Patent Description:
The present disclosure relates generally to freezing cylinder assemblies, and more particularly, to a microchannel freezing cylinder assembly used with a semi-frozen product dispensing apparatus. The present disclosure also relates to a method of cooling a product with the freezing cylinder disclosed herein.

Microchannel heat exchangers are used as evaporators in order to freeze dairy product for soft serve and shake production. Current technology utilizes an external distributor and multiple inlets and outlets in order to distribute the refrigerant to the microchannel flow paths. In the current technology there are typically six brazed joints on the distributor, four brazed joints on the freezing cylinder inlet, four joints on the freezing cylinder outlet, and four joints on the outlet header. This results in a total of <NUM> brazed joints. <CIT> describes a heat exchanger that includes a first tube extending along a central axis. The first tube defines a chamber that contains a first medium. A corrugated sheath of the heat exchanger is disposed radially outward from and extends circumferentially about the outer face for transferring heat through the inner tube. <CIT> describes a method of performing a heat treatment cycle on a volume of product in a frozen food dispensing machine. <CIT> describes an improved evaporator for a refrigeration system to reduce the temperature of a medium therein. <CIT> describes a cylindrical heat exchanger for use as a gas cooler in a thermal regenerative machine as a Stirling engine and includes an imperforate middle wall of sufficient strength and thickness to withstand the pressure exerted by the working fluid.

This disclosure relates to a microchannel freezing cylinder assembly that relocates the distribution mechanism from external to the freezing cylinder to within the freezing cylinder through the use of a pressurized header, several orifices, a second distribution header, and an outlet header. Refrigerant may enter an inlet header through a single inlet. The refrigerant may flow around the inlet header and pass from the inlet header to a distribution header through several orifices, such as <NUM> to <NUM> orifices. The refrigerant may flow from the distribution header to the microchannels that extend along the cylinder. This header and orifice design will ensure that refrigerant is distributed equally around the cylinder. The refrigerant may exit the microchannels into an outlet header within the cylinder. There may be a single outlet connection on the cylinder.

This disclosure moves the features which distribute and collect the refrigerant from outside the freezing cylinder to within the freezing cylinder. This design reduces the number of inlet connections on the freezing cylinder, such as from <NUM> to <NUM>. The number of outlets on the freezing cylinder may be reduced from <NUM> to <NUM>. The external distributor at the inlet and header at the outlet of the freezing cylinder will be eliminated with this design. This disclosure may reduce the cost to build the product through a reduction in the number of brazed joints and elimination of the external distributor and collector. This design may also improve the reliability through joint reduction.

This disclosure includes a freezing cylinder for use in a semi-frozen product dispensing apparatus, the freezing cylinder with an inner cylinder having an inlet end and an outlet end; an outer cylinder having an inlet end and an outlet end, wherein the outer cylinder is disposed coaxially over the inner cylinder; a plurality of microchannels on an exterior surface of the inner cylinder that extend parallel with a longitudinal axis of the inner cylinder, wherein the plurality of microchannels are located between the inner cylinder and outer cylinder; a first inlet header around the circumference of the inner cylinder, wherein the first inlet header is located near the inlet end of the inner cylinder; a second inlet header around the circumference of the inner cylinder, wherein the second inlet header is located between the first inlet header and the plurality of microchannels, wherein the second inlet header is in fluid communication with the plurality of microchannels; a header ridge located between first inlet header and the second inlet header, wherein the header ridge is configured to prevent fluid to flow from the first inlet header to the second inlet header; a plurality of orifices in the header ridge that are configured to allow fluid to flow from the first inlet header to the second inlet header; and an outlet header around the circumference of the inner cylinder, wherein the outlet header is located near the outlet end of the inner cylinder, wherein the outlet header is in fluid communication with the plurality of microchannels.

This disclosure includes a method of cooling a product with the freezing cylinder including the steps of providing a product to be cooled in an interior of the inner cylinder; adding refrigerant to the first inlet header through an inlet opening in the outer cylinder; moving refrigerant from the first inlet header to the second inlet header through the plurality of orifices; moving refrigerant from the second inlet header to the outlet header through the plurality of microchannels; and cooling the product by transferring heat from the product to the coolant as the refrigerant moves through the plurality of microchannels.

Referring to the figures, a microchannel freezing cylinder assembly <NUM> used with a semi-frozen product dispensing apparatus (not shown) is shown in <FIG>. The microchannel freezing cylinder assembly <NUM> includes a first cylinder <NUM> and a second cylinder <NUM>. The second cylinder <NUM> may be disposed coaxially over the first cylinder <NUM>. The second cylinder <NUM> may include a single inlet opening <NUM> and a single outlet opening <NUM> (shown in <FIG>). The inlet opening <NUM> and outlet opening <NUM> may be located on generally opposite sides of the second cylinder <NUM>. In one embodiment, the inlet opening <NUM> is located at the twelve o'clock position and the outlet opening <NUM> is located at the six o'clock position when viewing the assembly <NUM> from an axial end. In other embodiments, the inlet and outlet openings <NUM>, <NUM> may be disposed to face in generally opposite directions, such as the inlet opening facing in a direction within a range of the ten o'clock position and the two o'clock position (inclusive of all positions within this range) while the outlet opening <NUM> may face in a direction with a range of the eight and four o'clock positions (inclusive of all positions within this range). In other embodiments, the inlet and outlet openings <NUM>, <NUM> may both face in the same direction, or the same "general direction" - which is defined herein to be plus or minus one hour on a clock face. The inlet opening <NUM> and outlet opening <NUM> may also be located on opposite ends of the second cylinder <NUM>.

First cylinder <NUM> may include an inner chamber configured to contain the semi-frozen product. The inner chamber may include a first inner chamber opening <NUM> and a second inner chamber opening <NUM>. The refrigerant flowing in the microchannels may absorb heat from the semi-frozen product in the inner chamber and heat up and evaporate as it flows through the microchannels along the assembly <NUM>. In this manner, the refrigerant and semi-frozen product may be in a heat exchange relationship such that the semi-frozen product is cooled.

<FIG> shows an assembly <NUM> that has been slightly rotated along the longitudinal axis from the view shown in <FIG>. <FIG> shows outlet opening <NUM> in second cylinder <NUM> that is located on the opposite side from inlet opening <NUM>. Outlet opening <NUM> may be located on the bottom to allow gravity to assist removing the refrigerant from the assembly <NUM>.

<FIG> shows first cylinder <NUM> without second cylinder <NUM>. First cylinder <NUM> may include an inlet header <NUM>, a distribution header <NUM>, and an outlet header <NUM>. Inlet opening <NUM> is in fluid communication with the inlet header <NUM> when the first cylinder <NUM> is located within the second cylinder <NUM>. Outlet opening <NUM> is in fluid communication with the outlet header <NUM> when the first cylinder <NUM> is located within the second cylinder <NUM>.

First cylinder <NUM> may include several grooves <NUM> extending along the longitudinal length of first cylinder <NUM>. When the second cylinder <NUM> is located coaxially over first cylinder <NUM>, the grooves <NUM> may form the microchannels (similar to element 121a (<FIG>, <FIG>, <FIG>)) that contain the refrigerant. First cylinder <NUM> may include a ridge <NUM> located between the inlet header <NUM> and distribution header <NUM>. Ridge <NUM> may include several orifices <NUM>, for example <NUM> to <NUM> orifices <NUM>.

Orifices <NUM> may allow refrigerant to flow from inlet header <NUM> to distribution header <NUM>. The refrigerant may flow around the circumference of inlet header <NUM> and pass from the inlet header <NUM> to the distribution header <NUM> through orifices <NUM>. The pressure of the refrigerant in inlet header <NUM> may be higher than the pressure of the refrigerant in distribution header <NUM>. Orifices <NUM> may collectively act as a restriction orifice in order to achieve a controlled or desired flow of the refrigerant from the inlet header <NUM> to the distribution header <NUM>. Orifices <NUM> may restrict the flow of refrigerant from the inlet header <NUM> to the distribution header <NUM> by creating a permanent pressure loss between the inlet header <NUM> to the distribution header <NUM>. The collective area of the orifices <NUM> determines the rate of refrigerant flow through the orifices <NUM>. The refrigerant may flow around the circumference of the distribution header <NUM> to the microchannels that extend along the first cylinder <NUM>.

First cylinder <NUM> may include protrusions <NUM>, <NUM> located at the ends of first cylinder <NUM>. Protrusions <NUM>, <NUM> may provide an interference fit with second cylinder <NUM> in order to contain the refrigerant between first cylinder <NUM> and second cylinder <NUM>.

<FIG> is a closer view of one end of first cylinder <NUM>. <FIG> shows inlet header <NUM>, distribution header <NUM>, grooves <NUM>, ridge <NUM>, and orifices <NUM>. <FIG> shows that the orifices <NUM> may be spaced circumferentially around ridge <NUM>. The orifices <NUM> may be spaced evenly around ridge <NUM> or may be spaced unevenly around ridge <NUM> in order to optimize and/or even out the distribution of refrigerant into distribution header <NUM> and into the microchannels. In some embodiments, there may not be an orifice <NUM> located directly adjacent to inlet opening <NUM> in order to prevent a large amount of refrigerant flowing from inlet opening <NUM> into an orifice <NUM> located directly adjacent to inlet opening <NUM>.

<FIG> shows a detail view of a single orifice <NUM> with exemplary dimensions. Orifices <NUM> may be sized to collectively provide a desired cross-sectional area to allow refrigerant to flow from inlet header <NUM> to distribution header <NUM>. Each orifice <NUM> may be generally rectangular in shape, as shown in <FIG>. In other embodiments the orifice(s) may be other shapes, such as triangular, curved (such as circular, semicircular or partially circular, or other geometrical or arbitrary shapes), as long as the remaining material forming the ridge <NUM> makes contact with the inner surface of the second cylinder <NUM> to prevent refrigerant from flowing across the ridge <NUM> other than through the orifices <NUM> The depth and width of each orifice <NUM> may be varied as necessary to achieve the desired cross-sectional area, and one of ordinary skill with a thorough review of this disclosure will be able to design the number and size of orifices upon the ridge <NUM> without undue experimentation, as well as the other geometrical and numerical aspects of the inner cylinder. For example, the depth of each orifice <NUM>, shown as <NUM> inches in <FIG>, may be approximately half the depth of ridge <NUM>, or in other embodiments about <NUM>/<NUM>, <NUM>/<NUM>, or over half of the height of the ridge. As another example, the depth of each orifice <NUM> may be the depth of ridge <NUM> and each orifice <NUM> may be half, or <NUM>/<NUM>, <NUM>/<NUM>, or over half of the width of the orifice. One of ordinary skill, after a thorough review and understanding of this specification and the appended figures, will readily comprehend that the relative size and relative dimensions of the orifice is a function of the number of orifices provided as well as the desired differential pressure across the ridge <NUM>, and one of ordinary skill in the art would be able to design the desired orifices <NUM> to achieve the desired flow characteristics without undue experimentation. The depth and/or width of each orifice <NUM> may be selected for ease of manufacturability. For example, the width of each orifice <NUM>, shown as <NUM> inches in <FIG>, may be determined by the width of a tool, such as a drill bit, used to create each orifice <NUM> and the depth of each orifice <NUM> can be adjusted to achieve the desired cross-sectional area. As can be understood, in embodiments where the inner cylinder is machined, the depth and width of the orifice may have a lower bounds based upon the diameter of the drill bits or other tools available to machine these features.

<FIG> shows a detail view of grooves <NUM>. Grooves <NUM> may have a gear-tooth profile, as shown in <FIG>, as opposed to a square profile. Exemplary dimensions for the gear-teeth are shown in the table in <FIG>. Using a gear-tooth profile instead of a square profile for grooves <NUM> may ease the manufacture of grooves <NUM>. In some embodiments, the grooves <NUM> may be manufactured with the use of a hobbing machine. Using a gear-tooth profile may also increase the strength of the microchannels by providing a wider base of the sides of grooves <NUM> at the exterior of first cylinder <NUM> than if a square profile were used. In other embodiments, grooves with other profiles, such as square, triangular, trapezoidal, or arcuate and the like may be used. One of ordinary skill in the art with a thorough review of the subject specification and figures would appreciate that other grooves would be sufficient provided that they provided sufficient surface area for the needed heat transfer between the first cylinder <NUM> and the refrigerant and in conjunction allowed for a sufficient flow rate through the plurality of grooves based upon the supply pressure to the assembly <NUM>, and provided that the outer edges of the grooves make sufficient contact with the inner surface of the second cylinder <NUM> to prevent refrigerant from flowing out of the grooves as it flows across the first cylinder. One of ordinary skill in the art would be able to establish a suitable geometry, size, and number of grooves with only routine optimization and without undue experimentation.

In other embodiments, depicted schematically in <FIG>, the construction of portions of the first and second cylinders 102a, 104a may be reversed, with the second cylinder 104a still disposed coaxially over the first cylinder 102a and with coolant flowing across the outer surface of the first cylinder 102a between inlet and outlet openings 106a, 108a and with the semi-frozen product flowing through the chamber between the first and second openings 110a, 112a. (In this embodiment, components of similar functionality and structure are noted with consistent element numbers as the corresponding structure discussed above and depicted in <FIG> with a letter modifying the element number. For the sake of brevity, the structure and function of such components, to the extent that it is the same as the embodiment above, will not be described in this embodiment, but any material differences in components is discussed herein).

In this embodiment, the outer surface of the first cylinder 102a may be a smooth cylindrical surface, with the inner surface of the second cylinder 104a comprising structures that form an inlet header 114a, protrusions 126a, 128a, ridge 122a (and orifices 124a) and grooves 120a that form microchannels 121a. The radial tips of these features contact and form an interference fit with the outer surface of the first cylinder 102a to establish the flow of refrigerant through the assembly 100a and to prevent flow from bypassing these features (opposite to the embodiments below where the radial tips of these features - as shown in <FIG> - contact the inner surface of the second cylinder <NUM>. Otherwise the structure of first and second cylinders 102a, 104a and the components upon the inner surface of the second cylinder 104a are constructed in a like manner with the structure of the first and second cylinders <NUM>, <NUM> discussed above.

<FIG> shows a method <NUM> of using the microchannel freezing cylinder assembly <NUM>. Step <NUM> involves providing a semi-frozen product to be cooled in an interior of the inner cylinder. Step <NUM> adds refrigerant to the inlet header through an inlet opening in the outer cylinder. Step <NUM> moves refrigerant from the inlet header to the distribution header through the plurality of orifices. Step <NUM> moves refrigerant from the distribution header to the outlet header through the plurality of microchannels. Step <NUM> cools the semi-frozen product by transferring heat from the semi-frozen product to the refrigerant as the refrigerant moves through the plurality of microchannels.

Claim 1:
A freezing cylinder (<NUM>) for use in a semi-frozen product dispensing apparatus, the freezing cylinder (<NUM>) comprising:
an first cylinder (102a) having an inlet end and an outlet end;
an second cylinder (104a) having an inlet end and an outlet end, wherein the second cylinder (104a) is disposed coaxially over the first cylinder (102a);
a plurality of microchannels (121a) on an interior surface of the second cylinder (104a) that extend parallel with a longitudinal axis of the second cylinder (<NUM>), wherein the plurality of microchannels (121a) are located between the first cylinder (102a) and second cylinder (104a);
a first inlet header (114a) around the inner circumference of the second cylinder (104a), wherein the first inlet header (114a) is located near the inlet end of the second cylinder (102a);
a second inlet header (<NUM>) around the inner circumference of the second cylinder (104a), wherein the second inlet header (<NUM>) is located between the first inlet header (114a) and the plurality of microchannels (121a), wherein the second inlet header (<NUM>) is in fluid communication with the plurality of microchannels (121a);
a header ridge (122a) located between first inlet header (114a) and the second inlet header (<NUM>) and extending from the inner surface of the second cylinder (104a), wherein the header ridge (122a) is configured to prevent fluid flow from the first inlet header (114a) to the second inlet header (<NUM>);
a plurality of orifices (124a) in the header ridge (122a) that are configured to allow fluid flow from the first inlet header (114a) to the second inlet header (<NUM>); and
an outlet header (<NUM>) around the circumference of the first cylinder (<NUM>), wherein the outlet header (<NUM>) is located near the outlet end of the second cylinder (104a), wherein the outlet header (<NUM>) is in fluid communication with the plurality of microchannels (121a).