Isobutanol - An alternative biofuel for hand-held petrol products

Abstract: Pollution and environmental concerns require further improvements in engine technologyas well as research of alternative fuels. Users of handheld products are directlyexposed to the exhaust gas and thus to the occurring emissions, which cancause significant damage. Pursuing to reduce emissions is therefore a vital task.The European commission proposed a renewable energy directive, that claims abiofuel share of at least 6,8% by 2030 and a reduction of first generation fuel butan increasing of second generation fuels. Ethanol is up to now the most commonsource of renewable alternatives in gasoline blends. Isobutanol has several advantagesover ethanol and can be produced as a second generation biofuel.This thesis aims to get a better understanding on how isobutanol influences theemission and combustion in small two-stroke engines and furthermore what effectdifferent isobutanol blends with neat gasoline and alkylate have on the engine performance.Different isobutanol blends with neat gasoline as well as alkylate fuel have beenused and analyzed.This thesis has via an experimental study shown, that hydrocarbon as well as carbonmonoxide emission increased with increasing isobutanol percentage. Hence, nitrogenoxides emission decreased with isobutanol. Lower cylinder and exhaust temperatureswere measured with isobutanol blends. Through cylinder pressure measurements,the mass fraction burned, mass fraction burned 50% and rapid burningangle could be analyzed. It has shown that isobutanol blends reach a mass fractionburned of 50% slightly later and have a greater rapid burning angle.