Analytical generalized thermal resistance model for conductive heat transfer in pebble beds based on heat flux weighted temperature difference

What is it about?

We propose a novel concept for a particle contact thermal resistance model, which provides important references for heat conduction research within pebble beds. The innovation of our model lies in the first-time use of the concept of heat flux density-weighted temperature difference to define the generalized thermal resistance of particle conduction. We extend this research to the heat transfer studies of pebble beds, utilizing the discrete element method to randomly generate the pebble bed and employing externally applied internal heat sources to derive the effective thermal conductivity of the pebble bed. Our model has been compared and validated against other models and CFD models, showing good agreement with experimental values.

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Photo by Pawel Czerwinski on Unsplash

Photo by Pawel Czerwinski on Unsplash

Why is it important?

The advantages of our thermal resistance model are as follows: It has clear physical significance and can reflect the thermal dissipation capacity of the system. It takes into account the influence of boundary conditions, acknowledging that different boundary conditions affect thermal resistance differently. It considers the particle radius (most models assume that the particle radius is infinitely larger than the contact radius, thereby neglecting the impact of particle radius on thermal resistance). It accounts for the non-uniformity of temperature within the particles (most models assume uniform temperature inside the particles and an infinite thermal conductivity, which is evidently not applicable).

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