Conversion of Turbocharged Internal Combustion Engine to Gaseous Fuel Used in Agricultural Machinery

Abstract

Abstract This study focuses on the conversion of a turbocharged compression-ignition (diesel) engine UR-II 8602.12, originally installed in the Zetor 16145 tractor, into a spark-ignition (gas) unit operating on gaseous fuel. The study presents experimental results of performance, fuel economy, and emission characteristics under full-load speed sweep as well as part-load operation. The converted engine achieved a maximum corrected power output of 106.5 kW at 2200 rpm, representing an 8.5% reduction relative to the original diesel engine (116.5 kW). The corrected peak torque reached 462 N·m, which is 21% lower than the baseline diesel torque of 583 N·m. From an environmental perspective, carbon monoxide emissions remained very low (~0.05 vol. %), while hydrocarbon concentrations decreased with increasing mixture enrichment (from 377 ppm to 245 ppm). However, nitrogen oxides (NOx) exceeded the threshold of 500 ppm across the entire speed range, peaking at 2282 ppm at the maximum speed. Exhaust gas temperatures behind the turbine reached up to 650 °C, which, after accounting for thermal gradient, implies that the recommended limit of 630 °C at exhaust valves is exceeded at higher loads. The findings demonstrate that natural gas conversion can retain favourable power characteristics while lowering carbon-based emissions, yet further optimisation is required to control thermal stress and mitigate NOx formation.