Visual Investigation And Dimensionless Modeling Of The Vapor-Liquid-Solid Three-phase Flow

Combining circulating fluidization technique with boiling heat transfer,vapor-liquid-solid(V-L-S)circulating fluidized bed heat exchanger can effectivelyenhance heat transfer and also prevent and remove fouling. It occupies the wideapplication. However, the mechanisms of flow and heat transfer are complex. Inthis paper, a visual investigation on a vapor-liquid-solid three-phase naturalcirculating flow boiling system will be carried out.A new type of V-L-S three-phase natural circulating flow boiling system includingheating tube and circulating tube was established as experiment apparatus, whichis made of glass plated with transparent electrically heating film. In the V-L-Ssystem, flow characteristics, distributions of solids and characteristics of heattransfer were investigated by using the CCD measuring system, image processingsoftware developed by Tianjin University and precise platinum resistancetransducers. The conclusion that the characters of fluctuation with heat flux of theaxial distribution of solid holdup and the velocity of the particles in the system isdrawn.In the experiments, several kinds of particles were used in order to investigatedifferent influence on the heat transfer of the three-phase fluidized bed of theseparticles. However, the research available is mainly qualitative and there are onlylittle reports on modeling. In this paper, quantitative analysis was expatiated onand dimensionless model was established with vast experiment data. The resultshows that the model value and experimental value are consistent with each other,and the maximum deviation is ±10.9%.