Abstract
In slow freezing of water that includes solutes, pure ice is produced and most of the solutes are removed from the frozen phase and concentrated in an unfrozen liquid phase. At fast freezing rate, however, large part of the solutes from solution is captured into the freezing interface and then the solution is not concentrated. To prevent this capture of the solutes, the strong agitation of the freezing interface is very effective. We have been studying the applicability of ultrasonic irradiation to the agitating method, and found that the freeze concentration efficiency of solutes is improved greatly by this irradiation. In this paper, the effects of the freezing rate and the ultrasonic irradiation on the freeze concentration characteristics are reported.
