The effects of EGR rates and ternary blends of biodiesel/n-pentanol/diesel on the combustion and emission characteristics of a CRDI diesel engine

Abstract

An experiment was conducted to investigate the combined impacts of biodiesel and n-pentanol properties on the performance and emissions of a common-rail diesel engine at different exhaust gas recirculation (EGR) rates. Tested fuels are noted as D100 (diesel fuel), B10P20 (10% biodiesel, 20% n-pentanol and 70% diesel, by vol.), B20P10 (20% biodiesel, 10% n-pentanol and 70% diesel, by vol.), P30 (30% n-pentanol and 70% diesel, by vol.) and B30 (30% biodiesel and 70% diesel, by vol.). The results indicate that compared to D100, the ignition delays of B20P10 and B30 show different results with increased EGR rates. That is, although the cetane number of B20P10 and B30 is lower, the ignition delays of B20P10 are shorter than that of D100 when the EGR rate is over 30%. The addition of n-pentanol to diesel will result in high maximum pressure rise rate, but ternary blends of biodiesel/n-pentanol /diesel can solve or alleviate the problem without obvious decrease of indicated thermal efficiency (ITE). At high EGR rates, ternary fuels shows the advantages in decreasing total hydrocarbons (THC). There is no significant difference in nitrogen oxides (NOx) emissions for all fuels at the same EGR rate. B10P20 and B20P10 can not only reduce soot emissions but also reduce carbon monoxide (CO) emissions under different EGR rates compared with diesel. To summarize, B20P10 fuel has a better potential for combustion and emission characteristics, especially at relatively high EGR rates.