The Design of Experimental Studies in Gas-Solid Reaction Systems

6 The Design of Experimental Studies in Gas-Solid Reaction Systems 

In this section we shall attempt a synthesis of the ideas outlined in Chapters 2-4 and in the preceding sections of this chapter to outline the design of an experimental study of gas-solid reaction systems. This integration of experimental studies with the previously described mathematical model development is thought to be highly desirable, because experimental verification is an essential ingredient of any modeling work. Moreover, experimental work must form the basis of the improved mathematical representation of reaction systems. 

As discussed earlier, provided the reaction is thermodynamically feasible, the overall rate at which a solid pellet reacts with a gas may be limited by 

The objective of the experimental study is then to establish which of these steps or what particular combination thereof is rate controlling over the conditions of interest and then to develop a detailed inderstanding of this rate-controlling step(s). The term conditions of interest needs a more precise definition. If the experimental study is carried out as part of an application-oriented (industrial) program where some of the variables are fixed by certain extraneous constraints (e.g., fixed pellet size, reaction temperature, gas composition) then it might be sufficient to identify the rate-controlling step for this limited range of variables. 

The conditions of interest would be rather more broadly defined for more fundamental studies where one wishes to explore a much broader range of temperatures, particle sizes, etc. Let us now proceed by considering the various possible rate-contolling mechanisms. 

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