Research of a Diesel-to-Gas Converted Engine Operating on Propane–Butane

Abstract

Gas engines represent a promising direction in the development of modern transport due to the combination of high environmental performance and economic feasibility of their use. Gaseous fuels provide more complete and uniform combustion, which contributes to the reduction of harmful emissions, improvement of engine performance characteristics, decrease in operating costs, and extension of the service life of power units. Propane–butane has a number of advantages over natural gas when used in automotive applications. An analysis of its physicochemical properties indicates high values of the calorific value both of the fuel itself and of the fuel–air mixture, while its octane number is only slightly lower than that of natural gas. The D-243 diesel engine was converted into a spark-ignition gas engine designed to operate on propane–butane using the same technology as for natural gas conversion. However, the compression ratio was reduced to 11. Bench tests of the converted gas engine confirmed its operability. The power output of the gas engine remains at the level of the base diesel engine, while the hourly fuel consumption is slightly higher due to operation with richer air–fuel mixtures. Emissions of carbon monoxide and hydrocarbons are somewhat higher; however, soot is absent in the exhaust gases. Therefore, the overall toxicity of the exhaust gases of the gas engine is lower compared to that of the diesel engine. When switching to gaseous fuel, the costs of fuel and lubricants are reduced by nearly two times. The payback period for the conversion ranges from 9 to 16 months. Under these conditions, it is more advisable to convert automotive and agricultural machinery to operate on propane–butane, as its cost is lower compared to natural gas, the conversion expenses are also lower, and there is no reduction in the vehicle’s payload capacity.