Influence of fuel type on working parameters of testing combustion micro-engine

The choice of appropriate additives to alternative type of fuels determines the basic problem related with diversification of fuels used to the internal-combustion engines. The research micro engine with swept volume of 165 mm3 and the rotational speed reaching 25000 rpm was fuelled with various liquid fuels of the methyl and ethyl alcohol base. To the alcohol, additives were added with various percentage compositions, such like castor oil and nitro methane. In the fuel system the mixer of fuel with air was applied, that permitted on supply with the liquid fuel, but the composition of the fuel-air mixture was controlled with the quantity of supplied air. Registered was the graph of compression pressure in mini combustion chamber, the maximum power and shaft output torque was measured with the different composition fuels supplied to engine. Research proved that not only alcohol type applied as fuel, but also above all percentage participation of additives to the fuels influenced most on the micro engine work parameters. For the same type of alcohol, but with the different additives, the maximum power and the maximum torque differed significantly. For the micro engine of this type, the best fuel was based on the methyl alcohol and has composition of 60% methanol as fuel, 15% nitro methane (CH3NO2) as fuel additive and 25% of lubricant - castor oil. Article presents the design of the power shaft output micro engine, tested fuels, exemplary graphs of compression pressures in mini chamber on the prototype of a miniature power shaft engine, graphs of the rotary torque and of the engine power of supplied with various fuels.