Hybrid Methods to Quantify Ice Front Movement during Freeze-concentration Process

Freeze concentration is an emerging separation method that can be implemented as part of a water purification system, however, its development is still at pilot plant scale. One of the useful parameters for design and control of this process is the growth velocity of the crystal, commonly known as the limit velocity. Above this limit, ice crystals will capture solids and separation will lose quality. Two-hybrid no invasive methods to follow the displacement of the ice front during a freeze concentration (FC) procedure has been tested.The methods included image segmentation, string matching technique and a bio-inspired optical flow algorithm to calculate the ice front velocity. A thermal camera was used in the experiments in order to validate the estimated movement of the ice by the image analysis procedures. Both methods were successful to follow the movement of the ice front, and the estimated displacement was between 4 and 12 pixels in 15 minutes.