MIXED VEGETABLE AND DIESEL OIL AS FUEL

ABSTRACT Bio-fuel for diesel engines was introduced to the market in certain european countries recently. Vegetable oil as raw material for the bio-fuel originates from oilseed crops grown on set-aside land with EC subsidies. Production of the bio-fuel includes a conversion process – esterification, requiring a special equipment and a considerable input in the form of additives, energy, labour, etc. By-products from esterification e.g. glycerine and poluted water are unavoidable. To minimize the production expenses and to eliminate the by-products, an alternative fuel was found in the form of a mixture containing diesel oil and crude vegetable oil. For this purpose was choosen a naturally pure vegetable oil from seed of false flax – Comelina sativa. At the present time, camelina is not known as agricultural crop in practice. However, the crop can be grown under different climatic conditions using a low input and environmentally friendly cultivation without application of pesticides. Camelina oil is characterized by a high content of unsaturated fatty acids (about 90%). Iodine number of the oil is about 160. The mixed fuel was tested in a Farymann Diesel engine, run at constant optimum load of 4.00 kW with 3260 R/min. The engine was fuelled with pure diesel oil and two mixtures with camelina oil. Each fuel was tested by running the engine for 250 hr. Specific consumption of pure diesel oil was 271.6 g/kWh. When running the engine on the mixed fuel with 5% and 10% camelina oil, the specific consumption of fuel was 273.4 g/kWh and 277.1 g/kWh, respectively. Carbon deposits on the piston and combustion chamber, and the amounts of sood in the exhaust gas, were similar for all tested fuels. Carbon deposits on the injection nozzle were slightly increasing with increasing proportion of camelina oil in the mixed fuel. Independent on the fuel, after running for 250 hr, the function of the injectors was still within the norm for ordinary performance.