Impingement jet freezer and method

摘要

An impingement freezer having a zoned freezing chamber in which the temperature of each zone is independently controllable so that the temperature profile within the impingement freezer is coldest at a zone adjacent the outlet and warmest at a zone adjacent the inlet for maximum thermodynamic usage of the refrigerant. Additionally, the velocity of each of the impingement jets is independently adjustable from zone to zone so that in the zone adjacent the entrance of the freezing chamber, the impingement jets can be adjusted to have maximum velocity to produce maximum heat transfer coefficients and thereby an acceptable rate of cooling within the impingement jet freezer. Impingement jets are formed within nozzles that are tapered in two orthogonal directions to prevent frost build-up. Circulation within the impingement jet freezer is produced by venturi-like devices driven by vaporization of incoming refrigerant.