Abstract: A machine for freezing or chilling a liquid continuously to produce a slurry of the liquid and frozen crystals feeds the liquid into a vertically oriented heat transfer tube at its upper end. A refrigerant flow at the outer tube surface evaporates in a vapor/foam stream causing the liquid to freeze at the inner tube surface. A whip rod, preferably one that is free-standing, revolves over the inner surface to dislodge the frozen crystals mechanically and to distribute the liquid. An additive to the liquid such as ethylene glycol (in water) aids the dislodging. In one form, a mechanical flow guide surrounding the outer surface produces a thin, high velocity upward flow of the boiling refrigerant to increase the heat transfer. An orbital drive propels the whip rod. In one form the orbital drive includes a pair of horizontal plates coupled between the whip rod and at least one eccentric crank.

Abstract: An orbital evaporator has a vertical heat transfer tube or tubes mounted in a container driven in an orbital motion. A stiff whip rod is freely movable within the tube. Its lower end rests on a horizontal plate. The orbital motion causes the rod to roll over the interior surface of the tube to distribute the liquid in a thin film and to control fouling. A set of fins is mounted on the exterior of the tube to collect and channel the condensate to improve heat transfer through the tube. The fins are preferably longitudinal and the whip rod is preferably hydrophobic. Operating the evaporator with boiling temperatures substantially below 100.degree. C. in combination with the fins and a rolling whip rod allows operation as a desalinization unit for an indefinite period of time with a high total heat transfer coefficient. The evaporator preferably also includes a degasser to control the formation of a gas barrier at the exterior surface of the tube.