Performance Optimization of Compression Ignition Engine Fueled By Ternary Blends of Diesel, Biodiesel, and Propanol

Abstract

Compression ignition (CI) engines are widely used all over the world and are associated with higher fuel conversion efficiency, power output, torque output, durability, and reliability over spark ignition (SI) engines. However, there is the rapid depletion of fossil fuel reserves which has necessitated a search for alternative fuels for CI engines. Consequently, the main objective of this study was to optimize the performance of compression ignition engines fueled by ternary blends of diesel, biodiesel and propanol. The study’s specific objectives included the production of ternary blends, investigation of engine performance under varying blend concentrations and determination of the optimal blend concentration that minimizes emissions of pollutant gases. In this study, biodiesel was produced from waste vegetable oil through trans-esterification process and was blended with commercial diesel and propanol in ratios of 0% to 25%, 75% to 100% and 0% to 5%, respectively. The physical parameters of the ternary blends, such as density and viscosity, were determined and blends were used to run a 16.8-kilowatt Petter's two-cylinder engine running at a constant engine speed of 2000 rpm and brake power of 10 kilowatts. The desirability technique was used to determine the optimal values, which included minimizing nitrogen oxide (NOx), hydrogen oxide (HC), and carbon monoxide (CO) emissions while maximizing brake thermal efficiency (BTE). Using design expert software, the experiment was carried out via the response surface method (RSM). Responses included brake thermal efficiency, brake specific fuel consumption (BSFC), emissions of nitrogen oxide, hydrogen oxide, and carbon monoxide, and the variables were blended from diesel, biodiesel, and propanol. Gas emissions from the optimal blend were measured using exhaust gas detectors. Five solutions with desirability ranging from 0.667% to 0.828% were discovered. They each had unique blend proportions and responses. The optimal combination with 0.828 desirability was deemed the best. The blend of 75.01%, 24.604%, and 0.386% was found to be optimal, with responses of BTE 63.001%, BSFC 0.153kg/kWh, and emissions of NOx 82.347 ppm, CO 436.013 ppm, and HC 4.877 ppm, and physical properties of 0.972 g/cm3 density and viscosity of 4.363 cP. BTE increased by 9% when compared to pure diesel with a density of 0.96 g/cm3 and a viscosity of 6 cP, while BSFC, NOx, CO, and HC decreased by 15%, 12.87%, 15.23%, and 75%, respectively. Different blends have different physical attributes, like density and viscosity, which affected engine performance. There was no direct relationship between the two properties. No phase separation was observed in the blends. Based on the results, the optimal ternary blend of diesel, biodiesel, and propanol is recommended for internal combustion engines due to notable improvements in engine performance and reduced emissions. Additionally, we recommend that future studies investigate the long-term effects of using ternary fuel blends on engine components. This could be done by conducting durability tests and monitoring emissions over extended periods of use. In addition, we recommend that future research also investigate the possibility of using other biofuels such as bioethanol or biogasoline in the ternary blend, to see if they could also improve engine performance, emissions, and fuel consumption. However, further research is required to establish the life span of the optimal blend and to determine if its efficiency decreases over time.