Session: 02-03: Methanol in Compression Ignition Engines

Paper Number: 172457

172457 - Performance and Emission Characteristics of Diesel-Methanol Rcci Combustion With Egr in a Heavy-Duty Single Cylinder Research Engine 

Abstract: 

Methanol (CH₃OH), also known as wood alcohol, is considered a promising alternative fuel due to its relatively low production cost compared to other alternative fuels. It can be synthesized from natural gas via steam reforming and offers enhanced energy security, as it can be produced from various domestic carbon-based feedstocks, including biomass, coal, and natural gas.

Low-temperature combustion (LTC) strategies, such as Reactivity Controlled Compression Ignition (RCCI), utilize a high-reactivity fuel to initiate the combustion of a low-reactivity fuel. These strategies have demonstrated significant reductions in nitrogen oxides (NOx) emissions. However, they are often accompanied by increased emissions of unburned hydrocarbons (HC) and carbon monoxide (CO) due to incomplete oxidation at low temperatures. Prior studies have explored methanol as a low-reactivity fuel (LRF) in RCCI combustion, paired with diesel as the high-reactivity fuel (HRF). These studies, conducted under low-load conditions (approximately 5 bar Indicated Mean Effective Pressure, IMEPg), achieved exceptionally low NOx emissions (<0.5 g/kWh), minimal soot levels, and good engine stability (Coefficient of Variation of IMEPg (CoV of IMEPg < 5%) even at methanol energy substitution rates up to 80%.

Exhaust Gas Recirculation (EGR) is a proven emissions control technology traditionally used to reduce NOx emissions by recirculating a portion of exhaust gases back into the intake charge. Under LTC and RCCI conditions, EGR also enhances the oxidation of unburned HC and CO by promoting their reburning in subsequent cycles. This effect not only reduces HC and CO emissions but also improves combustion efficiency (CE), indicated fuel conversion efficiency (IFCE), and engine stability. Importantly, these benefits are achieved with minimal additional NOx emissions and without compromising the low soot characteristics of methanol-fueled RCCI. At approximately 50% EGR, combustion stability improved significantly, with the CoV of IMEPg reduced from <4% to <2%. Additionally, the methanol energy substitution increased from 80% to 90%.

These findings highlight the strong potential of methanol–diesel RCCI combustion, especially when combined with optimized EGR strategies, as a pathway to achieving ultra-clean, efficient, and stable operation in next-generation low-emission engine technologies.

Presenting Author: Yamini Baskara Babu The University of Alabama

Presenting Author Biography: Graduate student at The University of Alabama

Authors:

Yamini Baskara Babu The University of Alabama
Kalyan Srinivasan The University of Alabama
Sundar Krishnan The University of Alabama