Liquid petroleum gas as automotive fuel in South Africa

Van der Ham, Gert A. (2001-12)

Thesis (MEng)--University of Stellenbosch, 2001.

Thesis

ENGLISH ABSTRACT: The trends in worldwide fuel consumption and availability were studied, these indicated a bigger 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 compared with those of petrol and diesel fuels. The government's approach to LPG taxation and the structure of the fuel price was also considered 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. The information obtained from the background study was used to help in the conversion of a two litre petrol engine. The engine was equipped to run on petrol Injection, liquid phase LPG injection and LPG carburettion. In-cylinder pressures, exhaust emissions and fuel consumption were amongst the parameters that were recorded for each fuel. The in-cylinder pressure measurements were used to study the combustion characteristics of petrol and LPG. Computer modeling was also used to investigate the trends that were recorded and this gave valuable insight into the different combustion characteristics of each fuel and the effect of gaseous versus liquid supply. For the passenger bus market a 12 litre 6 cylinder diesel engine was converted to LPG operation only. This required several changes to the pistons, cylinder head, inlet manifold and the addition of an electronic ignition system. Some changes had to be made to the squish characteristics of the pistons to make it suitable for homogeneous fuel air mixtures. The reasons for this were studied and described. Dynamometer tests revealed inadequacies in the ignition system 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, so as to improve public transport and air quality in some of our cities.

AFRIKAANSE OPSOMMING: 'n Studie van tendense in wêreldwye energieverbruik en besikbaarheid is gedoen. Dit het aan die lig gebring dat die groei in die gebruik van gasagtige brandstowwe in die laaste dekade die van ru-olie oortref het. Die lewensvatbaarheid van Vloeibare Petroleum Gas (VPG) voertuie, ombouing sowel as lopende koste, is bestudeer en vergelyk met die van Petrol en Diesel voertuie. Die regering se benadering tot belasting op VPG en die struktuur van die brandstofprys is ook ondersoek om te bepaal of die gebruik van VPG in n groter skaal as tans lewenvatbaar is. Vir tegniese agergrond is gas aangedrewe voertuie wêreldwyd bestudeer om te sien watter brandstof-voorsiening stelsels en enjins gebruik word. Die verskillende stelsels word bondig beskryf. Hierdie inligting is onder meer gebruik in die ombouing van n twee liter petrolenjin na VPG. Die enjin is toegerus om op beide petrol en VPG te loop terwyl die VPG in gasfase met behulp van 'n vergasser of as vloestof deur brandstof inspuiting toegedien kon word. Ontbrandingskamerdruk, uitlaatgasse en brandstofverbruik is van die parameters wat tydens toetse gemeet is. Die ontbrandingskamerdukmetings is gebruik om die verbrandingskarakteristieke van elke brandstof te bepaal. Nagebootste verbrandingstempos is in n rekeraarprogram gebruik om verskillende verbrandings karakteristieke wat gemeet is te ondersoek en tendense te bevestig. Vir die swaarvoertuigmark is 'n 12 Liter diesel enjin ombebou na VPG gebruik. Die dieselpomp en inspuiters is vervang met elektroniese vonkontsteking en vonkproppe. Die verbrandingskamer moes verander word om spontane verbranding tydens samepersing te voorkom. Die redes hiervoor is ondersoek en beskryf. Dinamo toetse het tekortkominge uitgewys in die elektroniese vonkontstekingsstelsel wat nog nie ten volle aangespreek is nie. Aanbevelings is gemaak om die toenemende gebruik van VPG as motorvoertuigbrandstof in Suid Afrika aan te bevorder om sodoende beter gebruik te maak van die beskikbare energie uit ru olie en ander bronne. Aanbevelings is ook gemaak ten opsigte van die gebruik van VPG in openbare vervoer en verbetering van lug gehalte in sommige stede.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/52324
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