There is some question as to what actually occurs on injection. The patentees claim that the atomization at the nozzles, combined with the further breaking up of the fuel at the junction of the two streams in the combustion chamber, is sufficient to ignite the fuel at the temperature corresponding to 200 pounds compression, which would be in the neighborhood of 265° Fahrenheit. It must be conceded that the disturbance taking place when the oil streams meet will produce a thorough inter mingling of the air and fuel. This allows each minute globule of oil to be surrounded with air and undoubtedly contributes toward a very complete combustion if a flame be present. It does not appear that this would initiate the primary ignition. Another explanation has been offered which sounds logical.
Evidently the engine does depend on the absorption of heat from the combustion walls to assist the ignition since the engine will not fire the first few charges unaided. To start the engine a nickel-covered anode or resistance coil is used. A small dynamo supplies the current necessary to bring this coil to a red heat. On starting the engine, the electric current is thrown on to the element, and the oil charge is ignited exactly as in a hot-bulb low-compression engine. When the combustion chamber is thoroughly warmed the current flowing through the coil is dis continued, although the coil still remains in the combustion chamber. Quite likely the heat of combustion maintains it in a red-hot condition, although at a much lower temperature than when the electric current was flowing. It would appear that some heat other than that of compression is required. There also seems to be a second source of heat that might assist the „process.
The opening in the nozzle tip is about in diameter. If, in service, a fuel consumption of 16% h.p. per gallon is secured, and the engine operates at 200 r.p.m., then with a 100 h._p. engine the fuel consumed per minute would be or 23.1 cubic inches. At 200 r.p.m., operating on the four-stroke-cycle, the fuel per stroke would be .23 cubic inch per effective stroke. The injection does not cover more than 6 degrees; the injection of oil through the two atomizers is then at the rate of .02 cubic inch per degree of revolution or 1440 cubic inches per minute. The orifice at the nozzle tip is approxi mately y and the actual injection rate through the nozzle opening is at a linear velocity of 60,000 feet per minute. The weight of the injection charge is .0036 pound. When the two oil streams, issuing from the atomizers at this rate of speed, meet, it may be considered that all their velocity is destroyed and the energy developed by this impact appears as heat. The work
done would be IA MT' or 560 foot-pounds. The heat equivalent of 200 foot-pounds is 0.70 B.t.u. This heat is absorbed by the oil charge, which weighs .0036 pound, and is sufficient to raise the temperature of the oil charge some 400°. This tem perature increase added to that resulting from the compres sion is high enough to ignite the lighter hydrocarbons, which, in turn, ignite the heavy particles. The rate of flame propaga tion would be rapid since the oil stream is atomized in a very thorough manner.
'' Indicator Card. Price Engine.—Figure 240 is a card from this engine while Fig. 241 is a distorted card. The injection begins at 6 degrees ahead of dead-center and ceases at about 1; -de grees before dead-center.
One decidedly attractive feature of this engine is the high mechanical efficiency. This, in comparison with the efficiency of the Diesel engine, can be attributed mainly to the elimination of the air compressor, which usually absorbs from 7 to 10 per cent. of the engine's output.
Test on Price Engine.—Based on a series of tests conducted at the De La Vergne Machine Co. plant, before a committee of naval officials, on a 19X24 engine .using the Price injection system, the following report was submitted.
1. The fuel economy under favorable conditions was .395 pound per brake horsepower.
2. Fuel economies of .42 pound at full load could be maintained indefinitely.
3. The engine could be put in operation from a cold condition to full load at full speed in ten seconds.
4. Any fuel from 15-degree Mexican crude to light fuel oil could be used.
5. At all loads up to 20 per cent. overload the exhaust was invisible, and up to 30 per cent. overload the exhaust was tolerable.
6. A twenty-four-hour test, running full load ten minutes then stop ping five minutes, proved the engine to be safe against heat stresses, etc.
7. The engine could be stopped twenty minutes and started again without the assistance of the electrical igniter.
8. A mean pressure of 87 lbs. per sq. inch with respect to brake horsepower, which corresponds to approximately 100 lbs. per sq. inch mean effective pressure, was attained with clean exhaust.
9. The mechanical efficiency when operating above three-quarters load approximated 90 per cent.
Figure 242 presents the results of the test, showing the mechan ical efficiency and the fuel per brake horsepower. The fuel consumption compares favorably with the economies obtained from Diesels manufactured in the United States.