Liquid petroleum gas as automotive fuel in South Africa

[摘要] ENGLISH ABSTRACT:The trends in worldwide fuel consumption and availability were studied, these indicated abigger growth in gaseous fuel use than that of crude oil over the last decade.The economics (cost of converting and running vehicles on LPG) were studied and comparedwith those of petrol and diesel fuels.The government's approach to LPG taxation and the structure of the fuel price was alsoconsidered in an attempt to foresee what the future holds for LPG use in the motor industry.Gas fuelling systems that are currently available were studied and briefly described. Theinformation obtained from the background study was used to help in the conversion of a twolitre petrol engine. The engine was equipped to run on petrol Injection, liquid phase LPGinjection and LPG carburettion. In-cylinder pressures, exhaust emissions and fuel consumptionwere amongst the parameters that were recorded for each fuel. The in-cylinder pressuremeasurements were used to study the combustion characteristics of petrol and LPG. Computermodeling was also used to investigate the trends that were recorded and this gave valuableinsight into the different combustion characteristics of each fuel and the effect of gaseous versusliquid supply.For the passenger bus market a 12 litre 6 cylinder diesel engine was converted to LPG operationonly. This required several changes to the pistons, cylinder head, inlet manifold and theaddition of an electronic ignition system. Some changes had to be made to the squishcharacteristics of the pistons to make it suitable for homogeneous fuel air mixtures. The reasonsfor this were studied and described. Dynamometer tests revealed inadequacies in the ignitionsystem that still need to be addressed before the engine can be built into a bus.Recommendations are made as to best utilize LPG in the South African Automotive industry, soas to improve public transport and air quality in some of our cities.

[发布机构] Stellenbosch University