Combined Effect of Two Approximations to Critical Parameters in the Spontaneous Combustion of Cellulosic Materials

In the theory of Frank-Kamenetskii, the values of the critical Frank-Kamenetskii parameter and critical dimensionless temperature were obtained at two approximations. As we care more about the spontaneous of organic materials,we want to know how much effect the two approximations have for spontaneous combustion of organic materials. Cellulosic materials (such as sawdust) are typical organic materials of spontaneous combustion. In this paper, we provide an efficient indirect method to calculate the critical parameters of spontaneous combustion of cellulosic materials at different conditions. We can know that, the effect of dimensionless activation energy and Biot number to critical Frank-Kamenetskii parameter can be almost offset for cellulosic materials. However, the effect of dimensionless activation energy and Biot number to critical dimensionless temperature cannot be ignored. But, as the critical Frank-Kamenetskii parameter is more useful than the dimensionless temperature, the two approximations can be reasonable for spontaneous combustion of cellulosic materials or other materials like them.