Experimental investigation of radiative heat propagation in a simplified generic packed bed

Abstract

A novel test rig for the investigation of radiative heat transfer in packed beds has been developed and is introduced with representative experimental results. The individual components and the calibration are discussed. The generic packed bed is realized in a simplified way by an arrangement of parallel rods, which represent particles in pseudo-2D. In this arrangement, electrically heated rods provide the radiation propagating through the rod array to heat the passive counterparts. A sophisticated temperature-control scheme with a large number of thermocouples and infrared-imaging provides in-depth information about heat transfer in the system. Spectral radiation intensities are determined with a Fourier-transform infrared spectroscopy, which has been modified and validated for this specific application. In order to compare the influence of different surface properties of particles on the heat propagation and surface reflections, rod samples made of stainless steel and magnesium oxide are used. The influence of material properties becomes clearly visible by comparing the high radiation intensities resulting from a stainless steel rod array to the same geometry built from magnesium oxide rods. In addition, the influence of the surface properties is particularly evident in the infrared images since the reflections are significantly higher for the stainless steel samples than for the magnesium oxide samples. The experimental results in the current work demonstrate the ability of the test rig to provide data with a well-defined accuracy as a validation base for numerical radiation simulations in packed beds.