FLAMELESS COMBUSTION.^ 



By Carleton Ellis, Montclair, N. J. 



[With 1 plate.] 

 I. INTRODUCTION. 



The problem of the influence of hot surfaces upon gaseous com- 

 bustion is one which, from a purely scientific standpoint, has engaged, 

 for many years past, the attention of Prof. William A. Bone, of 

 Leeds University and the Imperial College, London ; and as his recent 

 work has been the direct outcome of earlier scientific investigation, 

 it will be appropriate, by way of introduction, to review briefly the 

 present position of science with respect to this important subject, as 

 stated by Prof. Bone. 



One may perhaps best arrive at an understanding of the term 

 '' flameless " or " surface '■ combustion by considering certain facts 

 which differentiate it from the more familiar processes of combustion 

 as they occur in ordinary flames. All hot surfaces have an accelerat- 

 ing influence upon chemical changes in gaseous systems. If, at any 

 temperature, a gaseous system, A, tends to pass over into another 

 system, B, contact with a solid at the same temperature will accelerate 

 the process. 



To take a very simple example, if a mixture of hydrogen and 

 oxygen in their combining proportions (electrolytic gas) were main- 

 tained in an inclosure with smooth glass walls at a temperature of, 

 say, 450° C, there would certainly be a tendency to form steam, but 

 the rate of change would be negligibly small. If, however, there 

 were brought into the system some porous solid material at the same 

 temperature, so that a large surface was exposed to the gases, the 

 rate of change would at once be rapidly accelerated in the layer of 

 gas immediately in contact Avith the hot surface. Steam, the product, 

 would diffuse outward from the surface, and the supplies of hydrogen 

 and oxygen at the surface would be renewed by diffusion inward. 

 Thus combustion would proceed heterogeneously at the surface until 

 the transformation of the original electrolytic gas into steam was 

 complete. In the circumstances just cited, the rate of combustion, 



^ Reprinted by permission from Transactions of the American Institute of Mining 

 Engineei's, vol. 43, 1912 (1913), pp. 612—630. Presented at a meeting of the New York 

 local section of the Institute, Apr. 12, 1912. 



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