Core Viewpoint - The article discusses the differences between diesel and gasoline engines, focusing on their combustion methods, structural differences, fuel characteristics, emissions, and after-treatment systems. Group 1: Combustion Method and Structure - The primary difference between diesel and gasoline engines lies in their combustion methods: gasoline engines use premixed flame propagation, while diesel engines rely on diffusion combustion [2] - Diesel engines operate on compression ignition (CI Engine), while gasoline engines use spark ignition (SI Engine) [2] - Diesel engines have higher fuel injection pressures, reaching up to 2500 bar, compared to gasoline engines, which typically max out at around 500 bar [3] Group 2: Efficiency and Compression Ratio - Diesel engines have a higher compression ratio (approximately 16-26) compared to gasoline engines (8-12), leading to greater thermal efficiency, which can reach 40%-45% or even over 50% in advanced models [4] - The structural simplicity of diesel engines contributes to their reliability, but they require heavier components to withstand higher explosion pressures [4] Group 3: Fuel Characteristics - Diesel has a higher energy density than gasoline, with 1 liter of diesel releasing energy equivalent to approximately 1.2 liters of gasoline [5] - Diesel engines face challenges in cold weather, as they can experience wax precipitation below 0°C, necessitating the use of low-temperature diesel [5] Group 4: Emissions and After-treatment Systems - Diesel engines emit lower carbon monoxide (CO) and hydrocarbons (HC) but higher nitrogen oxides (NOx) and particulate matter (PM) compared to gasoline engines [7] - Diesel vehicles are equipped with a diesel particulate filter (DPF) and a selective catalytic reduction (SCR) system to reduce NOx emissions, which involves injecting urea solution into the exhaust [8] - The urea solution used in SCR systems can freeze at temperatures below -11°C, requiring heating mechanisms to prevent freezing [8]