Abstract:
A refrigerator includes a housing that defines an enclosable storage space. The refrigerator includes a closed manifold which defines a chamber to contain refrigerant. The chamber is made up of three parts, a cooling pipe, a head pipe, and one or more heat pipes to communicate fluid between the cooling and head pipes. The heat pipes are flat, elongated, and are divided internally to form capillary channels to permit flow of refrigerant between the cooling and head pipes. An array of thermoelectric modules contacts a surface of the manifold to chill refrigerant within the manifold. A pump or compressor is not required to circulate the refrigerant within the system. A blower forces an air stream to cool the heating faces of the thermoelectric modules. A control unit may be used to maintain the operating temperature of the refrigerator. A refrigerator may be portable, with a portable power source or adapters. The manifold design is useful for modular refrigerator appliance designs. The manifold is also useful in other refrigerating systems, cold storage units and portable devices.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to refrigeration units, including refrigerator appliances, refrigerating systems, and cold storage units.  
           [0003]    2. Background  
           [0004]    Many earlier refrigeration systems have utilized refrigerants that are potentially harmful when released to the environment. Certain refrigerants are desirable because they present higher operating efficiencies when used in conventional systems, although they may pose adverse environmental risks. Some efforts have been made to replace such harmful gaseous fluids with alternative fluids that are less harmful to the environment. However, such systems have suffered from various limitations and relatively low heat transfer efficiencies.  
           [0005]    In addition, earlier cooling and heating systems have included conventional heat exchange manifolds, piping and pumping systems for refrigerants. Some of the earlier systems have also incorporated thermoelectric modules for specifically defined cooling or heating functions. By way of example, the following US Patents described examples of such earlier systems: U.S. Pat. No. 6,354,086 to Inoue et al., U.S. Pat. No. 5,232,516 to Hed, U.S. Pat. No. 5,269,146 to Kerner, U.S. Pat. No. 5,540,567 to Schirpke et al., U.S. Pat. No. 5,653,111 to Attey et al., and U.S. Pat. No. 5,675,973 to Dong. The foregoing examples describe conventional fluid pumping and piping systems for transportation of fluid within the heat transfer or cooling systems described in those patents.  
           [0006]    Some of the earlier systems have attempted to improve the efficiency of heat exchange by incorporating complex fluid agitators. U.S. Pat. No. 6,354,086 to Inoue et al. is an example of an earlier patent in which such agitators are described. U.S. Pat. No. 5,269,146 describes a closed system heating and cooling system for thermally insulated containers such as portable refrigerated chests, heated bottles and serving carts for hotels and restaurants. Thermally conductive fluid is circulated through a closed loop circulating system. The heated or cooled fluid is passed through an air core heat exchanger for heat exchange with surrounding ambient air. The patent describes that the fluid is pumped at high speeds through the closed system to promote efficient heat transfer.  
           [0007]    Korean patent 2000-54406 is an example of an earlier cooling system using a thermoelectric module and conventional heat transfer arrangement. Another example of an earlier heat transfer system employing a heat transfer pipe without thermoelectric module components, is described in Korean patent number 190443. All of these earlier systems include conventional piping and circulation systems for refrigerants or other fluids. Many of these systems are prone to leakage and system malfunctions associated with mechanical problems, such as compressor failures.  
           [0008]    These earlier systems have not addressed the advantages of providing refrigeration systems having the improved efficiencies associated with the use of natural forces and inherent fluid flow characteristics of the capillary flow systems described below.  
         SUMMARY OF THE INVENTION  
         [0009]    The invention includes a refrigeration apparatus. In one aspect, the manifold defines an inner chamber containing an effective amount of a selected refrigerant. The inner chamber comprises an elongated first chamber, an elongated second chamber, and a plurality of heat pipes which define capillary channels in fluid communication between the first and second chambers. A selected number of thermoelectric modules are used to cool the refrigerant contained within the manifold. Preferably, the thermoelectric modules are positioned in cooling contact with a thermal transfer area defined by the manifold. A blower is provided to remove excess heat from the heating faces of the thermoelectric modules.  
           [0010]    Thermoelectric modules are also known in the art as Peltier devices. Earlier examples of Peltier devices are generally wafer-like structures that produce heat and cooling effects upon application of electric current.  
           [0011]    In another aspect, a refrigeration device is provided. In this example, the refrigeration device includes a housing. The housing defines one or more interior spaces. The interior spaces are in cooling, thermal communication with one or more manifolds. Each manifold defines an interior chamber containing an effective amount of a selected refrigerant. The inner chamber of the manifold comprises:  
           [0012]    a first cylinder, a second cylinder, and a plurality of capillary channels defined by the heat pipes. The channels establish fluid communication between the first and second cylinders. A plurality of thermoelectric modules are arranged so that their cooling faces thermally communicate with the manifold.  
           [0013]    In this example, one or more blowers are provided to force an air stream to cool the heating faces of the thermoelectric modules.  
           [0014]    By way of example, in another aspect, the present invention includes a heat transfer manifold used with arranged banks of thermoelectric modules. The apparatus may be employed in association with refrigeration systems, including appliances, cold storage units and other cooling systems. The manifold is particularly useful in those instances where it is desirable to avoid the use of conventional refrigerants such as freon and other potentially harmful refrigerants.  
           [0015]    Examples of preferred refrigerants are described.  
           [0016]    The manifold is typically positioned in a generally vertical orientation when the manifold is in operation, as described in more detail further below. In one aspect, the manifold comprises an upper cooling pipe that is in parallel alignment with a vertically opposed feeder pipe or head pipe. The head pipe or cooling pipe may be provided with a fluid opening to input thermally conductive fluid. In some instances, the fluid opening may be resealable so that refrigerant may be re-charged into the manifold. A plurality of generally planar heat pipes are positioned between the cooling pipe and the head pipe. In some instances, it is desirable to position the heat pipes so that their planar faces are parallel to the longitudinal axes of the cooling pipe and head pipe. In this embodiment, the heat pipes are coplanar and positioned so that their planar faces are aligned along the lengths of the cooling pipe and head pipe.  
           [0017]    As noted above, a refrigerant is provided within the closed fluid reservoir of the manifold. Heat exchange occurs through the operation of the thermoelectric modules and the repeated evaporation and condensation of the refrigerant within the fluid reservoir of the manifold.  
           [0018]    Preferably, each heat pipe is generally elongated and flat. The heat pipe is internally divided into capillary channels running along the length of the heat pipe. Preferably, the channels form a single layer of capillaries running along the length of the heat pipe. Each capillary channel extends from one end of the heat pipe to the other end of the heat pipe. Each capillary channel provides fluid communication between the cooling pipe and the opposed head pipe.  
           [0019]    The manifold component may be used in combination with a plurality of thermoelectric modules that have been aligned in planar arrays so that all heating faces of the modules are along one side of the array, and the cooling faces of the modules are along the opposite side of the array. The row of modules is positioned adjacent to the manifold to establish cooling, thermal communication between the cooling faces of the modules and the manifold.  
           [0020]    In some instances, the row of thermoelectric modules may be placed in contact with a heat transfer surface defined by either the cooling pipe, head pipe, or a coplanar array of heat pipes. In the preferred embodiment, the cooling faces of the thermoelectric modules are placed in thermal communication with an elongated heat transfer surface defined by the cooling pipe.  
           [0021]    In one aspect of the invention, the capillary channels in a heat pipe are generally rectangular tubes defined by the interior walls of the heat pipe. Preferably, the interior walls extend orthogonally from one face of the heat pipe to the opposing face of the heat pipe. However, the capillaries may be manufactured to have other cross-sectional configurations that are not necessarily square or rectangular in shape. The relative size of the capillaries will vary according to the design requirements and characteristics of the desired cooling system. The diameter of the capillaries may be adjusted to accommodate the particular flow characteristics of a specific fluid selected for use in the system. Design characteristics, including the optimal diameters for the capillaries may be adapted to account for differences in fluid flow, heat transfer characteristics, surface tension, and other physical properties exhibited by different refrigerants.  
           [0022]    In a preferred embodiment, the manifold will be positioned for operation so that the capillaries will extend in a generally vertical direction. The fluid flow and heat transfer characteristics within the capillaries will be enhanced by this vertical arrangement. It is preferred that the rows of modules be positioned near the top of the manifold to enhance generally downward thermal and fluid flow tendencies within the capillaries.  
           [0023]    In a preferred embodiment, the capillaries are arranged in a single layer of capillaries within the outer walls of the heat pipes. In other instances, multiple layers of capillaries may be provided within the outer walls of a heat pipe, although in many cases, such an arrangement may not be preferred.  
           [0024]    The manifold component is preferably made of a relatively strong, resilient, and thermally conductive material and most preferably, a metal which is not susceptible to excessive corrosion. Aluminum is a particularly useful material of construction for many applications of the present invention. Of course, persons skilled in the art will understand that other materials, including other metals, alloys, or non metallic materials may be desirable for use in the particular conditions and circumstances under consideration.  
           [0025]    Preferably, the fluid within the reservoir is filled until the liquid phase occupies about 40% to 70% of the volume of the reservoir. The vapor phase will occupy between about 30% and 60% of the volume of the reservoir. In a preferred cooling application, a suitable coolant will be filled until about 60%-70% of the reservoir volume is filled with the liquid phase, and 30%-40% of that volume is filled with the vapor phase.  
           [0026]    Embodiments of the inventions may be made of modular components, unlike many conventional cooling system designs. For example, the cooling manifolds are self contained units, and once they are disconnected from a power source, and optional control unit, may be extracted from the enclosing structure. The removed manifold or other modular components may be repaired or replaced with relative ease. Many conventional systems have complicated piping and pumping systems, expensive components and present various obstacles to repair or replacement of the refrigerating cores. Conventional pumps, compressors, and other system components are often expensive. The invention includes embodiments which permit system designs avoiding the use of many expense conventional system components.  
           [0027]    Other embodiments of the invention include fixed cold storage compartments provided in buildings and other structures. By way of example, modular manifold arrangements may be provided for installation along one or more interior walls of an insulated cold storage compartment of a building. In other embodiments, refrigerator units may be manufactured for installation with storage compartments and vehicles, including truck trailers, shipping containers and other like structures. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]    In the following description, the invention is further explained in connection with a preferred embodiment making reference to the drawings in which:  
         [0029]    [0029]FIG. 1 is a perspective, exploded representation of a refrigerator appliance in which the major components are depicted in a disassembled view.  
         [0030]    [0030]FIG. 2 is a perspective representation of a cooling manifold wherein the major comments are depicted in an exploded view.  
         [0031]    [0031]FIG. 3 is a perspective depiction of an enlarged partial exploded view of a heat pipes and cooling pipe of the manifold depicted in FIG. 2.  
         [0032]    [0032]FIG. 4 is an enlarged partial view of two adjacent heat pipes depicted in FIG. 3.  
         [0033]    [0033]FIG. 5 is an enlarged partial sectional view of several adjacent heat pipes of the manifold and the head pipe portion the manifold shown in FIG. 2.  
         [0034]    [0034]FIG. 6 is a perspective depiction of a partial section of an upper portion of the manifold shown in FIG. 2.  
         [0035]    [0035]FIG. 7 is a perspective depiction of a partial section of an upper portion of the manifold shown in FIG. 2, further depicting an array of cooling fins adjacent the upper portion of the manifold.  
         [0036]    [0036]FIG. 8 is a perspective depiction of the air cooling components of the manifold shown in FIG. 2, depicted in exploded view. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0037]    [0037]FIG. 1 shows a refrigerator appliance as one embodiment of the present invention in an exploded view, featuring several major components of the refrigerator. Outer doors  100  enclose two interior compartments defined by a unitary shell  200 . A cooling manifold assembly  300  includes two manifold assemblies which surround opposing side walls of shell  200 . An outer housing  500  is provided to receive the other major components of the refrigerator appliance. Upper hinge mounts  510  and lower hinge mounts  520  are used to secure front doors  100  to the housing  500 .  
         [0038]    In FIG. 1, one of the two manifold assemblies is depicted in exploded view. The manifold assembly  300  includes two opposing banks of heat pipes  320 . The two banks of heat pipes are depicted in a generally, vertical arrangement. The two banks of heat pipes, when installed in the appliance, will be in thermal communication with a corresponding internal storage compartment of the appliance. The two banks of heat pipes are preferably parallel to the interior walls of the storage compartment. Each bank of heat pipes  320  is attached for fluid communication with a corresponding head pipe  330 . Refrigerant is charged within the interior chamber of the manifold. The refrigerant circulates without the use of a refrigerant pump or compressor. Each bank of heat pipes presents a substantial heat transfer area, due in part to the elongated, flat surfaces of the heat pipes. Similarly, the internal capillary structure of the heat pipes further enhances the effective heat transfer area between the refrigerant and the interior space of the storage compartment. The substantial heat transfer area enhances the overall efficiency of the refrigeration system.  
         [0039]    An upper cooling assembly  310  comprises a linear array of cooling fans, positioned in thermal communication above an array of thermoelectric modules  315  and an underlying cooling pipe  317 . FIG. 3 shows an enlarged partial view of the connection established between upper ends of heat pipes  320  and corresponding fluid ports leading to the interior chamber defined by cooling pipe  317 . Cooling pipe  317 , in this embodiment, provides a common chamber for circulating refrigerant contained within the manifold. The heat pipes of both opposing banks of heat pipes are in common, fluid communication with the interior chamber of the cooling pipe  317 . Refrigerant contained within the manifold communicates between the interior space defined by the cooling pipe  317  and the head pipes  330 . Each head pipe  330  defines an interior space for fluid communication between the opposite (lower) ends of the respective banks of heat pipes  320 . Refrigerant contained within the manifold communicates between head pipes  330  and the cooling pipe  317  via the capillary channels defined in each heat pipe. FIG. 4 shows a pair of adjacent ends of heat pipes  320 , arranged in a common plane, with each heat pipe having a single layer of capillary channels extending in parallel along the length of the corresponding heat pipe. The capillary channels in the heat pipes allow refrigerant to communicate between head pipes  330  and the common cooling pipe  317 . With reference with FIG. 5, downwardly oriented arrows represent chilled refrigerant traveling downwardly along the various capillary channels. Chilled refrigerant, travelling in plugs of condensed refrigerant liquid, descends along the capillary channels. At the same time, portions of the refrigerant will evaporate during operation of the manifold causing vapor plugs of the refrigerant to ascend through various capillary channels of the heat pipes (as represented by the upwardly pointing arrow). Evaporated refrigerant enters into the cooling pipe  317  where the refrigerant will be chilled by the cooling operation of an array of thermoelectric modules  315 .  
         [0040]    With reference to FIGS. 6, 7, and  8 , a linear array of thermoelectric modules  315  contacts a heat transfer surface defined by cooling pipe  317 . The thermoelectric modules  315  are all arranged so that their respective cooling faces are in contact with cooling pipe  317 . Consequently, the heating faces of the thermoelectric modules  315  face outwardly away from the cooling pipe  317 . The heating faces of the thermoelectric modules  315  are in thermal communication with an upwardly projecting bank of cooling fins  314 . Cooling fins  314  are arranged in parallel so that adjacent fins within the arrangement define air flow channels for air forced through the channels by a linear array of fans  312 . The fans force air across the cooling fins to remove excess heat generated by the heating faces of the thermoelectric modules  315 . The fans are operated, preferably, through a control unit (not shown) set to activate the fans during operation of the thermoelectric modules  315 . Similarly, the control panel (not shown) may be set to actively operate the thermoelectric modules to maintain a set, desirable temperature for the internal storage compartment of the refrigerator appliance.  
         [0041]    In FIG. 8, a detailed representation of the air cooling assembly is shown. As noted above, cooling pipe  317  defines a contact surface for the cooling faces of the array of thermoelectric module  315 . Cooling pipe  317  includes a capped port  318  that may be used to charge and refill the manifold with a selected refrigerant. The cooling assembly includes a protective gasket  316  which frames an array of thermoelectric modules  315 . The gasket  316  is positioned between the lower surface of the cooling fin array  314  and the heat transfer surface defined by the cooling pipe  317 . Gasket  316  protects the thermoelectric modules against accidental damage due to over tightening of the fasteners used to assemble the various components of the air cooling assembly. In addition, the gasket  316  may be provided with insulative qualities to inhibit undesirable heat transfer activity at the interface between the cooling fin array  314  and cooling pipe  317 . The cooling pipe  317 , the gasket  316 , and the base of the cooling fin array  314  define co-axial holes for receiving bolts  311  used to secure the vertically stacked components of the cooling assembly. By way of example, bolt  311  extends through a co-axial bore defined by a fan housing in fan array  312 , a bore defined by a support collar  313 , the base of cooling fin array  314 , a bore defined by gasket  316 , and a bore defined by cooling pipe  317 . The bolts  311  are secured within the assembly by nuts (not shown).  
         [0042]    In this embodiment, air is inducted into the air flow channels formed between opposing pairs of cooling fins  314 . The flowing air is warmed upon contact with the cooling fins  314  and is exhausted near the upper end of the outer housing of the refrigerator appliance. The heating faces of thermoelectric modules are thereby cooled to prevent overheating during operation of the refrigerator appliance.  
         [0043]    In this illustrated embodiment, the interior compartment of the appliance includes a freezer compartment and cooling compartment. The freezer and cooling compartments are arranged side by side. Two banks of heat pipes  320  i.e. one bank from the two depicted manifolds, extend vertically through the gap formed between the freezer and chilling compartments. The first manifold, used to chill the cooling compartment, may be operated by a control panel which is separate and distinct from a second control panel used to operate the freezer compartment. The two control panels may be operated and wired independently of each other.  
         [0044]    In the preferred embodiment, the cooling fans are arranged in two linear arrays, in which one array of fans is positioned above the cooling manifold for the freezer compartment and a second fan array is positioned above the manifold used to cool the cooling compartment. The two cooling fan arrays are controlled independently in the preferred embodiment.  
         [0045]    Although a refrigerator appliance is depicted in the preferred embodiment, other embodiments will be apparent. For example, a portable cooling chest may be provided in which a manifold is used for cooling one or more interior walls of the chest. The overall size, configuration and power demands of the manifold are in part, depend upon the surface area, volume, and insulative qualities of the portable cooling chest. (A cooling chest may be designed for optimal operation so that the chest is positioned, in its normal orientation, so that the heat pipes in the manifold define capillary channels orientated in a generally vertical direction.  
         [0046]    In a portable cooling chest, a portable power source, including, a storage battery or portable generator may be provided to power a pre-selected number of thermoelectric modules to cool the internal compartment of the chest. One or more cooling fans may be provided, as required. A cooling chest may also be provided with adapters to convert AC power to a DC power supply for the thermoelectric modules. Similarly, adapters may be provided to connect with power outlets in vehicles for powering accessories. Other power source arrangements may also be provided.  
         [0047]    The thermoelectric modules are supplied with electric current from a suitable power source which is not shown. The power source is typically a DC power unit selected with the appropriate operational requirements for the thermoelectric modules and heat transfer requirements for the particular application.  
         [0048]    A wide range of refrigerants may be used in the manifold of the invention, including conventional refrigerants. However, the following are two examples of preferred refrigerants, identified as OS-12b™ and OS-12a™, which are believed to offer certain environmental advantages, as compared to selected conventional refrigerants.  
                                                         TABLE 1                           1) OS-12b ™            Classification   OS-12b   HCFC-22   HFC-1               Molecular mass   113.38   120.93   102.03       Boiling temperature (C.)   −26.59   −29.8   −26.5       Heat of vaporization at 0 C.   248.3   149.8   198.7       (KJ/Kg)       Stabilities       Thermal   Stable   Stable   Stable       Chemical   Stable   Stable   Stable       Erosive   No   No   No       Flammability (LFL &amp; UFL)   None   None   None       Autoignition temperature (C.)   None   None   None       Toxicity   No   No   No       O.D.P. (Ozone depletion poten-   0   1   0       tial)       G.W.P. (Global warming potential   &lt;3   8,100   1,300       in relation to CO2 with 100 years       integration time)       Lubricant   Mineral   Mineral   Ester                    2) OS-12a ™            Classification   OS-12a   HCFC-22   HFC-1               Molecular mass   57.9   120.93   102.03       Boiling temperature (C)   −34.5   −29.8   −26.5       Heat of vaporization at 0 C.   367.0   149.8   198.7       (KJ/Kg)       Stabilities       Thermal   Stable   Stable   Stable       Chemical   Stable   Stable   Stable       Erosive   No   No   No       Flammability (LFL &amp; UFL)   3.7˜9.5%   None   None       Autoignition temperature (C.)   540   None   None       Toxicity   No   No   No       O.D.P. (Ozone depletion potential)   0   1   0       G.W.P. (Global warming potential   3   8,100   1,300       in relation to CO2 with 100 years       integration time)       Lubricant   Mineral/Ester   Mineral   Ester                  
 
         [0049]    The above Table 1 is reproduced from information published by Technochem Co., Ltd. (http://www.technochem.com), Republic of Korea.  
         [0050]    ™—Trade-mark of Technochem Co., Ltd., Republic of Korea  
         [0051]    Of course, other refrigerants may be selected for various reasons. After a suitable refrigerant is selected, it is preferable to evacuate entrapped air from the interior of the manifold, during manufacture of the manifold. For example, the air may be evacuated through an access port. In the preferred embodiment, substantially all of the entrapped air will be removed and thereafter, the refrigerant will be charged into the interior of the reservoir of the manifold.  
         [0052]    Certain other refrigerants will also be preferred for certain applications. For example, conventional refrigerants such as R-142, R-141B and others may be used in cooling applications with a suitably adapted heat exchange manifold.  
         [0053]    With respect to the heat pipe design, it is believed that capillaries with cross-sectional diameters of about 4 mm in diameter were particularly efficient in refrigeration applications. In some instances, it may be desirable to use capillaries with smaller effective diameters. Capillary tubes that are generally rectangular when viewed in cross section may have dimensions of 1 mm×1.4 mm or lower. In other instances, the capillaries may have cross-sectional dimensions of about 0.5 mm×0.6 mm. Of course, other sizes of capillaries may be selected, based on various design considerations.  
         [0054]    However, the optimal size of the capillaries may vary according to the physical properties of the thermally conductive fluid selected for use in a particular heat exchange system. For example, surface tension, fluid viscosity and other factors may affect the optimal effective diameter of the capillaries in a particular system. A number of factors may affect fluid performance and thus affect the optimal and maximum diameters of the capillaries to be provided in the refrigeration system.  
         [0055]    It will be appreciated that refrigerants will tend to flow within the internal channels of the manifold due in part to cooling of the fluid and the capillary action exerted on the fluid within the capillaries of the manifold. One of the advantages of the invention is that it is unnecessary to provide a circulating pump to circulate the refrigerant within the interior chamber of the manifold. Although there may be instances where a circulating pump may be added, such a pump would not be necessary to circulate the refrigerant provided within the manifold.  
         [0056]    The present invention has been described with reference to preferred embodiments. However, other embodiments of the invention, and variations and modifications thereof will be apparent to those persons having ordinary skill in the art. It is intended that those other embodiments, variations and modifications thereof, will be included within the scope of the present invention as claimed within the appended claims.