Theoretical and experimental investigation of SI engine performance and exhaust emissions using ethanol-gasoline blended fuels

In this study, potato waste bioethanol was evaluated as an alternative fuel for gasoline engines. The pollutant emissions and performance of a four stroke SI engine operating on ethanol-gasoline blends has been investigated experimentally and theoretically. In the theoretical study, a quasi-dimensional SI engine cycle model has been adapted for spark ignition engines running on gasoline-ethanol blends. A mathematical model using Matlab software was developed using the first law of thermodynamics and conservation equations to predict the SI engine performance for different blend ratios. The model was also used to evaluate the engine emissions and the mechanical and heat losses in the engine which is not included in this study. Experiments were performed with the blends containing 5, 10, 15 and 20 vol% ethanol. The results show that increasing ethanol-gasoline blended will marginally increase the power and torque output of the engine. For ethanol blends it was found that the brake specific fuel consumption (bsfc) was decreased using 5% and 10% ethanol while the brake thermal efficiency and the volumetric efficiency were increased. Exhaust gas emissions were measured and analyzed for unburned hydrocarbons (UHC), carbon dioxide (CO2), carbon monoxide (CO), Oxygen (O2) and Oxide of Nitrogen NOx at engine speeds ranging from 1000 to 5000 rpm. The concentration of CO and UHC emissions in the exhaust pipe were found to be decreased when ethanol blends were introduced. The concentration of CO2 and NOx was found to be increased when ethanol is introduced. Results obtained from both theoretical and experimental studies were compared. The simulation results have been validated against data from experiments and it results to a good agreement between the trends in the predicted and experimental results.