March, 1931
INDUSTRIAL AND ENGINEERING CHEMISTRY
and hard as the original sticks of electrode carbon, and may be shaped into spheres just as readily. BURNING THE PARTIcLEs-On burning particles of fuel having an appreciable ash content it was a t once evident that the accumulation of ash on the particle surface affects the rate of burning. The intermittent burning method of testing is therefore more difficult than for ash-free fuels. First, a comparison of results must be made between particles of identical initial dimensions. This does not apply t o ash-free fuels, because interpolation of the weight-time curves can be made between different particle sizes. The accumulation of ash on the surface of the particle prevents this in the former case. The technic illustrated by the following typical experiment has been used with seemingly satisfactory results, although sufficient data have not been obtained t o warrant any but the most general conclusions: A particle of initial weight 64 mg. was burned in three steps each of 30 seconds duration. After each step the ash was carefully removed before weighing the particle; therefore, a clean carbon surface was presented a t the beginning of each 30-second burning period. A second particle bf identical initial dimension was then burned for 60 seconds, and another for 90 seconds. Before weighing these particles after the burning period, the ash adhering to the surface was removed, so that the loss in weight during the burning interval represents carbon plus ash. On plotting these data, the weight-time and temperature-time curves appear as shown in Figure 15. DIsCuSsION-It will be seen, by comparing curves 1 and 2 in Figure 15, that accumulation of ash on the particle surface does slow down the rate of burning. It will also be observed that
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the surface temperature of the particle decreases with time instead of increasing as when a pure carbon particle burns. The nature of the ash accumulation will no doubt have an effect. For example, in the foregoing experiments with a fuel having a fusible ash (1190' C.) the ash accumulation consisted of very loosely packed, small sphere clusters of fused ash over the particle surface. There were numerous bare spaces between the ash spheres that still permitted burning to proceed a t a fairly rapid rate. When particles having a refractory ash (1600' C.) were burned, the ash was not fused, but adhered t o the surface as a dense blanket which slowed down the rate of combustion very materially in the latter stages. In fact, when a particle weighing 70 mg. was burned in one step to a point where it appeared to be completely consumed and only the ash husk remained, examination disclosed a considerable core of unburned carbon.
Literature Cited (1) Griffin, H. K.,Adams, J. R., and Smith, D . F . , IND. Ewc. CHEM.,21, 808 (1929). (2) Gudmundsen, Austin, "Mechanism of Combustion of Individual Particles of Solid Fuels," Thesis, Carnegie Institute of Technology, June, 1930. (3) Langmuir, Irving, J . Am. Chem. Soc., 37, 1154 (1915). (4) Reed, Donald, "Relative Flammability of Powdered Low-Temperature Coke and Coal," Thesis, Carnegie Institute of Technology, 1928. (5) Rhead, T.F. E., and Wheeler, R. V., J . Chcm. Soc., 97, 2178 (1910); 99, 1140 (1911); 101, 836, 846 (1912); 103, 461, 1210 (1913). (6) Thiele, E. W., and Haslam, R. T . , "Mechanism of the Steam-Carbon Reactions," Thesis, Massachusetts Institute of Technology, 1927.
Amount of Lubricating Oil Burned in the Gasoline Engine' Clarke C. Minter and Wm. J. Finn THETEXASCOYLPANY, BAYONNE, N. J.
INCE control of mixture ratio by exhaust-gas analysis a thinner film on the cylinder walls, with less accumulation has become quite common, a question often arises on the top of the piston. The relation between viscosity and regarding the error introduced into the calculations the amount of burning obviously cannot be applied to oil 3 by the combustion of an unknown amount of lubricating oil. on account of its gasoline content. That this error is not large is obvious when the ratio of oil Carbon Dioxide in Exhaust Using Hydrogen as Fuel consumed to gasoline consumed is considered, but it is PROPERTIES OF LUBRICATIIG clear also that all the oil consumed is not burned. Since COMPOSITION O F EXHA-CST OILS no data have ever been published showing how much oil OIL H?in excess Air in excess Viscosity actually undergoes combustion in the engine, the writers :;$,' Flash Saybolt 100" F. coz 0 2 COZ 0 2 at settled the point for the conditions of their experiments by running an engine on hydrogen and determining the amount F. Sec. % % % % of carbon dioxide in the exhaust gas. 0.1 0.1 0.3 10.2 0.9242 460 1178 0.1 0.2 0.3 3.7 Commercial electrolytic hydrogen was used in the experi0.0 0.2 6.0 0.1 0.5 3.4 ment. It was found by analysis that carbon dioxide and carbon monoxide were not present, The manufacturers 0.0 0.1 0.2 5.4 0.9340 370 318 0.0 0.0 0.2 4.5 state that very slight traces of hydrocarbons might be present 0.2 0.1 0.1 5.8 0.1 0.0 6.0 0.2 owing to the breaking down of lubricating oil in the com0.3 5.7 0.0 0.0 pressors. 0.2 5,s The hydrogen was led into the intake pipe of a single0.8 3.2 0.9160' 245 937 0 4 4.2 cylinder research engine, which was free from carbon deposits. The engine was lightly loaded and run a t 600 r. p. m. with a a Iso-Vis, contained 10 to 12 per cent of heavy ends of gasoline. spark advance of 22 degrees. The cooling water was kept at 100' C . The fresh oil was put in the cleaned crankcase It was observed that the temperature of the exhaust when of the engine and run on hydrogen until the engine and oil running the engine on hydrogen was about 100' C. lower than attained normal operating temperatures. The exhaust gas when operating on gasoline under approximately the same sample was sampled and analyzed in an Orsat apparatus. conditions. For this reason it is possible that slightly more The results for several ratios of hydrogen to air are shown lubricating oil would be burned when operating on gasoline in the accompanying table. because the oil film in the cylinder would be exposed to A negligible quantity of oil appears to be burned when hy- higher temperatures. drogen is in excess. An oil of low viscosity shows less burning These conclusions obviously should not be applied a t much than an oil of high viscosity, doubtless because less of the higher engine speeds, where the oil consumption sometimes former gets into the cylinders on account of the formation of increases greatly with a possible increase in the amount of oil burned. 1 Received October 22, 1930.
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