Systems and methods for producing hydrogen from ammonia using a continuous dual catalyst unit

Abstract

The present invention generally relates to a system and method for generating hydrogen from an ammonia-mounted vehicle, where the generated hydrogen is used as a fuel source for an internal combustion engine. The present invention utilizes an electric catalyst unit to initiate an ammonia cracking process on board during a cold start of the internal combustion engine, where a heat exchange catalyst unit is utilized when the exhaust gas from the internal combustion engine is heated to a threshold temperature suitable for carrying out the ammonia cracking process.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of U.S. Non - Provisional Application No. 17 / 986,265, filed on November 14, 2022, entitled "SYSTEMS AND METHODS FOR THE CATALYTIC PRODUCTION OF HYDROGEN FROM AMMONIA ON - BOARD MOTOR VEHICLES", which claims the benefit of U.S. Provisional Application No. 63 / 395,820, filed on August 6, 2022, entitled "SYSTEMS AND METHODS FOR THE CATALYTIC PRODUCTION OF HYDROGEN FROM AMMONIA ON - BOARD MOTOR VEHICLES", U.S. Provisional Application No. 63 / 355,959, filed on June 27, 2022, entitled "SYSTEMS AND METHODS FOR THE CATALYTIC PRODUCTION OF HYDROGEN FROM AMMONIA ON - BOARD MOTOR VEHICLES", and U.S. Provisional Application No. 63 / 312,121, filed on February 21, 2022, entitled "SYSTEMS AND METHODS FOR THE CATALYTIC PRODUCTION OF HYDROGEN FROM AMMONIA ON - BOARD MOTOR VEHICLES", all of which are commonly owned, and the disclosures of each are hereby incorporated by reference in their entirety into this specification.

[0002] The present invention generally relates to systems and methods for generating hydrogen from ammonia - on - board vehicles, where the generated hydrogen is used as a fuel source for an internal combustion engine.

Background Art

[0003] [Description of Related Technologies] The overall temperature rise on and above the Earth's surface indicates an important issue that the Earth is facing. The Earth's climate has changed significantly mainly due to human activities, and the transportation sector plays a major role in this global warming. For example, internal combustion engines have conventionally burned fossil fuels, which generates CO2, a known factor in global warming. Over the past decade, the transportation sector has advanced in making electric and hybrid-powered vehicles widely available. Generally, most of the electric and hybrid vehicles sold today tend to produce significantly less global warming emissions than most of the vehicles operating on fossil fuels, i.e., gasoline. However, the environmental benefits of electric and hybrid vehicles still mainly depend on how much fossil fuel is burned to charge these vehicles. For example, if a vehicle is charged using a power grid that consumes a large amount of coal, the environmental benefits will be reduced.

[0004] Furthermore, the batteries and fuel cells in electrified vehicles rely on raw materials such as cobalt, lithium, and rare earth elements. These materials are associated with serious environmental and human rights issues. For example, cobalt is particularly problematic. The mining of cobalt generates harmful waste and slag that can leach into the environment, and studies have shown high exposure rates to cobalt and other metals in communities around cobalt mining and processing facilities. To extract such metals from their ores, a process called refining is also required, which can release sulfur oxides and other harmful air pollutants.

[0005] In consideration of the ongoing environmental problems associated with current electric vehicles, ammonia has been proposed as an alternative to fossil fuels for use in internal combustion engines, considering its relatively high energy density and zero CO2 emissions when burned. However, pure ammonia burns too slowly and cannot complete combustion during the power stroke of a four-stroke engine operating at speeds of thousands of revolutions per minute (RPM). Therefore, pure ammonia cannot be efficiently used as fuel in small internal combustion engines, regardless of whether it is spark ignition (i.e., gasoline) or compression ignition (i.e., diesel). In other words, when ammonia burns, combustion produces a flame with a relatively low propagation speed. This low combustion speed of ammonia causes combustion to become unstable under operating conditions of low engine load and high engine speed.

[0006] In previous methods of fueling a combustion engine with ammonia, it was necessary to mix ammonia with a secondary combustion-promoting fuel such as gasoline, liquefied petroleum, or diesel. However, the requirements for the secondary combustion-promoting fuel change with the varying engine load and engine speed, which can cause control problems. Therefore, the use of a secondary combustion-promoting fuel usually requires an additional control mechanism that must be part of the engine management system.

[0007] Hydrogen has also been proposed as an alternative to fossil fuels for use in internal combustion engines, as it is extremely abundant and can rival the power of gasoline or diesel considering its lower calorific value. Hydrogen is easy to ignite because it has a high flame speed and a low ignition temperature and is known to burn approximately six times faster than gasoline. Most importantly, hydrogen produces zero CO2 emissions when burned.

[0008] However, an issue when using hydrogen mounted on a vehicle is that hydrogen is an extremely light and low-density gas and cannot be stored as easily as liquid fossil fuels. Hydrogen requires compression, cooling, or a combination of both. The use of compressed hydrogen fuel tanks mounted on a vehicle inherently creates a number of safety issues such as the risk of potential failure of the pressure vessel, leakage of hydrogen in a limited space, and the like.

[0009] It is known that hydrogen can be obtained from ammonia by catalytically decomposing ammonia into its constituent hydrogen and nitrogen components through a process called "cracking". However, the ammonia cracking process is an endothermic process that requires heat. When the power source mounted on an automobile is limited, it is difficult to generate the heat required to efficiently perform ammonia cracking on board.

[0010] Therefore, there is a need for a system and method for generating hydrogen for use as a fuel source for an internal combustion engine from an ammonia-mounted vehicle to address the aforementioned issues and drawbacks of on-vehicle storage of hydrogen for electric vehicles, internal combustion engines fueled by ammonia, and internal combustion engines fueled by hydrogen. SUMMARY OF THE INVENTION

[0011] In one embodiment, the present invention is a system for on-vehicle ammonia cracking for an internal combustion engine, comprising: an ammonia tank containing liquid ammonia; a heat exchange catalyst unit fluidly coupled to the ammonia tank, wherein the heat exchange catalyst unit receives exhaust gas from the internal combustion engine; and an electrocatalyst unit fluidly and continuously coupled to the heat exchange catalyst unit, wherein when the liquid ammonia vaporizes, gaseous ammonia flows from the ammonia tank to the heat exchange catalyst unit, and when the exhaust gas has reached a temperature sufficient to effect ammonia cracking, the gaseous ammonia undergoes a cracking process in the heat exchange catalyst unit, and when the exhaust gas has not reached a temperature sufficient to effect ammonia cracking, the gaseous ammonia exits the heat exchange catalyst unit and flows to the electrocatalyst unit to undergo the cracking process in the electrocatalyst unit.

[0012] In another embodiment, the present invention is a system for on-vehicle ammonia cracking for an internal combustion engine, comprising: an ammonia tank containing ammonia; a heat exchange catalyst unit fluidly coupled to the ammonia tank, wherein the heat exchange catalyst unit receives exhaust gas from the internal combustion engine and receives the ammonia from the ammonia tank; and an electrocatalyst unit fluidly and continuously coupled to the heat exchange catalyst unit, the electrocatalyst unit having an electric heater, wherein when the exhaust gas has reached a temperature sufficient to effect ammonia cracking, the ammonia undergoes a cracking process in the heat exchange catalyst unit, and when the exhaust gas has not reached a temperature sufficient to effect ammonia cracking, the ammonia exits the heat exchange catalyst unit and flows to the electrocatalyst unit to undergo the cracking process in the electrocatalyst unit, and hydrogen resulting from the cracking process flows to the internal combustion engine.

[0013] In yet another embodiment, the present invention is a system for on-vehicle ammonia cracking for an internal combustion engine, comprising: an ammonia tank containing ammonia; a heat exchange catalyst unit fluidly coupled to the ammonia tank, wherein the heat exchange catalyst unit receives exhaust gas from the internal combustion engine and receives the ammonia from the ammonia tank; and an electric catalyst unit fluidly and continuously coupled to the heat exchange catalyst unit, the electric catalyst unit being powered using a vehicle power system. When the exhaust gas has reached a temperature sufficient to effect ammonia cracking, the ammonia undergoes a cracking process in the heat exchange catalyst unit. When the exhaust gas has not reached a temperature sufficient to effect ammonia cracking: (1) the ammonia is preheated in the heat exchange catalyst unit; (2) the preheated ammonia exits the heat exchange catalyst unit and flows to the electric catalyst unit; and (3) the preheated ammonia undergoes the cracking process in the electric catalyst unit.

Brief Description of the Drawings

[0014] These and other embodiments of the present invention will be discussed with reference to the following exemplary and non-limiting figures, in which like elements are numbered alike.

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[0034] The following definitions are intended to assist in the explanation and understanding of the defined terms within the context of the present invention. These definitions are not intended to limit these terms to a narrower scope than that described throughout this specification. Such definitions are intended to include grammatical equivalents.

[0035] As used herein, the term "motor vehicle" refers to any moving vehicle that is capable of transporting one or more human passengers and / or cargo or performing work and is powered by any form of energy. The term "motor vehicle" includes, but is not limited to, (a) vehicles such as cars, trucks, vans, minivans, sport utility vehicles, passenger transport vehicles, goods transport vehicles, two-wheeled, three-wheeled, and four-wheeled vehicles, quadricycles, motorcycles, scooters, all-terrain vehicles, utility task vehicles, and the like; (b) aerial vehicles such as helicopters, airplanes, airships, drones, aerospace vehicles, and the like; (c) vessels such as dry cargo ships, liquid cargo ships, special cargo ships, tugboats, cruise ships, recreational boats, fishing boats, water motorcycles, jet skis, and the like; (d) locomotives; and (e) heavy machinery and equipment, generators, lawn mowers and tractors, agricultural equipment and machinery, forestry equipment and machinery, construction equipment and machinery, mining equipment and machinery, and the like.

[0036] As used herein, the term "internal combustion engine" refers to any engine, spark ignition gasoline engine, compression ignition diesel engine, rotary, reciprocating, or other engine in which combustion occurs within a combustion chamber, thereby performing work by exerting a force on a movable surface by the combustion products together with any other by-products, and obtaining mechanical output from the engine by the movable surface. The term "internal combustion engine" includes, but is not limited to, hybrid internal combustion engines, two-stroke engines, four-stroke engines, six-stroke engines, and the like.

[0037] As used herein, the term "catalyst" refers to a material that promotes a chemical reaction. The term "catalyst" includes, but is not limited to, one or more catalysts capable of promoting a cracking reaction such as an ammonia cracking reaction, whether used as a base catalyst and / or as an additional catalyst. For the purposes of the present invention, the catalyst may include, but is not limited to, lithium imide in variable proportions, nickel, iron, cobalt, iron cobalt, ruthenium, vanadium, palladium, rhodium, platinum, sodium amide, and the like, as well as various combinations thereof.

[0038] As used herein, the term "cracking" refers to one or more processes in which ammonia is decomposed into its constituent hydrogen and nitrogen components on at least one catalyst.

[0039] As used herein, the term "nickel alloy" refers to pure nickel or an alloy containing nickel as a main component. The term "nickel alloy" includes, but is not limited to, Inconel® 625, Inconel® 718, Inconel® 725, and other metal compounds containing nickel as a main component. Inconel® is a trademark of Special Metals Corporation, Huntington, West Virginia.

[0040] As used herein, the term "triply-periodic minimal surface (TPMS)" refers to a three-dimensionally repeated, mathematically defined structure with zero mean curvature and a large surface area.

DETAILED DESCRIPTION OF THE INVENTION

[0041] Aspects of the present invention are to be understood as being described herein with reference to the respective figures showing exemplary embodiments. The exemplary embodiments herein are not necessarily intended to represent all embodiments according to the present invention, but rather are used to describe a few exemplary embodiments. Thus, aspects of the present invention are not intended to be construed narrowly in view of the exemplary embodiments. Further, although the present invention is described with respect to its application in an internal combustion engine for an automobile, it is understood that the system may be implemented in any engine-driven environment that can be powered by ammonia and / or hydrogen fuel.

[0042] FIG. 1 is a perspective internal view of a heat exchange catalyst unit that utilizes a TPMS structure and functions as a heat exchanger and as a catalytic converter for carrying out ammonia cracking. The heat exchange catalyst unit 100 is made of metal and, in one embodiment, includes a gaseous ammonia inlet 102, a hydrogen outlet 104, a heated exhaust gas inlet 106, and an exhaust gas outlet 108. In one embodiment, the heat exchange catalyst unit 100 is made from a nickel alloy. In a preferred embodiment, the heat exchange catalyst unit 100 is made from Inconel® 625.

[0043] In one embodiment, the gaseous ammonia inlet 102, the hydrogen outlet 104, the heated exhaust gas inlet 106, and the exhaust gas outlet 108 may be made from the same metallic material as the heat exchange catalyst unit 100. In another embodiment, the gaseous ammonia inlet 102, the hydrogen outlet 104, the heated exhaust gas inlet 106, and the exhaust gas outlet 108 may be made from stainless steel, silver, bronze, and equivalent alloys.

[0044] Located between inlets 102, 106 and outlets 104, 108 is matrix 110. Matrix 110 is formed from widthwise surfaces 112 and lengthwise surfaces 114 that generally extend perpendicular to each other. Surfaces 112, 114 of matrix 110 create passageways that allow gaseous ammonia and heated exhaust gas to flow; these passageways are indicated by ammonia channels 116 and heated exhaust gas channels 118. Gaseous ammonia is supplied to heat exchange catalyst unit 100 via inlet 102, while heated exhaust gas is simultaneously supplied to inlet 106. Gaseous ammonia traverses matrix 110 via ammonia channels 116, while heated exhaust gas traverses the matrix via heated exhaust gas channels 118. Ammonia channels 116 and heated exhaust gas channels 118 are oriented in a generally perpendicular manner with respect to each other, and thus gaseous ammonia traverses matrix 110 at approximately a right angle to the heated exhaust gas.

[0045] In one embodiment, surfaces 112, 114 have a thickness of 1 to 2 millimeters, and each of surfaces 112, 114 may have the same thickness. In another embodiment, surfaces 112, 114 may each have a different thickness. In yet another embodiment, surfaces 112, 114 may vary in thickness as each traverses matrix 110. For example, surfaces 112, 114 need not have a uniform thickness across the entire width of matrix 110 and may have thicker or thinner portions at various locations.

[0046] As shown in FIG. 1, the matrix 110 physically separates the gases passing through the channels 116, 118, respectively, such that an unusually large surface area over which the heated exhaust gas exchanges its heat with gaseous ammonia is provided throughout the matrix 110. In one embodiment, the surfaces 112, 114 of the matrix 110 are coated with a catalyst that promotes the cracking of ammonia into its constituent hydrogen and nitrogen components. In this embodiment, the surfaces 112, 114 of the matrix 110 are coated with the catalyst using a washcoat or deposition technique that binds or adheres the catalyst to the surfaces 112, 114.

[0047] In another embodiment, a catalyst in the form of a separate catalyst medium is deposited in the passages forming the ammonia channels 116 and the heated exhaust gas channels 118. The separate catalyst medium may be porous, thereby allowing gaseous ammonia and exhaust gas to pass through the catalyst as they flow through the matrix 110, respectively.

[0048] In yet another embodiment, the surfaces 112, 114 of the matrix 110 may be coated with the catalyst described herein, and an additional separate catalyst medium may be deposited in the passages forming the ammonia channels 116 and the heated exhaust gas channels 118.

[0049] In one embodiment, the matrix 110 is made of metal and is fabricated from a nickel alloy. In a preferred embodiment, the matrix 110 is fabricated from Inconel® 625. The heat exchange catalyst unit 100 and the matrix 110 may be constructed from the same metallic material. In another embodiment, the heat exchange catalyst unit 100 and the matrix 110 may be constructed from different metallic materials.

[0050] The materials selected for the heat exchange catalyst unit 100 and the matrix 110 need to have the ability to withstand the corrosive environment resulting from the high temperature heated exhaust gas and the heated hydrogen gas generated from the cracking of ammonia.

[0051] In a preferred embodiment, the matrix 110 is in the form of a triply periodic minimal surface (TPMS), and the matrix 110 is three-dimensionally (3D) printed using powder metal. The 3D printing process is an additive manufacturing process that uses laser sintering to selectively melt the powder metal particles together and form a TPMS structure layer by layer. The TPMS structure of the matrix 110 provides a relatively large surface area with cells that can be confined within the dimensions and shape of the heat exchange catalyst unit 100.

[0052] The TPMS structure can be various crystalline structures with various patterns and profiles. In the embodiment shown in FIG. 1, the TPMS is a gyroid structure. The structure can be, among many others, but not limited to, in the form of a gyroid, diamond, orthogonal intersecting holes, split pea. Each of these forms has various surface areas. For example, in the embodiment shown in FIG. 1, the heat exchange catalyst unit 100 has dimensions of approximately 10×10×4 inches (25.4×25.4×10.16 centimeters). For the matrix 110 that fits within these dimensions, Table 1 provides approximate surface area values for various TPMS structures that can be utilized.

Table 1

[0053] However, it should be noted that the values in Table 1 are merely exemplary examples and are not intended to be limiting in any way. The individual cell sizes of the TPMS may be modified to increase or decrease the surface area of the matrix 110. For example, within the same volume of the heat exchange catalyst unit 100, the individual cell sizes may be enlarged to increase the overall surface area of the matrix 110, and conversely, the individual cell sizes may be reduced to decrease the overall surface area of the matrix 110.

[0054] The TPMS structure is ideal for matrix 110 as it allows heat to be dispersed across all surfaces of matrix 100, thereby facilitating the chemical reactions required for the ammonia cracking process. Considering that the arrangement of channels 116, 118 becomes narrower relative to each other as the surface area increases, there are substantial challenges when cleaning the surface of matrix 110 after it has been printed as the surface area of matrix 110 increases. However, as the cell size of matrix 110 increases, the surface area decreases, thereby reducing the throughput efficiency of the heat exchange catalyst unit 100. The surface area of matrix 110 may depend on the output requirements of the vehicle and its engine.

[0055] In one embodiment, the heat exchange catalyst unit 100 is sized and dimensioned to accommodate a matrix 110 having a surface area sufficient to facilitate the cracking process while still having a foam factor suitable for placement within a vehicle. The dimensions of the heat exchange catalyst unit 100 may vary and may range from a width of 5 - 30 inches (12.7 - 76.2 centimeters), a length of 5 - 30 inches (12.7 - 76.2 centimeters), and a height of 0.5 - 12 inches (1.27 - 30.48 centimeters).

[0056] In one embodiment, the heat exchange catalyst unit 100 has a generally square shape that houses a square-shaped matrix 110, as shown in FIG. 1, but this is merely an exemplary example and is not intended to be limiting in any way. In other embodiments, the heat exchange catalyst unit 100 may be of any polygonal shape, such as, for example, oval, rectangular, triangular, square, kite-shaped, trapezoidal, parallelogram-shaped, rhombus-shaped, and the like, as well as various 3D shapes such as, for example, cube, cuboid, sphere, cone, and the like.

[0057] In one embodiment, since the flow rate of the exhaust gas may be several orders of magnitude faster than the flow rate of ammonia, the ammonia inlet 102 has a smaller diameter than the heated exhaust gas inlet 106. Similar to the dimensions of the heat exchange catalyst unit 100, the diameters, shapes, and sizes of the inlets 102, 106 and the outlets 104, 108 may vary based on the output requirements of the vehicle and its engine.

[0058] FIG. 2 is a perspective internal view of the heat exchange catalyst unit 100 utilizing a TPMS structure, showing the flow of the heated exhaust gas and gaseous ammonia through the matrix. During operation, gaseous ammonia 200 is supplied to the inlet 102 and flows through the ammonia channel 116, while the heated exhaust gas 202 is simultaneously supplied to the inlet 106 and flows through the heated gas channel 118. The heated exhaust gas 202 heats the catalyst, whereby the gaseous ammonia 200 is cracked into its constituent hydrogen and nitrogen components 204. The resulting hydrogen and nitrogen components 204 exit the heat exchange catalyst unit 100 via the outlet 104 and are supplied to a downstream injection system for the engine, while the remaining exhaust gas 206 exits the heat exchange catalyst unit via the outlet 108.

[0059] FIG. 3 is a perspective view of the matrix 110 having a gyroidal TPMS structure, FIG. 4 is a perspective view of the matrix 110 having an orthogonal cross-hole TPMS structure, and FIG. 5 is a perspective view of the matrix 110 having a split pea TPMS structure. However, it should be noted that the TPMS structures shown in FIGS. 1 - 5 are merely exemplary examples and are not intended to be limiting in any way.

[0060] FIG. 6 is a top perspective view of a heat exchange catalyst unit 100 utilizing a TPMS structure. In one embodiment, the heat exchange catalyst unit 100 may be manufactured by welding inlets 102, 106 and outlets 104, 108 to a housing 600. In one embodiment, the housing 600 may include a cover (not shown in FIG. 6) that can be removed to inspect or replace the matrix 110. In another embodiment, the inlets 102, 106 and / or the outlets 104, 108 may be removably attached to the housing 600, and thus various inlets and outlets having various dimensions, sizes, and flow characteristics can be utilized with the housing 600 in a modular fashion.

[0061] FIG. 7 is a front cross-sectional view of a cylindrical heat exchange catalyst unit 700 utilizing a TPMS structure. Similar to the heat exchange catalyst unit 100 shown in FIG. 1, the cylindrical heat exchange catalyst unit 700 is made of metal and is fabricated from a nickel alloy. In a preferred embodiment, the cylindrical heat exchange catalyst unit 700 is made of Inconel® 625.

[0062] In one embodiment, the cylindrical heat exchange catalyst unit 700 includes an ammonia inlet 702, a hydrogen outlet 704, a heated exhaust gas inlet 706, and an exhaust gas outlet 708. Located between the inlets 702, 706 and the outlets 704, 708 is a matrix 710. The matrix 710 is formed from widthwise surfaces 712 and lengthwise surfaces 714 that generally extend perpendicular to each other. The surfaces 712, 714 of the matrix 710 create passages that allow gaseous ammonia and the heated exhaust gas to flow; these passages are indicated by ammonia channels 716 and heated exhaust gas channels 718.

[0063] Gaseous ammonia is supplied to the cylindrical heat exchange catalyst unit 700 through inlet 702, while the heated exhaust gas is simultaneously supplied to inlet 706. The gaseous ammonia traverses the matrix 710 axially, while the heated exhaust gas traverses the matrix laterally.

[0064] As shown in FIG. 7, the matrix 710 physically separates the gases passing through each of the channels 716, 718, thereby providing an unusually large surface area across the entire matrix 710 for the heated exhaust gas to exchange its heat with the gaseous ammonia. In one embodiment, the surfaces 712, 714 of the matrix 710 are coated with a catalyst that promotes the cracking of ammonia into its constituent hydrogen and nitrogen components. In this embodiment, the surfaces 712, 714 of the matrix 710 are coated with the catalyst using a washcoat or deposition technique that binds or adheres the catalyst to the surfaces 712, 714.

[0065] In another embodiment, a catalyst in the form of a separate catalyst medium is deposited in the passages forming the ammonia channels 716 and the heated exhaust gas channels 718.

[0066] In yet another embodiment, the surfaces 712, 714 of the matrix 710 may be coated with the catalysts described herein, and additional separate catalyst media may be deposited in the passages forming the ammonia channels 716 and the heated exhaust gas channels 718.

[0067] FIG. 8 is a front cross-sectional view of a cylindrical heat exchange catalyst unit 700 utilizing a TPMS structure, showing the flow of heated exhaust gas and gaseous ammonia through the matrix. During operation, gaseous ammonia 200 is supplied to the inlet 702 and flows through the ammonia channels 716, while the heated exhaust gas 202 is simultaneously supplied to the inlet 706 and flows through the heated gas channels 718. The heated exhaust gas 202 heats the catalyst, thereby cracking the ammonia 200 into its constituent hydrogen and nitrogen components 204. The resulting hydrogen and nitrogen components 204 exit the heat exchange catalyst unit 700 via the outlet 704 and are supplied to a downstream injection system for the engine, while the remaining exhaust gas 206 exits the heat exchange catalyst unit via the outlet 708.

[0068] FIG. 9 is a cross-sectional view of a cylindrical heat exchange catalyst unit 700 utilizing a TPMS structure, showing the flow of heated exhaust gas and gaseous ammonia through the matrix. As shown in FIG. 9, the surfaces 712, 714 of the matrix 710 create ammonia channels 716 and heated exhaust gas channels 718. Considering the rounded parts, fewer weld seams / joints compared to square and rectangular designs, and the resistance to the influence of thermal stress, the cylindrical design can provide efficiency for mass production.

[0069] It should be noted that the cylindrical shape of the cylindrical heat exchange catalyst unit 700 is merely an exemplary example and is not intended to be limiting in any way. In other embodiments, the heat exchange catalyst unit 700 may be of any polygonal shape such as, for example, oval, rectangular, triangular, square, kite-shaped, trapezoidal, parallelogram-shaped, rhombus-shaped, and the like, as well as various 3D shapes such as, for example, cube, cuboid, sphere, cone, and the like.

[0070] FIG. 10 is a perspective view of a heat exchange catalyst unit 1000 that utilizes a tube bundle structure and functions as a heat exchanger and a catalyst converter for performing ammonia cracking. The heat exchange catalyst unit 1000 is made of metal and, in one embodiment, includes a side wall 1002 including a gaseous ammonia inlet 1004. In one embodiment, the inlet side wall 1002 may include additional ports 1006 that can be used for various functions. For example, the port 1006 may function as an inlet or may be coupled to devices for detecting temperature, throughput, and / or pressure.

[0071] The heat exchange catalyst unit 1000 further includes a heated gas inlet 1008. In one embodiment, as will be described in more detail with reference to FIG. 11, the heated exhaust gas inlet 1008 includes a partition plate 1010 that uniformly diffuses the heated exhaust gas from the engine throughout the internal tube bundle structure housed in the heat exchange catalyst unit 1000. In one embodiment, the partition plate 1010 may have a grid or lattice structure.

[0072] The heat exchange catalyst unit 1000 includes an exhaust gas outlet 1012 located on the opposite side of the heated gas inlet 1008.

[0073] FIG. 11 is a front cross-sectional view of a heat exchange catalyst unit 1000 utilizing a tube bundle structure. In one embodiment, the tube bundle structure 1100 is provided inside the heat exchange catalyst unit 1000. The tube bundle structure 1100 is composed of individual tubes 1102 that extend along the width of the heat exchange catalyst unit 1000 from the side wall 1002 perpendicular to the inlets 1008 and outlets 1012.

[0074] In one embodiment, the tube bundle structure 1100 includes rows and / or columns of tubes 1102 arranged in an offset manner, and thus each adjacent row and / or column includes tubes that are offset from their adjacent tubes. This pattern maximizes the surface area that the gas contacts when the heated exhaust gas traverses the tube bundle structure 1100, thereby maximizing the amount of catalyst that is heated to facilitate the cracking process.

[0075] In one embodiment, the heat exchange catalyst unit 1000 includes at least one support structure 1104 that facilitates the 3D printing process and further provides stability against thermal stress during the operation of the heat exchange catalyst unit 1000.

[0076] Gaseous ammonia is supplied to the heat exchange catalyst unit 1000 via the inlet 1004, while the heated exhaust gas is simultaneously supplied to the inlet 1008. Heated exhaust gas traverses the lateral space between the tubes 1102, while Gaseous ammonia traverses the axial space inside the tubes 1102.

[0077] In one embodiment, the space between the tubes 1102 is filled with a catalyst in the form of a separate catalyst medium. In another embodiment, the tubes 1102 themselves are hollow and are also filled with a separate catalyst medium.

[0078] In yet another embodiment, the outer surface and / or inner surface of the tube 1102 is also coated with a catalyst using a washcoating or deposition technique that binds or adheres the catalyst to the surface.

[0079] FIG. 12 is a side cross-sectional view of a heat exchange catalyst unit 1000 utilizing a tube bundle structure 1100. In one embodiment, the heat exchange catalyst unit 1000 includes a side wall 1200 located opposite the side wall 1002. The side wall 1200 includes a hydrogen outlet 1202 and may include additional ports 1204 that can be used for various functions. For example, the port 1204 may function as an outlet or may be coupled to equipment for sensing temperature, throughput, and / or pressure.

[0080] During operation, gaseous ammonia is supplied to the inlet 1004 while heated exhaust gas is simultaneously supplied to the inlet 1008. The heated exhaust gas heats the catalyst, thereby cracking the ammonia into its constituent hydrogen and nitrogen components. The resulting hydrogen and nitrogen components exit the heat exchange catalyst unit 1000 via the outlet 1202 and are supplied to a downstream engine.

[0081] In one embodiment, the heat exchange catalyst unit 1000 is made from a nickel alloy. In a preferred embodiment, the heat exchange catalyst unit 1000 is made from Inconel® 625.

[0082] In one embodiment, the side walls 1002, 1200, the gaseous ammonia inlet 1004, the hydrogen outlet 1202, the heated exhaust gas inlet 1008, the partition plate 1010, the exhaust gas outlet 1012, and the support structure 1104 may be made from the same metallic material as the heat exchange catalyst unit 1000. In another embodiment, the side walls 1002, 1200, the gaseous ammonia inlet 1004, the partition plate 1010, the hydrogen outlet 1202, the heated exhaust gas inlet 1008, and the exhaust gas outlet 1012 may be made from stainless steel, silver, bronze, and equivalent alloys.

[0083] FIG. 13 is a front cross-sectional view of a two-pass heat exchange catalyst unit 1300 that utilizes a tube bundle structure 1100. In this embodiment, the support structure 1302 includes a fascia that receives side walls (not shown in FIG. 13). The support structure 1302 includes a partition plate 1304 that physically separates the tube bundle structure 1100 into a left portion 1306 and a right portion 1308. The partition plate 1304 extends along the width of the two-pass heat exchange catalyst unit 1300 between two side walls. In this embodiment, the gaseous ammonia inlet is located in a side wall that covers the left portion 1306, and the hydrogen outlet is located in a side wall that covers the right portion 1308.

[0084] During operation, gaseous ammonia is supplied to the gaseous ammonia inlet while the heated exhaust gas is simultaneously supplied to the inlet 1008. As the ammonia traverses the left portion 1306 of the tube bundle structure 1100, the heated exhaust gas heats the catalyst, thereby cracking the ammonia into its constituent hydrogen and nitrogen components. The remaining ammonia traverses back across the right portion 1308 of the tube bundle structure 1100 and continues to undergo cracking, thereby providing a two-pass cracking process. The resulting hydrogen and nitrogen components exit the two-pass heat exchange catalyst unit 1300 via the hydrogen outlet and are supplied to a downstream engine.

[0085] FIG. 14 is a block diagram of an on-vehicle ammonia cracking system for an internal combustion engine. The on-vehicle ammonia cracking system 1400 provides a mechanism for generating hydrogen from ammonia, thereby eliminating the need for an automobile to have a separate hydrogen tank.

[0086] Referring to FIG. 14, an ammonia liquid tank 1402 is mounted on an automobile or an engine. In one embodiment, the ammonia liquid tank 1402 can be coupled to a pump 1404. In one embodiment, the tank 1402 is refillable and / or replaceable. The pump 1404 is coupled to a port of the tank 1402 to facilitate delivery of ammonia from the tank 1402. For example, in a low temperature environment where the temperature is about 0° C. or lower, the vapor pressure of ammonia is not sufficient to push itself out of the tank 1402. Therefore, a pump 1404 is required to draw or push ammonia out of the tank 1402.

[0087] In another embodiment, an electric heater (not shown in FIG. 14) may be coupled to the tank 1402, for example, inside the tank 1402 or to the outer surface of the tank 1402, to heat the liquid ammonia contained in the tank 1402 to a temperature at which the liquid ammonia vaporizes into a gaseous form.

[0088] In one embodiment, a pressure regulator 1406 is coupled to the outlet of the tank 1402 and functions to control the amount and / or flow rate of ammonia drawn from the tank 1402 by the pump 1404. The pressure regulator 1406 monitors the pressure of the liquid ammonia in the tank 1402. When the pressure drops to a threshold pressure value at which the liquid ammonia can vaporize into a gaseous form, the pressure regulator 1406 opens and feeds the gaseous ammonia downstream. If there is any remaining liquid ammonia passing through the pressure regulator 1406, it is also fed to the injection system 1408 (e.g., via a T-joint on the supply line).

[0089] In one embodiment, a temperature control valve 1410 receives a temperature feedback signal 1412 including a temperature reading value from an electric catalyst unit 1420 during a cold start of an engine. The temperature feedback signal 1412 can be generated by a temperature sensor coupled to the electric catalyst unit 1420. When the electric catalyst unit 1420 reaches a threshold temperature suitable for performing an ammonia cracking process (i.e., when the temperature reading value is equal to or higher than the threshold temperature), the temperature control valve 1410 opens, and gaseous ammonia passes through the heat exchange catalyst unit 1418 and proceeds downstream toward the electric catalyst unit 1420, which is heated using electric power supplied from a vehicle power system 1422.

[0090] If the electric catalyst unit 1420 has not reached the threshold temperature, then the temperature control valve 1410 continues to monitor the temperature feedback signal 1412 and prevents the gaseous ammonia from proceeding downstream. The cold start operation will be described in more detail herein.

[0091] In one embodiment, the temperature of the heated exhaust gas entering the heat exchange catalyst unit 1418 is determined based on the current draw in the electric catalyst unit 1420, where the current draw indicates how effective the heat exchange catalyst unit 1418 is in the cracking of gaseous ammonia.

[0092] For example, if hydrogen and nitrogen passing from the heat exchange catalyst unit 1418 to the electric catalyst unit 1420 are present, the electric catalyst unit 1420 does not perform an ammonia cracking process and thus draws minimal or no current.

[0093] However, when gaseous ammonia passes from the heat exchange catalyst unit 1418 to the electric catalyst unit 1420, an ammonia cracking process will occur and current is drawn to heat a heating element provided within the electric catalyst unit 1420.

[0094] However, while the engine is under normal or high load operating conditions (i.e., not during cold start or low load operating conditions), since the heat exchange catalyst unit 1418 is heated to the threshold temperature by the heated exhaust gas from the engine, the on-vehicle ammonia cracking system 1400 does not utilize the electric catalyst unit 1420 to carry out the ammonia cracking process, and the heat exchange catalyst unit 1418 carries out the ammonia cracking process.

[0095] The heat exchange catalyst unit 1418 referred to in FIG. 14 may be any of the embodiments described herein, i.e., the heat exchange catalyst unit 100 utilizing the TPMS structure, the cylindrical heat exchange catalyst unit 700 utilizing the TPMS structure, the heat exchange catalyst unit 1000 utilizing the tube bundle structure, or the two-pass heat exchange catalyst unit 1300 utilizing the tube bundle structure.

[0096] The pressure control valve 1414 is positioned continuously with the temperature control valve 1410 and controls the amount of gaseous ammonia fed to the heat exchange catalyst unit 1418.

[0097] In one embodiment, the pressure control valve 1414 receives a pressure feedback signal 1416 from the heat exchange catalyst unit 1418. For example, the heat exchange catalyst unit 1418 may be coupled to a pressure transducer or the like (not shown in FIG. 14) that generates the pressure feedback signal 1416.

[0098] In one embodiment, to facilitate a cold start of the on-vehicle ammonia cracking system 1400 when the exhaust gas from the engine is not at a threshold temperature suitable for carrying out the ammonia cracking process, the electric catalyst unit 1420 is used to heat the catalyst, whereby gaseous ammonia can be cracked, and the resulting hydrogen is supplied to a downstream injection system for the engine. The engine can then burn the hydrogen to power the engine, whereby the heated exhaust gas is supplied to the on-vehicle ammonia cracking system 1400.

[0099] In one embodiment, the electrocatalyst unit 1420 is coupled to a vehicle power system 1422 such as a conventional vehicle battery. In another embodiment, the electrocatalyst unit 1420 may be heated via an auxiliary heat source / power source such as a renewable energy source, a portable battery source, an on-board electric battery pack, and / or a rechargeable battery.

[0100] In addition to facilitating a cold start of the on-board ammonia cracking system 1400, the electrocatalyst unit 1420 is utilized to assist the heat exchange catalyst unit 1418 while the engine is under low load operating conditions, such as when the vehicle is stopped, creeping, or idling. For example, during low load operating conditions, the engine exhaust gas temperature can drop significantly. The reduced temperature of the exhaust gas flowing into the heat exchange catalyst unit 1418 during such low load operating conditions may not be sufficient for the catalyst to crack ammonia. In one embodiment, depending on the particular catalyst utilized, the temperature of the exhaust gas needs to be at least from 400°C to 700°C to carry out the ammonia cracking process, and in a preferred embodiment, the temperature of the exhaust gas is at least 600°C to carry out the ammonia cracking process.

[0101] In this scenario, the cold gaseous ammonia passes through the heat exchange catalyst unit 1418 and is supplied downstream to the electrocatalyst unit 1420, which is heated using the power supplied from the vehicle power system 1422. When the electrocatalyst unit 1420 is heated to a threshold temperature suitable for carrying out the ammonia cracking process, the temperature control valve 1410 opens, enabling the gaseous ammonia to be fed to the heat exchange catalyst unit 1418 and ultimately to the electrocatalyst unit 1420. The electrocatalyst unit 1420 then carries out the ammonia cracking process, and the resulting hydrogen is supplied to a downstream injection system for the engine.

[0102] While the engine is under normal or high load operating conditions, when the exhaust gas flowing into the heat exchange catalyst unit 1418 reaches a threshold temperature suitable for carrying out the ammonia cracking process, the ammonia cracking process is carried out inside the heat exchange catalyst unit 1418. The resulting hydrogen and nitrogen pass downstream to the electric catalyst unit 1420 and further downstream to the gas-to-liquid or gas-to-gas heat exchange unit 1428, and then pass to the injection system 1430 for the engine. In one embodiment, the gas-to-liquid or gas-to-gas heat exchange unit 1428 can utilize the engine coolant and / or the engine radiator, or the input gaseous or liquid ammonia to facilitate the heat exchange process.

[0103] In one embodiment, the pressure regulator 1406 can be controlled using an electric servo motor to provide a stable flow of gaseous ammonia from the tank 1402. In another embodiment, a pulse width modulation injection valve may be used. The servo motor and / or the pulse generator may be controlled using an electronic control device such as an industrial PID controller (not shown in FIG. 14).

[0104] In one embodiment, the electronic control device is coupled to various components of the on-vehicle ammonia cracking system 1400 and may receive inputs from sensors such as temperature sensors and pressure transducers coupled to the pressure regulator 1406, the temperature control valve 1410, the pressure control valve 1414, and the heat exchange catalyst unit 1418 and / or the electric catalyst unit 1420.

[0105] In another embodiment, the electronic control device may be integrated into the hardware and software together with the vehicle's electronic control unit (ECU). In this embodiment, the flow rate of hydrogen fed to the engine's injection system can be measured and reported back to the ECU as a mechanism for controlling the injection method.

[0106] FIGS. 15 to 17 are various perspective views of the on-vehicle ammonia cracking system 1400 for an internal combustion engine described in FIG. 14.

[0107] Figure 18 is a perspective view of the electrocatalyst unit. In one embodiment, the electrocatalyst unit 1800 includes a housing 1802 that surrounds a ceramic tube 1900 (shown in FIG. 19). In one embodiment, the housing 1802 is a metal housing.

[0108] In one embodiment, the electrocatalyst unit 1800 includes a gaseous ammonia inlet 1804 and a hydrogen outlet 1806 provided at an opposite end of the electrocatalyst unit 1800. The electrocatalyst unit further includes power feeds 1808, 1810 for a heating element 1904 (shown in FIG. 19). In one embodiment, the electrocatalyst unit 1800 may include radial mounts 1812, 1814 that can be used for various functions. For example, the radial mounts 1812, 1814 may function as inlets, outlets, or may be coupled to devices for sensing temperature, throughput, and / or pressure. In one embodiment, the radial mount 1812 may each include or be coupled to a thermocouple, and the radial mount 1814 may include or be coupled to a pressure transducer.

[0109] Figure 19 is a cross-sectional view of the electrocatalyst unit 1800. In one embodiment, the ceramic tube 1900 houses the catalyst. The ceramic tube 1900 functions as an insulator, allowing heat to be focused and reflected towards the catalyst, thereby enabling the catalyst to be heated.

[0110] In one embodiment, a first screen 1901 and a second screen 1902 are provided at both ends of the ceramic tube 1900. The screens 1901, 1902 may be made from wires, wire meshes, or another metal mesh or matrix structure. In one embodiment, the screens 1901, 1902 may be made from a nickel alloy that is resistant to the heated hydrogen gas generated from the cracking of ammonia and is also resistant to gaseous ammonia itself.

[0111] In one embodiment, the heating element 1904 is also provided inside the ceramic tube 1900. A current passes through the heating element 1904 to heat the heating element 1904 to a threshold temperature suitable for carrying out the ammonia cracking process. In one embodiment, the heating element 1904 and the screens 1901, 1902 are made of a nickel alloy or other material resistant to hydrogen and ammonia, as nickel maintains a fairly constant resistance at high temperatures as opposed to steel, whose resistance decreases at high temperatures. Further, the nickel alloy may have higher corrosion resistance during exposure to ammonia and hydrogen at high temperatures (such as temperatures exceeding 600 °C, which may be achieved in the electrocatalytic unit 1800).

[0112] In a preferred embodiment, the heating element 1904 and the screens 1901, 1902 are made of Inconel® 625. In one embodiment, the heating element 1904 and the screens 1901, 1902 may be made of the same material. Alternatively, the heating element 1904 and the screens 1901, 1902 may be made of different materials from each other.

[0113] In one embodiment, the heating element 1904 may be an air process heater, a cartridge heater, a tubular heater, a band heater, a strip heater, an etched foil heater (or thin film heater), a ceramic heater, a ceramic fiber heater, a resistance wire, and the like.

[0114] In one embodiment, each end of the heating element 1904 is in contact with the power feed-throughs 1808, 1810. The power feed-throughs 1808, 1810 supply electricity to energize or heat the heating element 1904.

[0115] In one embodiment, the heating element 1904 is adjusted via an electronic control device coupled to the power feeds 1808, 1810 by utilizing readings from a thermocouple coupled to the radial fixture 1812, whereby the heating element 1904 maintains a threshold temperature suitable for performing the ammonia cracking process. The threshold temperature may be in the range of 400°C to 700°C, and in a preferred embodiment, the threshold temperature is at least 600°C.

[0116] In one embodiment, an electronic control device may be used to control an electric expansion valve (not shown in FIG. 19) coupled to the inlet 1804 by utilizing readings from a pressure transducer coupled to the radial fixture 1814 and / or a thermocouple coupled to the radial fixture 1812. When the gaseous ammonia received by the electric catalyst unit 1800 from the heat exchange catalyst unit reaches the threshold temperature, the electric expansion valve is utilized to maintain the vapor pressure of the gaseous ammonia. At these threshold temperature and pressure values, the electric expansion valve opens, allowing ammonia to enter the ceramic tube 1900.

[0117] In one embodiment, a catalyst, such as a separate catalyst medium, is deposited inside the ceramic tube. The gaseous ammonia undergoes a chemical reaction with the catalyst provided inside the ceramic tube 1900, and the resulting hydrogen and nitrogen components exit the electric catalyst unit 1800 via the outlet 1806 and are supplied to a downstream injection system for the engine.

[0118] In another embodiment, the heating element 1904 is coated with a catalyst that promotes the ammonia cracking process, and no separate catalyst is provided inside the ceramic tube 1900. In this embodiment, the catalyst is coated on the heating element 1904 using a washcoating or deposition technique that binds or adheres the catalyst to the surface of the heating element 1904.

[0119] In one embodiment, the heating element 1904 is a strip heater. The heating element 1904 may be coated with a catalyst on all surfaces, or alternatively, a catalyst sleeve may be disposed on the strip heating element 1904. In one embodiment, the strip heating element 1904 has a relatively low heat transfer efficiency, thereby enabling the skin (or boundary layer) temperature of the catalyst coating the exterior of the strip heating element 1904 to be maintained at a high level.

[0120] In another embodiment, the heating element 1904 is a spiral heater, a coil heater, or an air process heater, where the inner wall (including the integrated heating element) is coated with a catalyst.

[0121] In yet another embodiment, the catalyst is coated on the inner wall of the ceramic tube 1900. In this embodiment, the catalyst is coated on the inner wall of the ceramic tube 1900 using a wash coating or deposition technique that binds or adheres the catalyst to the wall surface.

[0122] The remaining figures are provided to show additional details and embodiments of the on-vehicle ammonia cracking system.

[0123] Although the principles of the present disclosure have been described in connection with the exemplary embodiments shown herein, the principles of the invention are not limited thereto and include any modifications, changes, or substitutions thereof.

Claims

1. A system for on-vehicle ammonia cracking for an internal combustion engine, comprising: an ammonia tank containing liquid ammonia; a heat exchange catalyst unit fluidly coupled to the ammonia tank, having an exhaust gas inlet, an exhaust gas outlet, an ammonia inlet, and a hydrogen outlet, wherein the heat exchange catalyst unit receives exhaust gas from the internal combustion engine via the exhaust gas inlet, and the exhaust gas exits the heat exchange catalyst unit via the exhaust gas outlet; and an electrocatalyst unit continuously and fluidly coupled to the heat exchange catalyst unit only via the hydrogen outlet, the electrocatalyst unit being configured to be internally heated to a temperature of at least 400 °C to effect ammonia cracking ; when the liquid ammonia vaporizes, gaseous ammonia flows from the ammonia tank to the ammonia inlet, when the exhaust gas has reached a temperature of at least 400 °C, the gaseous ammonia undergoes a cracking process in the heat exchange catalyst unit, when the exhaust gas has not reached a temperature of at least 400 °C, the gaseous ammonia exits the heat exchange catalyst unit and flows to the electrocatalyst unit where it undergoes the cracking process system.

2. The system according to claim 1, wherein the ammonia tank is coupled to a pump.

3. The system according to claim 1, wherein the electrocatalyst unit has an electric heater.

4. The system according to claim 1, wherein the heat exchange catalyst unit has a matrix including a series of rows and columns.

5. The system according to claim 4, wherein the surface of the matrix is coated with a catalyst.

6. The system according to any one of claims 1 to 4, wherein the heat exchange catalyst unit has an exhaust gas channel and an ammonia channel, and the exhaust gas channel and the ammonia channel are oriented in a perpendicular manner to each other.

7. The system according to claim 6, wherein the gaseous ammonia traverses the heat exchange catalyst unit through the ammonia channel substantially perpendicular to the exhaust gas traversing the heat exchange catalyst unit through the exhaust gas channel.

8. A system for on-vehicle ammonia cracking for an internal combustion engine, comprising: An ammonia tank containing ammonia; A heat exchange catalyst unit fluidly coupled to the ammonia tank, where the heat exchange catalyst unit receives exhaust gas from the internal combustion engine and receives the ammonia from the ammonia tank; and An electric catalyst unit fluidly coupled to the heat exchange catalyst unit via a single fluid path in series, the electric catalyst unit having an electric heater Comprising When the exhaust gas reaches a temperature sufficient to effect ammonia cracking, the ammonia undergoes a cracking process in the heat exchange catalyst unit, When the exhaust gas does not reach a temperature sufficient to effect ammonia cracking, the ammonia exits the heat exchange catalyst unit and flows to the electric catalyst unit where it undergoes the cracking process, Hydrogen resulting from the cracking process flows to the internal combustion engine System. **Claim 9**: The system according to claim 8, wherein the ammonia flows through a first channel inside the heat exchange catalyst unit, the exhaust gas flows through a second channel inside the heat exchange catalyst unit, and the first channel and the second channel are oriented perpendicular to each other. **Claim 10** The system according to claim 8, wherein when the ammonia undergoes the cracking process in the electric catalyst unit, the ammonia is preheated in the heat exchange catalyst unit before flowing to the electric catalyst unit. **Claim 11** The system according to claim 8, wherein the temperature sufficient to effect ammonia cracking is in the range of 400°C to 700°C. **Claim 12** The system according to claim 8, wherein the electric heater is selected from the group consisting of an air process heater, a cartridge heater, a tubular heater, a band heater, a strip heater, an etched foil heater, a thin film heater, a ceramic heater, a ceramic fiber heater, and a resistance wire. **Claim 13** The system according to claim 8, wherein the heat exchange catalyst unit has a matrix including a series of rows and columns. **Claim 14** The system according to any one of claims 8 to 13, wherein the heat exchange catalyst unit has a tube bundle structure including individual tubes extending along the width of the heat exchange catalyst unit perpendicular to an inlet for the exhaust gas. **Claim 15** A system for on-vehicle ammonia cracking for an internal combustion engine, an ammonia tank containing ammonia; a heat exchange catalyst unit fluidly coupled to the ammonia tank, wherein the heat exchange catalyst unit receives exhaust gas from the internal combustion engine and receives the ammonia from the ammonia tank; and an electric catalyst unit fluidly coupled to the heat exchange catalyst unit via a single fluid path in series, such that the exhaust gas does not flow from the heat exchange catalyst unit to the electric catalyst unit, and the electric catalyst unit is powered using a vehicle power system comprising when the exhaust gas has reached a temperature sufficient to effect ammonia cracking, the ammonia undergoes a cracking process in the heat exchange catalyst unit, when the exhaust gas has not reached a temperature sufficient to effect ammonia cracking: (1) the ammonia is preheated in the heat exchange catalyst unit, (2) the preheated ammonia exits the heat exchange catalyst unit and flows to the electric catalyst unit, (3) the preheated ammonia undergoes the cracking process in the electric catalyst unit a system.

16. The system according to claim 15, wherein the electric catalyst unit has an electric heater.

17. The system according to claim 16, wherein the electric heater is selected from the group consisting of an air process heater, a cartridge heater, a tubular heater, a band heater, a strip heater, an etched foil heater, a thin film heater, a ceramic heater, a ceramic fiber heater, and a resistance wire.

18. The system according to claim 15, wherein the electric catalyst unit has a separate catalyst medium deposited inside the electric catalyst unit.

19. The system according to claim 15, wherein the temperature sufficient to effect ammonia cracking ranges from 400°C to 700°C.

20. The system according to any one of claims 15 to 19, wherein hydrogen resulting from the cracking process flows to the internal combustion engine for use as a combustion co-fuel with the ammonia.

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