Ammonia hydrogen engine system integrating liquid ammonia cooling type EGR (Exhaust Gas Recirculation) and plasma reforming
By integrating a liquid ammonia-cooled EGR with plasma reforming into an ammonia-hydrogen engine system, the EGR exhaust gas cooling and liquid ammonia vaporization preheating are coupled, solving the problem of high energy consumption in on-board ammonia reforming hydrogen production systems. This achieves efficient waste heat recovery and system simplification, making it suitable for the field of zero-carbon engines.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INST OF ENERGY HEFEI COMPREHENSIVE NAT SCI CENT (ANHUI ENERGY LAB)
- Filing Date
- 2026-03-06
- Publication Date
- 2026-04-17
AI Technical Summary
In existing technologies, on-board ammonia reforming hydrogen production systems have high energy consumption and redundant EGR cooling and ammonia fuel pretreatment processes, lacking efficient integration solutions, resulting in low system energy utilization efficiency.
The integrated liquid ammonia-cooled EGR and plasma reforming ammonia-hydrogen engine system deeply couples EGR exhaust gas cooling and liquid ammonia fuel gasification preheating through a heat exchanger. It utilizes EGR waste heat to gasify liquid ammonia and produce hydrogen through plasma reforming. It adopts a plate-fin or shell-and-tube heat exchanger structure and combines palladium membrane or polymer membrane separation technology to purify hydrogen.
It achieves efficient recovery and utilization of engine waste heat, simplifies system structure, reduces dependence on external energy, improves energy integration efficiency and system compactness, and is suitable for space-constrained application scenarios.
Smart Images
Figure CN121875867A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of zero-carbon engines, and more specifically to an ammonia-hydrogen engine system integrating liquid ammonia-cooled EGR and plasma reforming. Background Technology
[0002] Ammonia (NH3), as a zero-carbon fuel, has attracted widespread attention in engine applications. However, ammonia's slow combustion rate and high ignition temperature lead to problems such as unstable combustion and low efficiency in pure ammonia engines. Blending with hydrogen is an effective way to improve the combustion characteristics of ammonia. Typically, hydrogen can be produced through an onboard ammonia reforming unit.
[0003] In existing technologies, on-board ammonia reforming hydrogen production systems mostly use external independent heating methods (such as electric heating or combustion heating) to provide energy for the reforming reaction, which increases the system's energy consumption and complexity. Meanwhile, high-power engines typically require EGR systems to reduce nitrogen oxides (NOx). x EGR exhaust gas requires additional cooling energy to cool down.
[0004] Currently, there is a lack of a system solution that can efficiently integrate and couple the waste heat recovery of the engine EGR system with the ammonia fuel reforming pretreatment process. EGR cooling and ammonia gasification preheating are two independent processes that both require energy, resulting in high system redundancy and energy utilization efficiency that needs to be improved. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and integrate a liquid ammonia-cooled EGR and plasma reforming ammonia-hydrogen engine system. This system can deeply thermocouple the two processes of EGR exhaust gas cooling and liquid ammonia fuel gasification preheating through a heat exchanger, so as to achieve efficient and in-situ utilization of exhaust gas waste heat, simplify the system structure and improve the overall energy efficiency.
[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:
[0007] An ammonia-hydrogen engine system integrating liquid ammonia-cooled EGR and plasma reforming includes:
[0008] The liquid ammonia-cooled EGR cooler has an internally isolated exhaust gas passage and liquid ammonia passage.
[0009] The exhaust gas passage inlet is connected to the engine exhaust pipe, and the outlet is connected to the engine intake pipe;
[0010] The liquid ammonia channel is connected to a liquid ammonia source at its inlet and outputs hot gaseous ammonia at its outlet.
[0011] The plasma reformer has its inlet connected to the hot gaseous ammonia outlet of a liquid ammonia-cooled EGR cooler, and an auxiliary burner is installed inside.
[0012] The hydrogen purification and distribution unit has its inlet connected to the outlet of the plasma reformer, its first outlet connected to the auxiliary burner via a hydrogen-blending branch, and its second outlet connected to the engine combustion chamber via the main hydrogen supply pipeline.
[0013] Among them, the heat from the EGR exhaust gas serves as the sole heat source for the vaporization of liquid ammonia, thus passively coupling the EGR cooling load with the vaporization rate of liquid ammonia.
[0014] In the above technical solution, the liquid ammonia-cooled EGR cooler ensures complete vaporization of liquid ammonia under the rated operating conditions of the engine.
[0015] In the above technical solution, the plasma reformer is a low-temperature plasma reformer with an inlet temperature adapted to 50-150℃.
[0016] In the above technical solution, the auxiliary burner maintains the catalyst active temperature when the reformer is started or under low load.
[0017] In the above technical solution, the liquid ammonia-cooled EGR cooler adopts a plate-fin or shell-and-tube heat exchanger structure.
[0018] In the above technical solution, the hydrogen purification and distribution unit adopts palladium membrane or polymer membrane separation technology.
[0019] In the above technical solution, the main hydrogen supply pipeline is equipped with an electronically controlled injection valve connected to the intake manifold.
[0020] In the above technical solution, the hydrogen-doped branch is equipped with a flow regulating valve.
[0021] A method for operating an ammonia-hydrogen fuel engine, employing any of the above-mentioned systems, includes:
[0022] Utilizing the waste heat from EGR exhaust gas to vaporize liquid ammonia;
[0023] The gaseous ammonia plasma was reformed into a hydrogen-containing gas.
[0024] The hydrogen is purified and distributed to the auxiliary burner and engine combustion chamber.
[0025] A ship or generator set power system that integrates any of the aforementioned ammonia-hydrogen fuel supply systems.
[0026] Compared with the prior art, the beneficial effects of the present invention are:
[0027] 1. High-efficiency energy integration: The innovative EGR cooling process, which is a "waste heat emission" process, is coupled with the liquid ammonia vaporization process, which is a "heat absorption demand" process, within the same heat exchanger. This enables in-situ and efficient recovery and utilization of engine exhaust heat, significantly reducing the system's dependence on external energy sources.
[0028] 2. System simplification and compactness: The elimination of a separate liquid ammonia preheater and part of the EGR cooling load reduces the number of components, making the system more compact, especially suitable for space-constrained applications such as ships and generator sets.
[0029] 3. Operational Synergy: The system's operating rhythm is naturally linked to the engine's operating conditions. When the engine load increases and the EGR rate rises, more waste heat is generated in the exhaust gas, which can vaporize more liquid ammonia, providing a raw material basis for the subsequent production of more combustion-supporting hydrogen, thus forming a virtuous cycle of energy and material flow synergy. Attached Figure Description
[0030] Figure 1 This is a schematic diagram illustrating the structural principle of the ammonia-hydrogen engine system integrating liquid ammonia-cooled EGR and plasma reforming as described in this invention.
[0031] The components include: 1. Engine; 2. Liquid ammonia source; 3. Liquid ammonia-cooled EGR cooler; 4. EGR valve; 5. Plasma reformer; 6. Hydrogen purification and distribution unit; 7. Hydrogen blending branch; 8. Main hydrogen supply pipeline; and 9. Air intake system. Detailed Implementation
[0032] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. However, the following embodiments are only for explaining the present invention, and the scope of protection of the present invention should include all the contents of the claims. Moreover, through the description of the following embodiments, those skilled in the art can fully implement all the contents of the claims of the present invention.
[0033] Example
[0034] This embodiment discloses an ammonia-hydrogen engine system integrating liquid ammonia-cooled EGR and plasma reforming, including a liquid ammonia-cooled EGR cooler 3, a plasma reformer 5, and a hydrogen purification and distribution unit 6.
[0035] The core innovation of the liquid ammonia-cooled EGR cooler 3 lies in its unique internal dual-channel heat exchange structure: an exhaust gas channel and a liquid ammonia channel. The exhaust gas channel is connected in series with the engine's EGR pipeline to circulate high-temperature EGR exhaust gas. The liquid ammonia channel is connected to the liquid ammonia supply pipeline. The two channels are isolated from each other but can fully exchange heat. Its working principle is essentially to use the high-temperature EGR exhaust gas as a heat source to heat the flowing liquid ammonia, causing it to undergo a phase change and completely vaporize. This process achieves two objectives simultaneously: first, it cools the EGR exhaust gas, meeting the engine's requirement for low-temperature EGR gas; second, it preheats the liquid ammonia fuel, providing gaseous ammonia at a suitable temperature for the subsequent reforming reaction, adapting to the optimal temperature range required for the low-temperature plasma reformer inlet operating temperature. Crucially, the vaporization rate of the liquid ammonia (i.e., the preheated ammonia production) is not actively controlled, but passively determined by the flow rate and temperature of the EGR exhaust gas under the current operating conditions (i.e., the EGR cooling load), forming an inherent and direct coupling relationship between the two.
[0036] The plasma reformer 5 receives preheated ammonia from the EGR cooler and decomposes it into a mixture of hydrogen and nitrogen through plasma-assisted catalysis or other methods. An auxiliary burner is installed inside the reformer to maintain the reaction temperature during startup or at low loads.
[0037] The hydrogen purification and distribution unit 6 purifies the hydrogen-nitrogen mixture from the reformer (e.g., using membrane separation technology) to obtain high-purity hydrogen. This unit has two outlets: one, via a hydrogen-blending branch 7, returns a portion of the hydrogen to the auxiliary burner of the plasma reformer 5 as fuel to maintain its operation or improve its cracking efficiency; the other, via the main hydrogen supply line 8, supplies hydrogen to the engine's air intake system 9 or direct injection system, where it mixes with air and participates in combustion to improve the combustion characteristics of ammonia.
[0038] Engine 1 uses ammonia as its primary fuel, and a portion of its exhaust gas is diverted from its exhaust pipe as EGR exhaust gas. The liquid ammonia-cooled EGR cooler 3 can employ a plate-fin or shell-and-tube heat exchanger to ensure high heat exchange efficiency and reliable isolation between the exhaust gas passage and the liquid ammonia passage. Low-temperature liquid ammonia (e.g., -33°C) from liquid ammonia source 2 is pumped into the liquid ammonia passage of the liquid ammonia-cooled EGR cooler 3. Simultaneously, high-temperature EGR exhaust gas (typically 400-600°C), with its flow rate regulated by EGR valve 4, enters the exhaust gas passage. The two fluids exchange heat in a counter-current or cross-flow manner within the liquid ammonia-cooled EGR cooler 3.
[0039] During this process, the sensible heat and some latent heat of the EGR exhaust gas are absorbed by liquid ammonia, causing the exhaust gas temperature to drop (e.g., to below 100-150°C), thus meeting the EGR cooling requirements. Meanwhile, the liquid ammonia, after absorbing heat, experiences a temperature increase and undergoes a dramatic phase change, completely transforming into gaseous ammonia at near-ambient pressure. It is important to emphasize that this design ensures that within the engine's typical operating range, the flowing liquid ammonia is always completely vaporized, and the amount of vaporization depends entirely on the current thermodynamic state (flow rate and temperature) of the EGR exhaust gas, i.e., the EGR cooling load.
[0040] Preheated ammonia gas (with a significantly increased temperature, for example, above 50°C, matching the temperature of the cryogenic plasma reformer 5) output from the liquid ammonia-cooled EGR cooler 3 is fed into the plasma reformer 5. The plasma reformer 5 can be a dielectric barrier discharge (DBD) or microwave plasma reformer, which, with the assistance of a catalyst, cracks ammonia gas into a mixture of approximately 75% hydrogen and 25% nitrogen. The auxiliary burner built into the plasma reformer 5 may require external ignition during system startup, but during normal operation, it primarily relies on hydrogen supplied by the hydrogen-doped branch 7 as fuel to maintain a suitable temperature field inside the reactor and promote the continuous and efficient ammonia cracking reaction.
[0041] The hydrogen-nitrogen mixture output from the plasma reformer 5 enters the hydrogen purification and distribution unit 6. This unit can employ a palladium membrane or polymer membrane separator to purify the hydrogen to a higher concentration (e.g., >99%). The purified hydrogen stream is split within the hydrogen purification and distribution unit 6. A portion of the hydrogen flows back to the auxiliary combustor of the plasma reformer 5 via the hydrogen blending branch 7 (which may be equipped with a regulating valve). The majority of the remaining hydrogen is delivered to the engine 1 via the main hydrogen supply line 8. The main hydrogen supply line 8 can introduce hydrogen into the intake manifold via an electronically controlled injection valve.
[0042] This system creatively combines the engine's EGR thermal management requirements with the ammonia fuel pretreatment requirements through the core component, the liquid ammonia-cooled EGR cooler 3. This achieves dual-purpose functionality and cascaded utilization of thermal energy, forming a basic platform for an ammonia-hydrogen fuel supply system with tightly coupled physical structure and self-driven energy flow.
[0043] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.
Claims
1. An ammonia-hydrogen engine system integrating liquid ammonia-cooled EGR and plasma reforming, characterized in that, include: A liquid ammonia-cooled EGR cooler (3) has an internally isolated exhaust gas passage and liquid ammonia passage; The exhaust gas passage inlet is connected to the exhaust pipe of the engine (1), and the outlet is connected to the intake pipe of the engine (1); The liquid ammonia channel is connected to a liquid ammonia source (2) at the inlet and outputs hot gaseous ammonia at the outlet. The plasma reformer (5) has its inlet connected to the hot gaseous ammonia outlet of the liquid ammonia-cooled EGR cooler (3), and is equipped with an auxiliary burner inside. The hydrogen purification and distribution unit (6) has its inlet connected to the outlet of the plasma reformer (5), the first outlet connected to the auxiliary burner through the hydrogen doping branch (7), and the second outlet connected to the combustion chamber of the engine (1) through the main hydrogen supply pipeline (8). Among them, the heat from the EGR exhaust gas serves as the sole heat source for the vaporization of liquid ammonia, thus passively coupling the EGR cooling load with the vaporization rate of liquid ammonia.
2. The system according to claim 1, characterized in that, The liquid ammonia-cooled EGR cooler (3) ensures that the liquid ammonia is completely vaporized under the rated operating conditions of the engine.
3. The system according to claim 1 or 2, characterized in that, The plasma reformer (5) is a low-temperature plasma reformer with an inlet temperature adapted to 50-150℃.
4. The system according to claim 3, characterized in that, The auxiliary burner maintains the catalyst active temperature during reformer startup or low load.
5. The system according to claim 1, characterized in that, The liquid ammonia-cooled EGR cooler (3) adopts a plate-fin or shell-and-tube heat exchanger structure.
6. The system according to claim 1, characterized in that, The hydrogen purification and distribution unit (6) uses palladium membrane or polymer membrane separation technology.
7. The system according to claim 1, characterized in that, The main hydrogen supply pipeline (8) is equipped with an electronically controlled injection valve connected to the intake manifold.
8. The system according to claim 1, characterized in that, The hydrogen-doped branch (7) is equipped with a flow regulating valve.
9. A method for operating an ammonia-hydrogen fuel engine, characterized in that, The system of any one of claims 1-8 comprises: Utilizing the waste heat from EGR exhaust gas to vaporize liquid ammonia; The gaseous ammonia plasma was reformed into a hydrogen-containing gas. The hydrogen is purified and distributed to the auxiliary burner and engine combustion chamber.
10. A ship or generator set power system, characterized in that, Integrate the ammonia-hydrogen fuel supply system according to any one of claims 1-8.