A Numerical Investigation of the Effect of Throttle Plate Angle Variation in CNG Carburetors on Emissions and Power Efficiency of Small-Scaled CNG Engines: A Parametric Study for Design Optimization

Abstract The 2018 world air quality report ranked Nigeria first among African countries with the worst particulate matter pollution, highlighting the need to design more efficient carburetion systems for mixing air and fuel in Internal Combustion Engines. This paper rigorously studies the effect of air-fuel ratio and Inlet pressure on the emission characteristics and power efficiency of compressed Natural Gas generators using computational fluid dynamics techniques with ANSYS. A simplified model of the carburetor is designed using SolidWorks in order to aid the conducting of a 3D simulation. Using ANSYS Species transport and Turbulent Model to incorporate the mixing and turbulent behavior of the fluid flow, the air fuel mixture is analyzed to study pressure drop, fuel concentrations and potential regions of poor mixing. Previous studies have shown that power efficiency improves with uniform air fuel mixing and decreases with higher pressure drop which increases the engine's workload and reduces the overall efficiency. Building on this, this study examines the effect of throttle plate angle variation which controls the air fuel ratio and pressure drop on emission and power efficiency, while proposing a cost effective and user-friendly carburetor system that allows users with lesser sophisticated knowledge to make adjustments to the throttle plate angle optimally. This work has the potential to contribute significantly to reducing generator-related emissions in Nigeria while advancing sustainable energy production.