From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Technical article from 'The Motor Trader' magazine comparing paraffin and petrol as fuel, detailing various vaporizers and starting systems.
| Identifier | ExFiles\Box 32\1\ Scan037 | |
| Date | 12th July 1916 | |
| THE MOTOR TRADER Paraffin v.{VIENNA} Petrol for Fuel.—II.* "Dry" Mixture Vaporizers. The characteristic of this system [unreadable] evaporates [unreadable] in contact with [unreadable] exhaust gases, and the mixture passes through a long [unreadable] to the cylinders. The mixture passage serves as a heater to the [unreadable] mixture. [unreadable] vaporizers [unreadable] a paraffin mixture is [unreadable] more [unreadable] than a gas-based [unreadable]. The paraffin, in fact, never is perfectly vaporized, [unreadable] the larger quantity of a vaporizer’s distribution system. When the heat is cut off, the heavy globules of paraffin [unreadable] deposit in the vaporizing chamber, and when the throttle is opened suddenly these may be drawn into the cylinders. [unreadable] in the Crossley-type large-bore motors it would be so serious as only a small and fixed amount of heat was available for the vaporizing chamber of any pattern. Another objection is that the path to the oil drain is obstructed [unreadable] extra to the old ideas of the pre-heated mixture, [unreadable] in the light of better knowledge, that the incoming mixture [unreadable] be observed that the mixture temperature, that is to say, must be that which is accomplished by using the minimum heat necessary [unreadable] is to secure this result without super-heating. [unreadable] exhaust gases, and the passage itself should be of such shape and size as will facilitate this concentration without undue throttling or back pressure on the exhaust. It is necessary, also, that the intake ports of the cylinders be as little as possible a source of heat loss to the incoming gas. Venturi Tube Vaporizers. As means to the end, the author appears to favour an adaptation of the Venturi tube, familiar to users of American carburetters for petrol vaporizing. Fig. 2 shows a section of this sort for vaporizing paraffin by exhaust heat. The merit of this lay-out in contrast with a series of baffles is the high velocity of the flow, due to the constricted throat of the Venturi tube. Fig. 3 illustrates an engine fitted with a Venturi shaped intake manifold. The details of the starting layout for such an apparatus are shown in the picture on the right. They will be seen to include an electric burner or pre-heater and a modified Roots blower for spraying the paraffin mixture. A direct start from paraffin is the aim of the new apparatus, which obviously suggests an advantage over systems requiring at least a supply of petrol for starting, and, as seen in a recent apparatus on the British markets, for taking up the drive at low engine speeds by means of an automatic shunt valve operated in conjunction with the main throttle. The author points out that electric heated vaporizers make a big demand on storage batteries, but there is a newer method of effecting the same purpose. It is known as the "Good," after the inventor, a resident in Brooklyn, N. York, and is described as a semi-automatic burner. It is said, also, to have been proved "thoroughly reliable." The details are shown in Fig. 4, and as fitted to an engine in Fig. 3, the burner is placed at the end of the intake header, and its flame passes along the inside of a small steel tube, inside and close to the bottom of the header. The burner flame raises this interior tube to a red heat in about fifteen seconds, the products of combustion passing out the end and downward to a point a little short of where the flame ever appears at the outlet. The good quality of combustion and the shortness and intensity of the flame are indicated by an analysis of the products, which showed only 2% of free oxygen and zero carbon monoxide. The "Good" Paraffin Starting Vaporizer. The construction of the burner is shown in the composite section view (Fig. 4). The vertical oil nozzle, fed from a float-chamber, is crossed horizontally by a jet of air, at about 1lb. pressure, produced by the smallest size of Wing blower. This detail is shown also beside the main section in Fig. 3. The crossing air jet makes a fine spray of oil which moves past the spark points where it is ignited automatically by the magneto geared to the Wing blower. The spark points are arranged as shown in the right-hand section view in Fig. 4, with the terminals bent up and toward each other. This causes the oil drops that collect to fall away to the lower loops by gravity, leaving the tips free to spark; before this was done the ignition was bad, but afterward it never failed in over a year. The spray flame escapes through an enlarged air chamber, supplying air around the spray to support the combustion, which becomes vigorous only beyond the radial guide vanes at the exit from the burner or at the entrance to the heating tube, tightly fastened to it. The air for supporting combustion is supplied by a small fan through a flexible metal tube, the fan being geared to a Wing blower and driven by the ignition magneto. It is stated that a turn of the shaft suffices to start the burner which continues alight as long as the engine is being run. Fig. 5 illustrates a self-contained apparatus of this sort, operated by a hand crank. It comprises a magneto and a Wing blower and fan, and measures about 7in. overall length, and 6in. height. Regarding the starting of an engine with this apparatus, the author says: "There is no trouble more than with gasoline except a slight starting lag, measured in seconds, due to the necessity for letting the starting burner develop the necessary starting heat. The engine idles and accelerates just as well as with gasoline; there is no smoke or carbon accumulation, and the operator would never know he was using kerosene, and is more independent of cold weather than with gasoline as now used." "With hand-cranking the burner gear may be rotated by the starting handle a few times before engaging the engine shaft; then pressing in the handle to pick up the engine, it will start promptly. It is desirable, although not necessary, that the burner be continued in operation a few minutes after the engine is started, and until the interior and the exhaust connections warm up." H.{Arthur M. Hanbury - Head Complaints} B. Agents' Section, Ltd. We append the following brief notes on new members of the Agents' Section, Ltd. :— P. Dyer and Sons, City Road, Cardiff.—Established 1875. Motor body builders, etc. John Peden & Co., Bank Street and John Finnie Street, Kilmarnock.—Established 1826. Specialists in motor body building in all branches. All repairs carried out on own premises. Patrick Hennessy, Castledermot, Co. Kildare, Ireland.—Established 1904. Maxwell agency. H.{Arthur M. Hanbury - Head Complaints} Cartwright, Wyvern Motor Works, Applegate Street, Leicester.—Established 1899. Specializes in repairs of every description on chassis or body work. Robt. McMurray, Hall Street, Ballybay, Co. Monaghan, Ireland.—Established 1908. B.S.A., Overland, and Ford agencies. Stocks tyres, petrol, oil, grease, and all accessories, and does vulcanizing, accumulator charging, and all repairs on the premises. Image Captions: 2.--Float Carburettor with Venturi tube Vaporizer. 3.--Engine Adapted for Direct Starting on Paraffin. 4.--Details of the "Good" Direct Paraffin Starting Burner. 5.--The "Good" Direct Paraffin Starting Apparatus. | ||