文摘
In this study, explicit criteria are derived for the applicability of the uniform temperatureapproximation (UTA) to unsteady heat transfer through the solid phase in assemblies of spheres.The sources of unsteadiness studied are temperature variation and contact area variation. It isshown that, for the case of temperature variation, the UTA cannot be used for a certain rangeof frequency of the fluctuations. For the case of contact area variation, the UTA is shown to beapplicable in all cases, provided that the contact radius is smaller than 10% of the particle radius.Following the assessment of its validity, the UTA is employed to illustrate the effect of aggregateand deposit morphology on the aggregate thermal relaxation behavior, considering the limitingcase of linear aggregates and simple two-dimensional on-lattice deposits.