Abstract:
An apparatus for providing heat transfer to a compartment includes a housing having a chamber therein for receiving dry ice and a first surface area exposable to a first space in the compartment for heat transfer; and a first assembly moveable with respect to the first surface area for covering a select portion of the first surface area to control heat transfer at the first space. The first assembly includes at least one pivotable louver.

Description:
BACKGROUND 
       [0001]    The present inventive embodiments relate to apparatus and methods to provide heat transfer for refrigeration of products, such as food products for example, that are in transit. 
         [0002]    In transit refrigeration (ITR) and temperature control inside refrigerated transport trucks or containers can be difficult to regulate. Temperature control of such systems, such as for example a carbon dioxide (CO 2 ) system, is desired for increasing the overall efficiency of the system process, as well as making such system suitable for daily product delivery services. A temperature control system enables chilled and frozen products to be transported effectively and efficiently. 
         [0003]    It would therefore be desirable to have an ITR apparatus which can regulate and control refrigeration at a single compartment and at a plurality of compartments concurrently depending upon the temperature demands for each compartment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    For a more complete understanding of the present embodiments, reference may be had to the following drawing figures taken in conjunction with the description of the embodiments, of which: 
           [0005]      FIG. 1  shows a perspective view of a heat transfer apparatus embodiment according to the invention; 
           [0006]      FIG. 2  shows a top plan view along line  2 - 2  of the embodiment in  FIG. 1 ; and 
           [0007]      FIG. 3  shows another embodiment of the heat transfer apparatus according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0008]    Referring to  FIGS. 1 and 2 , a heat transfer apparatus embodiment is shown generally at  10 . The apparatus includes a container  12  or bunker, wherein five (5) of the side walls  14  of the container  12  are insulated, while a sixth (6 th ) one of the side walls is not insulated and is constructed as a heat transfer side wall  16  of the container. The side walls  14 , 16  provide for a space  18  in the container  12 . CO 2  snow or dry ice  20  is provided in the space  18 . The container  12  is shown having a rectangular shape by way of example only, hence the number of side walls  14  that would be provided for such a structure. The apparatus  10  may be used for in transit refrigeration (ITR) of products such as food products for example. 
         [0009]    At least one louver  22 , door or slat, and for many applications a plurality of louvers, are mounted to the container  12  for pivotal movement with respect thereto. Each one of the louvers  22  is pivotally connected to the container  12  or the heat transfer side wall  16  by mechanical pivoting fasteners  24  such as for example hinges or pins. The pivoting fasteners  24  permit each one of the louvers  22  to rotate through at least 90 degrees with respect to the surface of the heat transfer side wall  16  for a purpose to be discussed hereinafter. 
         [0010]    As shown in particular in  FIG. 2 , each of the louvers  22  may be provided with insulation  26  along a surface thereof or alternatively, the entire louver  22  may be insulated. Insulation can take the form of any known insulation material available. A length of each one of the louvers  22  is such that when all of the louvers mounted to the heat transfer side wall  16  are folded or pivoted to be in contact with said side wall  16 , the louvers  22  provide an insulated surface similar to that provided by the insulated side walls  14 . Therefore, the louvers  22  positioned at  28  do not provide heat transfer at the side wall  16 . Such an arrangement is shown in  FIG. 2 , where certain of the louvers  22  as indicated generally at  28  have been folded downward to be parallel with and cover the heat transfer side wall  16 , while others of the louvers  22  shown generally at  30  remain in an upright opened or deployed position with respect to the side wall  16 . The positioning of the louvers  22  at  30  provides for an increased heat transfer at the side wall  16 . Each of the louvers  22  can be positioned separately from other ones of the louvers. 
         [0011]    Referring to  FIG. 1 , the plurality of pivoting louvers  22  enable a select surface area of the heat transfer side wall  16  to be exposed to convection currents  32  in a space or compartment  34 . All of the louvers  22  may be in the open or upright position  30 , in the closed or seated position  28 , or alternatively be arranged in any combination between the positions  28 , 30 . 
         [0012]    The air flow  32  may be the result of convection currents in the space  34 . The degree of cooling in the space  34  can be controlled by opening and closing the louvers  22  to expose a select amount of the surface area of the heat transfer side wall  16 . With all of the louvers  22  in the closed position  28 , the heat transfer side wall  16  is completely insulated and therefore minimal, if any, heat transfer effect will occur with respect to the air flow  32 . However, with all of the louvers  22  in the open position as shown generally at  30  in  FIG. 2 , the heat transfer side wall  16  is completely exposed to the air flow  32 , thereby providing for a maximum amount of heat transfer to occur to the air flow. Any degree of exposure of the air flow  32  to the heat transfer side wall  16  can be achieved by pivoting the louvers through a 90 degree path of rotation to provide the necessary amount of freezing or chilling of the space  34  by the air flow  32 . 
         [0013]    The embodiment shown in  FIG. 1  can be mounted to a side wall or roof of an ITR vehicle (not shown). If the apparatus  10  is mounted to the roof (not shown) for example, the louvers  22  when pivoted to the open position  30  will extend or point downward into the space  34  of the vehicle. 
         [0014]    The CO 2  snow  20  loaded into the space  18  from an inlet port  36  of the container  12  can be in pellet form or as snow particles generated from a CO 2  snow horn (not shown). Sensors (not shown) for sensing temperature of the space  34  can also be provided to generate a signal of the temperature of the space and communicate same to a control apparatus (not shown) to adjust opening and closing of the louvers  22  to provide the right amount of heat transfer effect to the air flow  32 . 
         [0015]      FIG. 3  shows another embodiment  40  of the ITR heat transfer apparatus. The apparatus  40  is constructed for use with a plurality of spaces  42 , 44  of a compartment  46 , wherein each one of the spaces may require a different temperature of cooling, i.e. for example the space  42  may be required for freezing products, while the space  44  may be required for keeping products only chilled or cooled. 
         [0016]    The apparatus  40  includes a container  48  having a side wall  50  defining a chamber  52  therein. The container  48  is provided with insulation  54  at four of the six sides of the side wall  50 . An inlet port  56  is provided to introduce CO 2  snow  58  into the chamber  52 . 
         [0017]    The side wall  50  has opposed side wall portions  60 , 62 . The side wall portions  60 , 62  are not insulated and therefore provide for the maximum heat transfer effect in view of their contact and exposure to the CO 2  snow  58 . It can be seen from  FIG. 3  that the chamber  52  in which the CO 2  snow  58  is disposed can also be constructed with a wall  64  which segregates the chamber  52  into a pair of chambers  58 A, 58 B for a purpose to be described hereinafter. As shown in  FIG. 3 , the chamber portion  58 A is exposed to the side wall portion  60 , while the chamber portion  58 B is exposed to the side wall portion  62 . In such a construction, the inlet port  56  would be disposed for access to both chamber portions  58 A, 58 B so that introduction of the CO 2  snow  58  can be with respect to both chamber portions. 
         [0018]    The uninsulated side portions  60 , 62  each have at least one and for most applications a plurality of moveable louvers  66 , 68  mounted thereto for pivoting movement with respect to each one of the respected side portions. In the embodiment of  FIG. 3 , the louvers  66  are mounted for pivoting movement with respect to the side wall portion  60  of the container  48  facing the space  42  where products are to be frozen. The louvers  68  are mounted for pivoting movement with respect to the side wall portion  62  of the container  48  facing the space  44  where products are to be chilled. The louvers  66 , 68  can be attached by mechanical fasteners (not shown) similar to that which were used in the embodiment shown in  FIGS. 1 and 2 , such as for example mechanical hinges. The louvers  66 , 68  have a construction similar to that of the louvers  22  of the embodiment in  FIGS. 1 and 2 , i.e. the louvers  66 , 68  may be provided with insulation along a surface which is exposed to the space  42  or space  44 , respectively, or the louvers  66 , 68  may be entirely insulated. 
         [0019]    The heat transfer apparatus  40  functions in a manner similar to that with respect to the embodiment of  FIGS. 1 and 2 , except that the apparatus  40  can provide heat transfer to air flow  70  in the space  42  for frozen products, and also heat transfer to the air flow  72  in the space  44  for chilled products. 
         [0020]    Since the space  42  is for frozen products, the maximum heat transfer effect will probably be necessary with respect to the CO 2  snow  58 . Therefore, a majority, if not all, of the louvers  66  are in the upright or completely open position to thereby expose the uninsulated side wall portion  60  to the air flow  70  for maximum heat transfer to be caused by the CO 2  snow  58 . For the space  44  however, only certain of the louvers  68  are in the open position because the amount of heat transfer necessary for the space  44  is not as great as is required for the space  42 . Therefore, certain of the louvers  68  are in the closed position lying against the side wall portion  62 , or are partially pivoted shut to prevent or limit heat transfer for the space  44 . In operation, one or a plurality of the louvers  68  may be closed or disposed in various angled positions commensurate to that which must occur between the air flow  72  and the side portion  62  to provide the necessary heat transfer for the space  44 . 
         [0021]    The air flows  70 , 72  are essentially warmer air, i.e. warm air rises in the compartment  46 . As the air flows  70 , 72  are exposed to the corresponding ones of the side wall portions  60 , 62  for heat transfer, the air flows cool and sink between corresponding ones of the louvers  66 , 68  as they proceed downward along the side wall portions  60 , 62 , whereupon airflow  74  is at a reduced temperature in the space  42 , while air flow  76  is also at a reduced temperature in the space  44 . 
         [0022]    Sensors  78 , 80  are mounted to be in communication with the spaces  42 , 44 , respectively, to sense freezing and chilling temperatures in the compartment  46 . The sensors  78 , 80  can be connected, wirelessly or otherwise, to a controller (not shown) to receive signals from the sensors to thereby adjust the louvers  66 , 68  to the required positions for heat transfer necessary at the spaces  42 , 44 . The sensors  78 , 80  can also be used with the embodiment of  FIG. 1 . 
         [0023]    CO 2  snow  58  will be consumed and therefore sublime in different degrees, depending upon its exposure to one of the side wall portions  60 , 62 . For example, the CO 2  snow  58  in the chamber portion  58 A which is closer to the side wall portion  60  will become more quickly reduced because the demand for heat transfer is increased in the frozen space  42  due to all of the louvers  66  being in the open or deployed position. In contrast, a level of the CO 2  snow  58  in the chamber portion  58 B which is closer to the side wall portion  62  will not sublime as quickly because certain of the louvers  68  are closed, thereby reducing the heat transfer effect and the related demand on use of the CO 2  snow, as the space  44  is only for chilling, as opposed to freezing. The independent movement of the louvers  66 , 68  provides for versatile temperature control to regulate spaces in an ITR container, truck, barge, etc. 
         [0024]    It will be understood that the embodiments described herein are merely exemplary, and that one skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as described and claimed herein. Further, all embodiments disclosed are not necessarily in the alternative, as various embodiments of the invention may be combined to provide the desired result.