Lagging critical thickness

When hrjk < 1, thin layers of lagging increase the heat loss and it is necessary to exceed the critical thickness given by equation 9.266 before any benefit is obtained from the lagging. 

By varying input parameters it is found that the critical thickness of the lagging decreases with increasing temperature of the pipe, i.e. the lagging must be thinner in order to avoid self-ignition. This is a requirement counteracting the quality of heat insulation. 

Experimental requirements or assumptions concerning transport not fulfilled, for example, the mixing behavior of fluids and gases, deviation from the ideal residence time distribution, critical dependence on particle size, the thickness of layers of cells, the response lag of the Po electrode. 

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