Heat transfer in a packed bed reactor with cocurrent downflow of a gas and a liquid

Abstract

The authors investigate hydrodynamics and radial heat transfer in packed column with cocurrent downflow of gas and liquid. The effect of flow regimes, of gas and liquid flow rates and of liquid properties are discussed. The heat transfer can be represented by the homogeneous model with one or two parameters: the bed effective radial thermal conductivity A r and if necessary a supplementary heat transfer resistance at the wall of the reactor 1 α w . The importance and complexity of the interaction between hydrodynamics and heat transfer are shown. The necessity of distinguishing two major hydrodynamic regimes (low and high interaction) to describe the heat transfer parameters is emphasized. Simple predictive relations are proposed for each regime, based on physical phenomena. Low interaction regime corresponds to trickling flow, whereas high interaction regime includes bubble flow and pulsed flow. The liquid holdup behaviour enables to interpret the heat transfer results in both cases. The results in cocurrent downflow are also compared to results in cocurrent upflow and to correlations of the literature.