An experimental investigation of heat transfer in a pebble bed

An experimental investigation is performed of heat transfer under conditions of longitudinal flow of water moving in a bed of glass pebbles past a flat heated wall. Experiments involving the flow of single-phase liquid are performed in the ranges of variation of filtration velocities from $6$ to $60$ mm/s and of heat fluxes from $40$ to $140$ kW/m$^2$ in the case of wall boiling, the experiments are performed in the ranges of variation of filtration velocities from $2$ to $50$ mm/s and of heat fluxes from $27$ to $86$ kW/m$^2$. The temperature distribution is measured over the height of the heated wall and over the cross section (depth) of the channel at the outlet from the pebble bed. The experimental data are processed for single-phase flow using numerical optimization techniques. The values of the coefficient of "turbulent" thermal conductivity in the pebble bed are obtained as a function of the process parameters