Patent Description:
<CIT> discloses a heat exchanger according to the preamble of claim <NUM> and describes a structure for supporting tubes of a heat exchanger in predetermined spaced relationship one with another, comprising spaced first and second members each having openings therethrough, defining a plurality of tube-receiving passageways. Expansible means are arranged between the first and second members adjacent each of the tube-receiving passageways. Each of the expansible means forms a wall portion of the associated tube-receiving passageway. The expansible means comprises an elastomeric material which expands when exposed to heat exchange medium.

<CIT> discloses a similar system wherein a structure for supporting tubes of a heat exchanger is provided with expansible means arranged about openings for receiving tubes of the heat exchanger.

According to a first aspect of the invention, there is provided a heat exchanger comprising: a body portion; a pair of end plates at least partially forming an enclosure with the body portion; a plurality of tubes extending through at least one of the body portion and the pair of end plates; and at least one tube sheet including a plurality of openings with a corresponding one of the plurality of tubes located in one of the plurality of openings, wherein the tube sheet is made of a material which expands in the presence of refrigerant, wherein: the at least one tube sheet is formed from a plurality of geometric shaped members and each of the plurality of geometric shaped members includes one of the plurality of openings and each of the plurality of geometric shaped members are made of a single unitary piece of material; and the plurality of geometric shaped members are hexagonal bodies that fit together to form the tube sheet.

Optionally, the heat exchanger is a non-baffled heat exchanger.

Optionally, the tube sheet at least partially follows an inner contour of the body portion.

Optionally, the tube sheet extends between <NUM>% and <NUM>% of a diameter of the body portion.

Optionally, the body portion includes a first refrigerant port and a second refrigerant port. At least one tube sheet includes a plurality of tube sheets.

Optionally, a support structure supports the tube sheet.

Optionally, the support structure includes a plurality of rods forming a matrix.

Optionally, the plurality of tubes include heat transfer enhancing features on an exterior surface that engage the at least one tube sheet.

According to a second aspect of the invention, there is provided a method of operating a heat exchanger comprising the steps of: supporting a plurality of tubes extending through a corresponding one of a plurality of opening in a tube sheet; and placing the tube sheet in contact with a refrigerant, wherein the tube sheet expands in response to contact with the refrigerant entering the heat exchanger and contacts the plurality of tubes, wherein: the tube sheet includes a plurality of geometric shapes assembled together to form the tube sheet; and the plurality of geometric shaped members are hexagonal bodies.

Optionally, the plurality of tubes include heat transfer enhancing features on an exterior surface that engage the tube sheet.

Optionally, the tube sheet extends between <NUM>% and <NUM>% of a diameter of a body portion of the heat exchanger.

Optionally, vibrations and movement of the plurality of tubes are reduced with the tube sheet in contact with the refrigerant.

Optionally, the heat exchanger is a non-baffled heat exchanger.

<FIG> illustrates an example heat exchanger <NUM>, such as an evaporator or a condenser, used in a refrigeration system or other device for transferring heat between multiple fluids. The heat exchanger <NUM> includes a body portion <NUM> enclosed by a pair of end plates <NUM>. A plurality of tubes <NUM> extend through the enclosure defined by the body portion <NUM> and the pair of end plates <NUM>. A water box <NUM> encloses the end plates <NUM> to provide fluid into or out of the plurality of tubes <NUM>. The plurality of tubes <NUM> are fluidly sealed with a corresponding one of the pair of end plates <NUM> to prevent fluid from leaving the heat exchanger <NUM> between the plurality of tubes <NUM> and the corresponding end plate <NUM> that the tubes <NUM> extend through.

Refrigerant enters the heat exchanger <NUM> through either a first port 26A or a second port 26B and exits the heat exchanger <NUM> through the other of the first port 26A or the second port 26B. In the illustrated example, the first and second ports 26A, 26B are located on opposite sides of the heat exchanger <NUM>. Although only a single first port 26A and a single second port 26B are shown in the illustrated example, there could be multiple first ports 26A and second ports 26B and the first ports 26A and the second ports 26B could be located in other portions of the heat exchanger <NUM>, such as the pair of ends plates <NUM>.

<FIG> illustrates a sectional view of the heat exchanger <NUM> taken along line <NUM>-<NUM> of <FIG>. As shown in <FIG>, the body portion <NUM> at least partially forms an internal cavity <NUM> with the end plates <NUM> (see <FIG>). In the illustrated example, the body portion <NUM> includes a circular cross section. However, the body portion <NUM> is not limited to having a circular cross-section and could form other cross-sectional shapes, such as squares, rectangles, or ovals.

The plurality of tubes <NUM> are at least partially supported by a tube sheet <NUM>. The tube sheet <NUM> includes an outer perimeter 32A that at least partially follows an inner contour 22A of the body portion <NUM>. The tube sheet <NUM> could be attached to the body portion <NUM> through a mechanical connection, such as a fastener or adhesive, or be friction fit against the inner contour 22A to allow some movement of the tube sheet <NUM>. In the illustrated example, the tube sheet <NUM> extends between <NUM>% and <NUM>% of a diameter of the body portion <NUM> to provide a region of the internal cavity <NUM> that is unobstructed by the tube sheet <NUM>. In another example, the tube sheet <NUM> could extend anywhere from <NUM>% up to <NUM>% of the diameter of the body portion. Additionally, the tube sheet <NUM> could be located inward from opposing sides of inner contour 22A of the body portion <NUM> such that there is an unobstructed region of the internal cavity <NUM> on opposite sides of the tube sheet <NUM>.

The tube sheet <NUM> can be made of an expandable material that is formed from a single unitary piece of material. The expandable material includes a material which will swell or expand in the presence of a working fluid, such as a refrigerant. For example, the expandable material expands in the presence of the working fluid by a process that includes at least one of adsorption of molecules of the working fluid onto the expandable material (e.g., onto the wettable surface) or diffusion of the working fluid into the expandable material. The expandable material can include a polymer material, for example, Nylon (e.g., Nylon <NUM>,<NUM>), polytetrafluoroethylene (PTFE), polyimide, polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polyamide-imide (PAI). The expandable material can optionally further include a filler material, for example, glass fiber, carbon fiber, basalt fiber, aramid fiber or the like. The expandable material can include <NUM> weight % (wt%) to <NUM> wt% filler material. The tube sheet <NUM> can be formed from a single piece of material through either casting the material in a die or machining a sheet of the material to the desired profile to accommodate the plurality of tubes <NUM> and the shape of the inner contour 22A. The working fluid can include R744 (CO2), R410a, R1234zd, R290 (propane), R1224yd, R1123, R1234ze, or another similar working fluid.

In the illustrated example, the tube sheet <NUM> includes a plurality of openings <NUM> that each have a diameter D1. The diameter D1 is larger than an outer diameter DT of each of the plurality of tubes <NUM> (see <FIG>). The difference in length between the diameter D1 and the diameter DT creates a spacing between the plurality of tubes <NUM> and a corresponding one of the openings <NUM>. The spacing formed between the plurality of tubes <NUM> and the corresponding one of the openings <NUM> allows for the plurality of tubes <NUM> to easily pass through the tube sheet <NUM> during assembly of the heat exchanger <NUM>.

<FIG> illustrate the tube sheet <NUM> in an expanded state when exposed to refrigerant. Refrigerant is introduced into the heat exchanger <NUM> through one of the first and second ports 26A or 26B and exits the heat exchanger <NUM> through the other of the first and second ports 26A or 26B. The refrigerant entering and exiting the heat exchanger <NUM> through the first and second ports 26A, 26B can be in at least one of a liquid state, a vapor state, or a two-phase state.

When the tube sheet <NUM> is in an expanded state, the diameter D1 of the openings <NUM> decreases to close the spacing between the openings <NUM> and the outer diameter of the corresponding one of the plurality of tubes <NUM>. This brings the tube sheet <NUM> into at least partial contact with the plurality of tubes <NUM> to stabilize the plurality of tubes <NUM> to prevent damage resulting from vibrations or movement during operation of the heat exchanger <NUM>. The tube sheet <NUM> can also include passages <NUM> extending through a mid-portion of the tube sheet <NUM> or edge passages <NUM> at least partially defined by the tube sheet <NUM> and the body portion <NUM>.

Also, the expanding properties of the tube sheet <NUM> in response to exposure to refrigerant eliminates the need for additional mechanical attachment between the tube sheet <NUM> and the plurality of tubes <NUM>. By eliminating the need for additional mechanical attachment between tube sheet <NUM> and the plurality of tubes <NUM>, the amount of time required to manufacture the heat exchanger <NUM> is greatly reduced due to a number of mechanical attachments between the plurality of tubes <NUM> and the tube sheet <NUM> and the level of precision needed to make those attachments.

Also, by eliminating the need for mechanical attachments between the tube sheet <NUM> and the plurality of tubes <NUM>, such as swaging or using fasteners, the plurality of tubes <NUM> can include heat enhancing features <NUM> over the entire length of the tubes <NUM>. This increases the heat transfer between the refrigerant in the internal cavity <NUM> and the fluid passing through the tubes <NUM>. Also, as shown in <FIG>, the tube sheet <NUM> has expanded such that the opening <NUM> contacts the tube <NUM> to provide support for the tube.

<FIG> illustrate another example opening 34A in the tube sheet <NUM>. The opening 34A is irregular in shape and includes a plurality of projections. When the tube sheet <NUM> is placed in contact with refrigerant, the tube sheet <NUM> expands and contacts the tube <NUM> (<FIG>) to prevent the tube <NUM> from moving or vibration during operation of the heat exchanger <NUM>. The projections in the opening 34A also allow refrigerant to pass between the tube <NUM> and the tube sheet <NUM>.

<FIG> illustrates a sectional view taken along line <NUM>-<NUM> of <FIG>. As shown in <FIG>, the tube sheets <NUM> only extend partially across a diameter of the internal cavity <NUM> to allow the flow of refrigerant through the heat exchanger <NUM>. In the illustrated example, there are three tube sheets <NUM> located in the internal cavity <NUM> and all three of the tube sheets <NUM> are all aligned along the same portion of the internal cavity <NUM> to allow movement of refrigerant as described above. In another example, the tube sheet <NUM> could be spaced from opposing sides of body portion <NUM> when the plurality of tubes <NUM> only extend through a middle portion of the internal cavity <NUM>.

<FIG> illustrates another example tube sheet <NUM> similar to the tube sheet <NUM> above except where described above or shown in the Figures. The tube sheet <NUM> includes openings <NUM> for accepting a corresponding one of the plurality of tubes <NUM> and reinforcement members <NUM> extending between the openings <NUM> in the tube sheet <NUM> forming a matrix. The reinforcement members <NUM> can be attached to an external surface of the tube sheet <NUM> to form a support structure or be located within the tube sheet <NUM> itself. The reinforcement members <NUM> can be metallic rods, such as steel or aluminum or the reinforcement members <NUM> can be fibrous. In the illustrated example, at least one of the reinforcement members <NUM> extends from a first perimeter location on the tube sheet <NUM> to a second perimeter location on the tube sheet <NUM> generally opposite the first perimeter location.

<FIG> illustrates yet another example tube sheet <NUM> similar to the tube sheet <NUM> above except where described above or shown in Figures. The tube sheet <NUM> is comprised of a plurality of body portions <NUM> each having a hexagonal shape and an opening <NUM> for accepting a corresponding one of the plurality of tubes <NUM>. As shown in <FIG>, the hexagonal bodies fit together to form a tube sheet <NUM> that closely approximates the inner contour 22A of the body portion <NUM>. The body portions <NUM> can fit together with a friction fit, an adhesive, or vibration welding technique. In the illustrated example, the body portions <NUM> are made of a single unitary piece of refrigerant expanding material.

The body portions <NUM> can easily be added or subtracted from the tube sheet <NUM> to customize the tube sheet <NUM> for a specific application. This reduces the amount of time needed to manufacture or machine additional tube sheets for low volume applications. Although the body portions <NUM> are shown as being hexagons in the illustrated example, other shapes are also contemplated such as triangles, pentagons, hexagons, squares, or rectangles.

<FIG> illustrates another example individual body portion <NUM> similar to the body portion <NUM> above except where described below or shown in the Figures. The body portion <NUM> can attach to an adjacent body portion <NUM> through the use of mounting legs <NUM> that are moveable within channels <NUM> in the body portion <NUM>. Because the mounting legs <NUM> are moveable and able to slide into the channels <NUM>, the mounting legs <NUM> can engage adjacent body portions <NUM> and lock the adjacent body portions <NUM> together to form a grid similar to the grid shown in <FIG>. Although the body portions <NUM> are shown as being hexagons in the illustrated example, other shapes are also contemplated such as triangles, pentagons, hexagons, squares, or rectangles.

Although the different non-limiting embodiments are illustrated as having specific components, the embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.

Claim 1:
A heat exchanger (<NUM>) comprising:
a body portion (<NUM>);
a pair of end plates (<NUM>) at least partially forming an enclosure with the body portion;
a plurality of tubes (<NUM>) extending through at least one of the body portion and the pair of end plates; and
at least one tube sheet (<NUM>) including a plurality of openings (<NUM>) with a corresponding one of the plurality of tubes located in one of the plurality of openings, wherein the tube sheet is made of a material which expands in the presence of refrigerant,
characterized in that the at least one tube sheet (<NUM>) is formed from a plurality of geometric shaped members (<NUM>; <NUM>) and each of the plurality of geometric shaped members includes one of the plurality of openings (<NUM>) and each of the plurality of geometric shaped members are made of a single unitary piece of material; and in that the plurality of geometric shaped members (<NUM>; <NUM>) are hexagonal bodies that fit together to form the tube sheet (<NUM>).