Combustion and emission characteristics of diesel engines fueled with diethoxymethane blends under varying load conditions

This study systematically evaluates the combustion, emission, and fuel economy characteristics of pure diesel and a diethoxymethane (DEM) blend (DEMDB, 1:4 vol ratio with diesel) in a diesel engine under varying load conditions. Experimental results demonstrate that both fuels exhibit increased peak in-cylinder pressure and a transition from single-peak to dual-peak heat release rate patterns with rising loads. DEMDB, characterized by low latent heat of vaporization and a distinct molecular structure, displays unique combustion behavior, with prolonged ignition delay and combustion duration at low loads but aligning closely with diesel at high loads. A key finding is that DEMDB significantly reduces soot emissions by 46.5 %–62.1 % across all loads compared to pure diesel, attributed to its oxygen-rich composition that suppresses polycyclic aromatic hydrocarbon formation. However, DEMDB increases NOx emissions by 3.4 %–8.1 % due to extended high-temperature combustion and oxygen-enhanced nitrogen oxidation. Brake thermal efficiency (BTE) of DEMDB is slightly lower than diesel at low loads but surpasses diesel at medium-to-high loads, reflecting enhanced combustion efficiency. These findings underscore DEM’s potential as a sustainable, biomass-derived diesel additive for achieving cleaner combustion, while highlighting the need for combustion phasing optimization and advanced aftertreatment to mitigate NOx emissions.