Modeling of a Liquid Phase LPG Fuel Injection System Development

Liquid phase Liquid Petroleum Gas (LPG) is a developing alternative fuel system for engines which can provide the emission benefits of LPG and the power of a gasoline engine. LPG is traditionally used in the gas phase, but has limited power and emission benefits when used this way. Modeling the fuel system is a necessary method to predict and analyze the state of the fuel to ensure the fuel is in the proper phase during fuel injection. LPG fuel used in the liquid phase is much more sensitive to vapourization than typical liquid fuels, such as ethanol, gasoline, or diesel. Previous fuel system models using isothermal assumptions are unsuitable because of this. New dynamic and steady state models were developed using thermodynamic fluids instead. The new models predict both the thermal and pressure behavior of liquid phase LPG fuel systems. Separate model components were constructed for each component in the fuel system to allow them to be used as design tools. A series of experiments were conducted to verify the accuracy of the models and to investigate the causes of different fuel pressure fluctuations. The work presented was conduced as a research project at Dalhousie University.