Insights into the Cold-Start Performance and Emission Characteristics of Ethanol–Diesel Blended Fuels Under Various Environmental Conditions

In light of the indispensable role of diesel engines in critical sectors such as heavy transportation, agricultural machinery, and shipping and the gradual depletion of fossil fuels, the strategic value of blended fuels has become increasingly prominent. However, the cold-start performance of diesel engines operating on blended fuels remains unclear. This study conducts a comprehensive simulation of the impact of various blended fuel ratios on the cold-start characteristics of diesel engines, focusing on low-temperature fluidity, combustion characteristics, and emissions. The research findings indicate that E30 and E50, as preferred blended fuels, exhibit excellent economic performance and environmental adaptability. Specifically, E30 demonstrates superior combustion performance and higher cylinder peak pressure under low-temperature conditions. In contrast, E50 shows a significant advantage in emissions performance, achieving 17.34% reductions in NOx and 9.7% in HC emissions compared to E30. In addition, a decrease in ambient temperature could help mitigate both NOx and HC emissions. Under simulated high-altitude conditions, E50 exhibits superior hypoxic adaptability compared to E30, achieving significant reductions in NOx (16.3%) and HC (9.7%). This study helps advance the development of clean alternative fuels for diesel engines by providing a theoretical foundation and practical guidelines for biodiesel selection across diverse environmental conditions.