In order to achieve a sustainable society, vegetable oil derived from solar energy is a major topic of interest. Vegetable oils are can potentially be utilized as fuel in applications such as engines, gas turbines, furnaces, boilers and steam power plants. In this paper, rapeseed oil as a fuel for diesel engine was studied. There are seven refinement processes that improve the quality of the oil because the rapeseed oil is mainly produced for food. Rapeseed oil is produced from the raw material through compression, solvent extraction, degumming, deoxidation, bleaching, deodorization and a final-refinement process. However, all of these refinement processes are not necessary if the oil is to be used for diesel fuel. The performance of the engines operated by the tested fuels, which were extracted at the end of each of the seven refinement stages, was investigated.
The major findings of this study are as follows. The brake thermal efficiency is unrelated to the refinement process and is almost equal to the performance with diesel fuel. Therefore, it is obvious that the tendency of CO2 emission is the same as that of the brake thermal efficiency. The THC emission, the NOx emission and the smoke density do not depend on the refinement processes of the rapeseed oil. The NOx emission and the smoke density level are almost equal to the situation when diesel fuel is used. In THC emission, all the tested fuels were lower than for the diesel fuel. The problem of deposits built-up in the combustion chamber is one which should be solved. Our overall conclusion is that all refinement processes can be omitted when the rapeseed oil is used as fuel in diesel engines.