Temperature Fluctuations and Heat Transfer in Liquid Drop Columns.

Abstract

Heat transfer characteristics in a liquid drop column (0.102 m ID×1.8 m in height) have been investigated by analyzing the temperature difference fluctuations between the immersed heater and the column proper. The temperature difference fluctuations are analyzed by resorting to chaos analysis; the fluctuations have been interpreted by means of phase space portraits as well as the Kolmogorov entropy. The effects of dispersed (kerosene) and continuous (water) liquid phase velocities on the temperature difference fluctuations and heat transfer coefficients are determined. To explain the influence of immiscible liquid flow on the heat transfer coefficient, hydrodynamics and phase holdup have also been discussed. It is found that the increase in the velocities of dispersed and continuous liquid phases results in the increase of turbulence in the column, which makes the system more complicated and irregular. The injection of gas (air) or particles (6.0 mm glass bead) into the column can increase the heat transfer coefficient considerably. However, the flow behavior of the immiscible mixture is more irregular and chaotic owing to the injection of gas, whereas the system has been more uniform and periodic by adding the solid particles into the column. The heat transfer coefficient has been correlated well in terms of operating variables.