Liquid co2 passive subcooler

Abstract

A heat exchanger associated with a duct for a first fluid including: a central duct portion in fluid communication with the duct having an interior space and an exterior surface; a valve having opened and closed positions engageable within the interior space of the central duct portion; at least one coiled conduit for a second fluid positioned about at least a portion of the exterior surface of the central duct portion; upper and lower duct portions in fluid communication with the central duct portion including stationary upper and lower duct portions and movable upper and lower duct portions having opened and closed positions; and an at least partially movable and/or removable shell engaged with the stationary upper duct portion and the stationary lower duct portion and enclosing the coiled conduit; and, a refrigeration apparatus and process including the same.

1 . A heat exchanger associated with a duct for a first fluid comprising:
 a central duct portion in fluid communication with the duct having an interior space and an exterior surface;   a valve having opened and closed positions engageable within the interior space of the central duct portion;   at least one coiled conduit for a second fluid positioned about at least a portion of the exterior surface of the central duct portion;   an upper duct portion in fluid communication with the central duct portion comprising a stationary upper duct portion and a movable upper duct portion having opened and closed positions;   a lower duct portion in fluid communication with the central duct portion comprising a stationary lower duct portion and a movable lower duct portion having opened and closed positions; and   an at least partially movable and/or removable shell engaged with the stationary upper duct portion and the stationary lower duct portion, and enclosing the coiled conduit.   
     
     
         2 . The heat exchanger of  claim 1 , wherein when the valve is in the open position, and the movable upper duct portion and the movable lower duct portion are in their closed positions, the first fluid passing through the duct passes substantially through the central duct portion. 
     
     
         3 . The heat exchanger of  claim 1 , wherein when the valve is in the closed position, and the movable upper duct portion and the movable lower duct portion are in their opened positions, the first fluid passing through the duct passes within the shell and around the at least one coiled conduit, thereby allowing heat to be transferred between the first fluid passing within the shell and the second fluid passing through the at least one conduit. 
     
     
         4 . The heat exchanger of  claim 1 , wherein the valve is a quarter-turn valve. 
     
     
         5 . The heat exchanger of  claim 1 , wherein the shell comprises at least two pieces which are movably and/or removably engaged on at least one side of the heat exchanger, allowing the shell to be opened such that the at least one conduit can be accessed from exterior to the shell, and wherein the at least two portions are removably engaged on another side of the heat exchanger. 
     
     
         6 . A refrigeration apparatus comprising: a refrigeration chamber; a liquid CO 2  storage apparatus for providing liquid CO 2  at above atmospheric pressure to the refrigeration chamber for flashing into gaseous CO 2  and CO 2  snow; and the heat exchanger of  claim 1 , wherein the at least one conduit is disposed between and in fluid communication with the storage apparatus and the refrigeration chamber for receiving and chilling the liquid CO 2  prior to said flashing; the second fluid is liquid CO 2  flowing through the at least one conduit and the first fluid is gaseous CO 2  flowing through the shell after the gaseous CO 2  exits the refrigeration chamber, thereby pre-cooling the liquid CO 2  prior to the liquid CO 2  exiting the at least one conduit of the heat exchanger and entering the refrigeration chamber. 
     
     
         7 . A refrigeration process, comprising supplying liquid CO 2  into a refrigeration chamber, flashing the liquid CO 2  into gaseous CO 2  and solid CO 2  to provide a cooling effect within the refrigeration chamber, and exhausting gaseous CO 2  from the refrigeration chamber, wherein the liquid CO 2  is the second fluid passing through the at least one conduit of the heat exchanger of  claim 1  prior to entering the refrigeration chamber and the gaseous CO 2  is the first fluid passing through the shell of the heat exchanger after exiting the refrigeration chamber when the valve is in the closed position and the movable upper duct portion and lower duct portion are in their open positions, thereby pre-cooling the liquid CO 2  prior to entering the refrigeration chamber. 
     
     
         8 . The process of  claim 7 , wherein the liquid CO 2  enters the at least one conduit at about −12° F. (−24.4° C.) to about 2° F. (−16.7° C.) and exits the at least one conduit at about −36° F. (−37.8° C.) to about −5° F. (−20.6° C.), wherein pressure of the liquid CO 2  is substantially the same at entry and exit of the at least one conduit of the heat exchanger. 
     
     
         9 . The process of  claim 8 , wherein the pressure of the liquid CO 2  as it passes through the heat exchanger is about 239 psig to about 300 psig. 
     
     
         10 . The process of  claim 7 , wherein the gaseous CO 2  enters the shell of the heat exchanger at about −90° F. and about atmospheric pressure and exits the shell at about −50° F. (−45.6° C.) to about −20° F. (−28.9° C.) and about atmospheric pressure. 
     
     
         11 . The process of  claim 7 , wherein greater than about 48% of the liquid CO 2  is converted into solid CO 2  upon flashing within the refrigeration chamber. 
     
     
         12 . The process of  claim 7 , wherein at least about 55% of the liquid CO 2  is converted into solid CO 2  upon flashing within the refrigeration chamber. 
     
     
         13 . The process of  claim 7 , further comprising opening the valve and closing the movable upper duct portion and the movable lower duct portion, whereby the gaseous CO 2  flows substantially through the central duct portion. 
     
     
         14 . The process of  claim 13 , further comprising opening the shell to access the at least one conduit. 
     
     
         15 . The process of  claim 14 , further comprising at least one of cleaning, sanitizing or maintaining at least a portion of the at least one conduit.