Comparative engine testing of Bio-CNG and Gasoline: Performance and emission impacts in a 175 CC engine

Abstract

Bio-CNG has emerged as a potential replacement for conventional fossil fuels used in road vehicles, a major source of global air pollution. This research aimed to perform comparative performance and emission analysis under various conditions to observe its viability. A Bajaj, 175 CC powered gasoline, 4-stroke, and carbureted engine was chosen and converted to the bi-fuel system that operates either with gasoline or bio-CNG using an electronically controlled solenoid valve. The engine power and traction forces were measured under the road's 0^o, 4^o, and 8^o inclination at no load and 5kW load coefficients. Vehicle exhaust emission levels (CO, CO₂, HC, and lambda) were measured at the idle rpm of the engine (1240 RPM for petrol and 1022 RPM for bio-CNG). The experimental data from the chassis dynamometer revealed significant reductions in power and traction force under various conditions. Furthermore, emissions analysis from exhaust gas analyzer showed remarkable reductions of 98% for CO and 89% for HC, but there was a 16.67% increase in CO2 levels. This research provides insights into the potential benefits and challenges of bio-CNG conversion for small-engine vehicles and suggests possible measures to improve the performance of converted vehicles.