Oscillating flow freezer

Abstract

A freezer for a product includes a housing having a sidewall defining a chamber in the housing, and an inlet and an outlet in communication with the chamber; and a pair of pistons operatively associated with the housing and in communication with the chamber, the pair of pistons operable out of phase with each other for oscillating a gas flow within the chamber. A method is also provided for reducing a temperature of a product in a freezer.

What is claimed is: 
     
         1 . A freezer for a product, comprising:
 a housing having a sidewall defining a chamber in the housing, and an inlet and an outlet in communication with the chamber; and   a pair of pistons operatively associated with the housing and in communication with the chamber, the pair of pistons operable out of phase with each other for oscillating a gas flow within the chamber to contact the product.   
     
     
         2 . The freezer of  claim 1 , further comprising a cryogen injection apparatus having a first end in communication with the chamber and a second end in communication with a source of liquid cryogen. 
     
     
         3 . The freezer of  claim 2 , further comprising a transport apparatus extending from the inlet through the chamber to the outlet for moving the product through the freezer. 
     
     
         4 . The freezer of  claim 2 , wherein the cryogen injection apparatus comprises at least one nozzle connected to the first end of the cryogen injection apparatus for providing a cryogenic substance to the chamber. 
     
     
         5 . The freezer of  claim 2 , wherein the cryogen injection apparatus comprises a manifold connected to the first end, the manifold having at least one nozzle for providing a cryogenic substance to the chamber. 
     
     
         6 . The freezer of  claim 1 , further comprising a bleed gas exhaust pipe in communication with the chamber proximate one of the pair of pistons for controlling removal of a portion of the oscillating gas flow from the chamber and preventing atmosphere external to the freezer from entering the chamber. 
     
     
         7 . The freezer of  claim 1 , further comprising an inlet exhaust funnel positioned proximate the inlet, and an outlet exhaust funnel positioned proximate the outlet. 
     
     
         8 . The freezer of  claim 1 , further comprising an inlet door mounted to the housing at the inlet and operable for restricting atmosphere external to the housing from entering the chamber, and an outlet door mounted to the housing at the outlet and operable for restricting the atmosphere external to the housing from entering the chamber. 
     
     
         9 . The freezer of  claim 2 , further comprising a control apparatus in communication with the pair of pistons and the cryogen injection apparatus for controlling upstrokes and downstrokes of the pair of pistons and injection of a cryogenic substance into the chamber. 
     
     
         10 . The apparatus of  claim 2 , wherein the liquid cryogen is selected from the group consisting of carbon dioxide and nitrogen. 
     
     
         11 . A method for reducing a temperature of a product in a freezer, comprising:
 providing a product to a chamber of the freezer for reducing a temperature of the product;   injecting a cryogen substance into the chamber;   oscillating an air flow within the chamber to charge the air flow with the cryogen substance; and   contacting the product with the oscillating air flow.   
     
     
         12 . The method of  claim 11 , wherein the oscillating an air flow comprises operating a pair of pistons out of phase and in communication with the chamber for providing the oscillating air flow. 
     
     
         13 . The method of  claim 12 , wherein the operating comprises operating strokes of each one of the pair of pistons out of phase with other strokes of the other one of said pair, and each of said strokes extending along a distance of from 2 to 6 mm. 
     
     
         14 . The method of  claim 11 , further comprising:
 removing a portion of the oscillating air flow from the chamber; and   establishing a temperature gradient across the chamber during the removing.   
     
     
         15 . The method of  claim 14 , further comprising controlling the injecting a cryogen substance, the oscillating an air flow and the removing a portion of the oscillating air flow to provide the temperature gradient across the chamber.