remaining reactor structure can include cheaper and / or non-electrically conductive materials. Referring to FIG. 4, a reactor 400 having a two-stage reactor structure 402 including a pre-reactor portion 404 and a secondary portion 406. The pre-reactor portion 404 includes electrically conductive materials, such as those described herein, which allow inductive heating. An inductive heater 408 surrounds the pre-reactor portion 404. In operation, the inductive heater 408 heats the surrounded portion of the two-stage reactor structure 402, e.g., the pre-reactor portion 404. In some examples, the pre-reactor portion 404 includes electrically conductive base metal (e.g., iron, copper, or nickel) such that the pre-reactor portion 404. The secondary portion 406 can include either a base metal, or a platinum group metal for decomposing the ammonia fuel and is heated through autothermal decomposition of the gaseous fuel to form the reformed fuel.

[0062] The secondary portion 406 may optionally include the same electrically conductive materials and not be surrounded by the inductive heater 408. The portion of the reactor structure which is being inductively heated includes the electrically conductive support structure described herein. The pre-reactor arrangement of reactor 400 can be used in any cold - start fuel reformation system described herein.

[0063] The pre-reactor portion 404 can also be used to ignite the autothermal reaction. If the incoming fuel and air are heated at high intensity for a short time, they can be coaxed into igniting on the catalyst directly downstream of the pre-reactor portion 404.

[0064] Some examples of the cold - start fuel reformation system can include a fuel (e.g., ammonia, hydrogen, or mixture of both) burning manifold within a duct surrounding the reactor and an exhaust condenser. Burning the fuel within the duct provides heat energy to the reactor and to an exhaust condenser downstream of the flash valve. This increases the temperature of the gas before entering the heat exchanger and raises the temperature of the reactor to beneficially increase the ammonia decomposition efficiency.

[0065] Referring now to FIG. 5, a cold - start fuel reformation system 500 having a duct 502 which encloses an exhaust condenser 504, a reactor 506, and a fuel manifold 508 is shown. The fuel reformation system 500 includes the fuel source 102, flash valve 110, and heat exchanger 104 of FIG. 1. In general, a portion of the fuel which travels through the reactor 506 is ignited by an ignitor (e.g., by a spark, hot-surface, or glow plug) and burned within the duct 502 and delivers heat to the reactor. The duct 502 is open at one end to receive a gas flow, such asenvironmental air, e.g., through natural convection or forced induction. The manifold 508 includes a number of openings (e.g., holes, or vents) so that the reformed fuel can exit the manifold 508 at a known rate. The fuel exiting the manifold 508 is burned at the ratio of ammonia and hydrogen that the reactor structure 514 produces based on the current temperature (e.g., from 0% hydrogen to 100 % hydrogen). The ratio of hydrogen to ammonia increases as the reactor structure 514 is heated. The gas flows from the open end and over the manifold 508 and burning hydrogen streams, thus warming the gas flow. The warmed gas flows through the duct 502 to an exhaust end thereby providing additional heat energy to the reactor 506 and the exhaust condenser 504.

[0066] The reactor 506 and the heat exchanger 516 are within the duct 502 and receive heat energy from the warmed gas flowing through the duct 502. The reactor 506 includes a reactor structure 514 for decomposing ammonia into nitrogen and hydrogen, and a heat exchanger 516 surrounding the reactor structure 514. The exhaust condenser 504 receives the gaseous fuel from the flash valve 110 which flows through a channel 510. The exhaust condenser 504 includes a surrounding heat exchanger 512 to exchange heat energy with the heated air and combustion exhaust in the duct 502. In this manner, the air and exhaust which are heated by combustion at the manifold 508 are passed over the reactor 506 and the exhaust condenser 504. This increases the energy efficiency of the fuel reformation system 500 by warming gaseous fuel within the channel 510, creating a higher gas temperature before entering the reactor structure 514, and heating the reactor structure 514 which beneficially increases decomposition efficiency.Examples of the heat exchange elements of the heat exchangers 512 and 516 include tubes, fins, coils, bars, or plates.

[0067] A portion of the reformed fuel exiting the reactor structure 514 is directed to the manifold 508 for burning in the duct 502. The remaining reformed fuel is directed to the heat exchanger 104 to exchange heat energy between the reformed and the gaseous fuels.

[0068] In another example, the exhaust condenser 504 and the reactor 506 are a single unit with exchange stages occupying different channels, such as in a finned-tube heat exchanger. Such examples can operate without a heat exchanger 104 outside of the duct, thereby facilitating reduced overall form factors.

[0069] Referring now to FIG. 6, a fuel reformation system 600 is shown in which fuel flows from the fuel source 102 and adiabatically expands following the flash valve 110. The gaseousfuel then enters an integrated exchange reactor 604 which includes channels to permit the gas to flow between the first channel 510, a heat recovery channel 618, the reactor structure 514, and a hydrogen cooling channel 616. The channels can be in contact, such as heat recovery channel 618 and hydrogen cooling channel 616, to provide heat exchange through a shared wall, or connected to common heat exchange structures 620 which transfer heat between the gases within the different channels. FIG. 6 is a cross-sectional view of the fuel reformation system 600 showing the heat exchange structures 620 (e.g., heat exchange structures 620a-d) enclosing channel 510 and reactor structure 514. In some examples, the heat exchange structures 620 enclose heat recovery channel 618 and hydrogen cooling channel 616 as well.

[0070] The fuel reformation system 600 uses the manifold 508 to provide fuel for ignition and combustion as described with respect to FIG. 5. The fuel reformation system 600 integrates the heat exchanger 104 described previously into the integrated exchange reactor 604 such that heat exchange between the gaseous fuel and the reformed fuel takes place within the duct 502 to capture more of the heat energy released as the fuel bums.

[0071] The embodiments provided herein include hydrogen production systems coupled to intakes of ammonia-burning devices. One non-limiting example of such an ammonia-burning device is an ammonia internal combustion engine. Such engine systems include an endothermic reforming reactor in a reactor chamber integrated into the exhaust manifold of an engine. The hydrogen production systems described herein operate at start-up to provide a flow of ammonia and hydrogen to the engine to be burned and generate waste heat to heat the primary reforming reactor. Various embodiments of the systems described herein can also include catalytic reactors that are not detached from the engine. Thermal integration of the primary reforming reactor with the engine systems provided herein can provide the advantage of mitigating heat losses from exothermic reforming reactions and for feeding the necessary heat into endothermic reactions.

[0072] Referring to FIG. 7, the engine system 700 having the cold - start fuel reformation system 100 connected to an intake manifold 711 can provide advantages for engine conditions where an engine exhaust gas temperature is not sufficiently high enough to achieve reforming in the primary reforming reactor, e.g., during a cold-start. In such a situation, the reforming reactor 702 would not normally convert a significant amount of the fuel, so a significant unburned fuel will remain in the engine exhaust. The exemplary thermally integrated cold-start engine system 700 provided herein includes an engine 701, a reforming reactor 702, and a reactor chamber 703in connection with the cold - start fuel reformation system 100 of FIG. 1. The cold - start fuel reformation system 100 provides an initial flow of reformed fuel to the engine system 700 at start up, such as when the engine exhaust gas temperature is not sufficiently high enough to achieve reforming in the primary reforming reactor 702.

[0073] In general, the reforming reactor 702 is configured for receiving and reforming an inlet fuel 712 including one or more reactants and / or a feed fuel, e.g., NH3. The inlet fluid 712 can include one or more vaporized reactants or fuels. The engine 701 is configured to receive a reformed fuel 710 from the reforming reactor 702 into an intake manifold 711.

[0074] Once a temperature of the engine system 700 is achieved, the reformed fuel 710 exits the reactor 702 and enters the intake manifold 711 of the engine 700. At the intake manifold 711, the reformed fuels 710 are mixed with incoming air. The reformed fuels 710 can optionally be passed through an auxiliary heat exchanger using an engine coolant or a liquid coolant from a separate cooling loop. Cooling the fuels 710 lowers the overall density of the intake mixture entering the engine 700, which helps to increase the volumetric efficiency. The reformed fuel 710 is burned in the engine cylinders 713 using standard injectors.

[0075] The engine 700 produces an exhaust gas 706 by burning the reformed fuel 710 to generate power. The reformed fuel 710 exits the reforming reactor 702 and flows to the engine 701.

[0076] The reactor chamber 703 is sized and shaped to receive the reforming reactor 702. The reactor chamber houses the reforming reactor 702 as well as direct flow of exhaust gases 706 exiting from the engine 701 to the reactor chamber 702. At least a portion of the reactor chamber 703 is coupled to the housing of the engine 701 so that the reactor chamber 703 is fluidly coupled to one or more outlets of an exhaust manifold 705 of the engine 701. In some cases, the reactor chamber 703 is an integral part of (e.g., an extension of) the exhaust manifold 705 that is sized and shaped to receive the reforming reactor 702. The exhaust gas 706, exiting from the exhaust manifold 705, is fluidly connected to interior portions of the reactor chamber 703 such that the exhaust gas 706 can flow along a surface of the reforming reactor 702. Reformation requires energy that can be provided in the form of thermal energy. Thus, the arrangement of the engine 701, the reactor 702, and reactor chamber 703 allows for an efficient heat exchange to occur between the engine 701 and the reactor 702 via the exhaust gases, suchthat thermal energy produced from the internal combustion engine 701 can be used to provide energy to promote a reforming reaction (or process) in the reactor 702.

[0077] The gases 706 enter an after-treatment catalyst chamber 708 to reform exhaust gases before exiting to the ambient environment. The catalyst chamber 708 allows for the beneficial use of after-treatment catalyst reactions, such as selective catalytic reduction of NOx. Briefly, aftertreatment for NOx selective catalytic reduction (SCR) includes the catalytic reactor 707 with injection of a reductant material into the inlet exhaust gas 706 stream. The reforming reactor 707 can be used to supply both hydrogen and gaseous hydrocarbons suitable for NOx SCR. Suitable active materials for reformed gas NOx SCR include silver on alumina support.

[0078] The engine system 700 promotes thermal exchange to occur between the exhaust gas 706 and the reactor 702 coupled heat exchange elements between the catalyst chamber 708 and the reactor 702. As shown, a chamber wall 709 of the catalyst chamber 708 contacts the wall 704 of the reactor 702 such that heat is exchanged between the chamber 708 and the reactor 702 to beneficially increase the reforming efficiency of the reactor 702.

[0079] Additionally or alternatively, the system 700 includes structures that prevent the exhaust gas 706 from the engine 701 from entering the interior portion of the reactor 702 such that the exhaust gas 706 from the engine 701 can flow through heat exchange structures, for example, perforated fins (not shown), which allow for gaseous cross-flow (e.g., traverse flow) along the body of the reactor 702 before the exhaust gas 706 exits from an outlet end of the reactor chamber 703. The exhaust gas 706 can exit the reactor chamber 703 and enter another chamber or portion of the system, such as a turbine portion of a turbocharger.

[0080] Disclosed herein is a method of operating an ammonia combustion device at start up, e.g., before exhaust gas from an ammonia internal combustion engine, or other ammonia combustion device, is sufficiently hot to heat a primary reactor. The method 800 can be used to operate the engine 700 disclosed herein.

[0081] A first reactor is heated to a first temperature value (step 802).

[0082] A first fuel is provided to the first reactor (step 804). As disclosed herein, the fuel is a gaseous fuel which includes ammonia. In some examples, the ammonia does not include additional hydrogen during step 804.

[0083] The fuel is reformed into a reformed fuel (step 806). In general, the fuel is reformed such that at least some of the ammonia is reformed into nitrogen and hydrogen. The reformed fuel contains a higher percentage of hydrogen than the inlet fuel by mass.

[0084] The reformed fuel is provided to an intake manifold of the ammonia internal combustion engine (step 808).

[0085] The second fuel is combusted in the ammonia combustion system thereby generating an exhaust gas (step 810). The reformed fuel is combusted in the ammonia engine to produce heated exhaust gases.

[0086] The exhaust gases are directed along a flow path along the outer surfaces of a primary reactor of the ammonia internal combustion engine (step 812). The exhaust gases heat the primary reactor to a temperature sufficient to facilitate the ammonia reformation reaction when fuel is provided to the primary reactor. The temperature of the primary reactor is monitored until a reformation temperature is achieved. When the reformation temperature is achieved, the fuel flow to the first reactor is terminated.ExamplesExample 1 - Results

[0087] FIG. 9 is a schematic illustration of an exemplary inductively heated reactor structure testing system 900. Briefly, a fuel source 914 (e.g., a source of NH3) is in fluid communication with one end of a reforming reactor 902. The reactor 902 includes an insulator 904 and a reactor structure 906 within inductive heater 916. The coils 918 of the inductive heater are connected to a power source 910 and an inverter 912. A thermocouple 908 is installed at ends of the reactor structure 906 to monitor the temperature within the reactor 902.

[0088] Fuel was flowed from the source 914 into the reactor 902. The reactor 902 was inductively heated using the inductive heater 916. The fuel decomposed within the structure 906. The resultant reformed fuel was monitored for ammonia / hydrogen / nitrogen content.

[0089] One embodiment of the systems and methods described herein was tested using the system 900. The insulator 904 was manufactured as a stainless steel tube (e.g., 300-series stainless steel, which is a paramagnetic material), with a nickel-metal foam (e.g., ferromagnetic) used as the reactor structure 906, e.g., which can provide any reactor structure described herein.The reactor structure 906 was placed within a copper tubing coil, e.g., inductive heater 916, and subjected to high-frequency low-voltage current (e.g., 48VAC @ 100kHz).

[0090] An image of the coils 918 surrounding the insulator 904 in the reactor 902 is shown in FIG. 10. The reactor structure 906 is not shown as it is surrounded by the insulator 904. The system 900 resulted in heating of the reactor structure 906 to approximately 720 °C, which was sufficient for decomposing ammonia to hydrogen and nitrogen (e.g., > 99% decomposition).

[0091] Depending on the flow of ammonia, which can vary (e.g., between 1 gram per second (g / s) to 100 g / s), a reactor structure of sufficient volume / mass can be sized appropriately to fully decompose ammonia to hydrogen and nitrogen while being heated through inductive means.Example 2 - Ring-shaped Induction Heater

[0092] Forming a connected magnetic field within the inductive heater can reduce the magnetic field strength outside of the reactor and reduce energetic losses, e.g., increase efficiency, and reduce hazards such as unintentionally heated bodies near the reactor. Forming the reactor as a ring, as shown in FIG. 11, can provide advantages such as a connected magnetic field within the reactor by reducing divergence of the magnetic field within an inductive coil and at the ends of the reactor structure.

[0093] In some examples, the system can additionally include a coil of electrically conductive material (e.g., an inductive coil) that wraps around the ring-shaped reactor (or an annular reactor). An electric signal is applied to the coil to generate a magnetic field which, due to the ring-shaped reactor, reduces or eliminates magnetic divergence at the respective ends of a tubular reactor structure. In this way, a ring-shaped reactor increases heating efficiencies of the inductive heater heating the reactor structure. In some examples, the field can be entirely within the connected loop, which prevents external materials from being heated or changing the field shape within the coil. The shape of the reactor can be any closed shape, e.g., ring-shaped, circular, ovular, or including sharp bends such as a rectangle.

[0094] The current applied to the inductive coil can advantageously create a directional, collimated magnetic field within the coil and within the reactor structure being inductively heated. Such a magnetic field may diverge at the open ends of the coil to wrap around the outside of the coil and form a continuous field. In contrast, the reforming reactor 206 shown in FIG. 2 is a straight tube shape in which the magnetic field generated by the inductive heater 208 divergesat the respective ends thus decreasing the magnetic field density near the ends of the reactor structure 218.

[0095] An example ring-shaped reforming reactor 1006, which includes an inductive heater 1008, is shown in FIG. 11. The reforming reactor 1006 is similar to and can provide the functionality of the reactors 106 and 206 previously described. The reforming reactor 1006 includes an inductive heater 1008 surrounding (e.g., wrapped around) insulation 1020 and reactor structure 1018. As discussed above, the inductive heater 1008 can include conductive coils that are attached to a power source 1016 and an inverter 1022.

[0096] The coils 1024 of the inductive heater 1008 are shown wrapping around the entire length of the ring-shaped reactor structure 1006. The coils 1024 wrapping entirely around the length of the structure 1006 generate a uniformly collimated magnetic field within the reactor 1006 and reduce magnetic field divergence within the reactor structure 1018 thus increasing heating and reformation efficiency of the reactor.

[0097] The reactor structure 1018 is curved to match without contacting the inner surfaces of the insulation 1020. The reactor structure 1018 includes two halves which extend along the majority of the inner volume of the insulator 1020. In such embodiments, having the two halves extend as far as possible within the inner volume of the insulator increases the reformation efficiency of the reactor 1006. In some examples, the reactor structure 1018 is a unitary body having an inlet into which fuel flows, and an exit port out of which reformed fuel flows.

[0098] The inductive heater 1008 can generate a collimated magnetic field within the reactor structure 1018 to cause the reactor structure 1018 to heat. Ammonia (NH3) enters the reactor 1006 and flows within the reactor structure 1018 (arrow entering at bottom of reactor 1006).

[0099] In some examples, the insulation 1020 for containing the reactor structure 1018 includes a paramagnetic material, e.g., a material having a magnetic permittivity with respect to free space of less than one. Exemplary paramagnetic materials can include an austenitic material, e.g., 300- series stainless steel. In some embodiments, the reactor structure 1006 excludes the use of any diamagnetic materials, including in the insulation 1020.

[0100] In general, a material (such as a ferromagnetic or ferrimagnetic material) can be heated if the material is within the magnetic field generated by the reactor, e.g., near the intended target materials to be heated for fuel reformation. In some examples, a body composed of susceptible materials is nearby and within the magnetic field generated by the reactor 1006. Heating of suchbodies can constitute a hazard or a waste of energy (e.g., unexpectedly heated items near the reactor structure 1018 can pose a danger to a user or flammable materials, or causing inductive heating in a material which is not the reactor structure 1018). In some examples, susceptible materials are not as insulation or field guides used in or near the reactor structure 1018. In some embodiments, the system excludes ferromagnetic or ferrimagnetic materials in the area surrounding, e.g., external to, the reactors.

[0101] Laminated structures like those used in iron-core transformers and electromagnets can be used to prevent external heating of this return pathway structure. The laminations prevent the generation of significant eddy currents, e.g., the mechanism in which induction heating works. Using a highly laminated iron guide, for example, strong direction of the magnetic field pathway can be achieved due to the ferromagnetic nature of iron. The laminations prevent eddy currents from forming with the laminated structure thus preventing unwanted heating.

[0102] While this specification contains many details, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features specific to particular examples. Certain features that are described in this specification in the context of separate implementations can also be combined. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple embodiments separately or in any suitable subcombination.

Claims

What is claimed is:

1. A method of operating an ammonia combustion system, comprising: heating a first reactor of the ammonia combustion system to a first temperature; flowing a first fuel to the first reactor, the first fuel comprising ammonia; reforming the first fuel into a second fuel; providing the second fuel to an intake of the ammonia combustion system; combusting the second fuel in the ammonia combustion system and thereby generating an exhaust gas, flowing the exhaust gas from an exhaust of the ammonia combustion system along outer surfaces of a second reactor of the ammonia combustion system; and, when a second temperature of the second reactor exceeds a threshold temperature, terminating the flow of the first fuel to the first reactor.

2. The method of claim 1, comprising: providing a stream of a combustion gas along with the first fuel to the first reactor; and terminating the stream of combustion gas when the second temperature exceeds a threshold temperature value.

3. The method of claim 2, wherein the heating comprises inductively heating, resistively heating, heating by combusting a portion of the second fuel, or a combination thereof.

4. The method of one of claim 2 or claim 3, comprising: transferring heat energy between the second fuel and the first fuel before the first fuel is provided to the second reactor.

5. The method of any one of claims 2-4, comprising, before providing the first fuel to the first reactor, transitioning the first fuel from a liquid state to a gas state.

6. The method of any one of claims 2-5, wherein the first fuel is ammonia, and the second fuel comprises hydrogen.

7. The method of claim 6, wherein reforming comprises catalytically decomposing the first fuel by flowing the first fuel over a structure comprising a platinum group metal, a base metal, or both.

8. The method of any one of claims 2-7, wherein reforming comprises reforming the first fuel until the second fuel comprises less than 5 % ammonia.

9. The method of any one of claims 2-8, comprising exchanging heat energy between the first fuel and the second fuel.

10. The method of any one of claims 2-9, comprising combusting a portion of the second fuel to provide heat energy to the first reactor.

11. An engine system, the system comprising: an engine comprising an intake for receiving a first fuel from a fuel source and an exhaust for releasing an exhaust gas; a fuel reformation system for providing a second fuel to the intake of the engine, the fuel reformation system comprising: a reactor having a first end for receiving the first fuel, a second end for exhausting the second fuel, and a wall forming an outer surface and an inner surface, the inner surface defining an interior cavity; a reactor structure within at least a portion of the interior cavity for producing the second fuel from the first fuel; a heater configured to heat the reactor structure; and a heat exchanger configured to receive the first fuel from the fuel source and second fuel from the reactor, such that heat energy is transferred between the second fuel and the first fuel and having an outlet connected to the intake for providing the second fuel to the intake; anda reforming reactor comprising a first end portion, a second end, a wall forming an outer surface and an inner surface, the inner surface defining an interior cavity for receiving the first fuel, a second fuel, reactants for the first fuel, or combinations thereof, and wherein the exhaust of the system is sized and shaped for receiving a portion of the reforming reactor such that the exhaust gas flows along a surface of the reforming reactor within the exhaust.

12. The system of claim 11, comprising: an exhaust condenser comprising a fluid channel surrounded by a first heat exchange element; a fuel manifold having a plurality of outlets, configured to receive a portion of the first fuel from the second end of the reactor such that the portion of the first fuel exits the plurality of outlets; an ignitor arranged to ignite fuel expelled from at least one of the plurality of outlets, and wherein the reactor is surrounded by a second heat exchange element.

13. The system of claim 12, wherein the first heat exchange element and the second heat exchange element comprise at least one of a reticulated foam, a honeycomb structure, or a plurality of fins.

14. The system of claim 12 or claim 13, comprising a duct defining an interior space enclosing the exhaust condenser, reactor, and the fuel manifold having a first inlet opening and a second outlet opening.

15. The system of any one of claims 11-14, wherein the heat exchanger comprises the first heat exchange element and the second heat exchange element.

16. The system of any one of claims 11-15, wherein the engine is an internal combustion engine, a gas turbine, an industrial boiler, or a duct burner.

17. An engine system, the system comprising:an engine; and a fuel reformation system comprising: a ring-shaped reactor having a first end for receiving a first fuel, a second end for exhausting a second fuel, and a wall forming an outer surface and an inner surface, the inner surface defining an interior cavity, a reactor structure within at least a portion of the interior cavity for producing the second fuel from the first fuel, wherein the reactor structure has a complementary shape that aligns with the ring-shaped reactor.

18. The system of claim 17, wherein the engine comprises an intake for receiving a first fuel and an exhaust for releasing an exhaust gas; and wherein the system comprises: a heater configured to heat the reactor structure; and a heat exchanger configured to receive the first fuel and second fuel from the ringshaped reactor and exchange heat between the second fuel and the first fuel, the heat exchanger having an outlet connected to the intake for providing the second fuel to the intake.

19. The system of claim 18, wherein the heater is an inductive heater comprising conductive coils surrounding an entire length of the wall of the ring-shaped reactor.

20. The system of claim 19, further comprising an insulation surrounding at least a portion of the wall of the ring-shaped reactor, wherein the insulation is within an inner volume of the conductive coils.

21. The system of claim 20, comprising a reforming reactor comprising a first end portion, a second end, a wall forming an outer surface and an inner surface, the inner surface defining an interior cavity for receiving the first fuel, a second fuel, reactants for the first fuel, or combinations thereof, and wherein the exhaust of the system is sized and shaped for receiving a portion of the reforming reactor such that an exhaust gas of the engine flows along a surface ofthe reforming reactor within the exhaust wherein the insulation has a magnetic permittivity relative to free space of less than one.

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