AU5796000A - An evaporator unit - Google Patents

Description

WO 01/06185 PCT/AU00/00845 1 An Evaporator Unit Field of the invention The invention relates to an evaporator unit and in particular to a universal evaporator unit for use in a pre-existing refrigeration unit. 5 Background of the invention Modern day electric refrigerator units have been commonplace within almost every household in the industrialised world for at least the last sixty years. Household refrigerator units typically comprise a refrigerator chest having a sealed door in which food products are stored. The refrigerator unit also includes a refrigerant compressor for compressing the 10 refrigerant gas which is also connected to a condenser to condense the refrigerant gas to a liquid. The refrigerant liquid in is first passed through a filter drier to thereby filter out any impurities before it is pumped through a capillary unit whereby the liquid expands and cools to a low temperature suitable for freezing. This cooled refrigerant gas is passed to an evaporator coil located within a sealed container at the top of the refrigerator casing, adjacent to the 15 refrigerator's freezer compartment. The evaporator coil is sealed within the top of the refrigerator chest during manufacture of the refrigeration unit, usually in a moulding process. The evaporator coil is connected to the compressor so that after the refrigerant gas has passed through the compressor, it is then returned to the condenser whereby the process of condensing the gas to a lower temperature is 20 repeated. A problem with such refrigeration units is that as the evaporator coil is sealed within the top casing of the refrigerator chest, when the evaporator coil begins to leak or degrade, it is not possible to replace the evaporator coils and the whole refrigerator unit must be discarded. Hence, significant costs can be incurred in replace the refrigeration unit and will add to landfill 25 problems when dumping the unit at a rubbish disposal site, although the condenser and electric motor itself may still function. The applicant does not concede that the prior art discussed in this specification forms part of the common general knowledge in the art at the priority date of this application.

WO 01/06185 PCT/AU00/00845 2 Summary of the invention It is an object of the invention to provide an improved evaporator unit specifically adapted for use with a pre-existing refrigeration unit. According to a first aspect of the present invention, there is provided an evaporator unit specifically adapted for use with a pre-existing refrigerator chest of the type comprising an evaporator coil sealed within a compartment of the refrigerator chest to thereby provide a heat sink within the refrigeration chest when refrigerant gas passes from a inlet end to an outlet end of said evaporator coil, said inlet and outlet ends connected to a refrigeration cycle system located on the outside of the refrigeration chest to thereby supply cool refrigerant gas to said ) inlet end and remove heated gas from said outlet end, said evaporator unit comprising: a replacement cooling coil assembly adapted to be mounted to an internal wall of the refrigerator chest and connectable to said refrigeration cycle system, where in use, the cooling refrigerant is supplied to the replacement cooling coil assembly by the refrigeration cycle system, in order to refrigerate the interior of the refrigerator chest and thereby being adapted to replace the original evaporator coil located within said compartment. The replacement cooling coil assembly may comprises a casing mountable to said internal wall of the refrigerator chest and having at least two openings formed therein and a cooling tube located within said casing and having an inlet and outlet connectable to said refrigeration cycle system. Furthermore, the replacement cooling coil assembly may also comprises an air flow means mounted to the casing for drawing air through one of said openings and over said cooling tube, where in use, the air flow means draws air over the cooling tube in order to facilitate refrigeration within the refrigerator chest. The cooling tube may be bent into a serpentine formation so that the tube makes a plurality of passes within said casing and a plurality of heat exchange fins may be provided along the surface of said cooling tube. Both ends of the cooling tube can also be connected to the inlet and outlet ends via a bore drilled made through an internal wall of said refrigeration chest.

WO 01/06185 PCT/AU00/00845 3 Optionally, the air flow means comprises a fan which may be mounted adjacent to one of said at least two openings. One of said at least two openings may further comprise a multiplicity of narrow slits extending through the casing to allow air to flow therethrough. Furthermore, a defrost heater element may be provided on the bottom of the casing to evaporate condensate formed within the casing during operation and a condensate outlet opening may also extends through the bottom wall of said casing for removal of condensate formed within the casing. In another aspect of the present invention, there is provided an evaporator unit specifically adapted for use with a pre-existing refrigerator chest of the type comprising an ) evaporator coil sealed within a compartment of the refrigerator chest to thereby provide a heat sink within the refrigeration chest when refrigerant gas passes from a inlet end to an outlet end of said evaporator coil, said inlet and outlet ends connected to a refrigeration cycle system located on the outside of the refrigeration chest to thereby supply cool refrigerant gas to said inlet end and remove heated gas from said outlet end, said evaporator unit comprising: 5 a casing mountable to said internal wall of the refrigerator chest and having at least two openings formed therein; a cooling tube located within said casing and having an inlet and outlet connectable to said refrigeration cycle system; and air flow means mounted to the casing for drawing air through one of said openings and ) over said cooling tube, where in use, the air flow means draws air over the cooling tube in order to facilitate refrigeration within the refrigerator chest; wherein where in use, the cooling refrigerant is supplied to the cooling tube by the refrigeration cycle system, in order to refrigerate the interior of the refrigerator chest and thereby replace the original evaporator coil located within said compartment. 5 In yet another aspect of the present invention, there is provided an evaporator unit specifically adapted for use with a pre-existing refrigerator chest of the type comprising an evaporator coil sealed within a compartment of the refrigerator chest to thereby provide a heat sink within the refrigeration chest when refrigerant gas passes from a inlet end to an outlet end of said evaporator coil, said inlet and outlet ends connected to a refrigeration cycle system WO 01/06185 PCT/AU00/00845 4 located on the outside of the refrigeration chest to thereby supply cool refrigerant gas to said inlet end and remove heated gas from said outlet end, said evaporator unit comprising: a cooling tube located within said casing and having an inlet and outlet connectable to said refrigeration cycle system; and 5 air flow means mounted to the internal wall of said refrigeration chest for drawing air over the cooling tube in order to facilitate refrigeration within the refrigerator chest; wherein where in use, the cooling refrigerant is supplied to the cooling tube by the refrigeration cycle system, in order to refrigerate the interior of the refrigerator chest and thereby replace the original evaporator coil located within said compartment. ) In still another aspect of the present invention, there is provided a method to attach an evaporator unit to a pre-existing refrigerator chest of the type comprising an evaporator coil sealed within a compartment of the refrigerator chest to thereby provide a heat sink within the refrigeration chest when refrigerant gas passes from a inlet end to an outlet end of said evaporator coil, said inlet and outlet ends connected to a refrigeration cycle system located on the outside of the refrigeration chest to thereby supply cool refrigerant gas to said inlet end and remove heated gas from said outlet end, said method comprising the steps of: (a) deconnecting said inlet and outlet ends connected to said refrigeration cycle system; (b) mounting a replacement cooling coil assembly to an internal wall of the ) refrigerator chest; (c) connecting said replacement cooling coil assembly to the refrigeration cycle system; (d) supplying cooling refrigerant to the replacement cooling coil assembly by the refrigeration cycle system, in order to refrigerate the interior of the refrigerator chest and thereby i replace the original evaporator coil located within said compartment. Another aspect of the invention provides an evaporator unit for use with a pre-existing refrigerator chest having refrigerant apparatus for the supply of cooling refrigerant, the evaporator unit comprising: WO 01/06185 PCT/AU00/00845 5 a casing mountable to the refrigerator chest and having at least two openings formed therein; a cooling tube provided within the casing and connectable to said refrigerant apparatus, air flow means mounted to the casing for drawing air through one of said openings and over said cooling unit; where in use, the air flow means draws air over the cooling unit in order to refrigerate the internal refrigerator chest. A further aspect provides an evaporator unit for use with a pre-existing refrigerator chest having refrigerant apparatus for the supply of cooling refrigerant, evaporator unit comprising: a cooling unit adapted to be mounted to an internal wall of the refrigerator chest and connectable to said refrigerant apparatus, and air flow means mounted adjacent to the cooling unit for passing air over the cooling unit; where in use, the air flow means causes air to be passed over the cooling unit in order to refrigerate the interior refrigerator chest In one embodiment of the invention, the evaporative tube is bent into a serpentine formation so that the tube makes a plurality of passes within the refrigerator chest. The heat exchange fins comprise a plate of material having a high thermal conductivity which have slits formed along its surface in a configuration which allows the bends of the tubes to be inserted therethrough. During construction of the unit, bends along the edges of the tube are drawn through the slits and the fins moved along the tubes for location and contact thereon. In the description and claims of this specification the word "comprise" and variations of that word, such as "comprises" and "comprising" are not intended to exclude other features, additives, components, integers or steps but rather, unless otherwise stated explicitly, the scope of these words should be construed broadly such that they have an inclusive meaning rather than an exclusive one.

WO 01/06185 PCT/AU00/00845 6 Brief description of the drawings Notwithstanding any other forms which may fall within the scope of the present invention, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: 5Fig. 1 is an illustration of front view of a preferred embodiment of a evaporator unit; Fig. 2 illustrates a side cross-sectional view of the evaporator unit shown in Fig. 1; Fig. 3 illustrates a rear view of the evaporator unit of Fig. 1; Fig. 4 illustrates a front view of an evaporator coil unit located within the casing of the evaporator unit shown in Fig. 1 to Fig. 3 above; ) Fig. 4A illustrates a top view of the evaporator coil unit of Fig. 4; and Fig. 5 illustrates a side view of the evaporator coil unit of Fig. 4. Fig. 6 is a schematic illustration of a pre-existing refrigerated chest of the type to which the evaporator unit of Fig. 1 is specifically attach to connect to; Fig. 7 is a schematic illustration of the evaporator unit of Fig. 1 connected to the pre existing refrigerator chest. Detailed description of the embodiments A preferred embodiment provides an evaporator unit that can be mounted the inner wall of a pre-existing refrigerator chest of the type. The pre-existing refrigerator chest comprises an evaporator coil that is sealed within a top compartment of the refrigerator chest to thereby provide a heat sink within the refrigeration chest when refrigerant gas passes from an inlet end to an outlet end of the evaporator coil. The inlet and outlet ends are connected to a refrigeration cycle system located on the outside of the refrigeration chest to thereby supply cool refrigerant gas to the inlet end and thereby remove heated gas from said outlet end. The evaporator unit comprises a replacement cooling coil assembly which is mounted to an internal wall of the refrigerator chest. The cooling coil assembly can be connected to the refrigeration cycle system so that in use, the cooling refrigerant is supplied to the replacement cooling coil assembly by the refrigeration cycle system to thereby refrigerate the interior of the WO 01/06185 PCT/AU00/00845 7 refrigerator chest. This permits the replacement of the original evaporator coil located within the compartment, when the original evaporator coil is defective, for example, due to leakage. Referring now to Fig. 1, there is shown a replacement cooling coil assembly in the form of a universal evaporator unit 10 which is mountable to a refrigeration unit (refer to Fig. 7) as 5 will be described further below. The evaporator unit 10 comprises a rectangular shaped casing having a front wall 12, a base 14, a rear wall 16 (shown in Fig. 3), two side walls 18 and 19 and a top wall 22. The front wall 12 is provided with a multiplicity of inlet openings 24 formed on the surface of front wall 12, for allowing air to be drawn into the internal casing during operation of ) the evaporator unit 10, as will be further described below. Referring now also to Fig. 2, located above the inlet openings 24 is an outlet which has an airflow means in the form of electric evaporator fan 28 mounted on support bracket 30 (refer to Fig. 2) which is mounted on rear wall 16, so that the electric fan 28 is adjacent to the outlet opening 26. Optionally, the fan may be mounted on a panel formed in the casing during the p manufacturing process and in other embodiments, may be mounted outside the casing, adjacent the outlet opening 26. Although it is not shown in this example of the invention, the outlet opening 26 may be provided with a protective grid covering which allows air to flow through the opening by the operation of the electric fan 28, but which prevents articles from entering or passing through the Opening 26 and possibly causing injury to the fan 28. Referring now to Fig. 3, the evaporator unit 10 can be mounted to an internal side wall of a refrigerator chest by locating support screws secured to the side wall of the freezer compartment of the refrigerator chest, which are passed through the holes 32 provided on the corner edges of the rear wall 16. There is also provided on the rear wall 16, an access hole 34, 34' (refer to Fig. 2) which respectively provide apertures for the connection of the evaporator unit 10 with an inlet connected to a pre-existing capillary (or expansion valve) and an outlet connected to a compressor, as will be explained below. Referring now to Fig. 4 and 4a, there is shown a cooling tube in the form of evaporator coil tube 40. Fig. 5 illustrates a side view of the evaporator coils looking from the direction of WO 01/06185 PCT/AU00/00845 8 arrow 42 shown in Fig. 4. The evaporator coil tube 40 is provided within the casing, substantially adjacent to the area shown by broken lines 36 of Fig's 1, 2 and 3. With reference to Fig's 4, 4A and 5, the evaporator coil tube 40 comprises a copper evaporator tube 44 which has been bent in a serpentine formation so that the tube makes five passes within the casing of the evaporator unit 10. Along the length of each tube pass, are a series of evaporator fins 46 which assist in heat transfer. The fins 46 are formed of a material having high thermal conductivity such as aluminium. These fins 46 contact the exterior surfaces of each pass of the evaporator tube 44 so as to increase the heat exchange surface area provided between the evaporator tube 40 within the casing of the evaporator unit 10. In the preferred embodiment, the fins 46 have a series of slits 48 formed on its surface as will be seen more clearly in Fig. 5, which are provided for location of the passes of the tubes therethrough. In this regard, during the manufacture of the evaporator coil tube 40, the bends between each pass of the tube 44, are inserted into the slits 48 and the evaporator fins 46 are slid along the external surface of the evaporator tubes 44 for placement thereon as will be seen in Fig. 4. Hence, it is not necessary to weld the evaporator fins 46 to the evaporator tubes 44, which substantially decreases the manufacturing time of the evaporator coil tube 40. Referring now to Fig's 4 and 5, there is shown an inlet end 50 and an outlet end 52 of the evaporator tube 44 for the respective in and out flow of refrigerant fluid therethrough, as will be described below. The inlet and outlet end 50, 52, extend through access hole 34 and the inlet end 50 is connected to a refrigerant inlet tube , which is in fluid communication with a pre-existing capillary unit. The outlet end 52 is connected to a refrigerant outlet pipe which is in fluid communication with a pre-existing compressor provided on the external surface of the refrigeration chest. A pre-existing evaporator chest is shown in Fig. 6, in which a refrigerator chest 60 of the type used in common households is shown by the dashed lines 62 representing a top compartment of the refrigeration chest 60. An evaporator coil 64 is moulded in the top compartment 62 during construction of the refrigerator 60.

WO 01/06185 PCT/AU00/00845 9 The refrigerator 60 also comprises a door 65 which is operatively opened by a person pulling on handle 66 to access refrigeration chamber 68 in which food and other items are stored. The dashed lines 70 represent the inner walls of the chamber 68. Connected to a back wall 72 of the chamber 68 is a heat exchange coil 74 that is connected to the wall 72 via support arms 76 and 76'. The heat exchange coil is connected to a compressor 76 via pipe 78 and the compressor is located at the base of the refrigerator 60. As is known in the art, the refrigerator operates by the compressor 76 compressing refrigerant gas to the heat exchange tube 74 where it is cooled to a refrigerant liquid at high pressure. The liquefied refrigerant then passes via outlet pipe 80 to an expansion valve 82 ) located adjacent to a top wall of compartment 62. As the liquefied refrigerant passes through expansion valve 82, the refrigerant drops to a lower pressure and evaporates and thereby absorbs heat as it passes through the evaporative coils 64. Cooled liquid is then passed out of the outlet pipe 84 and back towards the compressor via pipe 86. When a pre-existing evaporator coil, such as coil 64 which is moulded into a top compartment of the refrigeration chest, degrades and leaks refrigerant gas, the refrigeration unit no longer works although the condenser, the compressor and the capillary unit are continuing to function. The installation method of the embodiment will now be explained. Referring now to Fig. 7 there is shown a schematic illustration of the evaporative unit 10 connected to the inner wall 72 of the refrigeration chamber 68. The pipes 83, 84 are isolated and the evaporator coil 64 is not longer connected to the compressor 76 and the expansion valve 82. The evaporator 10 is be mounted to the refrigeration chest 60 by drilling two holes for the refrigerant inlet pipe 83 and the outlet pipe 83' for connection to the inlet end 50 and outlet end 52 respectively of the evaporator unit 10. The evaporator unit 10 provides a replacement within the chamber 68 for the original evaporator coil 64 as the usual refrigeration system described above operates. It should be realised that the schematic illustration of the refrigerator 60 and the associated refrigeration system shown in Fig. 6 and Fig. 7 is not of the same dimensions or WO 01/06185 PCT/AU00/00845 10 drawn to scale as an actual refrigerator but is shown in the dimensions here for the purposes of illustration. In use, the condenser condenses refrigerant gas (such as SOLKANE 134A), so that it goes to a low temperature, and the refrigerant gas is transferred the capillaries (also known as an expansion valve) wherein it expands to a gas and thereby cools before being passed through the refrigerant inlet pipes to the inlet end 50 of the evaporator tube 44. The refrigerant gas passes through the evaporator tube 44 so that heat is removed from the internal refrigeration chest by the heat exchange of the tubes and the evaporator fins 46, which is enhanced by convective heat transfer caused by the operation of the evaporator fan 28 as will be discussed below. After passing through the evaporator tube 40, the refrigerant gas leaves at a higher temperature through outlet end 52. The heated refrigerant gas then passes to the compressor so as to compress the gas before it passes back through to the condenser and the process is repeated. The convective operation of the fan 28 will now be described. As the cooled refrigerant moves through the evaporator coil unit 44, the evaporator fan 28 switches on and begins to operate so that air within the refrigeration chest is drawn in through inlet openings 24 and passes over the evaporative fins 46 and evaporator tube 44 so as to maximise the heat removal from the air within the refrigeration unit chest. The cooled chest air is then expelled out through the opening 26 by the fan 28, causing the air within the chest to lower and thereby providing refrigeration of the internal refrigeration unit. The convective heat transfer caused by the action of the fan 28, enables a good rate of heat exchange per surface area of the evaporator tube 40, which allows for a compact design whereby the casing of the universal unit 10 is of aesthetically attractive slender rectangular design. The fan 28 can be connected electrically to the pre-existing electronics of the refrigerator. In this embodiment, the evaporator unit 10 is also provided with a defrost termination thermostat 38 which assists the evaporator unit 10 working in a defrosting operation. In this regard, the defrost termination thermostat would be connected to a defrosting/heating element located on the coils 44, which in operation reduce the ice build up on WO 01/06185 PCT/AU00/00845 11 the coils and increase the efficiency of the coil operation. Such a heating element would preferably extend for the full length of the coils. The chamber evaporator unit 10 is preferably mounted within the freezer compartment of the chamber 68, but may in other embodiments, be mounted within the refrigeration compartment where non-frozen food is stored. In this regard, there may be provided in other embodiments of the invention, a switch on the evaporator unit 10 which enables it to operate on a freezer cycle (ie the cool down period is longer) or normal refrigeration cycle. There may also be provided a seal on the rear wall 16, for allowing the rear wall to seal with the internal side wall of the refrigeration chest and thereby prevent uncooled air from passing between the inlet and outlet refrigerant tubes. The container of the evaporator tube 10 is formed of moulded fibreglass, plastic or fabricated metal, which is usually used in the manufacture of white good products such as COLOURBOND®. In other embodiments the evaporator unit 10 may not necessarily be connected to the inside of the refrigeration chest but could be located on the outside of the chest with an opening such as opening 26 in fluid communication with the internal chest of the refrigeration unit. In such an embodiment, insulation is preferably provided around the evaporator unit 10 and around an opening which can be present to draw air in the chest, over the evaporator coil tube 40. It will be appreciated that as the evaporator unit 10 is able to be connected to a pre existing refrigeration unit, having an evaporator unit in its top section which has broken down, it is not necessary to throw away the whole refrigeration unit as the evaporator unit 10 can be fixed to the refrigeration unit 10 as described above and allow it to continue to operate. Not only does this reduce the replacement costs of a fridge but also reduces the landfill problems associated with having to dump the fridge chest at a garbage disposal area. It should also be understood that although the specific examples given in this example of the invention are for a refrigeration unit of the type being a typical domestic refrigeration unit, the evaporator unit could also have application in other refrigeration units such as in commercial refrigeration cases.

WO 01/06185 PCT/AU00/00845 12 It would be appreciated by a person skilled in the art that numerous variations and/or modifications may be made to the present invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are therefore, to be considered in all respects to be illustrative and not restrictive.

Claims (19)

1. An evaporator unit specifically adapted for use with a pre-existing refrigerator chest of the type comprising an evaporator coil sealed within a compartment of the refrigerator chest to thereby provide a heat sink within the refrigeration chest when refrigerant gas passes 5 from a inlet end to an outlet end of said evaporator coil, said inlet and outlet ends connected to a refrigeration cycle system located on the outside of the refrigeration chest to thereby supply cool refrigerant gas to said inlet end and remove heated gas from said outlet end, said evaporator unit comprising: a replacement cooling coil assembly adapted to be mounted to an internal wall of ) the refrigerator chest and connectable to said refrigeration cycle system, where in use, the cooling refrigerant is supplied to the replacement cooling coil assembly by the refrigeration cycle system, in order to refrigerate the interior of the refrigerator chest and thereby being adapted to replace the original evaporator coil located within said compartment.

2. An evaporator unit as claimed in claim 1, wherein said replacement cooling coil i assembly comprises: a casing mountable to said internal wall of the refrigerator chest and having at least two openings formed therein; and a cooling tube located within said casing and having an inlet and outlet connectable to said refrigeration cycle system.

3. An evaporator unit as claimed in claim 2, wherein said replacement cooling coil assembly comprises: air flow means mounted to the casing for drawing air through one of said openings and over said cooling tube, where in use, the air flow means draws air over the cooling tube in order to facilitate refrigeration within the refrigerator chest.

4. An evaporator unit as claimed in claim 2, wherein said cooling tube is bent into a serpentine formation so that the tube makes a plurality of passes within said casing.

5. An evaporator unit as claimed in any one of claims 2 to 4, wherein a plurality of heat exchange fins are provided to extend from the surface of said cooling tube. WO 01/06185 PCT/AU00/00845 14

6. An evaporator unit as claimed in any one of claims 2 to 5, wherein both ends of said cooling tube are connected to said inlet and outlet ends via a bore made through an internal wall of said refrigeration chest.

7. An evaporator unit as claimed in any one of claims 2 to 6, wherein said air flow 5 means comprises a fan.

8. An evaporator unit as claimed in claim 7, wherein said fan is mounted adjacent to one of said at least two openings.

9. An evaporator unit as claimed in any one of claims 2 to 8, wherein one of said at least two openings further comprises a multiplicity of narrow slits extending through the casing ) to allow air to flow therethrough.

10. An evaporator unit as claimed in any one of claims 2 to 9, wherein a heater element is provided on the bottom panel of the casing to evaporate condensate formed within the casing during operation.

11. An evaporator unit as claimed in any one of claims 2 to 9, wherein a condensate Outlet opening extends through the bottom wall of said casing for removal of condensate formed within the casing.

12. An evaporator unit specifically adapted for use with a pre-existing refrigerator chest of the type comprising an evaporator coil sealed within a compartment of the refrigerator chest to thereby provide a heat sink within the refrigeration chest when refrigerant gas passes from a inlet end to an outlet end of said evaporator coil, said inlet and outlet ends connected to a refrigeration cycle system located on the outside of the refrigeration chest to thereby supply cool refrigerant gas to said inlet end and remove heated gas from said outlet end, said evaporator unit comprising: a casing mountable to said internal wall of the refrigerator chest and having at least two openings formed therein; a cooling tube located within said casing and having an inlet and outlet connectable to said refrigeration cycle system; and WO 01/06185 PCT/AU00/00845 15 air flow means mounted to the casing for drawing air through one of said openings and over said cooling tube, where in use, the air flow means draws air over the cooling tube in order to facilitate refrigeration within the refrigerator chest; wherein where in use, the cooling refrigerant is supplied to the cooling tube by the refrigeration cycle system, in order to refrigerate the interior of the refrigerator chest and thereby replace the original evaporator coil located within said compartment.

13. An evaporator unit specifically adapted for use with a pre-existing refrigerator chest of the type comprising an evaporator coil sealed within a compartment of the refrigerator chest to thereby provide a heat sink within the refrigeration chest when refrigerant gas passes from a inlet end to an outlet end of said evaporator coil, said inlet and outlet ends connected to a refrigeration cycle system located on the outside of the refrigeration chest to thereby supply cool refrigerant gas to said inlet end and remove heated gas from said outlet end, said evaporator unit comprising: a cooling tube located within said casing and having an inlet and outlet connectable to said refrigeration cycle system; and air flow means mounted to the internal wall of said refrigeration chest for drawing air over the cooling tube in order to facilitate refrigeration within the refrigerator chest; wherein where in use, the cooling refrigerant is supplied to the cooling tube by the refrigeration cycle system, in order to refrigerate the interior of the refrigerator chest and thereby replace the original evaporator coil located within said compartment.

14. A method to attach an evaporator unit to a pre-existing refrigerator chest of the type comprising an evaporator coil sealed within a compartment of the refrigerator chest to thereby provide a heat sink within the refrigeration chest when refrigerant gas passes from a inlet end to an outlet end of said evaporator coil, said inlet and outlet ends connected to a refrigeration cycle system located on the outside of the refrigeration chest to thereby supply cool refrigerant gas to said inlet end and remove heated gas from said outlet end, said method comprising the steps of: (a) deconnecting said inlet and outlet ends connected to said refrigeration cycle system; WO 01/06185 PCT/AU00/00845 16 (b) mounting a replacement cooling coil assembly to an internal wall of the refrigerator chest; (c) connecting said replacement cooling coil assembly to the refrigeration cycle system; (d) supplying cooling refrigerant to the replacement cooling coil assembly by the refrigeration cycle system, in order to refrigerate the interior of the refrigerator chest and thereby replace the original evaporator coil located within said compartment.

15. An evaporator unit for use with a pre-existing refrigerator chest having refrigerant apparatus for the supply of cooling refrigerant, the drop in evaporator unit comprising: a replacement cooling coil assembly, adapted to be mounted to an internal wall of the refrigerator chest and connectable to said refrigerant apparatus, where in use, the cooling refrigerant is supplied to the cooling coil assembly by the refrigerant apparatus, in order to refrigerate the interior of the refrigerator chest.

16. An evaporator unit for use with a pre-existing refrigerator chest having refrigerant apparatus for the supply of cooling refrigerant, the evaporator unit comprising: a casing mountable to the refrigerator chest and having at least two openings formed therein; a cooling tube provided within the casing and connectable to said refrigerant apparatus, air flow means mounted to the casing for drawing air through one of said openings and over said cooling unit; where in use, the air flow means draws air over the cooling unit in order to refrigerate the internal refrigerator chest.

17. An evaporator unit for use with a pre-existing refrigerator chest having refrigerant apparatus for the supply of cooling refrigerant, evaporator unit comprising: a cooling unit adapted to be mounted to an internal wall of the refrigerator chest and connectable to said refrigerant apparatus, and WO 01/06185 PCT/AU00/00845 17 air flow means mounted adjacent to the cooling unit for passing air over the cooling unit; where in use, the air flow means causes air to be passed over the cooling unit in order to refrigerate the interior refrigerator chest. 5

18. An evaporator unit specifically adapted for use with a pre-existing refrigerator chest, substantially as herein described with reference to the accompanying drawings.

19. A method to attach an evaporator unit to a pre-existing refrigerator chest, substantially according to any one of the examples described herein with reference to the accompanying drawings.