Natural permeation combustion

For natural permeation combustion, the reactant gas may flow in either the same (cocurrent flow. Fig. 27a) or opposite (countercurrent flow. Fig. 27b) direction as that of combustion wave propagation, and in some cases even in both directions Fig. 27c). One-dimensional flow regimes can be achieved by placing the sample in a quartz tube, which in turn can be closed at one end (Pityulin et al, 1979). In the general case (see Fig. 26), the reactant gas also enters from the side surface, and the process can be described by two- or three-dimensional numerical simulations (cf Ivleva and Shkadinskii, 1981 Dandekar et al., 1990, 1993). In this section, results for the simpler one-dimensional case are analyzed and features of the higher dimensional studies are briefly discussed. 

Nanoparticles are not only a product of new nano-technologies, but are also present in the environment, and nanoscale phenomena permeate and often control natural processes.12 Humans have always experienced exposure to nanosized particles, but with the advent of the industrial revolution, this exposure from anthropogenic sources (e.g. internal combustion engines, power plant etc.) has increased dramatically. 

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