Abstract:
An ice-making machine comprises a heat exchanger including a generally cylindrical, tubular body defining a generally cylindrical internal surface. The body is formed of corrodible material and has at least one refrigerant passage extending therethrough. End plates are provided at opposite ends of the body. A refrigerant inlet delivers refrigerant to the at least one refrigerant passage and a refrigerant outlet collects refrigerant having passed through the at least one refrigerant passage. An inlet delivers fluid from which ice is to be made into the body to permit the refrigerant to extract heat from the fluid and an outlet permits the egress of ice from the body. A cylindrical sleeve lines the internal surface and is formed from generally non-corrodable material. At least one blade is in contact with the sleeve and is movable about an axis to move across the sleeve and remove cooled fluid therefrom. A drive moves the at least one blade across the

Description:
CROSS-RELATED APPLICATIONS 
     The present application is a continuation application of U.S. application Ser. No. 09/134,834 filed on Aug. 17, 1998 now U.S. Pat. No. 6,056,046, which is a divisional application of U.S. application Ser. No. 08/633,704 filed on Apr. 19, 1996, now issued under U.S. Pat. No. 5,884,501. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to ice-making machines and in particular to an ice-making machine having a heat exchanger body with integrally formed refrigerant passages therein and to a heat exchanger therefore. 
     BACKGROUND OF THE INVENTION 
     Ice-making machines are well known in the art and many designs have been considered. For example, Applicant&#39;s U.S. Pat. No. 4,796,441 issued on Jan. 10, 1989 discloses an ice-making machine having a chamber with a fluid inlet to receive a brine solution from which ice is to be made and a fluid outlet to permit the egress of an ice-brine slurry from the housing. The interior surface of the chamber defines a heat exchange surface. A blade assembly is mounted on a rotatable shaft extending through the center of the chamber. The blade assembly is in contact with the heat exchange surface. A motor rotates the shaft at a rate such that the interval between successive passes of the blade assembly over the heat exchange surface is such so as to inhibit the formation of ice crystals on the heat exchange surface. 
     A tubular jacket surrounds the chamber. A refrigerant inlet and a refrigerant outlet communicate with the space between the jacket and chamber and are positioned at opposed ends of the ice-making machine. Refrigerant flowing from the inlet to the outlet boils and in so doing, cools the brine solution in contact with the heat exchange surface. Refrigerant leaving the ice-making machine via the outlet is compressed before being fed back to the inlet. Rings are welded to the jacket at laterally spaced locations to provide structural stability to the ice-making machine allowing it to withstand internal pressures. Although this ice-making machine works satisfactorily, it is time consuming and expensive to manufacture. 
     It is therefore an object of the present invention to provide a novel ice-making machine and a heat exchanger therefore. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention there is provided an ice-making machine comprising: 
     a heat exchanger including a generally cylindrical, tubular body and having a generally cylindrical internal heat exchange surface, said body being formed of corrodable material and having at least one refrigerant passage extending therethrough; 
     end plates at opposite ends of said body; 
     a refrigerant inlet to deliver refrigerant to said at least one refrigerant passage; 
     a refrigerant outlet to collect refrigerant having passed through said at least one refrigerant passage; 
     an inlet to deliver fluid from which ice is to be made into said body to permit said refrigerant to extract heat from said fluid; 
     an outlet to permit the egress of ice from said body; 
     a cylindrical sleeve lining the interior of said body and defining said heat exchange surface and being formed from generally non-corrodable material; 
     at least one blade in contact with said sleeve and movable about an axis to move across said sleeve and remove cooled fluid therefrom; and 
     a drive to move said at least one blade across said sleeve. 
     According to another aspect of the present invention there is provided an ice-making machine comprising: 
     a heat exchanger including a generally cylindrical, tubular body and having a generally cylindrical internal heat exchange surface, said body having at least one refrigerant passage extending therethrough and being constituted by a plurality of arcuate segments; 
     end plates at opposite ends of said body; 
     a refrigerant inlet to deliver refrigerant to said at least one refrigerant passage; 
     a refrigerant outlet to collect refrigerant having passed through said at least one refrigerant passage; 
     an inlet to deliver fluid from which ice is to be made into said body to permit said refrigerant to extract heat from said fluid; 
     an outlet to permit the egress of ice from said body; 
     at least one blade in contact with said surface and movable about an axis to move across said surface and remove cooled fluid therefrom; and 
     a drive to move said at least one blade across said surface. 
     According to still yet another aspect of the present invention there is provided an ice-making machine comprising: 
     a heat exchanger including a generally cylindrical, tubular body and having a generally cylindrical internal heat exchange surface, said body having at least one refrigerant passage extending therethrough; 
     end plates at opposite ends of said body, each of said end plates including an outer metal flange and an inner plastic insert; 
     a refrigerant inlet to deliver refrigerant to said at least one refrigerant passage; 
     a refrigerant outlet to collect refrigerant having passed through said at least one refrigerant passage; 
     an inlet to deliver fluid from which ice is to be made into said body to permit said refrigerant to extract heat from said fluid; 
     an outlet to permit the egress of ice from said body; 
     at least one blade in contact with said surface and movable about an axis to move across said surface and remove cooled fluid therefrom; and 
     a drive accommodated by said inserts to move said at least one blade across said surface. 
     According to still yet another aspect of the present invention there is provided an ice-making machine comprising: 
     a heat exchanger including a generally cylindrical, tubular body and having a generally cylindrical internal heat exchange surface, said body having a plurality of longitudinally extending refrigerant passages extending therethrough; 
     end plates at opposite ends of said body; 
     a refrigerant inlet receiving refrigerant and including refrigerant tracks adjacent one end of said body to deliver refrigerant to selected ones of said refrigerant passages; 
     refrigerant interconnects adjacent an opposite end of said body, said interconnects connecting said selected ones of said refrigerant passages to selected others of said refrigerant passages; 
     a refrigerant outlet collecting refrigerant from said selected others of said refrigerant passages; 
     an inlet to deliver fluid from which ice is to be made into said body to permit said refrigerant to extract heat from said fluid; 
     an outlet to permit the egress of ice from said body; 
     at least one blade in contact with said surface and movable about an axis to move across said surface and remove cooled fluid therefrom; and 
     a drive accommodated by said end plates to move said at least one blade across said surface. 
     According to still yet another aspect of the present invention there is provided an ice-making system comprising: 
     a plurality of ice-making machines arranged in an array, each of said ice-making machines including: 
     a heat exchanger including a generally cylindrical, tubular body and having a generally cylindrical internal heat exchange surface, said body having at least one refrigerant passage extending therethrough; 
     end plates at opposite ends of said body, each of said end plates including an outer metal flange and an inner plastic insert; 
     a refrigerant inlet to deliver refrigerant to said at least one refrigerant passage; 
     a refrigerant outlet to collect refrigerant having passed through said at least one refrigerant passage; 
     an inlet to deliver fluid from which ice is to be made into said body to permit said refrigerant to extract heat from said fluid; 
     an outlet to permit the egress of ice from said body; 
     at least one blade in contact with said surface and movable about an axis to move across said surface and remove cooled fluid therefrom; and 
     a drive accommodated by said inserts to move said at least one blade across said surface; 
     a connector coupling the refrigerant inlets of each of said ice-making machines, said connector including an inlet receiving refrigerant from a refrigerant source and delivering said refrigerant to each of said refrigerant inlets; and 
     a collector coupling the refrigerant outlets of each of said ice-making machines and having an outlet to return refrigerant to said source. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the present invention will now be described more fully with reference to the accompanying drawings in which: 
     FIG. 1 is a cross-sectional view of an ice-making machine in accordance with the present invention; 
     FIG. 2 is a cross-sectional view of the body of the ice-making machine heat exchanger taken along the line  2 — 2  in FIG. 1; 
     FIG. 3 is an end view of a gasket forming part of the ice-making machine of FIG. 1; 
     FIG. 4 is an end view of a blade assembly forming part of the ice-making machine of FIG. 1 taken in the direction of arrow  5 ; 
     FIG. 5 is a perspective view of the blade assembly of FIG. 4; 
     FIG. 6 is a perspective view of the portion of FIG. 3 showing the interconnections between refrigerant passages in a refrigerant circuit within the ice-making machine of FIG. 1; 
     FIG. 7 is a schematic of the ice-making machine of FIG. 1 connected to an ice-brine slurry recirculation circuit; 
     FIG. 8 is a front elevational view of a plurality of stacked ice-making machines in accordance with the present invention; 
     FIG. 9 is a side elevational view of the stacked ice-making machines of FIG. 8 taken in the direction of FIG. 8; 
     FIG. 10 a  is an end view of a heat exchanger body for an ice-making machine in accordance with the present invention; 
     FIG. 10 b  is an enlarged portion of Figure 10 b;    
     FIG. 11 a  is an end view of another embodiment of a heat exchanger body for an ice-making machine in accordance with the present invention; 
     FIG. 11 b  is an enlarged portion of FIG. 11 a;    
     FIG. 12 a  is an end view of yet another embodiment of a heat exchanger body for an ice-making machine in accordance with the present invention; 
     FIG. 12 b  is an enlarged portion of FIG. 12 a;    
     FIG. 13 a  is an end view of yet another embodiment of a heat exchanger body for an ice-making machine in accordance with the present invention; 
     FIG. 13 b  is an enlarged portion of FIG. 13 a;    
     FIG. 13 c  is another enlarged portion of FIG. 13 a;    
     FIG. 14 a  is an end view of still yet another embodiment of a heat exchanger body for an ice-making machine in accordance with the present invention; 
     FIG. 14 b  is an enlarged portion of FIG. 14 a;    
     FIG. 15 a  is an end view of still yet another embodiment of a heat exchanger body for an ice-making machine in accordance with the present invention; 
     FIG. 15 b  is an enlarged portion of FIG. 15 a;    
     FIG. 16 a  is a front elevational view, partly in section, of another embodiment of an ice-making machine in accordance with the present invention; 
     FIG. 16 b  is a cross-sectional view of a bottom end plate forming part of the ice-making machine of FIG. 16 a;    
     FIG. 16 c  is a bottom plan view of an aluminum flange forming part of the bottom end plate of FIG. 16 b;    
     FIG. 17 shows top plan and cross-sectional views of a plurality of ice-making machines arranged in an array and having refrigerant passages joined by a common collector; 
     FIGS. 18 a ,  18   b  and  18   c  are cross-sectional, top plan and side elevational views of another embodiment of an ice-making machine in accordance with the present invention; 
     FIGS. 19 a ,  19   b  and  19   c  are front elevational and cross-sectional views of yet another embodiment of an ice-making machine in accordance with the present invention; 
     FIGS. 20 a ,  20   b  and  20   c  are front elevational and cross-sectional views of yet another embodiment of an ice-making machine in accordance with the present invention; 
     FIG. 21 a  is a cross-sectional view of yet another embodiment of an ice-making machine in accordance with the present invention; 
     FIG. 21 b  is a side-elevational view of the ice-making machine of FIG. 21 a;    
     FIG. 22 a  is a cross-sectional view of yet another embodiment of an ice-making machine in accordance with the present invention; 
     FIG. 22 b  is a front elevational view of a heat exchanger body forming part of the ice-making machine of FIG. 22 a;    
     FIG. 22 c  is an enlarged cross-sectional view of a portion of FIG. 22 b;    
     FIG. 23 a  is a cross-sectional view of yet another embodiment of an ice-making machine in accordance with the present invention; 
     FIG. 23 b  is a front elevational view of a heat exchanger body forming part of the ice-making machine of FIG. 23 a;    
     FIG. 24 a  is a front elevational view, partly in section, of yet another embodiment of an ice-making machine in accordance with the present invention; 
     FIG. 24 b  is an enlarged cross-sectional view of a portion of the ice-making machine of FIG. 24 a;    
     FIG. 24 c  is a top plan view of a heat exchanger body forming part of the ice-making machine of FIG. 24 a;    
     FIG. 24 d  is an enlarged cross-sectional view of a portion of the heat exchanger body of FIG. 24 c;    
     FIG. 24 e  is an enlarged cross-sectional view of another portion of the heat exchanger body of FIG. 24 c;    
     FIG. 25 a  is an end view partly in section of a blade assembly for an ice-making machine in accordance with the present invention; 
     FIG. 25 b  is a cross-sectional view of an ice-making machine embodying the blade assembly of FIG. 25 a;    
     FIG. 26 a  is a cross-sectional view of yet another embodiment of an ice-making machine in accordance with the present invention; 
     FIG. 26 b  is an enlarged portion of FIG. 26 a  ; and 
     FIG. 26 c  is a top plan cross-sectional view of the ice-making machine of FIG. 26 a.   
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1, an ice-making machine is shown and is generally indicated to by reference numeral  10 . As can be seen, ice-making machine  10  includes a generally cylindrical housing  12  constituted by a cylindrical central heat exchanger body  14  and a pair of end plates  16  and  18  respectively secured to the ends of the heat exchanger body  14  by suitable fasteners (not shown). Gaskets  20  (best seen in FIG. 3) are positioned between the end plates  16  and  18  and the heat exchanger body  14  to seal the housing  12  and inhibit fluid leakage. 
     FIGS. 1,  2  and  6  best illustrate the heat exchanger body  14 . As can be seen, the heat exchanger body  14  is of a single piece construction formed from extruded aluminum and includes a cylindrical interior surface  30  which defines the heat exchange surface of the ice-making machine  10 . The heat exchange surface  30  is coated with a corrosion and erosion resistant agent. The corrosion and erosion resistant agent is in turn coated with a release agent such as Teflon® to inhibit the deposition of ice crystals thereon. 
     A plurality of refrigerant circuits  32 , in this example four, constituted by longitudinally extending refrigerant passages  34 , are integrally formed in the heat exchanger body  14  and are circumferentially spaced about the heat exchanger body. Each refrigerant circuit  32  includes a plurality of refrigerant passages  34 , in this case five which are labelled #1 to #5. The cross-sectional area of each of the refrigerant passages  34  in each refrigerant circuit  32  is different. 
     Specifically, the #1 and #2 refrigerant passages  34  are elliptical and have major axes aligned with radial lines extending from the center of the heat exchanger body  14 . The #3 refrigerant passages  34  are circular. The #4 and #5 refrigerant passages  34  also are elliptical. However, the major axes of these refrigerant passages are tangential to the heat exchange surface  30 . As can be seen, the # 1  refrigerant passages have the smallest cross-sectional area. The cross-sectional area of the refrigerant passages  34  increases with the assigned notation so that the # 5  refrigerant passages have the largest cross-sectional area. The elliptical cross-section of the #1, #2, #4 and #5 refrigerant passages  34  increases the surface area of the refrigerant passages as compared with circular passages and thereby increases heat transfer between brine solution contacting the heat exchange surface  30  and refrigerant flowing through the refrigerant passages  34 . This of course increases the efficiency of the ice-making machine. As one of skill in the art will appreciate, other refrigerant passage cross-sections can be selected to increase the surface area of the refrigerant passages. 
     The interior of each refrigerant passage  34  is preferably designed to create turbulence as refrigerant flows through the refrigerant circuits  32  thereby to enhance boiling of the refrigerant. In this particular embodiment, this is achieved by providing a turbulence creating structure on the interior surfaces  36  of the refrigerant passages  34 . Although not shown, it is preferred that the turbulence creating structure includes small trapezoidal fins on the interior surfaces  36 , referred to as microfins. 
     The spacing between adjacent refrigerant passages  34  in each of the refrigerant circuits  32  and the good thermal conductivity of the aluminum heat exchanger body portion  14  allows heat transfer between the refrigerant circulating through the refrigerant passages  34  and brine solution contacting the heat exchange surface  30  to occur about generally the entire circumference of the refrigerant passages  34  and not just the portion of the refrigerant passage walls proximal to the heat exchange surface  30 . This allows the efficiency of the ice-making machine  10  to be increased. 
     Referring now to FIGS. 1 and 6, the end plates  16  and  18  are better illustrated. The end plates  16  and  18  in this embodiment are annular and are formed in two pieces. If desired, the end plates may be casted as a single piece. Each end plate  16 ,  18  includes a central insert  16   a ,  18   a  formed of plastic material and an outer annular aluminum flange  16   b ,  18   b  surrounding and secured to the plastic insert  16   a ,  18   a  by suitable fasteners (not shown,). The end plates  16 ,  18  are bolted to opposed ends of the heat exchanger body  14 . 
     The outer flange  16   b  of end plate  16  has four refrigerant inlets  50  integrally formed therein, two of which are shown in FIG.  1 . Each refrigerant inlet  50  is connected to the #1 refrigerant passage  34  of a different refrigerant circuit  32  and receives a flow of refrigerant. Interconnect passages  54  are also formed in the outer flange  16   b  of end plate  16  and interconnect the #2 and # 3  refrigerant passages  34  and the #4 and #5 refrigerant passages  34  of each refrigerant circuit  32 . 
     The outer flange  18   b  of end plate  18  has four refrigerant outlets  60  formed therein, two of which are shown in FIG.  1 . Each refrigerant outlet  60  is connected to the #5 refrigerant channel  34  of a different refrigerant circuit  32  and allows the refrigerant to exit the ice-making machine  10 . Interconnect passages  64  are also formed in the outer flange  18   b  of end plate  18  to interconnect the #1 and #2 refrigerant passages  34  and the #3 and #4 refrigerant passages  34  of each refrigerant circuit  32 . FIG. 6 illustrates the interconnections between the refrigerant passages  34  in one of the refrigerant circuits  32  as established by the interconnect passages  54  and  64  respectively. 
     The central insert  18   a  of end plate  18  includes a brine solution inlet  66  and an ice-brine slurry outlet  68  to permit the ingress of brine solution or ice-brine slurry into the ice-making machine  10  and to permit the egress of an ice-slurry brine from the ice-making machine  10 . The brine solution inlet  66  co-operates with a hollow shaft  70  extending from the end plate  18  and partially into the central body portion  14 . A bushing  72  on the end plate  18  allows the hollow shaft  70  to rotate about its longitudinal axis relative to the end plate  18 . 
     A drive shaft  80  extends through the central insert  16   a  of end plate  16  and partially into the central body portion  14  before terminating at a pointed end  82  near the open end of the hollow shaft  70 . Bushings  84  on the end plate  16  allow the drive shaft  80  to be rotated about its longitudinal axis by way of a motor (not shown) relative to the end plate  16 . A seal  86  acts between the central insert  16   a  of end plate  16  and the shaft  80  to inhibit fluid leakage. 
     A blade assembly  90  (best seen in FIGS. 1,  4  and  5 ) is mounted on the hollow shaft  70  and the drive shaft  80  and includes a cylindrical blade carrier  92  through which three spaced, passages  94  are provided. One end of each passage  94  is in fluid communication with the open end of the hollow shaft  70  while the opposite end of each passage  94  is positioned to discharge brine solution towards the heat exchange surface  30 . The passages  94  are spaced 120° about the blade carrier  92  to balance the load placed on the shaft  82  as brine solution flows along the passages  94 . The radial spacing  95  between the outer surface of the blade carrier  92  and the heat exchange surface  30  is small, in this example ¼ inch, to maintain high velocity brine solution flow through the ice-making machine  10  and inhibit the formation of ice crystals on the heat exchange surface  30 . 
     The blade carrier  92  has a plurality of equi-circumferentially spaced, longitudinal keyed slots  96  formed in its outer surface. Each keyed slot  96  receives a plurality of blades  98  separated by spacers  100 . The arrangement of blades  98  and spacers  100  along each slot  96  is such that the blades  98  accommodated by the various slots  96  are longitudinally offset but slightly overlap. Since the blades  98  are spaced about the blade carrier  92  by approximately 120° and are in contact with the heat exchange surface  30 , the blades  98  help to center the shaft  82  with respect to the housing  12 . Springs  102  act between the blades  98  at the ends of the slots  96  and the spacers  100  to push the blades  98  towards the respective end plates  16 ,  18 . 
     Each blade  98  includes a flexible body  104  having one end  106  of a shape complimentary to the keyed slots  96 . The free end  108  of the body  104  terminates in a hook  110  defining an edge  112  to contact and ride against the heat exchange surface  30 . The blade  98  may be in the form of a composite with the hook  110  being formed of material more rigid than that of the flexible body  104 . Alternatively, the blade  98  may be formed from a single rigid material and profiled to allow the body  104  to flex in the desired manner. The top surfaces of the spacers  100  are serrated to define scraper elements  116 . 
     Referring now to FIG. 7, the ice-making machine  10  is shown connected to an ice-making system. As can be seen, the refrigerant inlets  50  are connected to the outlet of a condenser unit  120  by way of an inlet header (not shown). The refrigerant outlets  60  are connected to the inlet of the condenser unit  120  by way of an outlet header (not shown). The condenser unit  120  condenses and compresses refrigerant exiting the ice-making machine  10  by way of the refrigerant outlets  60  before recirculating the refrigerant to the refrigerant inlets  50 . The ice-brine slurry outlet  68  is connected to a discharge conduit  122 . Discharge conduit  122  leads to an outlet  124  as well as to a recirculation conduit  126 . Recirculation conduit  126  leads to an inlet conduit  128  which also receives brine solution. The inlet conduit  128  supplies brine solution and/or ice-brine slurry to the brine solution inlet  66 . A pump  130  is positioned along the recirculation conduit  126  to recirculate ice-brine slurry. The amount of brine solution entering the inlet conduit  128  and mixing with the recirculated ice-brine slurry can be controlled to allow the ice fraction of ice-brine slurry produced by the ice-making machine  10  to be adjusted as desired. 
     The operation of the ice-making machine  10  will now be described. In operation brine solution or ice-brine slurry (hereinafter referred to as brine solution) is fed into the ice-making machine  10  through the brine solution inlet  66 . The brine solution flows through the hollow shaft  70  and is then directed by the pointed end  82  of the drive shaft  80  towards the three passages  94  in the blade carrier  92 . The brine solution flows along the three passages  94  until the brine solution exits the blade carrier  92  adjacent the heat exchange surface  30 . While this is occurring, refrigerant enters each of the refrigerant circuits  32  by way of the refrigerant inlets  50 . The refrigerant flows along the refrigerant passages  34  of each refrigerant circuit  32  and exits the refrigerant circuits  32  via the refrigerant outlets  60 . As the refrigerant flows through the refrigerant passages  34  in the heat exchanger body  14 , the refrigerant absorbs heat through the heat exchange surface  30  and boils. The brine solution in contact with the heat exchange surface  30  is thus supercooled. 
     To avoid deposition of ice on the heat exchange surface  30  which would inhibit heat transfer to the refrigerant and thereby reduce the efficiency of the ice-making machine  10 , the blade assembly  90  is rotated by the motor driven drive shaft  80 . Specifically, the blade assembly  90  is rotated at a rate of speed that is fast enough to allow the blades  98  to remove the supercooled brine solution from the heat exchange surface  30  prior to crystallization of ice crystals on the heat exchange surface  30 . The supercooled brine solution therefore crystallizes in the brine solution between the blade carrier  92  and the heat exchange surface  30  allowing the brine solution to act as a secondary refrigerant in the formation of fine ice crystals throughout the brine solution. 
     The flexible nature of the blade bodies  104  allows the blades to conform to the heat exchange surface  30  as the blades  98  are rotated. If a layer of ice should inadvertently form on the heat exchange surface  30 , the blades  98  will flex until they overlie the outer surface of the blade carrier  92 . When this occurs, the scraper elements  116  project radially beyond the blades  98  allowing the scraper elements  116  to scrape the ice layer and avoid damage to the blades  98 . 
     The small radial spacing  95  between the blade carrier  92  and the heat exchange surface  30  ensures high velocity brine solution flow from the passages  94  to the ice-brine slurry outlet  68  in the end plate  18 . This further assists to inhibit the formation of ice crystals on the heat exchange surface  30 . 
     In order to increase efficiency of the ice-making machine  10 , the refrigerant passages  34  in each refrigerant circuit  32  increase in cross-sectional area along the length of the refrigerant circuit. The increased cross-sectional area maintains a high velocity of refrigerant as the refrigerant circulates through the refrigerant circuits  32  while avoiding a high pressure drop along the length of the refrigerant circuits  32  helping to increase the efficiency of the ice-making machine. In addition, the staggered arrangement of the various refrigerant passages  34  in each refrigerant circuit  32  helps to equalize heat transfer over the circumference of the heat exchanger body  14  and thereby maintain a uniform temperature within the ice-making machine  10 . Moreover, the microfin structure on the interior surfaces  36  of the refrigerant passages  34  enhances boiling of the refrigerant thereby improving its heat transfer ability. 
     As those of skill in the art will appreciate, the present ice-making machine allows fine ice particles in a brine solution to be made efficiently by increasing and equalizing heat transfer between the brine solution and the refrigerant over basically the entire heat exchange surface. 
     Although the end plate  18  has been described as having the brine solution inlet and the ice-brine slurry outlet provided therein, the brine solution inlet and ice-brine slurry outlet can be provided in end plate  16  or the brine solution inlet can be provided in one end plate and the ice-brine slurry outlet can be provided in the other end plate. Also, although end plate  16  is shown to include the refrigerant inlets and end plate  18  is shown to include the refrigerant outlets, the position of the refrigerant inlets and outlets can be reversed. Also, both the refrigerant inlets and refrigerant outlets can be formed in either the end plate  16  or end plate  18  if desired. 
     Referring now to FIGS. 8 and 9 another embodiment of an ice-making machine in accordance with the present invention is shown. In this embodiment, like reference numerals will be used to indicate like components with a suffix “1” added for clarity. As can be seen, a plurality of ice-making machines  10 ′ are stacked in an array. In this embodiment, the outer flanges  16   b ′,  18   b ′ of the end plates  16 ′,  18 ′ are hexagonal allowing the ice-making machines  10 ′ to be nested. The refrigerant inlets  50 ′ in the end plates  16 ′ are arranged in pairs. Each pair of refrigerant inlets  50 ′ is connected to a refrigerant conduit  200  extending between opposed sides of the end plates  16 ′. The open ends of the refrigerant conduits  200  are aligned with the refrigerant conduits  200  in the end plates  16 ′ of adjacent ice-making machines  10 ′. O-ring seals  202  act between adjacent ice-making machines  10 ′ to inhibit refrigerant leakage. A base  204  is attached to the end plate  16 ′ of the bottom ice-making machine  10 ′ of each stack to seal one end of the refrigerant conduits  200 . An inlet header  206  is attached to the end plate  16 ′ of the top ice-making machine  10 ′ of each stack to receive a flow of refrigerant and allow the refrigerant to be delivered to each of the ice-making machines  10 ′ in the stack. 
     The end plates  18  are of a similar design to allow refrigerant exiting the refrigerant circuits in each of the ice-making machines  10 ′ to be fed to refrigerant conduits. The refrigerant conduits in the end plates  18  of the ice-making machines  10 ′ in each stack are interconnected and lead to an outlet header attached to the top ice-making machine  10 ′ in each stack. 
     Although not shown, the end plates  16 ′ and  18 ′ can also be designed to include a similar arrangement for the brine solution inlet and ice-brine slurry outlet. This modular design of the ice-making machines allows the ice-making machines to be arranged in an array of a size selected to produce ice-brine slurry at the desired capacity. 
     Although the refrigerant passages have been described as being coated with a corrosion and erosion resistant agent and receiving the flow of refrigerant directly, the refrigerant passages and interconnect passages can be lined with tubing if desired to accommodate the flow of refrigerant along the refrigerant circuits. 
     Referring now to FIGS. 10 a  and  10   b , an alternative embodiment of a heat exchanger body is shown and is generally indicated to by reference numeral  224 . Similar to the first embodiment, the heat exchanger body is of a single piece construction formed from extruded aluminum and includes a cylindrical interior surface  230 . A plurality of cylindrical, refrigerant passages  234  extend through the body at generally equal, circumferentially spaced locations. The cross-sectional area of each refrigerant passage  234  is the same. 
     A thin cylindrical sleeve  235  formed of stainless steel lines the interior surface  230  to protect the heat exchanger body  224  from corrosion and erosion. The sleeve  235  is heat shrunk to the heat exchanger body and defines the heat exchange surface contacted by the rotating blades. The abutting ends  237  of the sleeve  235  are welded to inhibit brine solution from contacting the heat exchanger body. 
     FIGS. 11 a  and  11   b  show yet another embodiment of a heat exchanger body  224 A similar to that of FIGS. 10 a  and  10   b . In this embodiment, the cylindrical sleeve  235 A is glued to the interior surface  230 A of the heat exchanger body. The ends  237 A of the cylindrical sleeve  235  are joined by an adhesive  239 A. A thin strip of tape  241 A disposed between the sleeve  235 A and the heat exchanger body  230 A is secured to the sleeve  235 A and runs the length of the adhesive  239 A to form a seal thereby to inhibit brine solution from leaking through the adhesive and contacting the heat exchanger body  224 A. 
     FIGS. 12 a  and  12   b  show yet another embodiment of a heat exchanger body  224 B similar to that of FIGS. 10 a  and  10   b . In this embodiment, the cylindrical sleeve  235 B is also glued to the interior surface  230 B of the heat exchanger body. The ends  237 B of the cylindrical sleeve overlap and are glued to one another. The overlap is small, in this case {fraction (2/1000)}″, to minimize effects on the rotating blades. The overlapping ends  237 B are also arranged so that the blades rotate in a direction away from the step  243 B defined by the interior end of the sleeve  235 B. 
     Referring now to FIGS. 13 a  to  13   c  yet another embodiment of a heat exchanger body  324  is shown. In this embodiment, the cylindrical heat exchanger body is constituted by a plurality of interlocking elongate, arcuate extruded aluminum segments  351 . Refrigerant passages  334  extend longitudinally through the arcuate segments  351  at spaced locations. The abutting ends of the arcuate segments include co-operating formations  353 . As shown, the cooperating formations joining the arcuate segments differ although similar formations can be used at each joint between arcuate segments  351 . In this embodiment, similar to the first embodiment, the interior surface  330  of the heat exchanger body  324  is coated with a corrosion and erosion resistant agent. 
     FIGS. 14 a  and  14   b  show a heat exchanger body  324 A identical to that of FIGS. 13 a  to  13   c . In this case, however, the heat exchanger body  324 A is lined with a cylindrical sleeve  335 A identical to that shown in FIGS. 10 a  and  10   b  to protect the heat exchanger body from corrosion and erosion. 
     FIGS. 15 a  and  15   b  show yet another embodiment of a heat exchanger body  324 B. In this embodiment, the heat exchanger body is constituted by a plurality of circumferentially spaced, elongate, arcuate extruded aluminum segments  351 B. Refrigerant passages  334 B extend longitudinally through each arcuate segment. An inner cylindrical sleeve  335 B identical to that of FIGS. 10 a  and  10   b  lines the interior of the arcuate segments  351 B to define the cylindrical heat exchange surface contacted by the rotating blades. A cylindrical clamp  355 B surrounds the arcuate segments  351 B to inhibit their movement. Fasteners in the form of nuts and bolts  357 B (only one of which is shown) secure the ends of the clamp  355 B at spaced locations along its length. 
     Referring now to FIGS. 16 a  to  16   c , another embodiment of an ice-making machine in accordance with the present invention is shown and is indicated to generally by reference numeral  410 . The ice-making machine includes a housing  412  constituted by a cylindrical heat exchanger body  424  similar to that shown in FIGS. 10 a  and  10   b , and upper and lower end plates  416  and  418  secured to opposed ends of the heat exchanger body by suitable fasteners (not shown). The fasteners pass through aligned holes  420  in the end plates  416  and  418  and heat exchanger body  424 . Gaskets (not shown) are positioned between the heat exchanger body  424  and the end plates  416  and  418  to inhibit leakage. 
     FIG. 16 b  better illustrates the lower end plate  418 . As can be seen, the lower end plate includes a lower outer, annular aluminum flange  418   a , an inner plastic insert  418   b  and an upper outer, annular aluminum flange  418   c . An annular plate  422  is disposed between the upper and lower outer flanges  418   c  and  418   a  respectively. The upper outer annular flange  418   c  includes three outer refrigerant inlets  440  to which refrigerant conduits  442  receiving a flow of refrigerant are connected. Refrigerant passages  444  extend through the annular flange  418   c  and are aligned with the refrigerant passages  434  in the heat exchanger body  424 . The refrigerant inlets  440  communicate with an annular refrigerant track  446  (see FIG. 16 c  ) formed in the undersurface of the flange  418   c . Fingers  448  extend inwardly from the refrigerant track  446  and terminate at every second refrigerant passage  444 . 
     The lower outer annular flange  418   a  has an annular refrigerant channel  450  formed therein. An opening  452  is formed in the side of the flange  418   a  and accommodates a refrigerant outlet  454  which communicates with the refrigerant channel  450 . 
     The plate  422  separating the upper and lower annular flanges  418   a  and  418   c  respectively, has a plurality of holes formed in it. The holes are aligned with the refrigerant passages  444  in the upper outer annular flange  418   c  that do not communicate with the fingers  448 . Thus, these refrigerant passages  444  communicate with the refrigerant channel  450  in the lower flange  418   a.    
     The plastic insert  418 b is clamped to the upper and lower flanges  418   a  and  418   c  by C-clamps  418 d. An opening  455  is provided in the insert  418   b  and accommodates a brine solution inlet  457 . The plastic insert  418   b  also accommodates a bushing  484 . 
     The upper end plate  416  is also of a multipiece construction and includes an outer aluminum flange  416   a  and an inner plastic insert  416   b  clamped to the flange by C-clamps  416   d . The flange  416   a  has a plurality of interconnect passages  416   c  formed therein. Each interconnect passage  416   c  communicate with a pair of adjacent refrigerant passages  434  formed in the heat exchange body  424 . The plastic insert  416   b  has an opening  456  therein accommodating an ice-brine slurry outlet  458 . A central opening  460  is also provided in the plastic insert  416   b  and accommodates a bushing  462 . 
     A drive shaft  480  extends centrally through the housing  412 . One end of the drive shaft is accommodated by the bushing  484  in the plastic insert  418   b . The other end of the drive shaft extends through the plastic insert  416   b  and bushing  462  and is coupled to a motor  482 . 
     A blade assembly  490  is mounted on the drive shaft  480  within the heat exchanger body  424 . The blade assembly  490  includes a cylindrical blade carrier  492  surrounding the drive shaft. Three elongate blades  498  are mounted on the carrier  492  at spaced locations and contact the heat exchange surface. The blades  498  arc pivotally mounted on spaced posts  500  extending radially from the blade carrier  492 . Springs  502  act between the blades  498  and the posts  500  to bias the blades  498  so that they form angles with respect to the tangent of the heat exchange surface equal to approximately 110 degrees. The blades  498  are notched; however, the notches  498   a  in the blades are staggered so that the entire heat exchange surface is contacted by at least one blade. 
     In operation, brine solution is fed into the ice-making machine  410  through the brine solution inlet  454 . At the same time, the motor  482  rotates the drive shaft  480  and hence the blade assembly  490  so that the blades  498  sweep across the heat exchange surface. While the above occurs, refrigerant is fed into the refrigerant conduits  442  and delivered to the refrigerant inlets  440 . As refrigerant enters the refrigerant inlets  440 , the refrigerant is directed into the annular refrigerant track  446  by the plate  422  which isolates the refrigerant track  446  and refrigerant inlets  440  from the refrigerant channel  450 . Refrigerant directed into the refrigerant track  446  flows into the fingers  448  and then into every second refrigerant passage in the heat exchanger body  424  through every second refrigerant passage  444 . The refrigerant delivered to every second refrigerant passage in the heat exchanger body flows the length of the heat exchanger body to the upper end plate  416 . When the refrigerant in the refrigerant passages reaches the upper end plate  416 , the interconnect passages  416   c  direct the refrigerant into the adjacent refrigerant passages in the heat exchanger body  424 . The refrigerant in turn flows the length of the refrigerant passages back down to the lower end pate  418 . When the refrigerant reaches the lower end plate  418 , the refrigerant flows into the refrigerant passages  444 , through the holes in the plate  442  and enters the refrigerant channel  450 . The refrigerant is collected in the channel  450  and is discharged via the refrigerant outlet  454 . As the refrigerant flows through the refrigerant passages in the heat exchanger body  424 , the refrigerant absorbs heat from the brine solution through the heat exchanger body and boils. The brine solution in contact with the heat exchanger surface is thus, supercooled. 
     To avoid disposition of ice on the heat exchange surface, the motor  482  rotates the drive shaft  480  so that the blades  498  sweep across the heat exchange surface fast enough to remove the super-cooled brine solution from the heat exchange surface prior to crystallization of ice crystals on the heat exchange surface. The super-cooled brine solution therefore crystallizes in the brine solution between the blade carrier  492  and the heat exchange surface allowing the brine solution to act as a secondary refrigerant in the formation of fine ice crystals throughout the brine solution. The ice-brine slurry created in the heat exchanger body  424  exits the ice-making machine through the ice-brine slurry  458  outlet as additional brine solution is fed into the ice-making machine  410 . 
     As will be appreciated, in this embodiment refrigerant passes only along two refrigerant passages in the heat exchanger body  424  before being discharged ensuring efficient heat transfer. Also, because the end plates  416  and  418  include outer aluminum flanges and inner plastic inserts, manufacturing costs are significantly reduces. In addition, since refrigerant is delivered to the refrigerant track  446  at three equally spaced locations, the distribution of refrigerant to the refrigerant passages in the heat exchanger body  424  is generally even thereby maintaining generally uniform heat exchange within the ice-making machine  410 . 
     FIG. 17 shows a plurality of ice-making machines  410  of the type shown in FIGS. 16 a  to  16   c  arranged in symmetrical 2×2 array. As can be seen, in this arrangement, the lower end plates  418  are generally rectangular in top plan. The lower outer flange  418   a  of each end plate however still includes a circular refrigerant channel  454 . An opening  452  is formed through the lower flange  418   a  of each end plate and partially intersects the refrigerant channel  454 . A collector  506  secured to the bottom of the array includes four channels  508  each communicating with one of the openings  452 . The channels  508  lead to a single refrigerant outlet  454 . This allows refrigerant fed to three refrigerant inlets  440  of each ice-making machine  410  to be collected and discharged at a common point. 
     Referring now to FIGS. 18 a  to  18   c , yet another embodiment of an ice-making machine in accordance with the present invention is shown and is generally indicated to by reference numeral  510 . As can be seen, the ice-making machine includes a generally cylindrical housing  512  constituted by a central heat exchanger body  524  and upper and lower end plates  516  and  518  respectively. The heat exchanger body  524  is constituted by a plurality of stacked rings of abutting arcuate segments  551  formed of extruded aluminum. Refrigerant passages  534  extend through the arcuate segments. A stainless steel sleeve  535  is secured to the inner surface of the heat exchanger body to define a cylindrical heat exchange surface and protect the heat exchanger body from corrosion and erosion. 
     A refrigerant inlet header  561  extends the length of the heat exchanger body  524  and communicates with one end of each refrigerant passages  534  in the heat exchanger body. The refrigerant inlet header  561  includes a refrigerant inlet  563  and a plurality of refrigerant outlets  565  each of which is in line with a respective refrigerant passage  534  in the heat exchanger body. A refrigerant outlet header  567  also extends the length of the heat exchanger body and communicates with the opposite end of each refrigerant passage  534  in the heat exchanger body. The refrigerant outlet header  567  includes a plurality of inlets  569  in line with the refrigerant passages  534  in the heat exchanger body and a refrigerant outlet  571 . 
     A drive shaft  580  extends centrally through the housing  512  and is coupled to a motor (not shown). A pair of blades  598  are mounted on the drive shaft  580  via longitudinally spaced, radial extending arms  600 . Each blade  598  is notched and is wedge-shaped in plan. The blades  598  contact the heat exchange surface and are rotated at a speed sufficient to inhibit deposition of ice crystals on the heat exchange surface as described previously. 
     Referring now to FIGS. 19 a  to  19   c , yet another embodiment of an ice-making machine in accordance with the present invention is shown and is generally indicated to by reference numeral  610 . In this embodiment, the housing  612  includes a heat exchanger body  624  constituted by an array of upright rectangular plates  651  formed of extruded aluminum. Refrigerant passages  634  extend vertically through each of the plates. Opposed major sides of the plates are lined with a stainless steel sheet to define heat exchange surfaces and protect the plates from erosion and corrosion. A drive shaft  680  extends centrally through the housing and carries a plurality of blades  698  mounted on arms  700  extending radially from the drive shaft  680  at spaced locations. Each blade  698  is notched and wedge-shaped, and is in contact with a respective one of the heat exchange surfaces. Refrigerant inlet headers  661  are mounted on the top of the rectangular plates  651  and include refrigerant inlets  663  receiving a flow of refrigerant and refrigerant outlets  665  aligned with the refrigerant passages  634  in the rectangular plates  651 . Refrigerant outlet headers  667  are mounted on the bottom of the rectangular plates  651  and include refrigerant inlets  669  in line with the refrigerant passages  534  in the rectangular plates and refrigerant outlet headers  671 . 
     Referring now to FIGS. 20 a  to  20   c , another embodiment of an ice-making machine similar to that shown in FIGS. 19 a  to  19   c  is illustrated. In this embodiment, the plates  651  A defining the heat exchanger body include central curved sections to increase the surface area of the heat exchange surfaces contacted by the rotating blades  698 A. 
     Referring now to FIGS. 21 a  and  21   b  yet another embodiment of an ice-making machine in accordance with the present invention is shown and is generally indicated to by reference numeral  710 . In this embodiment, the heat exchanger body  724  is constituted by a thin, elongate rectangular aluminum extrusion  751  having spaced longitudinally extending refrigerant passages  734  therein. The extrusion  751  is wound to form a helix and is lined with a stainless steel tube  735  defining an inner generally cylindrical heat exchange surface. A refrigerant inlet header  761  is coupled to one end of the extrusion to deliver refrigerant to each of the refrigerant passages  734 . A refrigerant outlet header  767  is coupled to the other end of the extrusion to collect refrigerant from the refrigerant passages  734 . 
     Referring now to FIGS. 22 a  to  22   c , yet another embodiment of an ice-making machine in accordance with the present invention is shown and is generally indicated to by reference numeral  810 . In this embodiment, the heat exchanger body  824  is in the form of a spiral plate  851 . Opposed major sides of the plate are covered by stainless steel sheets  835  defining heat exchange surfaces. The spiral plate  851  is constituted by an elongate, thin rectangular extrusion having spaced longitudinally extending refrigerant passages  834  therein that has been wound. The inner end of the spiral plate  851  is sealed and an internal passage  851  a is formed through the spiral plate to interconnect the refrigerant passages  834  therein (see FIG. 22 c ). Refrigerant inlet and outlet headers  861  and  867  respectively are coupled to the outer end of the spiral plate  851 . The refrigerant inlet header  861  communicates with some of the refrigerant passages  834  while the refrigerant outlet header  867  communicates with the remaining refrigerant passages  834 . Refrigerant delivered to refrigerant passages  834  through the refrigerant inlet header  861  flows in an inward spiral along the refrigerant passages until it reaches the end of the spiral plate at which time the refrigerant is directed into the other refrigerant passages where it flows back in an outward spiral to the refrigerant outlet header  867 . 
     FIGS. 23 a  and  23   b  show an ice-making machine similar to that shown in FIGS. 22 a  and  22   b . In this embodiment, the rectangular extrusion is wound in a spiral and then unwound in an adjacent spiral to form side by side spiral plates  851 A. The refrigerant inlet header  861 A is coupled to one end of the spiral while the refrigerant outlet header  867 A is coupled to the other end of the spiral allowing refrigerant to flow through all of the refrigerant passages in the same direction. 
     Referring now to FIGS. 24 a  to  24   e , yet another embodiment of an ice-making machine in accordance with the present invention is shown and is generally indicated to by reference numeral  910 . In this embodiment, the ice-making machine includes a plurality of concentric cylindrical heat exchanger bodies  924 . Each heat exchanger body  924  is formed from a plurality of elongate arcuate segments  951  joined by adhesive  925 . Spaced, longitudinally extending refrigerant passages  934  extend through the arcuate segments. The inner and outer surfaces of each heat exchanger body  924  are lined with stainless steel to define heat exchange surfaces. 
     A blade assembly  990  is associated with each heat exchange surface. Each blade assembly  990  includes an elongate corrugated plate  990   a  depending from a support  990   b  positioned above the heat exchanger bodies. Blades  998  are secured to the corrugated arms  990   a  by fasteners  990   c  and contact a portion of a respective heat exchange surface. The corrugated arms  990   a  positioned between two heat exchanger bodies  924  carry blades  998  which contact heat exchange surfaces of both heat exchanger bodies. The support  990   b  is mounted on the end of a drive shaft  980  which is rotated by a motor  982 . 
     During operation, refrigerant is delivered to the refrigerant passages  934  in the heat exchanger bodies and brine solution is delivered into the ice-making machine so that it contacts each of the heat exchange surfaces of the heat exchanger bodies. The drive shaft  980  is rotated by the motor thereby to import rotation of the support  990   b . As the support rotates so do the arms  990   a  causing the blades  998  to sweep across the heat exchange surfaces at a rate sufficient to avoid deposition of ice crystals on the heat exchange surfaces. 
     Since this arrangement provides a plurality of concentric heat exchange surfaces, the capacity of the ice-making machine is significantly increased. 
     Referring now to FIGS. 25 a  and  25   b , an alternative embodiment of a blade assembly for an ice-making machine having a single cylindrical heat exchange surface is shown and is generally indicated to by reference numeral  1000 . In this embodiment, the blade assembly includes a carrier  1002  surrounding the drive shaft  1082  within the heat exchanger body  1024 . Similar to the first embodiment, the drive shaft is hollow and is coupled to a brine solution inlet  1054 . Spaced, radially extending passages  1100  extend through the carrier and communicate with the drive shaft to deliver brine solution into the body of the heat exchanger body. The carrier  1002  supports three blades  1098  which contact the heat exchange surface. The blades are oriented such that they form an angle of attack with respect to the tangent of the heat exchange surface equal to approximately 110 degrees. 
     Springs  1102  are accommodated within the blades  1098  to bias the blades towards the heat exchange surface. The blades are however movable into the carrier should the blades encounter an obstruction on the heat exchange surface when rotating. This inhibits the blades from breaking should an obstruction such as ice form on the heat exchange surface. 
     Referring now to FIGS. 26 a  to  26   c , yet another embodiment of an ice-making machine in accordance with the present invention is shown. In this embodiment, the ice-making machine includes a heat exchanger body constituted by a plurality of thin extruded spaced plates. Spaced refrigerant passages extend through each of the plates. Facing surfaces of the plates are lined with stainless steel to define a pair of heat exchange surfaces. A refrigerant inlet header is secured to one end of the plates to allow refrigerant to be supplied to the heat exchanger body. A refrigerant outlet header is secured to an opposite end of the plates. The inlet and outlet header seal the sides of the heat exchanger body. The sides of the plates are sealed to define a chamber for brine solution. A blade assembly is accommodated within the chamber. The blade assembly includes a frame supporting a plurality of spaced diagonal blades. The blades are semi-circular when viewed from the end. The frame passes through the refrigerant inlet header and is coupled to a drive shaft reciprocated by a motor. 
     During operation, brine solution is fed into the chamber via a brine inlet and refrigerant is supplied to the refrigerant passages via the refrigerant inlet header. As this is done, the motor is actuated to reciprocate the drive shaft and hence the frame so that the diagonally extending blades oscillate within the chamber and contact the heat exchange surfaces. Supercooled brine solution removed from the heat exchange surfaces crystallizes in the body of solution within the chamber to form ice-brine slurry which exits the ice-making machine via the ice-slurry outlet. 
     Although specific embodiments of the present invention have been described, those of skill in the art will appreciate that variations and modifications may be made to the present invention without departing from the scope thereof as defined by the appended claims.