Session: 02-02: Alternative CI Fuels, Ignition, and Combustion Strategy

Paper Number: 197493

197493 - Dibutyl Oxymethylene Ether as an Alternative Fuel for Heavy-Duty Compression Ignition Engines – Opportunities and Challenges 

Abstract: 

Emissions of nitrogen oxides (NOx) and soot have been significantly reduced in modern heavy-duty diesel engines by employing various in-cylinder and aftertreatment strategies. In addition to these advancements aimed at overcoming the traditional NOx vs soot trade-off, ongoing research focuses on identifying renewable, low-carbon liquid fuels as a drop-in replacement for diesel. This study evaluates one such low-carbon oxygenated liquid fuel (dibutyl oxymethylene ether (B1B)), which is part of the family of oxymethylene ethers (OMEx).  Dibutyl oxymethylene ether is a larger alkyl-group-terminated OME that has ~20 percent oxygen by mass, a higher lower heating value (LHV) compared to other lower alkyl group OMEs such as dimethyl oxymethylene ether, and a significantly higher cetane number (~76) compared to ultra low sulfur diesel in the US. Previous research has shown that longer chain alkyl group OMEs offer better seal compatibility and good lubricity for the diesel injection system, making B1B a potentially viable drop-in fuel substitute for diesel. Neat B1B was used without any additives in a high-pressure common rail direct injection system on a heavy-duty single-cylinder engine at different loads (~5-15 bar IMEPg) at 1339 rpm (B-speed). Cylinder pressure and heat release data were acquired to evaluate combustion characteristics, including ignition delay and combustion duration. Additionally, engine performance and emissions were investigated. The present work also characterized the impact of engine operating parameters (e.g., start of injection (SOI), multiple injections, boost pressure, rail pressure, and exhaust gas recirculation (EGR)) on B1B combustion. The experiments were focused on mitigating (or possibly eliminating) the traditional NOx-soot tradeoff in diesel combustion, improving or maintaining diesel-equivalent fuel conversion efficiencies, and minimizing any adverse impacts on engine performance and emissions.  Specifically, with an oxygenated, inherently low-sooting fuel such as B1B, EGR can be leveraged to reduce NOx emissions without any adverse impact on soot. Overall, given its favorable physical properties (high cetane number, good lubricity, etc.) combined with its ability to be utilized in modern common rail injection systems (with no significant modifications), B1B appears to be a viable, drop-in liquid alternative for diesel fuel in heavy-duty compression ignition engines.

Presenting Author: Hariraja Thothadri The University of Alabama

Presenting Author Biography: Hariraja Thothadri is a Ph.D. student in Mechanical Engineering at The University of Alabama. His doctoral research is focused on liquid alternative fuels for compression ignition engines.

Authors:

Hariraja Thothadri The University of Alabama
Yamini Baskara Babu The University of Alabama
Anurag Gaur The University of Alabama
Kalyan Kumar Srinivasan The University of Alabama
Sundar Rajan Krishnan University of Alabama