N.sub.2 tunnel freezer

A cryogenic freezer for freezing food products comprising

• a tunnel-like enclosure having an enclosure and an exit and having thermally insulated side, top and bottom walls,
• a tank located within said enclosure for holding a reservoir of liquid cryogen, said tank having thermally insulated side and bottom walls, with said tank insulated walls being spaced above said enclosure insulated bottom wall and inward from said enclosure insulated side walls,
• means for conveying products being frozen from said entrance to said exit,
• said conveying means containing a section which travels through said reservoir, and
• blower means mounted in said enclosure for circulating cold cryogenic vapor which is created by vaporization of cryogenic liquid in said tank,
• whereby the presence of cold cryogenic vapor between said insulated bottom and side walls of said tank and said insulating bottom and side walls of said enclosure substantially retards the entry of heat into liquid cryogen in said reservoir through the bottom or the side walls of said tank thereby increasing efficiency.

A cryogenic freezer comprising

• a thermally insulated tunnel-like enclosure having an entrance and an exit,
• means for conveying products being frozen from said entrance to said exit,
• means for contacting products being frozen with liquid cryogen at a region located between said entrance and said exit and thereby creating cryogen vapor at said contact region,
• a blower located in an upper region of said enclosure adjacent said contact region and having a fan blade mounted for rotation about a generally vertical axis,
• upstream and downstream baffle means associated with said blower and linked together for complementary movement so as to respectively regulate the flow of vapor from said blower in upstream and downstream directions,
• means for monitoring a condition of the atmosphere which is indicative of the atmosphere in said enclosure in the region of said entrance, and
• means for adjsuting the orientation of said baffle means in accordance with the condition monitored to avoid undesirably large amount of vapor from exiting said enclosure via said entrance.