Heat transfer in packed beds with cocurrent downflow of liquid and gas

NÉSTOR JAVIER MARIANI; OSVALDO MIGUEL MARTÍNEZ; GUILLERMO FERNANDO BARRETO

Santa Fé, Argentina.

Congreso; III Mercosur Congress on Process Systems Engineering & I Mercosur Congress on Chemical Engineering; 2001

Facultad de Ingeniería-Universidad Nacional del Litoral, CERIDE, INTEC, INGAR.

The aim of this work is to investigate radial heat transfer in a packed bed column with cocurrent downflow of liquid and gas. For this purpose, an experimental device consisting in a jacketed tube with constant wall temperature was set-up. The experimental method is based on measuring the radial temperature profile at two angular positions and for different bed heights. The effects of gas and liquid flow rates and particle size were studied. Glass spherical particles of four different sizes were used; the aspect ratio (tube to particle diameter ratio) ranging from 4.67 to 34.26. Water and air were employed as model fluids. The heat transfer process was represented by a two-dimensional pseudohomogeneous plug flow (2DPPF) model with two parameters, the radial effective thermal conductivity (ker) and the wall heat transfer coefficient (hw). ker is well correlated with liquid and gas Reynolds numbers and aspect ratio. On the other hand, the values of hw cannot be suitable analyzed, for all the aspect ratio studied, in the frame of this model because of the so-called “wall effect”. The experimental information was also analized using a one-dimensional pseudohomogeneous model with one parameter (hT). In this case, data were adequately correlated as a function of the main operating variables, and a simple expression was developed for predicting purposes.