Experimental analysis of forced convective heat transfer in novel structured packed beds of particles

Followed by the numerical study of Yang et al. (2010), the macroscopic hydrodynamic and heat transfer characteristics in some novel structured packed beds are experimentally studied in this paper, where the packings of ellipsoidal or non-uniform spherical particles are investigated for the first time with experiments and some important results are obtained. For present experiments, the interstitial heat transfer coefficient in the packed bed is determined using an inverse method of transient single-blow technique. The effects of packing form and particle shape are carefully investigated and the experimental and numerical results (Yang et al., 2010) are also compared in detail. Firstly, it is discovered that, the computational method reported by Yang et al. (2010) might be appropriate for heat transfer predictions in structured packings, while it might underestimate the friction factors, especially when the porosity is relatively low. Secondly, it is found that, the traditional Ergun's and Wakao's equations might overpredict the friction factors and Nusselt numbers for the structured packings, respectively, and some experimental modified correlations are obtained. Furthermore, it is also revealed that, both the effects of packing form and particle shape are significant to the macroscopic hydrodynamic and heat transfer characteristics in structured packed beds. With proper selection of packing form, such as simple cubic packing (SC) and particle shape, such as ellipsoidal particle, the pressure drops in the structured packed beds can be greatly reduced and the overall heat transfer performances will be improved. These experimental results would be reliable and useful for the optimum design in industry applications. (C) 2011 Elsevier Ltd. All rights reserved.