Estimation of hydrodynamic and heat transfer characteristics of bubble column by analysis of wall pressure measurements and CFD simulations

Abstract

Hydrodynamic and heat transfer characteristics have been measured in a 0.385 m i.d. air-water bubble column. The superficial gas velocity was varied in the range of 0.028-0.25 m s⁻¹. The average circulation velocity (V_C) and the length scales were obtained by cross-correlation analysis of two pressure sensors located at some distance from each other. The values of cross-correlation analysis also suggested the existence of interacting multiple circulation cells. It was possible to estimate the V_C up to a superficial gas velocity of 0.14 m s⁻¹. The surface renewal time was estimated from pressure-time series by using eddy isolation model, which was used for calculating the wall heat transfer coefficient (h_W). Computational fluid dynamic (CFD) simulations were also performed by using a Reynolds number k-ε model for predicting V_C and wall heat transfer coefficient. A detailed comparison has been presented between the CFD predictions, present experimental measurements and the published work of Drahos et al. (1991), Groen et al. (1995) and Vial et al. (2000) for V_C and that of Burkel (1974), Lewis et al. (1982) and Verma (1989) for h_W.