Industrial & Engineering Chemistry Research, Vol.52, No.6, 2434-2438, 2013
External Coefficient of Heat Transfer by Convection in Mixed Vessels Using Vertical Tube Baffles
Many correlations in the literature have been proposed to predict the external heat transfer coefficient, but most of them are suggested for batch operations. This paper aims to experimentally investigate a steady state condition (usually found in industrial processes) of mixed vessels equipped with a four 45 degrees pitched-blade turbine and vertical tubular baffles to determine the external heat transfer coefficient. An empirical correlation based on the work of Sieder-Tate [Ind. Eng. Chem. 1936, 1429-1435] for a steady state condition using standard configuration of a mixing system is being proposed. A sucrose solution of 20% and 32% concentrations (w/w) and a mixing apparatus with a 50 L cylindrical flat bottom vessel are employed. Water was used as heating fluid running inside the vertical tubular baffles with an inlet temperature range from 25 to 45 degrees C and an impeller speed from 30 to 330 rpm. A new fit correlation was proposed based on the Sieder-Tate modeling, yielding good agreement with experimental data in steady states with deviations of less than 15% between observed and predicted external heat coefficients.