Effects of Chaotic Temperature Fluctuations on the Heat Transfer Coefficient in Liquid-Liquid-Solid Fluidized Beds

Abstract

The effect of chaotic temperature fluctuations on the immersed heater-to-bed heat transfer coefficient (h) are investigated in a liquid-liquid-solid fluidized bed (0.152 m ID × 2.5 m in height). The time series of temperature fluctuations are measured and analyzed by means of the multidimensional phase space portraits and Kolmogorov entropy (K), in order to characterize the chaotic behavior of heat transfer coefficient fluctuations in the bed. The overall heat transfer coefficient is inversely proportional to the Kolmogorov entropy of temperature fluctuations, as well as the fluctuation range of heat transfer coefficient (Δhi). The Kolmogorov entropy and fluctuation range of the heat transfer coefficient (Δhi) increase with increasing dispersed phase velocity, but decrease with increasing particle size. However, they attain their minima with variation of the continuous phase velocity as well as the bed porosity, at which point the flow regime of particles in the beds changes. The overall heat transfer coefficient is directly correlated with the Kolmogorov entropy, as well as the fluctuation range of heat transfer coefficient.