Division of Information Technology, Engineering and the Environment
School of Advanced Manufacturing and Mechanical Engineering
School of Advanced Manufacturing and Mechanical Engineering
Thesis Abstract
Current trend shows that bio-diesel has high potential as an alternative fuel for internal combustion engine to support depleting petroleum based fuel resources. However, bio-diesel has lower calorific value and higher viscosity as compared to ordinary fuel. Lower calorific value means the energy contain in the bio-diesel is less than energy contain in ordinary fuel and therefore it consumes more fuel for the same power produce by diesel when using in Compression Ignition (CI) engine. Pushing the fuel rack further is the main solution for this problem but unfortunately it already reaches its limit. Alternatively, an additive is added into the fuel to increase the calorific value of bio-diesel. Higher viscosity of the bio-diesel indicates that the molecules are less prone to evaporation since is heavier than diesel. Because of that, these heavier molecules cannot burn in normal combustion process with current injection system and swirl present in the combustion chamber. Therefore, the engine will experience in reduction of combustion efficiency and increase carbon deposits inside the combustion chamber. Increasing the in-cylinder swirl shows a good potential to solve the problem of heavier molecules. The swirl flow will be used to break up the heavier molecules and mixed these molecules with air and also kept the fuels away from cool region of combustion chamber. Based on that potential, this project will investigate the effects of Guide Vane Swirl and Tumble Device (GVSTD) to the performance of naturally aspirated CI engine. The basic model of GVSTD consists of simple fins imposed inside intake system. Through computer simulations, the results of air flow characteristics are compared with ordinary intake system. Number of blades are varied to generate more swirl but compromised with the pressure drop along the intake system. The angles of GVSTD are also varied to observe the best managed velocity swirling vector. Different length of blades is tested to examine the tumble effects. Other parameters such as depth and contour of the blade also varied to optimize the design of GVSTD to improve in-cylinder air motion. Based on the results of the simulation, the model of GVSTD will be fabricated. Experiments on the effect of the GVSTD will be performed on CI engine for diesel and bio-diesel. The results of the experiments will be analysed and from that a conclusion will be derived.
