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Progress with Injection-ignition Producer-gas Conversions

2nd April 1943, Page 19
2nd April 1943
Page 19
Page 19, 2nd April 1943 — Progress with Injection-ignition Producer-gas Conversions
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RESEARCH work in connection with the conversion of compression-ignition engines to producer gas, retaining the fuel-injection system, is now being conducted by the I.A.E., as we announced in our issue dated March 12.

Among the first tests were investigations into the injection timing and the quantities of liquid fuel required. A brief account of the results obtained in these respects was included in the announcement referred to above. Since then brief details of later tests have been released, by the Research Department of the Institution, and these relate to the matter of gas and air proportioning. • Various Gas Mixing Valves Readings were taken with independent control of gas and air throttles, with the Zenith Mark V valve and " Glasgow " manifold, with the " Glasgow " gas 'mixer and with the I.A.E. mixer. In addition, trials were made with only oil fuel to obtain standard readings.

With independent air and gas control a performance was obtained that was little inferior to that on only oil fuel. Air settings to give the best results at specific speeds were used in the trials with the Zenith valve, and by this means outputs nearly as good as with independent control were recorded at certain of these specific speeds but not all of them and not at other speeds.

The "Glasgow " valve gave readings of similar ,character, and neither this nor the Zenith were satisfactory at maximum r.p.m.

Best results were obtained with the I.A.E. device, From 1,000 r.p.m. to 1,500 r.p.m. the figures are only just short of those on oil, whilst at 1,750 a b.m.e.p of 86.6 was recorded as against 78.2 with liquid fuel. This former figure was obtained with a gas having a calorific value of 130 B.Th.U., whilst with gas of 118 E.Th.U, it was as high as 77.5.

Whilst the compression-ignition engine running on only oil, is controlled by quantity of fuel, the air induced being always the maximum, the producer-gas engine is controlled by regulating the quantity. of mixture. Accordingly a problem, which at first eight is rather baffling, arises when the two systems are combined.

This matter of proportioning the airgas mixture, therefore, is obviously different from what it is in the case of the converted petrol engine. From the trials, certain facts have already appeared in this connection, notably that, under conditions of part load, it is undesirable to throttle the air flow so that the quantity is reduced below • that giving maximum purser at full load.

There is, apparently, a considerable measure of quality control. So far as enginerunning is concerned, the gas supply can be cut down and, the mixture rendered weaker without smoke or misfiring, but this practice results in the flow through the producer being. reduced and, in consequence, good gas soon ceases to be supplied. This constitutes a limiting factor at the lower end of the scale.

With regard to the Zenith mixing valve, it was hoped that this would

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Organisations: Research Department

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