AU628091B2 - Improved evaporator - Google Patents

Description

I 628091

AUSTRALIA

PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: *9 It o at 0 cC i 09 IS *1 99CC TO BE COMPLETED Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: BY APPLICANT GORDON S-TEWAR-T- 36 Viret Street, New South Wales, Australia Hunters Hill, 2110, Gordon Stewart ARTHUR S. CAVE CO.

Patent Trade Mark Attorneys Level Barrack Street SYDNEY N.S.W. 2000

AUSTRALIA

2' Complete Specification for the invention entitled IMPROVED

EVAPORATOR.

The following statement is a full description of this invention including the best method of performing it known to me:- 1 ASC 49 so 108 1 9 1:3/ 1O/C-) 0445J/PP IMPROVED EVAPORATOR The present invention relates to evaporators and more particularly relates to improvements in an evaporator coil especially adapted for the production of ice cubes.

There are in existence ice making evaporators which essentially comprise a coil formed from copper piping in which a refridgerant gas travels according to conventional practice.

The coil is overlain by a layer of interengaged cups which provide receptacles for ice formation when the evaporator is in use. Whilst this arrangement for an evaporator coil has been found to be effective, a number of shortcommings have manifested themselves during use in ice production.

Ice is formed using the evaporator in the following way.

The evaporator coil and cup assembly is generally disposed in a vertical attitude. Refridgerant gas is passed through the pipe network forming the coil and this cools the copper to a marked degree. Water is passed over the coil but more particularly over the cups. Due to the low temperature at the base of the cups (due to the said base being in conjunction with the cooled pipes) water entering the cups and engaging the base of the cup freezes. This process continues until all water which has remained in the cups freezes thus, forming a cube of ice in each cup. Heat is then applied to the pipe coil so that the ice cubes can be released from the cups.

One problem which has been experienced with the particular cup configuration previously used is in the resistance to release of the ice cubes due to concave outward and/or inward wall surfaces in the cups which are a necessary 2 1718j o I~ 00 0 0 00 4 4

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00 4 0 consequence of the existing manufacturing techniques. The resistance to release of the ice cubes due to the aforesaid cause, generally slows down ice production leading to an overall reduction in the efficiency which could be achieved if this problem was not manifest.

The prior art cups are formed from relatively thick copper plate which is stamped and bent to form each cup.

Buckling in the cup walls occurs during the manufacturing process creating the aforesaid concavity or convexity in the cups.

A further problem with the prior art cups relates to the relatively high heat required to dislodge the ice cubes from the cups due to their configuration. This increases the time for release of the ice cubes after their formation. The increase in the heat required is also due to the copper bulk in the plates which form the ice cups.

The present invention seeks to improve the efficiency of ice production using an evaporator by reducing the time involved in the frost/defrost cycle. This is done by the provision of an improved ice cup configuration on the coil and a new manufacturing method for creation of this configuration.

The efficiency is achieved both by the new configuration and by a reduction in the volume of material to form the cups. The heat required to release ice cubes is dramatically reduced as a consequence of the reduced volume of material in the cups.

The cups for use with the present invention are formed from flat plates preferably copper plates having no convexity or concavity in any one plane. There are essentially two plate sizes, a first being narrow and rectangular and a second being -3- 1718j i -C wider than the first but also rectangular. The first of theplates in conjunction with the second form the cups in a manner to be described in detail below.

In addition to this improvement, it has been found that if the coil pipes are flattened so as to present a greater surface area to the base of tile cups formed by the plates a greater efficiency is achieved in the frost and defrost cycles.

According to the apparatus form, the invention comprises an evaporator of the type comprising a coil array and an array of cups, characterised in that the cups are formed by a series of channel sections welded together to form an array of 0 0 0 Schannels, said channels being divided at equal or unequal intervals by metal plates to thereby form said arrAy of cups, said array of cups being fixed to said coil.

*0 40 o 0 i A further improvement in the evaporator relates to the provision of the greater number of coil pipes per unit area due to the formation of mitred U bends. According to conventional methods the pipe coils are formed by providing continuous U bends enabling a continuous run of piping. The pipe diameter size previously has placed a limitation on the possible size of S •the U bend thereby putting a limitation on the distance between the pipes for a particular pipe diameter. The pipe diameter has previously dictated the size of the U bend. The U bends have now been made independent of pipe diameter as an improved technique has been employed whereby mitred joints enable reducing or enlarging junctions to be achieved allowing very small U bends where pipes of large diameters are used in the formation of the coil.

4 1718j 71 17 1 8j/KW The present invention seeks to overcome the aforesaid prior art disadvantages by providing a more efficient means of ice production by reducing the time iqvolved in the frost/defrost cycle.

In the broadest form of the apparatus aspect the present invention comprises; an evaporator for use in the production of ice of the type comprising cooling and/or heating coils attached to an array of ice cups, characterised in that the said cups are formed on the front, back or back and front of the coils from an array of interengaging flat plates; wherein each cup of the array is formed by said interengaging between two preformed first wide plates and two second narrow plates.

15 According to the preferred embodiment of the apparatus, 9 °the plates are either welded or soldered to the coils o° wherein the cups of the array are formed in rows with each 0row of cups formed by interengagement between two of said preformed first wide plates disposed in a first direction and a multiplicity of second narrow plates spaced apart and o o odisposed in a second direction.

0"o°o In one broad form of the method aspect of the present invention comprises; 00 a method of fabrication of an evaporator of the type which generally comprises a piped coil array to which is attached "an array or arrays of cups each formed from plates of two different sizes as hereinbefore described characterised in that the method comprises the steps of; forming each of at least two first plates into a shape substantially resembling an L with a reclining wall, up turning the horizontal extremity of the L to form a low wall, inserting aligned notches or cuts in the reclining back and low wall formed in the said at least two first plate, affixing each of the said at least two first plates onto the piped coil array in an abutting but parallel p relationship such that the reclining wall of one first plate engages the low wall of an adjacent first plate, 7 17l8j/iW inserting at least two second plates into the aligned notches such that one second plate is inserted in aligned notches so as to form in conjunction with another second plate at least one or a row of cups, connecting the said first plates to the said second plates by soldering or welding.

According to the broadest form of the method aspect, the present invention comprises; an improved method of fabrication of an evaporator of the type generally comprising a piped coil array and an overlying array of cups each formed from plates of two different sizes, characterised in that the improved method comprises the steps of; a) arranging an array of piping continuously to form a coil; S 15 b) forming an array of overlying cups frcm a series of flat 0 plates of a first size and plates of a second size 0 comprising the steps of; 00 Co Si) forming two bends in the first of said flat plates o °o to form a reclining wall, a lower wall and a base integral with each of' said walls; 000o ii) inserting spaced apart aligned notches or cuts in o00 *both of the said walls of the said first plate; iii) inserting at least two of the second sized plates into the said notches so that the first plates are disposed substantially normally to the longitudinal axis of said second plates thereby forming an array of cups; o ot 4 49 44 4 4 4t I I 9t

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I 44 4 St

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4*4 4414 iv) applying welds at the joins of said plates and welding the so formed cups to the said pipe coil.

In the preferred embodiment a further improvement to the manner of assembly of the piped coil comprises the welding and mitring of pipe members to form return U bends said U bend optionally converting a pipe of one diameter size to a pipe of either greater or lesser diameter.

The invention will now be described in more detail according to a preferred but non limiting embodiment and with reference to the accompanying illustrations wherein; Figure 1 shows an isometric view of an evaporator element having ice forming cups thereon on one side.

Figure 2 shows a side elevational view of the ice forming cups showing the configuration of one of the plates following bending.

Figure 3 shows an isometric view of the plates which combine to form the ice cups.

Figure 4 shows the tabs on the first plate which are used to stabilise the array of cups.

Figure 5 shows a cup array on both sides of the piped coil array.

Referring to figure 1 there is shows an isometric view of an evaporator element 1. This element is a representative section of a full evaporator assembly for the manufacture of ice. The evaporator element comprises a coiled pipe array 2 and an array of cups 3 located on the pipe array 2. The cups are formed according to the preferred embodiment by use of a comb" ttion of a series of first plates 5 and second plates 4.

Preferably the first plate is worked so as to form a 6 1718j substantially L shaped configuration having a first deep wall-,' a second shallow wall interconnected by a base. According to the present invention the cups are fabricated and subsequently fixed to the coil array 2 in the following manner.

The second plate 4 is prepared according to the desired depth of cup; thus the width of plate 4 is the sole determinant of this. Each second plate 4 comprises a substantially rectangular elongated plate having its shortest dimension commensurate with the depth of the first deep wall of the first plate 5. The first plate 5 is shown in figure 3 after the o bending and cutting operations have been performed on it. The S plate 5 is initially flat. A first longitudinal bend is then S placed in the plate forming a narrow wall 6. A second longitudinal bend is placed in the plate to form a deeper wall S 7. After bending, from an end view the plate has a oblique channel appearance with the long and short walls being evident. The first plate in this configuration resembles an L shape. At equal or unequal spacings along the longitudinal length of plate 5, cuts 8 and 9 respectively are placed through the full depth of each walls 7 and 6 (see figure These cuts are spaced along the length of the channel according to the width of the ice block required to be formed by the cups.

When the required number of plates have been bent and cut as described above, they are placed over the top of coil array 2 so that the short wall 6 of each first plate abuts the deep wall 7 of an adjacent first plate. The narrow wall may then be welded to the deep wall of the abutting first plate. This is repeated until the selected number of first plates are joined.

The second plates 4 may then be inserted into the cuts 8 7 1718j ii and 9. Each first plate is partitioned in segments by virtue, of the placement of the second plates thereby forming the ice cups. Spot welds may be placed where necessary to secure and brace the plates.

One advantage of this method is the reduced amount of metal required to form the cups thereby reducing material costs. Furthermore, due to the flatness of the sidewalls of each ice compartment so formed the prior art problems associated with the release of the ice cubes is eliminated. As the prior art method of manufacture of the cups introduced S concaves or convexes in the cup wall surfaces as a result of 00 the manufacturing technique used, the ice blocks tended to 0 to resist removal. Removal may now occur more easily due to the S flatness of the wall forming plates and with a reduction .n the *It amount of heat required to effect ice removal.

In figure 1 it can be seen that there is a resultant variation in the heights of plates 4 and deep wall 7 of plate This height differential enables an ice bridge to form so that ice blocks in one row remain connected by the bridge. It Me, ,ti is desirable that this bridge be kept to an optimum thickness so that each ice block in a row can break away from an adjacent block. The cup arrangement of this invention provides a quite narrow bridge which is easily broken.

The cup array is soldered to the piped coil array by placing the two arrays in an oven. A jig holds the cup array to the pipe array and the heating of the solder allows the two arrays to be fixed together via the base of the first plate It is found that the employment of the aforesaid cup fabrication method and the utilisation of the evaporator so 8 1718j r i formed would reduce the cost of manufacture of the evaporator by up to 30% and also will increase the efficiency of production. Production costs are reduced by the reduction in the heat requirement for release of the ice blocks.

A further improvement relates to the production of a more efficient pipe coil configuration by the use of mitred U bends. This has enabled the use of half inch pipes in the coil to be spaced much closer than previously, resulting in more efficient performance of the coil. Previously, due to the restrictions on U bend sizes, 3/8" pipes was the maximum size S that could be used to enable the minimum size U bend to be achieved using conventional bending techniques. The mitring j and welding/soldering of the U bend joints enables reduction or Senlarging couplings to be effected at the U bend.

II

A further improvement involves the flattening of the coil tubes to enable a greater surface area of coil to engage the base of the cups thereby improving the efficiency of Lh.e frost and defrost cycles.

In an alternative embodiment of the invention the refridgeration coils are sandwiched between two layers of cup arrays (see figure This has proven to be a most efficient means of increasing production of ice due to improved utilisation of energy from the coil. Effectively, a mirror image of the evaporator element in figure 1 is formed by the two layers of cup arrays.

Figure 5 shows an isometric view of an evaporator having a cup array on both the top and underside of the piped coil array. This effectively doubles the ice production. The cup array 8 is affixed to the piped coil array as previously -9- 1718j

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described.

The cups arrays may also be arranged in multiple tier form or in detached segments along the coil on either or both sides of the coil.

In a further embodiment the coils may be arranged so as to enable an array of plates to be attached to a multiple decker coil arrangement (not shown) thereby increasing ice production.

In an alternative form of the method aspect of the ~invention and in particular as an alternative to step b(iii) as previously described the following variation to the fabrication Oo° technique may be adopted. The said second plates have tabs 9 So fabricated along at least one longitudinal dimension preferably o ~at regular spaced intervals (see figure The plate is most efficiently formed by stamping or cutting the plate so that the tabs 9 are integral with the plate and disposed along at least 0001 one edge. The intervals between tabs may be variable. When a said second plate is inserted into the slots cut in the said second plate the tabs protrude through each notch forming a means to effectively key the second plate to the first plate.

This greatly assists in stabilising the cup arrays during manufacture and also eliminates the need for joint soldering of the plates. Soldering is still nevertheless required to affix the cup arrays to the coils.

When the tabs protrude through the slots these are simply folded over to engage the base of the first plate. This assists the engagement between the first and second plates and provides the aforesaid stability.

10 1718j 7 It will be recognised by persons skilled in the art that numerous variations and modifications can be made to the present invention without departing from the overall spirit and scope of the invention as broadly described herein.

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Claims (23)

1. An evaporator for use in the production of ice of the type comprising cooling and/or heating coils attached to an array of ice cups, characterised in that the said cups are formed on the front, back or back and front of the coils from an array of interengaging flat plates; wherein each cup of the array is formed by said interengaging between two preformed first wide plates and two second narrow plates.

2. An evaporator according to claim 1 wherein the cups of the array are formed in rows with each row of cups formed by interengagement between two of said preformed first wide plates disposed in a first direction and a multiplicity of said second narrow plates spaced apart and disposed in a rr 0 15 second direction.

3. An evaporator according to claim 2 wherein the said first and second directions are normal to each other, such ro: rthat the cups formed by the said plates are square or rectangular. S 20

4. An evaporator according to claim 3 wherein each of the said first wide plates in cross section comprise a first high wall and a second lower wall both continuous with a base with each of said first and second walls and base having a planar surface.

5. An evaporator according to claim 4 wherein each of the said second narrow plates comprise an elongated plate having one dimension approximating or being slightly deeper than the dt th of said first deep wall thereby enabling the formation of an ice bridge between adjacent cups.

6. An evaporator according to claim 5 wherein, when the cups are to be formed, each of a series of said second plates engage with a series of the said first plates via slots in the said first deep wall and said second shallow walls such that the said first and second plates interlock said second plates also having tabs along one edge to facilitate said interlocking.

7. An evaporator according to claim 6 wherein said first Pplate forms a predominantly L shaped channel when viewed in cross section. 2 a C 1718j/KW 13

8. An evaporator according to claim 7 wherein a series of first plates are disposed along the coils in a parallel configuration such that the said first deep wall of one plate abuts the second shallow wall of an adjacent plate.

9. An evaporator according to claim 8 wherein a series of second plates are disposed in a spaced apart parallel arrangement in said second direction and in engagement with said first plates via notches therein such that an array of cups are formed over the area of the coil.

10. An evaporator according to claim 9 wherein each of the cups of the array are dimensionally identical.

11. An evaporator according to claim 10 wherein, in each of said first plates, the said first deep wall and the narrow wall are disposed at an angle to the said base.

12. An evaporator according to claim 11 wherein there is an array of cups disposed on the front and back of the coils.

13. An evaporator according to claim 12 wherein the coils comprise copper tubing which engages the said base of the said first plates.

14. An evaporator according to claim 13 wherein the said copper tubing is flattened in order to present a greater surface area to the said base of the said first plates to thereby facilitate temperature transfer between the said tubing and said base.

15. An evaporator according to claim 14 wherein the tubing has bends formed therein by mitring of the ends of the tube to be joined thereby enabling lengths of the tubing to be disposed close together.

16. An evaporator according to claim 15 wherein the mitring of the piped coil joints enable a tight U bend to be formed in the piped coil.

17. An evaporator according to claim 16 wherein the piped coil array is formed from pipes of various diameters.

18. A method of fabrication of an evaporator of the type which generally comprises a piped coil array to which is attached an array or arrays of cups each formed from plates of two different sizes as hereinbefore described characterised in that the method comprises the steps of; forming each of at least two first plates into a shape k Y V 1718j /KW 14 substantially resembling an L with a reclining wall, up turning the horizontal extremity of the L to form a low wall, inserting aligned notches or cuts in the reclining back and low wall formed in the said at least two first plate, affixing each of the said at least two first plates onto the piped coil array in an abutting but parallel relationship such that the reclining wall of one first plate engages the low wall of an adjacent first plate, inserting at least two second plates into the aligned notches such that one second plate is inserted in aligned notches so as to form in conjunction with another second plate at least one or a row of cups, ~15 connecting the said first plates to the said second plates by soldering or welding. o

19. A method according to claim 18 wherein the first plate comprises after formation thereof, a reclining wall and a lower wall each of which walls are continuous with a base 20 interposed therebetween.

A method according to claim 19 wherein the second plate comprises an elongated rectangular plate with a series of tabs along one edge to facilitate engagement between said first and second plates.

21. A method according to claim 20 wherein an array of cups is formed on the front and back of the piped coil array.

22. A method of fabrication of an evaporator hereinbefore described comprising a piped coil array and an overlying array or arrays of cups each formed from plates of two different sizes characterised in that the improved method comprises the steps of; a) arranging an array of piping continuously to form a coil; b) forming an array of overlying cups from a series of first and second flat plates comprising the steps of; i) forming two bends in the first of said flat plates to form a reclining wall, a lower wall and a base integral with each of said walls; ii) inserting spaced apart aligned notches or cuts in both of the said walls of the said first plate; 1718j/KW iii) inserting at least two of the second sized plates into the said notches so that the first plates are disposed substantially normally to the longitudinal axis of said second plates thereby forming an array of cups; iv) joining said plates to each other and to the so formed cups to the said pipe coil, by soldering or welding.

23. A method according to claim 22 wherein an array of cups is formed on the front and back of the piped coil array. DATED this 25th day of May, 1992. onn o o 0 a 0 U O a bo O S t n pa o a a aD a a ED t t t GORDON STUART By His Patent Attorneys DAVIES COLLISON CAVE