US-12624673-B2 - Ammonia-fueled engine based on oxygen enhancement and ammonia-rich combustion control method thereof

US12624673B2US 12624673 B2US12624673 B2US 12624673B2US-12624673-B2

Abstract

An ammonia-fueled engine based on oxygen enhancement and reactive activity control, and an ammonia-rich combustion control method thereof are provided. The ammonia-fueled engine based on oxygen enhancement includes a jet ignition device and an ammonia gas injector. An oxygen injector is provided on the jet ignition device. During the operation of the ammonia-fueled engine, the ammonia gas injector firstly injects ammonia fuel into a combustion chamber, and ammonia gas in the combustion chamber enters a prechamber inner cavity through a jet hole during a compression stroke, and the oxygen injector firstly injects oxygen gas into a prechamber to reduce an ammonia concentration in a gas mixture in the prechamber, dilute the gas mixture in the prechamber, improve the reaction activity of the gas mixture, and ensure the speed and intensity of an initial flame; and then a jet flame is formed to ignite over-concentrated ammonia-air mixture in the combustion chamber.

Inventors

Lei Zhou
Zongkuan LIU
Lijia Zhong
Haiqiao WEI
Gequn SHU

Assignees

TIANJIN UNIVERSITY

Dates

Publication Date: 20260512
Application Date: 20241202
Priority Date: 20240327

Claims (6)

1 . An ammonia-fueled engine based on oxygen enhancement, comprising a jet ignition device ( 4 ), a piston ( 1 ), a cylinder head ( 7 ), a cylinder liner ( 8 ), and an ammonia gas injector ( 5 ), wherein a combustion chamber ( 2 ) is formed between the piston ( 1 ) and the cylinder head ( 7 ), and an end of the jet ignition device ( 4 ) and an end of the ammonia gas injector ( 5 ) extend into the combustion chamber ( 2 ); the jet ignition device ( 4 ) comprises a prechamber inner cavity ( 13 ), a spark plug ( 9 ), an oxygen injector ( 11 ), and a fuel injector ( 12 ); the spark plug ( 9 ) is located in the prechamber inner cavity ( 13 ), injection ports of the oxygen injector ( 11 ) and the fuel injector ( 12 ) extend into the prechamber inner cavity ( 13 ); and the oxygen injector ( 11 ) is configured to inject oxygen gas into the prechamber inner cavity ( 13 ) to reduce a concentration of a gas mixture in the prechamber inner cavity ( 13 ).
2 . The ammonia-fueled engine based on oxygen enhancement according to claim 1 , wherein the jet ignition device ( 4 ) comprises a shell ( 10 ) and a prechamber front end ( 15 ); the shell ( 10 ) and the prechamber front end ( 15 ) are in detachable connection, and a cavity formed between a bottom of the shell ( 10 ) and an inner wall of the prechamber front end ( 15 ) is the prechamber inner cavity ( 13 ), a jet hole ( 14 ) is provided on the bottom of the prechamber front end ( 15 ), for communicating the prechamber inner cavity ( 13 ) with the combustion chamber ( 2 ), and threads are provided on partial outer wall of the prechamber front end ( 15 ) for threaded connection to the cylinder head ( 7 ) of an engine.
3 . An ammonia-rich combustion control method of the ammonia-fueled engine based on oxygen enhancement according to claim 2 , comprising the following steps: during operation of an ammonia-fueled engine, injecting, by an ammonia gas injector ( 5 ), ammonia fuel into a combustion chamber ( 2 ) to form a concentrated ammonia-air mixture with an equivalence ratio of 1.0-1.2 in the combustion chamber ( 2 ); during a compression stroke, due to the compression of a piston ( 1 ), enabling ammonia gas in the combustion chamber ( 2 ) to enter a prechamber inner cavity ( 13 ) through a jet hole ( 14 ); before a spark plug ( 9 ) ignites, injecting, by an oxygen injector ( 11 ), oxygen gas into the prechamber inner cavity ( 13 ) to reduce an ammonia concentration in a gas mixture in the prechamber inner cavity ( 13 ); and at a position close to compression top dead center, igniting, by the spark plug ( 9 ), the gas mixture in the prechamber inner cavity ( 13 ) to form a jet flame through the jet hole ( 14 ), and then igniting a concentrated ammonia-air mixture in the combustion chamber ( 2 ) to complete combustion work of an engine.
4 . The ammonia-rich combustion control method of the ammonia-fueled engine based on oxygen enhancement according to claim 3 , wherein oxygen injection quantity of the oxygen injector ( 11 ) is determined according to an operating condition of the engine, so as to generate prechamber jet flames with different intensities.
5 . The ammonia-rich combustion control method of the ammonia-fueled engine based on oxygen enhancement according to claim 3 , wherein ammonia injection quantity of the ammonia gas injector ( 5 ) is regulated and controlled by an ECU (electronic control unit) of the engine, and a thermodynamic environment with a fuel-air equivalence ratio greater than 1 is achieved in the combustion chamber ( 2 ).
6 . The ammonia-rich combustion control method of the ammonia-fueled engine based on oxygen enhancement according to claim 3 , wherein the volume and structure of the prechamber inner cavity ( 13 ) and a diameter and amount of the jet hole ( 14 ) are selected according to an engine type and the operating condition.

Description

CROSS-REFERENCE TO RELATED APPLICATION This patent application claims the benefit and priority of Chinese Patent Application No. 202410360234.0 filed with the China National Intellectual Property Administration on Mar. 27, 2024, the disclosure of which is incorporated by reference herein in its entirety as part of the present application. TECHNICAL FIELD The present disclosure belongs to the technical field of internal combustion engines, and in particular to an ammonia-fueled engine based on oxygen enhancement and reaction activity control, and an ammonia-rich combustion control method thereof. BACKGROUND In the application of traditional fossil fuels, ammonia (NH3), a burning alternative fuel, is a promising and feasible carbon emission reduction technological path. However, there are two key challenges in ammonia combustion: firstly, the ammonia is poor in combustion characteristics, and is difficult in ignition and stable combustion under conventional conditions. Secondly, because of its high nitrogen content, there is a risk of high NOx emission in ammonia combustion. The implementation of the engineering application of ammonia combustion needs the full understanding of the characteristics of ammonia combustion and NOx emission, and targeted research on combustion enhancement and NOx control measures. In recent years, researchers have carried out in-depth research on ammonia combustion, trying to explore economic, simple and efficient ammonia combustion enhancement measures and NOx emission control strategies, and have achieved a lot of valuable research results. The ammonia combustion enhancement mainly starts from the aspects of fuel side improvement, oxidant side adjustment and combustion conditions improvement, etc., and the enhancement measures mainly include blended burning, partial precalcining combustion, oxygen-enriched combustion, preheating combustion and enhanced mixing. The NOx in ammonia combustion mainly comes from the nitrogen contained in the fuel itself, so the NOx control strategies mainly start with controlling the oxidation conditions of ammonia, and air classification is one of the most effective methods. Meanwhile, ammonia itself is also an efficient NOx reducing agent, and making full use of such characteristics, reasonable configuration of mixed strategies according to the combustion temperature conditions is also conducive to the effective control of NOx. However, the ammonia, when used as engine fuel, is poor in the combustion characteristics, such as high spontaneous combustion temperature, slow flame propagation speed and narrow combustible range, leading to unstable combustion, low efficiency and poor performance of the ammonia-fueled engine. In addition, when the in-cylinder combustion status is poor, the engine also faces the risk of increased nitrogen oxide emission and ammonia escape. Therefore, the development of an efficient and clean combustion mode is a big challenge for ammonia-fueled engine. SUMMARY In the prior art, it is found that injecting high-activity fuel (such as hydrogen) into the prechamber still cannot break through the limit of EGR (exhaust gas recirculation). The present disclosure provides an ammonia-fueled engine based on oxygen enhancement and reaction activity control, and an ammonia-rich combustion control method thereof. From the perspective of changing oxygen gas in the prechamber, efficient combustion is achieved, the limit of lean combustion is expanded, and stable ignition and combustion are achieved. An objective of the present disclosure is achieved through the following technical solution: An ammonia-fueled engine based on oxygen enhancement includes a jet ignition device, a piston, a cylinder head, a cylinder liner, and an ammonia gas injector. A combustion chamber is formed between the piston and the cylinder head, and an end of the jet ignition device and an end of the ammonia gas injector extend into the combustion chamber. The jet ignition device includes a prechamber inner cavity, a spark plug, an oxygen injector, and a fuel injector. The spark plug is located in the prechamber inner cavity, and injection ports of the oxygen injector and the fuel injector extend into the prechamber inner cavity. The oxygen injector is configured to inject oxygen gas into the prechamber inner cavity to reduce a concentration of a gas mixture in the prechamber inner cavity. An ammonia-rich combustion control method of the ammonia-fueled engine based on oxygen enhancement includes the following steps: during operation of an ammonia-fueled engine, injecting, by an ammonia gas injector, ammonia fuel into a combustion chamber to form a concentrated ammonia-air mixture with an equivalence ratio of 1.0-1.2 in the combustion chamber;during a compression stroke, due to the compression of a piston, enabling ammonia gas in the combustion chamber to enter a prechamber inner cavity through a jet hole;before a spark plug ignites, injecting, by an oxygen injector,