ICE scaling prevention with a fluidized bed heat exchanger

In most ice crystallization processes, scraped surface heat exchangers are applied to prevent ice scaling, but these apparatuses have disadvantages such as high investment and maintenance costs, especially for large-scale applications. An interesting alternative is a fluidized bed heat exchanger in which fluidized steel particles prevent ice scaling. This paper presents results from ice crystallization experiments with a single-tube fluidized bed heat exchanger. During the experiments, ice crystals were formed in aqueous solutions of different solutes with varying concentrations. The experiments revealed that ice scaling was only prevented when a certain temperature difference between wall and solution was not exceeded. This maximum temperature difference appeared to increase linearly with the solute concentration and was higher in aqueous solutions with low diffusion coefficients. The observed phenomena are explained by the hypothesis that ice scaling is only prevented when the crystal growth rate of ice crystals on the wall does not exceed the scale removal rate induced by the fluidized steel particles.