The performance and emissions characteristics of diesel/biodiesel/alcohol blends in a diesel engine

Biodiesel has great potential as an alternative fuel for diesel engines. However, poor low-temperature flow property and high viscosity of biodiesel limit its use in engines. Therefore, alcohol comes into researchers’ eyes as a promising additive for diesel–biodiesel (DB) blends. In this study, the effects of lower and higher alcohol contents with different speeds on combustion and emissions characteristics were investigated in a modified single cylinder diesel engine. The results indicated that the maximum pressure rise rate (MPRR) maintained a consistent drop ratio as speed increased from 1500 rpm to 1800 rpm for the tested fuels. However, B10E10 (10% biodiesel and %10 ethanol by volume) had a big drop, which meant that engine’s power ability had a big loss at high speed. The declining rate with speed decreased for indicated thermal efficiency (ITE) when adding alcohol to diesel–biodiesel blends, especially n-pentanol. Moreover, compared with other tested fuels, B10P10 (10% biodiesel and 10% n-pentanol) had smaller cycle variation and more stable combustion state as speed changed, despite it had the highest coefficient of variation (COV) at 1000 rpm. It can be found that has advantages in combustion stability, and can well reduce the total hydrocarbon (THC) and carbon monoxide (CO) emissions under the condition of medium speed commonly used by vehicle. Overall consideration, using diesel/biodiesel/alcohol ternary fuels may be a better choice for diesel engines.