Cryogenic gas-assisted mechanical refrigeration cooling system apparatus and method

Abstract

A method and apparatus for cooling articles, particularly having applications for chilling extrusions, food, and similar articles, utilizing a vaporized cryogen in combination with conventional refrigeration. The vaporized cryogen provides a substantially dry atmosphere from which an evaporator of the conventional refrigeration unit may remove energy. The vaporized cryogen may be circulated at a controlled velocity to provide improved temperature control in the system.

What is claimed is:  
     
         1 . A method of cooling an article comprising: 
 a) introducing liquid cryogen into a feed chamber wherein said liquid cryogen is substantially vaporized;    b) circulating said vaporized cryogen from said feed chamber into a separate cooling chamber containing said article to be cooled;    c) circulating said vaporized cryogen from said feed chamber into said cooling chamber and around said article in said cooling chamber to cool said article; and    d) operating a refrigeration unit having an evaporator in heat transferring contact with said vaporized cryogen to remove heat from said vaporized cryogen.    
     
     
         2 . The method of  claim 1  further comprising: 
 e) sensing the temperature in at least one of said feed chamber and said cooling chamber;  
 f) calculating a wind chill temperature in said cooling chamber, said wind chill temperature being a function of the temperature in said cooling chamber and the velocity at which said vaporized cryogen is circulated through said cooling chamber over said article; and  
 g) controlling the removal of heat by said refrigeration unit to maintain a desired wind chill temperature within said cooling chamber.  
 
     
     
         3 . The method of  claim 1  further comprising: 
 e) sensing the temperature in at least one of said feed chamber and said cooling chamber;  
 f) calculating a wind chill temperature in said cooling chamber, said wind chill temperature being a function of the temperature in said cooling chamber and the velocity at which said vaporized cryogen is circulated through said cooling chamber over said article; and  
 g) controlling said velocity to cause said wind chill temperature to correspond to a desired wind chill temperature.  
 
     
     
         4 . The method of  claim 1  further comprising controlling introduction of additional liquid cryogen into said feed chamber to cause the temperature therein to correspond to a desired temperature.  
     
     
         5 . The method of  claim 2  wherein cooling efficiency is optimized comprising: 
 a) first operating said refrigeration unit to increase removal of heat from said vaporized cryogen;  
 b) thereafter increasing said velocity to a maximum velocity to increase said rate of cooling of said article; and  
 c) thereafter introducing additional liquid cryogen only when necessary to at least one of maintain and increase said rate of cooling such that a maximum cooling rate is achieved using a minimum amount of liquid cryogen.  
 
     
     
         6 . The method of  claim 3  wherein cooling efficiency is optimized comprising: 
 a) first operating said refrigeration unit to increase removal of heat from said vaporized cryogen;  
 b) thereafter increasing said velocity to a maximum velocity to increase said rate of cooling of said article; and  
 c) thereafter introducing additional liquid cryogen only when necessary to at least one of maintain and increase said rate of cooling such that a maximum cooling rate is achieved using a minimum amount of liquid cryogen.  
 
     
     
         7 . The method of  claim 1  further comprising venting pressure build-up in at least one of said feed chamber and said cooling chamber due to at least said introducing said liquid cryogen in said feed chamber.  
     
     
         8 . The method of  claim 1  wherein said feed chamber and said cooling chamber are a plurality of feed chambers and cooling chambers and each of said plurality of feed chambers and cooling chambers are individually controllable to at least one of introduce said liquid nitrogen, vaporize said liquid cryogen, operate said refrigeration unit and circulate said vaporized cryogen.  
     
     
         9 . The method of  claim 8  wherein cooling efficiency is optimized comprising: 
 a) first increasing said operation of said refrigeration unit to a maximum heat removal to at least one of maintain and increase said rate of cooling of said article;  
 b) thereafter increasing said velocity to a maximum velocity to at least one of maintain and increase said rate of cooling of said article; and  
 c) thereafter introducing additional liquid cryogen only when necessary to at least one of maintain and increase said rate of cooling such that a maximum cooling rate is achieved using a minimum amount of liquid cryogen.  
 
     
     
         10 . The method of  claim 9  further comprising heating each of said at least one of said plurality of feed and cooling chambers to increase the temperature therein to cause the temperature to correspond to said desired temperature.  
     
     
         11 . The method of  claim 10  wherein efficiency is optimized comprising: 
 a) first decreasing said velocity to decrease said rate of cooling; and  
 b) thereafter increasing the temperature in each of at least one of said plurality of feed and cooling chambers only when necessary to at least one of maintain and decrease said rate of cooling such that a desired rate of cooling is achieved using a minimum amount of energy.  
 
     
     
         12 . The method of  claim 1  wherein said article is one of a plurality of individual articles and a generally continuously produced article, the method further comprising feeding said one of a plurality of individual articles and a generally continuously produced article through said cooling chamber for cooling thereof.  
     
     
         13 . An apparatus for cooling an article comprising: 
 a) a feed chamber;    b) a source of liquid cryogen;    c) an inlet into said feed chamber in fluid communication with said source of liquid cryogen;    d) a valve disposed between said inlet and said source of liquid cryogen, said valve controllable to admit said liquid cryogen into said feed chamber, said liquid cryogen at least partially vaporizing in said feed chamber;    e) a cooling chamber generally separated from said feed chamber;    f) at least one intake passage connecting said feed chamber and said cooling chamber, said at least one intake passage providing fluid communication therebetween;    g) means for circulating said vaporized cryogen in said feed chamber to at least one of aid in substantial vaporization of said liquid cryogen within said feed chamber and circulate said vaporized cryogen in said cooling chamber via said at least one intake passage to cool said article;    h) a refrigeration unit having an evaporator adapted to absorb heat from a surrounding atmosphere, said evaporator being positioned in energy absorbing communication with said vaporized cryogen, said refrigeration unit controllable to remove heat from said vaporized cryogen.    
     
     
         14 . The apparatus of  claim 13  further comprising: 
 h) a temperature sensor for sensing temperature in at least one of said feed chamber and said cooling chamber;  
 i) said means for circulating controllable at variable speeds to circulate said vaporized cryogen over said evaporator and said article at a variable velocity to create a variable wind chill temperature in said cooling chamber; and  
 j) a controller connected to said temperature sensor, said controller controlling at least one of said refrigeration unit and said means for circulating to cause said wind chill temperature to correspond to a desired wind chill temperature.  
 
     
     
         15 . The apparatus of  claim 14  further comprising said valve controllable by said controller to introduce said liquid cryogen into said feed chamber to cause the temperature in at least one of said feed chamber and said cooling chamber to correspond to a desired temperature.  
     
     
         16 . The apparatus of  claim 13  wherein apparatus further comprises: 
 a) a return chamber communicating with a return side of said means for circulating;  
 b) at least one return passage connecting said cooling chamber and said return chamber, said at least one return passage providing fluid communication therebetween; and  
 c) said means for circulating further circulating said vaporized cryogen from said central cooling chamber to said return chamber via said at least one return passage.  
 
     
     
         17 . The apparatus of  claim 16  wherein said at least one intake passage and at least one return passage further comprise at least two intake passages and at least two return passages.  
     
     
         18 . The apparatus of  claim 13  further comprising: 
 a) a pair of openings provided in generally opposing sides of said cooling chamber through which an article to be cooled may be passed to be cooled in said central cooling chamber; and  
 b) a seal at each of said pair of openings to maintain said cooling chamber generally sealed from the atmosphere.  
 
     
     
         19 . The apparatus of  claim 13  further comprising a heating unit disposed in at least one of said feed chamber and said cooling chamber, said heating unit controllable by said controller to raise the temperature in at least one of said feed chamber and said cooling chamber to cause the temperature therein to correspond to a desired temperature.  
     
     
         20 . The apparatus of  claim 13  further comprising a vent in communication with at least one of said feed chamber and said cooling chamber to release pressure therein resultant from at least vaporization of said liquid cryogen therein when said pressure reaches a predetermined level.  
     
     
         21 . The apparatus of  claim 15  wherein: 
 a) said feed chamber and said cooling chamber further comprise a plurality of feed and cooling chambers, each of said plurality of feed chambers having at least said source of liquid cryogen, said inlet, said valve, said means for circulating, said refrigeration unit and said temperature sensor; and  
 b) said controller providing a desired temperature in each of said plurality of feed and cooling chambers independently of others of said plurality of feed and cooling chambers.  
 
     
     
         22 . The apparatus of  claim 21  wherein said controller further comprises a plurality of controllers, each of said plurality of controllers associated with a respective one of said plurality of feed and cooling chambers.  
     
     
         23 . The apparatus of  claim 13 , wherein said cooling chamber includes at least one metal tooling device adapted to make cooling contact with said article.  
     
     
         24 . The apparatus of  claim 23 , wherein said at least one metal tooling device is selected from a calibrator and a sizing template.  
     
     
         25 . An apparatus for cooling an article comprising: 
 a) a feed chamber;    b) a source of liquid cryogen in fluid communication with said feed chamber;    c) a valve disposed between said source of liquid cryogen and said feed chamber, said valve controllable to admit said liquid cryogen into said feed chamber, said liquid cryogen at least partially vaporizing in said feed chamber;    d) a cooling chamber generally separated from said feed chamber and in fluid communication therewith, said cooling chamber adapted to contain said article for cooling;    g) means for circulating said vaporized cryogen in said feed chamber to at least one of aid in substantial vaporization of said liquid cryogen within said feed chamber and circulate said vaporized cryogen to said cooling chamber to cool said article; and,    h) a refrigeration unit, said refrigeration unit having an evaporator adapted to absorb heat from a surrounding atmosphere, said evaporator being positioned in energy absorbing communication with said vaporized cryogen.