Combustion and emissions of substituted dioxolane – hydrotreated vegetable oil renewable fuel blends in a heavy-duty diesel engine

Abstract

Given the accelerating pace of global warming, there is a pressing need for decarbonisation of the transport sector so as to reduce global greenhouse gas emissions. Alternative renewable fuels derived from biomass or the upcycling of waste are central to achieving this transition. Among these, molecules containing the dioxolane functional group have emerged as promising fuel candidates. Although the combustion kinetics of the dioxolane functional group have been studied, the effects of substituted dioxolanes on combustion characteristics and emissions in practical engine applications remain largely unexplored. This study presents the first experimental evaluation of 2-ethyl-2-methyl-1,3-dioxolane (2-EMD), a substituted dioxolane, as a major fuel component in a heavy-duty compression–ignition engine. 2-EMD was blended with hydrotreated vegetable oil (HVO) at 30% and 70% by volume, and tested under constant indicated mean effective pressure (IMEP) and start-of-combustion (SOC) conditions. The 30%(v/v) 2-EMD blend exhibited an ignition delay identical to that of neat HVO. However, increasing the percentage blend level of 2-EMD to 70%(v/v) resulted in a longer ignition delay and a correspondingly higher apparent peak heat release rate (PHRR), elevating NOx emissions due to increased premixed combustion. Across both blends, 2-EMD reduced incomplete combustion products (CO and THC). These findings highlight the potential of 2-EMD as a viable drop-in biofuel component for heavy-duty engines at moderate blend levels of up to at least 30%(v/v).