Investigation of engine performance and exhaust gas emissions by using bio-diesel in compression ignition engine and optimisation of bio-diesel production from feedstock by using response surface methodology

摘要

Bio-diesel, derived from the transesterification of vegetable oils or animal fats with simple alcohols, has attracted more and more attention recently. As a cleaner burning diesel alternative, bio-diesel claims to have many attractive features including: biodegradability, nontoxicity, renewability and low emission profiles. Free fatty acid (FFA) esterification and triglyceride (TG) transesterification with low alcohols molar ratio are the central reactions for the bio-diesel production. This study presents an experimental investigation into the effects of running biodiesel fuel and its blends on conventional diesel engines. Bio-fuels provide a way to produce fuels without redesigning any of the engine technology present today, yet allowing for green house emissions to decrease. Bio-diesel is one of these types of emerging bio-fuels, which has an immediate alternative fuel, while providing a decrease in green house gas emissions, as well as a solution to recycling used Waste Vegetable Oils which are otherwise disposed. This study shows how by blending bio-diesel with petroleum diesel at intervals of B5, B10, B15, and B20 decrease green house gas emissions significantly while maintaining similar performance output and efficiency with respect to 100% petroleum diesel. The focus of this research is to optimize the biodiesel production from crude sunflower oil. The effect of variables including methanol/oil molar ratio, NaOH catalyst concentration, reaction time, reaction temperature, and rate of mixing on the bio-diesel yield was examined and optimized by response surface methodology (RSM). Besides, a second-order model was deduced to predict the biodiesel yield. Confirmation experiment was further conducted, validating the efficacy of the model. Transesterification of sunflower oil was carried out using low molecular weight alcohols and sodium hydroxide. For sunflower oil, a central composite design with eight factorial, six center and six axial points was used to study the effect of catalyst concentration, molar ratio of methanol to sunflower oil and reaction temperature on percentage yield of the biodiesel. Catalyst concentration and molar ratio of methanol to sunflower oil were the most influential variables affecting percentage conversion and percentage initial absorbance. Maximum percentage yield of 95 % is predicted at a catalyst concentration of 1.1 % (wt/wt) and methanol to sunflower oil molar ratio of 6.8:1 at reaction time of 66 min and temperature of 35°C. In general, the sunflower oil biodiesel exhibited friendly environmental benefits and acceptable stability, demonstrating its feasibility as an alternative fuel.