High Viscosity Liquids and Solids

Here we consider the case of a viscous or even solid reactive material contained in a vessel of known geometry. In this case, heat transfer takes place by pure conduction there is no flow within the reactive material. The situation is stable, when the heat losses by conduction compensate for the heat release in the material. Thus, the following questions must be answered Under which conditions may a thermal explosion (runaway) be triggered Under which conditions is the heat transfer by conduction sufficient to compensate for the heat release  

Conductive heat transfer does not require any motion of atoms or molecules, as only the interactions between atoms or molecules transfers heat. The heat flux expressed in W rn 2 can be described using Fourier s law  

This equation expresses the proportionality of the heat flux to the temperature gradient in the material considered. The transfer takes place in the opposite 

If we consider the heat balance on a slice of thickness dx and section A, the heat accumulated in the slice is equal to the difference of the entering flux minus the 

Applying the first principle of thermodynamics, we find that the rate of temperature change is 

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