Abstract: A cryogenic freezer apparatus for food products, including a thermally insulated enclosure and conveyor means for conveying products through the enclosure. A cryogen unit in the enclosure produces cryogen vapor near the enclosure entrance, and a blower unit is located in the enclosure adjacent the entrance thereof. The blower unit is selectively reconfigurable in response to a blower control signal to selectively direct cryogen vapor in varying directions, drawing cryogen vapor away from a first portion of the enclosure and blowing cryogen vapor toward a second portion of the enclosure. A photocell unit outside the enclosure, adjacent the entrance thereof, detects cryogen vapor exiting the enclosure entrance and generates at least one sensor output signal in response thereto, being indicative of the amount of cryogen vapor exiting.

Abstract: A cryogenic freezer apparatus for food products includes a conveyor within a thermally insulated enclosure. A cryogen injecting unit is located in said enclosure adjacent the opening thereof, and responsive to a cryogen control signal for introducing liquid cryogen in said enclosure. A blower unit in said enclosure directs cryogen vapor away from said enclosure opening toward the interior of said enclosure. The output of said blower unit being controllable by a blower control signal. A sensing unit within said enclosure senses the cooling capacity of the cryogen vapor at the enclosure opening and generates a sensor output signal which is indicative of the amount of cryogen vapor escaping out of said opening. A control unit, coupled to said sensing unit, said injecting unit, and to said blower unit generates a cryogen control signal and a blower control signal in response to the sensor output signal.