Particle to particle conduction

Hi, I am trying to use the Mfix-dem method to the solve particle to particle heat transfer in a fixed bed.
It seems that there are parameters to be used for the particle to particle conduction but I couldn’t find the contents about it in the documents.

In the Mfix Equations document, the energy balance equation for solids phases only includes heat transfer terms relating to fluid-solid and radiation heat transfer.

Please give me a comment if someone knows about this problem.

Thanks!