US-12624654-B2 - Stratified nitrogen enriched air (NEA) strategies and methods to reduce NOx emissions from engines

Abstract

A method for injecting nitrogen into an internal combustion engine cylinder includes moving a piston back and forth in a cylinder and injecting pure nitrogen into a combustion chamber during the compression stroke. The method includes injecting the fuel and nitrogen into different regions to create a stratified gas environment, igniting the fuel, and releasing exhaust emissions. An engine system for injecting nitrogen into an internal combustion engine includes a cylinder, a first intake line, one or more nitrogen injectors, and a fuel injector. An engine system for injecting nitrogen into an internal combustion engine includes a cylinder, an intake line, and a multi-nozzle injector with a fuel nozzle and a nitrogen nozzle.

Inventors

• Vallinayagam Raman
• Jaeheon Sim
• Junseok Chang

Assignees

• SAUDI ARABIAN OIL COMPANY

Dates

Publication Date

20260512

Application Date

20240125

Claims (20)

1. 1 . A method for injecting nitrogen into an internal combustion engine cylinder, comprising: moving a piston axially back and forth in a cylinder of an internal combustion engine between a top dead center position and a bottom dead center position in a cycle, the cycle comprising: an intake stroke; a compression stroke; a combustion stroke; and an exhaust stroke; injecting pure nitrogen into a combustion chamber of the cylinder before the piston reaches top dead center during the compression stroke; injecting fuel into the combustion chamber of the cylinder; wherein the pure nitrogen and the fuel are injected into different regions of the combustion chamber to create a stratified gas environment with a high nitrogen concentration region and a low nitrogen concentration region within the combustion chamber; igniting the fuel in the stratified gas environment; and releasing an amount of exhaust emissions from combustion of the fuel during the exhaust stroke.
2. 2 . The method of claim 1 , wherein the pure nitrogen injecting uses one or more nitrogen injectors.
3. 3 . The method of claim 2 , wherein the one or more nitrogen injectors are located on a top of the cylinder, a side of the cylinder, or combinations thereof.
4. 4 . The method of claim 1 , wherein the pure nitrogen is injected from a top of the cylinder into a bowl region on a head of the piston to provide the stratified gas environment with a higher concentration of nitrogen in the bowl region relative to remaining regions in the combustion chamber.
5. 5 . The method of claim 4 , wherein the higher concentration of nitrogen is concentrated in the bowl region by injecting the pure nitrogen with a spray angle ranging from 90 to 120 degrees and at a nitrogen injection timing ranging from 10 to 20 crank angle degrees before a fuel injection timing for injecting the fuel.
6. 6 . The method of claim 1 , wherein the pure nitrogen is injected from a top of the cylinder into the combustion chamber with a spray angle ranging from 160 to 180 degrees at a nitrogen injection timing ranging from 10 to 20 crank angle degrees before a fuel injection timing for injecting the fuel to provide the stratified gas environment with a higher concentration of nitrogen in a cylindrical region in the combustion chamber relative to remaining regions in the combustion chamber, wherein the cylindrical region of the high concentration of nitrogen extends centrally through the combustion chamber between a head of the piston and the top of the cylinder.
7. 7 . The method of claim 1 , wherein the pure nitrogen is injected from a nitrogen injector at a top of the cylinder into the combustion chamber to provide the stratified gas environment with a higher concentration of nitrogen in a spherical region around the nitrogen injector to provide the stratified gas environment with a higher concentration of nitrogen in the spherical region relative to remaining regions in the combustion chamber.
8. 8 . The method of claim 3 , wherein the stratified gas environment comprises a higher concentration of nitrogen in a region of the cylinder based on the location of the one or more nitrogen injectors.
9. 9 . The method of claim 1 , wherein the pure nitrogen is generated from a membrane-based system.
10. 10 . The method of claim 1 , wherein the pure nitrogen is generated from a pressure swing adsorption system.
11. 11 . The method of claim 1 , further comprising: providing air to a nitrogen generation system from an external air source, a turbocharger, or a combination thereof; and generating the pure nitrogen from the nitrogen generation system.
12. 12 . An engine system for injecting nitrogen into an internal combustion engine, comprising: a cylinder comprising a combustion chamber and a piston slidably positioned in the cylinder; a first intake line fluidly connected to the combustion chamber via a first intake port; one or more nitrogen injectors fluidly connecting a source of pure nitrogen to the combustion chamber; a fuel injector fluidly connecting a fuel source to the combustion chamber; wherein the one or more nitrogen injectors provide nitrogen to the combustion chamber to create a stratified gas environment with a high nitrogen concentration region and a low nitrogen concentration region within the combustion chamber.
13. 13 . The engine system of claim 12 , wherein the source of pure nitrogen comprises a membrane-based system.
14. 14 . The engine system of claim 12 , wherein the source of pure nitrogen comprises a pressure swing adsorption system.
15. 15 . The engine system of claim 12 , wherein when a first of the one or more nitrogen injectors is in an open configuration, a second nitrogen injector is in a closed configuration, and when the second nitrogen injector is in the open configuration, the first nitrogen injector is in the closed configuration.
16. 16 . The engine system of claim 12 , wherein the one or more nitrogen injectors are located on a top of the cylinder, a side of the cylinder, or combinations thereof.
17. 17 . An engine system for injecting nitrogen into an internal combustion engine, comprising: a cylinder comprising a combustion chamber and a piston slidably positioned in the cylinder; an intake line fluidly connected to the combustion chamber via an intake port; and a multi-nozzle injector connected to the cylinder, the multi-nozzle injector comprising: a fuel nozzle fluidly connecting a fuel source to the combustion chamber; and a nitrogen nozzle fluidly connecting a source of pure nitrogen to the combustion chamber.
18. 18 . The engine system of claim 17 , wherein the fuel nozzle circumferentially surrounds the nitrogen nozzle.
19. 19 . The engine system of claim 17 , wherein the multi-nozzle injector is located on a top of the cylinder.
20. 20 . An engine system for injecting nitrogen into an internal combustion engine, comprising: a cylinder comprising a combustion chamber and a piston slidably positioned in the cylinder; one or more nitrogen injectors fluidly connecting a source of pure nitrogen to a first and a second intake line; the first intake line fluidly connected to the combustion chamber via a first intake port configured to direct air with atmospheric concentrations of nitrogen to the combustion chamber; the second intake line fluidly connected to the combustion chamber via a second intake port configured to direct the pure nitrogen to the combustion chamber; and a fuel injector fluidly connecting a fuel source to the combustion chamber.

Description

BACKGROUND Internal combustion engines emit gaseous pollutants such as carbon monoxide (CO), carbon dioxide (CO2), unburned hydrocarbons, nitrogen oxide (NOx) as well as solid pollutants such as particulate matter. As legislation has tightened the rules for vehicle emissions, new exhaust purification systems have been developed to reduce emissions. Environmental concerns and government regulations have led to efforts focused on improving the removal of combustion by-products and exhaust pollutants from vehicle engine exhaust gases. Nitrogen in a combustion chamber of an internal combustion engine may decrease the combustion rate and thus decrease NOx emissions. Accordingly, there exists a need for a process of including nitrogen in an internal combustion engine to reduce NOx emissions while maintaining engine efficiency. SUMMARY This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. In one aspect, embodiments disclosed herein relate to methods for injecting nitrogen into an internal combustion engine. The internal combustion engine has an axially moving piston in a cylinder moving between a top dead center position and a bottom dead center position in a cycle containing an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke. The methods may include injecting pure nitrogen into a combustion chamber of the cylinder before the piston reaches top dead center during the compression stroke. The fuel is injected into a different region of the combustion chamber from where the pure nitrogen is injected to create a stratified gas environment within the combustion chamber. The fuel in the stratified gas environment is ignited and exhaust emissions are released from combustion of the fuel during the exhaust stroke. In another aspect, embodiments disclosed herein relate to engine systems for injecting nitrogen into an internal combustion engine including a cylinder with a combustion chamber and a piston slidably positioned in the cylinder. The system includes a first intake line fluidly connected to the combustion chamber through a first intake port. One or more nitrogen injectors fluidly connect a source of pure nitrogen to the combustion chamber and a fuel injector fluidly connects a fuel source to the combustion chamber. In another aspect, embodiments disclosed herein relate to engine systems for injecting nitrogen into an internal combustion engine with a cylinder comprising a combustion chamber and a piston slidably positioned in the cylinder. An intake line fluidly connects to the combustion chamber through an intake port. A multi-nozzle injector is connected to the cylinder containing a fuel nozzle fluidly connecting a fuel source to the combustion chamber and a nitrogen nozzle fluidly connecting a source of pure nitrogen to the combustion chamber. In another aspect, embodiments disclosed herein relate to engine systems for injecting nitrogen into an internal combustion engine including a cylinder comprising a combustion chamber, a piston slidably positioned in the cylinder, first intake line fluidly connected to the combustion chamber through a first intake port, and a second intake line fluidly connected to the combustion chamber through a second intake port. One or more nitrogen injectors fluidly connects a source of pure nitrogen to the first and the second intake line and a fuel injector fluidly connects a fuel source to the combustion chamber. Any combinations of the various embodiments and implementations disclosed herein can be used in a further embodiment, consistent with the disclosure. Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims. BRIEF DESCRIPTION OF DRAWINGS Wherever possible, like or identical reference numerals are used in the figures to identify common or the same elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale for purposes of clarification. FIG. 1A is a schematic view of a cylinder in an internal combustion engine in accordance with one or more embodiments. FIG. 1B is a three-dimensional depiction of a piston bowl with an annular depression formed in the top surface. FIG. 1C is a three-dimensional depiction of a piston bowl with a multi-lobed depression formed in the top surface. FIG. 1D is a schematic view of a cylinder in an internal combustion engine with separate nitrogen and fuel injectors in accordance with one or more embodiments. FIG. 1E is a schematic view of a cylinder in an internal combustion engine with a multi-nozzle injector in accordance with one or more embodiments. FIGS. 2A-B show schematics depicting nitrogen stratificat