Abstract

VAN DER WALT, N. R.  and  RALLIS, C. J.. Waste Heat Recovery in SI Engines by the Dissociation of Methanol Fuel. R&D j. (Matieland, Online) [online]. 1990, vol.6, pp.8-12. ISSN 2309-8988.

Methanol is the most likely replacement for petroleum as a liquid fuel for automotive engines. By using the thermal energy of the engine coolant and exhaust gases to dissociate methanol into hydrogen and carbon monoxide, regeneration can be achieved. A single cylinder SI engine was instrumented to investigate this technique. Dissociation was simulated by fuelling the engine simultaneously with dissociated methanol from a gas cylinder and liquid methanol. Improvements in efficiency of up to 27% over normal throttled operation on methanol were achieved. The proportion of dissociated methanol in the fuel which gave maximum efficiency varied from 100% at no load to 40% at maximum power. Analysis of combustion chamber pressure data showed that the addition of dissociated methanol significantly increases the rate of combustion and limits of flammability of methanol. The use of a small dissociator which always operates at maximum capacity is recommended as the best compromise between engine efficiency and cost.

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