Experimental Investigation of Prechamber Enabled Mixing-Controlled Combustion With Natural Gas – A Pathway to Ultra-Low Methane Emissions

Document Type

Article

Publication Date

7-15-2025

Publisher

Elsevier

Source Publication

Fuel

Source ISSN

0016-2361

Original Item ID

DOI: 10.1016/j.fuel.2025.134757

Abstract

With increasing focus on the global climate crisis, there is strong interest in exploring ways to decarbonize many industries. Natural gas reciprocating engines are used for power generation, gas compression, and pipeline transmission. Due to its low reactivity, most natural gas engines today are premixed lean burn spark ignited (SI) engines. These engines produce criteria pollutants, such as nitrogen oxides (NOx) and carbon monoxide (CO), but due to their premixed nature, also produce relatively large amounts of unburned methane (CH4) emissions. This study explores advanced combustion strategies for natural gas engines, particularly focusing on prechamber enabled mixing-controlled combustion (PCMCC), aiming to enhance performance and reduce methane emissions in large-bore natural gas engines. PCMCC uses an actively fueled prechamber to ignite direct injected natural gas, resulting in a non-premixed mixing-controlled combustion event that dramatically reduces methane emissions. Single-cylinder engine experiments were conducted to compare current premixed spark ignition technology and the PCMCC concept. PCMCC with natural gas fuel can achieve a consistent ∼75 % to 99 % reduction in methane emissions over a wide range of NOx emission levels. With the use of internal EGR, PC MCC NOx emissions were reduced to ∼1 g/kW-hr, which is similar to current engine technology, while maintaining ultra-low methane slip of ∼0.1 g/kW-hr, which is ∼99 % lower than current engine technology. Both concepts deliver equal gross indicated thermal efficiencies at similar compression ratios. However, due to its non-premixed nature, PCMCC operates without the fear of knock or preignition, and thus can operate at higher compression ratios providing an advantage in thermal efficiency compared to its premixed spark ignition counterpart. This study shows that PCMCC has potential to be a disruptive natural gas engine technology to dramatically reduce methane emissions, and thus greenhouse gas emissions, in the near term.

Comments

Fuel, Vol. 392 (July 15, 2025). DOI.

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