Performance of a Diesel Engine Fueled by Rapeseed oil Blended with Oxygenated Organic Compounds

This investigation reports engine performance, combustion characteristics, and exhaust emissions with alternative diesel fuels of blends of vegetable oil and various fuel additives (fuel improving agents). To improve the oil viscosity and distillation characteristics, the study used liquid oxygenated agents with lower boiling points and higher volatility than gas oil. The experiments used rapeseed oil and eight kinds of oxygenates: ethanol, 1-propanol, 1-butanol, 1-pentanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, and dibutyl ether. An ordinary small single cylinder DI diesel engine was used and the blending ratio was defined as the volume %; the proportion of oxygenate in the fuel was from 0% (neat rapeseed oil) to 29 or 33%. The results showed that all of the above oxygenates except ethanol and 2-methoxyethanol had good solubility in rapeseed oil (by manual mixing) at room temperature. Compared with gas oil as the standard fuel, the blended fuels including oxygenates with ether chains showed similar specific energy consumption (BSEC) at high loads, while the BSEC was 2 - 5% higher at low loads. The smoke emissions with the ether oxygenates blended in the rapeseed oil decreased linearly with increases in the oxygen content of the fuel. Performance tests also showed that with up to 33% (vol.) of oxygenate addition, the blended fuels with 2-ethoxyethanol, 2-butoxyethanol, or dibutyl ether realize stable combustion similar to gas oil operation.