Improved Combustion Efficiency in Methanol/Renewable Diesel Dual Fuel Combustion by Advanced Injection Timing and Increased Intake Temperature: Single-Cylinder Experiment 2023-01-1641

Conventional diesel combustion (CDC) is known to provide high efficiency and reliable engine performance, but often associated with high particulate matter (PM) and nitrogen oxides (NO_X) emissions. Combustion of fossil diesel fuel also produces carbon dioxide (CO₂), which acts as a harmful greenhouse gas (GHG). Renewable and low-carbon fuels such as renewable diesel (RD) and methanol can play an important role in reducing harmful criteria and CO₂ emissions into the atmosphere. This paper details an experimental study using a single-cylinder research engine operated under dual-fuel combustion using methanol and RD. Various engine operating strategies were used to achieve diesel-like fuel efficiency. Measurements of engine-out emissions and in-cylinder pressure were taken at test conditions including low-load and high-load operating points. At each engine condition, advanced injection timing showed a reduction in combustion loss, including reductions in carbon monoxide (CO) and unburned hydrocarbons (UHC). A maximum pressure rise rate (MPRR) was set at 15 bar/CAD which limited the advance of injection timing advance at high load. MPRR was below the limit at low load even for the highest methanol substitution rate. The effect of increased intake temperature was also investigated at low load. Higher intake temperatures resulted in reduced combustion losses but also limited the allowable injection timing advance.

In summary, this work (1) demonstrates the feasibility of operating a heavy-duty diesel engine under dual-fuel (RD and methanol) combustion mode, and (2) provides a pathway towards optimized engine and emissions performance.