Abstract

JAWUREK, H. H.. Improving the performance of biogas fuelled SI engines for rural use. R&D j. (Matieland, Online) [online]. 1990, vol.6, pp.1-7. ISSN 2309-8988.

Performance and combustion characteristics of a portable engine-alternator set fuelled with stimulated biogases are presented. It is shown that optimisation of the ignition timing can lead to substantial increases in maximum power. Thus for a gas of composition 70% CH₄/30% CO₂ the advancement of ignition from its original value of 14° before TDC (fixed, intended for petrolfuelling) to 29° before TDC results in an 11% increase in maximum power. With a gas of 45% CO2 content the corresponding figures are 30% and 32°. Increasing the compression ratio (CR) from its original value of 6,4 to the region of 7 to 8 leads to a 3% increase in maximum power. Further raising of the CR results in decreased output. Supplementation of biogas fuels with petrol is very effective in combating the poor combustion, harsh running and low power output that are obtained with gases of high CO₂ content. Such dual fuelling is beneficial with biogases of all qualities and at all gas/petrol ratios, but particularly so with small quantities of petrol and very poor gases.

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