ACCURACY OF MODEL PREDICTIONS AND RELIABILITY OF EXPERIMENTAL-DATA FOR HEAT-TRANSFER IN PACKED-BEDS

The reliability and accuracy of experimental data and model predictions is investigated for the effective radial thermal conductivity (lambda(er)) and the wall heat transfer coefficient (alpha(w)) in packed beds in the absence of chemical reaction. The most common type of test equipment is shown to have suffered a crucial shortcoming. Experimental and mathematical procedures are developed to recover accurate data. Several models for predicting lambda(er) and alpha(w) are compared with experimental results, for which packings of spheres, cylinders and Raschig rings were employed. This work explains and reconciles differences between the most promising theoretical approaches and data sets in the existing literature. It is concluded that modifications of the models of Zehner and Bauer and of Hennecke can be recommended for practical use for all the particle shapes mentioned above. For studies of other shapes, advice is given on appropriate apparatus and operating procedure.