KR200475201Y1 - High temperature graphite heat exchanger - Google Patents

Abstract

A heat exchanger for use as a graphite heat exchanger 100, particularly as a solar energy receiver as part of a thermal process in a solar power system, includes an energy collection panel 112, a heat spreader 116, and thermal elements 114 ), Wherein the heat spreader is formed of a flexible graphite having a density of at least about 0.6 g / cc and a thickness of less than about 10 mm, and wherein the heat spreader also includes a first side and a second side, The diffuser has a heat transfer relationship with the thermal element, and the energy collection panel comprises one or more sheets or blocks of graphite.

Description

[0001] HIGH TEMPERATURE GRAPHITE HEAT EXCHANGER [0002]

The present invention relates to an improved high temperature graphite heat exchanger and more particularly to a graphite energy receptor for use in a solar thermal process that provides more and more uniform heat transfer as elements of a solar power system. The graphite heat exchanger includes a thermal element containing a heat transfer fluid and provides efficient heat transfer to the transfer fluid for solar power generation. The heat exchanger may further include a heat spreader, which includes one or more sheets of compressed particles of exfoliated graphite that are thermally associated with the thermal elements to improve heat transfer .

As interest in the environment, fuel supply reduction, and energy efficiency continues to increase, solar power facilities are becoming a global concern. A typical solar power plant has a tower-shaped configuration in which a field of a heliostat reflects sunlight to a solar receiver mounted on the tower structure. The concentrated solar energy in the receiver, or in the heat exchanger, heats the internal fluid, such as hydrogen, helium, oil or molten salt, to high temperatures. For example, in a solar power tower, a "cold" molten salt at about 300 ° C is heated to 565 ° C and then pumped to a storage tank.

For power generation, a heat transfer fluid such as molten salt or helium is pumped into the steam generation system to generate steam for a typical Rankine-cycle turbine system, which in turn produces electricity. When oil is used as the heat transfer fluid, a similar process is employed. In order to maximize the efficiency of the solar tower, a high thermal conductivity material, such as graphite, is advantageous in assisting in acquiring, storing and transferring solar energy through the power generation process.

Thus, by making it possible to take advantage of the anisotropic nature of one or more carbon or graphite, in particular of a flexible graphite sheet such as, for example, a sheet of compressed particles of exfoliative graphite, There is a need for a heat exchanger, i.e., a solar thermal receiver, to improve the uniformity of heat transfer provided by the thermal element and to improve the heat flux acquired from and transferred to environmental energy. Ideally, such solar energy receivers are resistant to high temperatures and thermal cycling, and can maximize the use of solar energy while reducing heat loss due to convection and radiation.

In one embodiment of the present invention, a heat exchanger system includes a thermal element, such as a conduit or passage, that receives a transfer fluid, and a heat spreader, such as one or more sheets of compressed particles of exfoliated graphite And one or more flexible graphite sheets.

In another embodiment of the present invention, the heat spreader is in thermal contact with the thermal element to maximize heat flux between the energy collecting panel and the thermal element, which generates heat transfer.

In yet another embodiment, the heat spreader is a "underside" of the thermal element (the lower side is used in connection with the surface being heated; in other words, the lower side refers to the opposite surface of the surface exposed to the energy source To maximize the heat flux from the energy collection panel to the thermal element.

Yet another embodiment provides a heat spreader that improves the thermal flux to the thermal element, such that the heat spreader allows more thermal energy to be absorbed by the thermal element.

In another embodiment of the present invention, a heat spreader comprising at least one sheet of compressed particles of exfoliated graphite having a density of at least about 0.6 grams per cubic centimeter (0.6 g / cc) comprises a thermal element, Are placed in thermal contact with all of the surfaces of the heat exchanger system where heat transfer occurs as well.

In another embodiment, the heat spreader has a density of at least about 0.1 g / cc, most preferably at least about 1.5 g / cc, and / or has a thickness of less than about 10 mm.

In another embodiment, a heat spreader comprising at least one sheet of compressed particles of exfoliated graphite having a thermal conductivity parallel to major surfaces of at least about 140 watts per square meter (140 W / mK) And may also be in contact with an energy collection panel that is also generally heated by the sun.

Yet another embodiment of the present design includes a heat spreader having a thermal conductivity of at least about 220 W / mK, and more preferably at least about 300 W / mK.

In another embodiment of the present invention, the thermal element (s) of the heat exchanger for the solar power system is disposed in a groove or slot formed between the energy collection panel and the composite graphite substrate, and the heat spreader is disposed between the energy collection panel and the composite graphite substrate .

In another embodiment of the heat exchanger, the heat spreader comprises at least two components, a first component and a second component, wherein the first component of the heat spreader is located between the thermal element and the graphite substrate. The second component of the heat spreader may be located elsewhere.

In some embodiments, the graphite substrate includes a recess sized to receive a thermal element. A heat spreader may cooperate with the substrate to form a substrate diffuser recess.

In another embodiment, the heat exchanger system may comprise layers of graphite, and a thermal element is located between the layers of such graphite. Such an embodiment may also include a thermal element and a heat spreader positioned in heat transfer relationship with the various layers of graphite.

In another embodiment, the heat exchanger system may include a layer of graphite traversed by a thermal passageway containing a heat transfer fluid therein. This embodiment may also include a heat spreader positioned in a heat transfer relationship with the graphite and thermal passageways.

Each embodiment of the heat exchanger may include a solar energy receiver.

In one embodiment, the heat exchanger system may also include a substrate, preferably formed of synthetic graphite, having a recess sized to receive a thermal element, the substrate being disposed on a second side of the heat spreader The heat spreader is positioned between the thermal element and the substrate, and the substrate has a thermal conductivity greater than about 120 W / mK. Further, in some embodiments, the heat spreader may comprise two components: a first component and a second component, wherein the first component of the heat spreader is positioned between the thermal element and the substrate. In certain embodiments, the second component of the heat spreader extends across the recess, such that the second component of the heat spreader is positioned between the energy collecting panel and the thermal element at the recess.

Another aspect of the present invention is a substrate comprising a recess; And a heat spreader, wherein the heat spreader comprises at least one sheet of compressed particles of exfoliated graphite having a density of at least about 0.6 g / cc and a thickness of less than about 10 mm, wherein the heat spreader To form a substrate / diffuser recess that extends into the recess of the substrate and is sized to accommodate the thermal element. In other words, the heat spreader is located in the recess of the substrate, so that a recess is formed by the heat spreader when the heat spreader is seated in the recess of the substrate to form what is referred to as a substrate / diffuser recess. The heat spreader may be formed of two components, a first component and a second component, wherein the first component of the heat spreader cooperates with the substrate to form a substrate diffuser recess.

In another aspect, the invention features a structural element having a first surface and a second surface; A protective layer having a first surface and a second surface; A thermal element positioned proximate a second surface of the structural element and having a portion disposed toward the second surface of the structural element and a portion disposed away from the structural element with respect to each other; A heat exchanger system having a heat spreader comprising at least one sheet of compressed particles of exfoliated graphite wherein the heat spreader is located in a heat transfer relationship with both the second surface of the structural element and the thermal element, And wherein the heat spreader is positioned in a heat transfer relationship with a portion of the thermal element disposed in a direction away from the second surface of the structural element.

Another aspect of the present invention includes providing a heat exchanger system, comprising: (a) a structural element having a first surface and a second surface; (b) a thermal element located adjacent to the second surface of the structural element and having a portion disposed toward the second surface of the structural element and a portion disposed away from the structural element, ; And (c) a heat spreader comprising at least one sheet of compressed particles of exfoliated graphite, the heat spreader being positioned in a heat transfer relationship with both the second surface of the structural element and the thermal element, Includes a heat spreader positioned in a heat transfer relationship with a portion of the thermal element disposed in a direction away from the second surface of the structural element.

In one embodiment of the heat exchanger, the heat spreader comprises at least one sheet of compressed particles of exfoliated graphite, and one of the sheets has a heat transfer relationship with the entire surface of the thermal element. Preferably, the at least one sheet of compressed particles of exfoliated graphite has a density of at least about 0.6 g / cc, more preferably at least about 1.1 g / cc, and also at least 1.5 g / cc. In addition, one or more sheets of compressed particles of exfoliated graphite may have an in-plane heat of greater than or equal to about 140 W / mK, more preferably greater than or equal to about 220 W / mK, or greater than or equal to about 300 W / Conductivity can be obtained.

The heat transfer system may also include a substrate disposed proximate a second surface of the structural element such that the heat spreader is positioned between the substrate and the structural element, wherein the substrate has a high conductivity, that is, the substrate has a thermal conductivity greater than about 120 W / Plane direction, and more preferably greater than about 150 W / mK.

Another aspect of a heat exchanger system includes providing a heat exchanger system for a solar tower, the system comprising: (a) an energy collection panel having structural elements having a first surface and a second surface; (b) a protective coating located adjacent to the first surface of the structural element and having a portion disposed toward the first surface of the structural element and a portion disposed away from the structural element, relative to each other; (c) a heat spreader comprising at least one sheet of compressed particles of exfoliative graphite, wherein at least one sheet of compressed particles of exfoliative graphite has a density of at least about 0.6 g / cc and a flatness of at least about 140 W / The heat spreader having a thermal conductivity, the heat spreader being located in a heat transfer relationship with a second surface of the structural element, and also the heat spreader being located in a heat transfer relationship with the thermal element.

These and other embodiments, which will become apparent to those skilled in the art from the following detailed description, will be apparent to those skilled in the art and may be acquired by the provision of a heat exchanger system, such a heat exchanger system comprising a thermal element including a surface; And a flexible graphite heat spreader having a density of at least about 0.6 g / cc, preferably a density of at least about 1.1 g / cc, and a thickness of less than about 10 mm, and further comprising a first side and a second side, Wherein the heat spreader at least partially surrounds the thermal element such that a first side of the heat spreader is surrounded by a portion of the thermal element surface and a portion of the thermal element The heat spreader is positioned relative to the thermal element such that it is in a transfer relationship.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the nature and characteristic of the invention as claimed in the appended claims. The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments of the present invention and, together with the description, serve to explain the principles and operation of the disclosure. Those skilled in the art will readily and clearly understand other and further features and advantages of the present invention when referred to the following description in conjunction with the accompanying drawings.

1 is a perspective view illustrating an embodiment of a heat exchanger according to the present invention.
Figure 2 is a partial cross-sectional view of the heat exchanger of Figure 1;
3 is a cross-sectional view of the heat exchanger of FIG.
Figure 4 is a partial cross-sectional view of the heat exchanger of Figure 3;
5-9 are partial cross-sectional views of a graphite heat exchanger in accordance with various embodiments described herein.
10 is a partial sectional view showing an embodiment of the graphite layer.
11 is a partial cross-sectional view of one embodiment of a graphite layer comprising a heat spreader.
Figure 12 is a partial cross-sectional view of one embodiment of a graphite layer comprising a heat spreader and a thermal highway.
Figure 13 is a partial cross-sectional view of an embodiment of the graphite layer (s) included in the heat exchanger in an exploded view.
14 is a partial cross-sectional view of one embodiment of a graphite layer (s) included in a heat exchanger with a heat spreader.
Figure 15 is a partial cross-sectional view of an offset graphite layer (s) that may be included in a heat exchanger in an exploded view.
16 is a partial cross-sectional view of one embodiment of offset graphite layers that may be included in a heat exchanger with a heat spreader.

As discussed above, the heat exchanger system preferably includes an energy collection panel, which may consist of one or more sheets of flexible graphite and graphite, such as one or more sheets of compressed particles of exfoliative graphite, and in one embodiment , And a substrate that can be made of synthetic graphite.

Although this subject matter has been described in the context of a high temperature solar heat exchange system, it should be appreciated that the present invention is not limited to a floor or ceiling system, a resistance system, an under-floor staple up system, Heating system; And that the concepts of the present invention also relate to other types of heat exchanger systems, including various cooling systems to which the present invention may also be applied.

In a particular embodiment, unlike a heat spreader comprising compressed particles of the above-described exfoliated graphite formed using natural graphite in a preferred embodiment, the substrate and the energy collection panel can be made of an isostatically- Which is also referred to as preferably artificially or produced graphite, processed from microparticulate microparticles, especially processed from microparticles. In some embodiments, the synthetic graphite may also be formed by extrusion molding. The graphite used to form the substrate and the energy collection panel is made from a carbon-based material, rather than being mined as a natural material.

As described above, the present invention relates to a heat exchanger comprising a heat spreader comprising a flexible graphite, such as one or more sheets of compressed particles of exfoliated graphite. The heat spreader should have a density of at least about 0.6 g / cc, more preferably at least about 1.1 g / cc, and most preferably at least about 1.5 g / cc. From a practical point of view, the upper limit for the density of the graphite sheet heat spreader is about 2.0 g / cc. The heat spreader (even if made of more than one sheet of compressed particles of exfoliated graphite) should have a thickness of less than about 10 mm, more preferably less than about 2 mm, and most preferably less than about 1 mm.

In practical applications of the present invention, a plurality of graphite sheets may be laminated as a single article for use as a heat spreader, provided that the laminate of the plurality of graphite sheets satisfies the density and thickness requirements described above . Sheets of compressed particles of exfoliated graphite may be laminated by a suitable adhesive such as a pressure sensitive adhesive or thermally activated adhesive located therebetween. The adhesive selected should be balanced between bond strength and thickness minimization and thermal bonding must be able to maintain proper bonding at the intended service temperature. Suitable adhesives will be known to those skilled in the art and include acrylic resins and phenolic resins.

The graphite sheet (s) constituting the heat spreader will have thermal conductivity (referred to as "in-plane thermal conductivity") parallel to the sheet plane of greater than about 140 W / mK in actual use. More preferably, the thermal conductivity parallel to the plane of the graphite sheet (s) is at least about 220 W / mK, more preferably at least about 300 W / mK. In certain embodiments, the heat spreader has an in-plane thermal conductivity of at least about 500 W / mK. In another embodiment, the in-plane thermal conductivity may be greater than about 1500 W / mK. One example of a suitable graphite sheet is the Graf® material available from GrafTech International Holdings Inc. of Parma, Ohio.

Of course, it will be appreciated that the higher the thermal conductivity in the plane, the more efficient the thermal diffusivity of the heat spreader. From a practical point of view, the sheets of compressed particles of exfoliated graphite having in-plane thermal conductivity up to about 600 W / mK are all that necessary. The expression "thermal conductivity parallel to the plane of the sheet" and "thermal conductivity in the plane" indicates that the sheet of compressed particles of the peelable graphite has two main surfaces, Will be able; Accordingly, "thermal conductivity parallel to the plane of the sheet" and "thermal conductivity in the plane" will constitute thermal conductivity along the major surfaces of the sheet of compressed particles of the peelable graphite.

Other embodiments of heat spreaders may include pyrolytic graphite or a graphite sheet that may include a composite of natural graphite and pyrolytic graphite and such graphite sheet may have an in-plane thermal conductivity of 600 W / mK or greater Can provide; In fact, a thermal conductivity as high as 1500 W / mK can be obtained. In certain embodiments, "pyrolysis graphite" refers to a graphite material formed from a carbonized polymer film. For example, in the production of some embodiments of pyrolytic graphite, a film such as a polyimide film is first cut and molded in anticipation of subsequent shrinkage during the carbonization step. During carbonization, a large amount of carbon monoxide is typically released from the film, resulting in significant shrinkage of the film. Carbonization occurs as a two-stage process, where the first stage occurs at significantly lower temperatures than the second stage. During the first stage of polyimide film carbonization, the weight loss is mainly due to breakage in the carbonyl groups in the imide portion of the polyimide film. Specifically, ether oxygen appears to be lost at the end of the first stage. In the second stage of carbonization, nitrogen gas is released during decomposition of the imide group of the film. The graphitization process involves a high temperature heat treatment utilizing a heat treatment temperature that results in different alignment of the carbon atoms. The resulting pyrolytic graphite has a high degree of crystallographic orientation of the c-axis perpendicular to the surface of the sheet (high degree) and, consequently, is highly anisotropic. In fact, any of the structural elements of heat exchanger 100 may comprise composite graphite comprising pyrolytic graphite or pyrolytic graphite.

Similarly, the heat exchanger includes a high temperature heat absorbing plate (sometimes referred to as an energy collecting plate) and a substrate, each of which may comprise a synthetic graphite. In one embodiment, the synthetic graphite may be a medium-grain graphite, and such intermediate particle graphite may be present at a maximum of about 1.0 mm, preferably from about 0.6 mm to about 0.9 mm Coke < / RTI > particle size. In another embodiment, the synthetic graphite forming the heat absorbing plate and substrate is a micro-particle graphite having an average coke particle size of 0.024 mm or less. Synthetic graphite, including energy collection panels and graphite substrates, has particles with a thermal conductivity of about 120 W / mK or greater. Further, in some embodiments of the heat exchanger, the heat absorbing plate and / or the substrate may comprise extruded graphite so that each of them can provide anisotropy and thereby direct heat to the heat spreader, Can effectively support the heat transfer at the < / RTI >

It will be appreciated that although the heat exchanger of the present invention is described primarily in the context of a solar thermal power generation system, the principles of the present invention may be applied to heating or cooling systems embodied in any other similar heat exchanger system.

Referring to the accompanying drawings, FIG. 1 schematically illustrates a high temperature heat exchanger 100. The high temperature heat exchanger 100 includes an energy collection panel 112 having a protective coating 110 wherein heat is absorbed through the protective coating when the heat exchanger 100 is exposed to sunlight. Depending on the particular application, the thermal element 114, which may be a heating or cooling element, or alternatively a passageway for the heat transfer fluid, has a thermal transfer relationship with the energy collection panel 112. A heat transfer relationship means that heat energy is transferred from one article or entity to another.

The following description relates primarily to heating elements as thermal elements 114. It will be appreciated that the thermal element 114 may also include a cooling element. The thermal element 114 may be referred to more generally as a heat transfer element that can be heated or cooled. In the heat exchanger 100, the thermal element 114 is heated by its periphery. The thermal elements 114 may also include recesses, cavities, or passageways for transporting heat transfer fluids and formed as an available space between the various other structural features of the heat exchanger 100 have.

The thermal element 114 may also be any available type of heat transfer element, including a conduit or tube network for transferring a heat transfer fluid or gas, but is not limited to such a conduit or tube network. The phrase "heat transfer fluid" may include any fluid, gas, gel, and / or phase transformation medium suitable for thermal energy transfer.

The protective coating 110 may be any conventional material used for preventing oxidation as a type suitable for use in a solar thermal system. Suitable thermal elements 114 and panels 112 are described in more detail below.

A heat spreader 116 comprising one or more sheets of compressed particles of exfoliated graphite has a thermal transfer relationship with the energy collection panel 112 and is thereby thermally coupled to the energy collection panel 112. The phrase "thermal coupling" refers to a conduction, convection, or radiation relationship (the latter two relationships are such that the heat spreader 116 is in physical contact with the energy collection panel 112 It is to be understood that the invention is not limited to these embodiments. As will be described in greater detail below, the synthetic graphite substrate 118 lies beneath the energy collection panel 112, where the heat spreader 116 is located between the graphite substrate 118 and the energy collection panel 112 .

It will be appreciated that the energy collection panel 112 need not be directly coupled to the heat spreader 116 and may be separated therefrom by various layers of graphite or other materials. Accordingly, when one layer of material in the heat exchanger 100 is described as being on top of the other, it is not meant that the layers must physically contact one another unless there is further specific mention. In fact, any of the components of the heat exchanger 100 may have a heat transfer relationship or a heat exchange relationship without physical contact with the other components.

Since the energy collection panel 112 is associated with photothermal conversion of solar energy, such panels are heated to very high temperatures, and these temperatures promote oxidation. In order to extend the life of the energy collection panel 112, a protective coating 110 is provided to slow down the rate of oxidation. The protective coating 110 may be any conventional material capable of prolonging the life of the graphite at elevated temperatures, for example, quartz or quartz, by protecting the graphite from oxidation.

Heat spreader 116 also has a heat transfer relationship with thermal element 114. The thermal element 114 may be, for example, a heat transfer material or device commonly found in conventional heat exchanger systems. For example, the thermal element 114 may be an electrical wiring element or may be of a type including a tube network for transporting a heat transfer fluid such as molten salt or helium. In solar power towers, such tube systems typically use titanium or stainless steel tubes. Such systems may also utilize other heat-conductive tube materials that are corrosion resistant.

The tubes of the thermal element 114 may also include a series of impermeable, semi-permeable, or permeable graphite tubes, which may receive helium, other phase transformation media, or heat- Can guide. Such a graphite tube may be made of a series of resins impregnated impermeable or semi-impermeable. The use of a graphite tube as the thermal element 114 may mitigate any deviation in the coefficient of thermal expansion of each of the various materials used to construct the hot heat exchanger 100 according to the present disclosure.

If, as in some graphite tubes, the tube containing the thermal element 114 is not impervious, it may be desirable to minimize gas loss from the permeable or semi-permeable tube, i. E., Permeable or semi-permeable thermal element 114 The heat exchanger 100 may be pressurized with positive pressure with helium or other heat transfer gas. Also, although shown generally round in cross-section, thermal element 114 may also have other cross-sectional shapes such as elliptical, square, rectangular, and the like.

To improve the absorptivity, the heat spreader 116 may include a graphite having a small particle size with a polished surface finish. The better the surface finish, the smaller diameter tubes and higher heat transfer fluid velocities can be realized, which in turn improves the overall thermal flow through the heat spreader 116.

In some embodiments of the heat exchanger 100, the substrate 118, as shown in Figures 1, 3 and 4-9, has excellent strength properties in high temperature applications such as SLX®Graphite produced by GrafTech International Holdings Inc. Such as a medium-grain graphite having an average particle size of about < RTI ID = 0.0 > The thermal conductivity of the substrate 118 should be at least about 120 W / mK, more preferably at least about 150 W / mK in the in-plane direction when the fabricated or synthetic graphite material is used. Preferably, micro-particle graphite may also be used, but this is not necessary. In such a case, the graphite substrate 118 may help to transfer as much heat energy as possible from the energy collection panel 112 to the thermal element 114.

As will be appreciated, heat spreader 116 may include one or more sheets of compressed particles of exfoliative graphite and be positioned between substrate 118 and energy collection panel 112. In such a case, since heat spreader 116 has a heat transfer relationship with both thermal element 114 and energy collecting panel 112, heat spreader 116 can dissipate heat energy to energy collecting panel 112 Will diffuse more evenly from the surface into and out of the thermal element 114 (through heating or cooling).

Most preferably, the heat spreader 116 has a heat transfer relationship with the entire outer surface of the thermal element 114. However, in other embodiments, the heat spreader 116 may also have a heat transfer relationship with a portion of the thermal element 114 furthest from the energy collection panel 112. In other words, as viewed in the direction of FIGS. 1-4, the heat spreader 116 will have to be at least partially surrounded by the thermal element 114, (Most preferably, actual physical contact) with the entire surface of the thermal element 114, but instead only with a portion of the thermal element 114.

In this manner, the heat spreader 116 is configured to provide thermal energy (e.g., heat) from the portions or surfaces of the thermal element 114 that have the heat transfer relationship furthest from the energy collection panel 112 Thereby improving the thermal flux for the thermal element 114. [0035] In addition, the flexibility and conformability of the heat spreader 116 can improve heat transfer with the energy collection panel 112, which is a significant advantage in terms of efficiency. In addition, since the heat spreader 116 has a relatively uniform cross-sectional thickness and density, the desired physical properties of the heat spreader 116 are uniform over the entire surface.

In one embodiment of the heat exchanger 100 shown in Figure 5, if the sheets of compressed particles of exfoliated graphite used to form the heat spreader 116 have flexible properties, the heat spreader 116 May be located between the substrate 118 and the energy collection panel 112 and extend below the thermal element 114 (the term "down" refers to the direction away from the energy collection panel 112 Quot; thermal element 114 "). Instead, the heat spreader 116 may be formed of two distinct components, a first heat spreader component 116a and a second heat spreader component 116b, as shown in Figures 2 and 3, will be. The first heat spreader component 116a comprises one or more sheets of compressed particles of exfoliative graphite and is positioned between the substrate 118 and the energy collection panel 112 as described above, (Not shown). Instead, as shown in FIG. 6, the first heat spreader component 116a does not extend into the area where the thermal element 114 is located; Or first heat spreader component 116a extends completely across the upper surface of the thermal element 114 and thereby makes good thermal contact with the upper portion of the thermal element 114. [

The second heat spreader component 116b is a discrete component that thermally (and preferably physically) contacts and at least partially surrounds the thermal element 114 or about its surface, (Most preferably in physical contact) with the first heat spreader component 116a, as shown in Figures 2 and 3, and includes the lower or side portions of the first heat spreader component 114, and as shown in Figures 2 and 3. The second heat spreader component 116b may be formed of one or more sheets of compressed particles of exfoliated graphite or may be made of other materials such as anisotropic materials such as metals such as aluminum. The second heat spreader component 116b may have a different density and / or lower through-plane conductivity than the first heat spreader component 116a. In some embodiments, the second heat spreader component 116b may have a lower planar-through conductivity than the first heat spreader component 116a to reduce heat loss. For example, in some embodiments, the second heat spreader component 116b may provide some shielding to the substrate 118 to minimize heat loss.

In some arrangements, it may also be desirable (and not shown) to have a second heat spreader component 116b that partially surrounds only the sides of the thermal element 114, 2 heat spreader component 116b and such a second heat spreader component is again installed or attached to the first heat spreader component 116a.

In another embodiment, if the second heat spreader component 116b maintains a heat transfer relationship (and most preferably, a substantial physical contact) with the first heat spreader component 116a, as shown in Figure 8, The second heat spreader component 116b may completely surround the thermal element 114 or extend around it.

In another embodiment, the substrate 118 or the energy collection panel 112 comprises a graphite plate of high thermal conductivity that is continuously stacked. The graphite plate may, for example, comprise a layered natural graphite such as GrafTech 占 SS500 with a thermal conductivity of 500 W / mK. Instead, a continuously stacked synthetic graphite plate could be used. Ideally, stacked plates are formed using graphite with high thermal conductivity to rapidly transfer heat from the surface of heat spreader 116 to thermal element 114.

In another embodiment, the substrate 118 or energy collection panel 112 comprises a porous carbon or conductive graphite foam block, which acts as a thermal receiver. In some embodiments, a graphite foam having a thermal conductivity of about 120 W / mK or greater, preferably about 200 W / mK or greater at ambient temperature is used as the substrate. The heat transfer fluid may be directed through the porous substrate or through a cut through passage through the substrate. The orientation and number of passages through the substrate depend on the required pressure drop across the receiver. A series of conduits that can be aligned vertically with respect to the gas flow can cut the substrate to improve porosity and reduce the pressure drop across the substrate. In one embodiment, the conductive graphite foam block may be sealed from the atmosphere.

The energy collection panel 112 may also include a non-porous carbon or graphite block. The substrate may include inexpensive graphite from anode grade cokes with a thermal conductivity of 100 W / mK or greater, even at 150 W / mK or greater at room temperature.

The use of the heat spreader 116 in the heat exchanger 100 with the heat spreader in more thermal contact with the heating element can significantly improve the heat flux from the energy collection panel 112 to the thermal element 114 have. Thus, the heating elements for the heating system can be more closely aligned with each other, and / or the temperature of the transfer fluid flowing through the tube can be further increased, resulting in a significant improvement in energy efficiency.

In one embodiment of the heat exchanger 100, a thermal element 114 is fastened or directly joined to create a gas or fluid flow passage 122 between the blocks 120, as shown in FIG. Or may be formed by continuous graphitized blocks 120 that are cemented indirectly and the passageway 122 is equivalent to the thermal element 114. In one embodiment, a heat transfer fluid, such as helium, may be allowed to flow unobstructed through the passageway 122 to transfer heat to and from the heat exchanger 100. In FIG. 9, the thermal element 114 is formed as a passage 122 between the graphite blocks 120.

In some embodiments, the graphite used to form the block 120 may be resin impregnated to reduce the permeability of the blocks. The graphite blocks 120 may be joined together using the high temperature graphite cement. In addition, the total heat exchanger 100 may be pressurized with positive pressure using helium or alternatively another heat transfer fluid, to minimize gas loss from the passageway 122. Pressing the heat exchanger 100 is particularly advantageous when the graphite forming the block 120 and the passageway 122 is not impervious.

When a portion of the heat exchanger 100 is pressurized, helium is often used as a heat transfer fluid. Helium is useful as an inert gas with a high heat capacity; However, other phase change media may alternatively be used to press heat exchanger 100. [

10-12, the thermal element 114 includes one or more graphite blocks 124 (not shown) having a series of pre-machined passages 126 that are cut from the block to form graphite block plenums ). ≪ / RTI > Graphite block 124 may also be referred to as a "layer of graphite "," sheet of graphite ", or "piece of graphite ". As shown in FIG. 10, the processed passage 126 forms a thermal element 114 in some embodiments of the heat exchanger 100.

As shown by FIG. 11, the passageway 126, and thus the thermal element 114, can be lined with a layer of graphite, which functions as a heat spreader 116. In effect, passageway 126 may be entirely or partially lined with one or more sheets of compressed particles of exfoliative graphite, heat spreader 116, which may be lined with thermal elements < RTI ID = 0.0 > Heat transfer relationship.

12, one or more sheets of compressed particles of exfoliative graphite, i.e., thermal highway 117, may traverse graphite block 124 and be accommodated within graphite block 124 Or passageways 126 to assist heat transfer to it uniformly and efficiently. Figure 12 illustrates one embodiment that includes a specially oriented thermal highway 117; However, the thermal highway 117 may be positioned differently and positioned to extend through the passageway 126 as the geometry of the passageway 126 changes.

Thermal highway 117 has a thermal conductivity of at least about 50 W / mK; In some embodiments, a synthetic or natural graphite material having a thermal conductivity of greater than or equal to about 150 W / mK. Each embodiment of heat exchanger 100 including a graphite block may be pressurized to aid heat transfer and to prevent heat loss.

13, the thermal element 114 may be formed by connecting a first graphite block 128 and a second graphite block 130, each of which may include one or more blocks 128 130, and one or more half slots. One half-shaped slot may be semi-cylindrical in shape. Accordingly, when the first graphite block 128 and the second graphite block 130 are connected to each other, the two blocks 128 and 130 are connected to each other through the heat exchanger 100, Or other heat transfer fluid to flow. The blocks may be bolted together, joined together using hot graphite cement, or connected by any other means known in the art. A resulting passage 126 similar to the thermal element 114 may be formed between any number of graphite blocks 128,130.

In order to reduce the thermal path length between the protective layer 110 and the thermal element 114, the thickness of the graphite blocks 128, 130 may be minimized. 14, the inner side of the passageway 126 is lined with a heat spreader 116, including natural or synthetic graphite, to ensure maximum heat flow around each perimeter of the passageway It will be possible. The heat spreader 116 may comprise, for example, one or more sheets of compressed particles of exfoliated graphite. The heat spreader 116 will be able to partially or fully liner the passageway 126. [ In order to offset any expansion of the received heat transfer fluid, the heat spreader 116 may be inflated upon heating.

The size of the passageway 126 may be increased between the heat transfer fluid inlet of the heat exchanger 100 and the heat transfer fluid outlet. Such an increase in the passage size may proceed along the path of the heat transfer fluid through the heat exchanger 100. As the heat exchange fluid travels through heat exchanger 100 and is heated, the size of passageway 126 increases. The increase in the passage size helps to reduce the pressure drop across the heat exchanger, which can be achieved by heating the heat transfer fluid as heat transfer fluid, such as, for example, helium, And swelling. The use of graphite provides a structurally robust path that allows the heat transfer fluid to travel through the heat spreader 116 at high temperatures.

In addition, the number of passages 126 may be variable. For example, instead of a smaller number of larger holes, a plurality of smaller diameter passages may be bored through a thin graphite block. The small holes will have a larger surface area per unit volume, thereby maximizing the heat flow from the graphite to the heat transfer fluid. The pressure drop in the small holes will be larger, but conventional modeling can be used to optimize the population of holes versus the intrinsic strength of the block.

Additionally, as shown in FIG. 15, a series of passageways 126 in a plurality of layers may be used to maximize heat transfer. A plurality of graphite blocks 128 and 130 may form a layer to form a passageway 126 and the passageways 126 created by the stacked blocks 128 and 130 may be offset from each other to effect heat transfer It will be able to promote further. Irrespective of the offsets of the passages 126, the distal ends of each of the blocks 128 and 130 may be line up and flush together.

The layers of the passageway 126 are offset from each other by a row so as to minimize the thickness of the graphite and to reduce the thickness of the thermal element 114 from the outer surface of the heat spreader 116 to the thermal element 114, It will be possible to reduce the thermal path to the passageway 126 and consequently the thermal path to the heat transfer fluid. Here again, as shown in FIG. 16, the heat spreader 116 may be able to partially or completely liner the passageway 126 to minimize thermal gradients.

All cited patents and publications mentioned herein are incorporated herein by reference.

Having thus described the invention herein, it will be appreciated that the invention may be varied in many ways. All such variations and modifications may be practiced in any suitable combination. Such modified and modified embodiments are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications and variations are intended to be included within the scope of the claims of utility model registration claims will be.

Claims (15)

A heat exchanger system comprising:
(a) a thermal element comprising a surface;
(b) a heat spreader comprising at least one graphite sheet having a density of at least 0.6 g / cc and a thickness of less than 10 mm, the heat spreader further comprising a first surface and a second surface, A heat spreader positioned relative to the thermal element to be in a heat transfer relationship with a portion of the surface of the thermal element;
(c) a substrate comprising graphite, the substrate positioned relative to the heat spreader in a heat transfer relationship with the heat spreader; And
(d) an energy collection panel located opposite the thermal element from the substrate; / RTI >
Wherein the substrate comprises at least one synthetic graphite layer.
Heat exchanger system.
The method according to claim 1,
Wherein the substrate comprises a recess having a size to receive the thermal element,
Wherein the substrate is disposed adjacent to the heat spreader such that the heat spreader is positioned between the thermal element and the substrate,
Wherein the substrate has a thermal conductivity greater than 150 W / mK,
Heat exchanger system.
3. The method according to claim 1 or 2,
Wherein the heat spreader comprises two components, a first component and a second component,
And wherein a first component of the heat spreader is positioned between the thermal element and the substrate.
Heat exchanger system.
delete 3. The method of claim 2,
Wherein the heat spreader comprises two components, a first component and a second component,
And wherein a second component of the heat spreader extends across the recess such that a second component of the heat spreader is located between the thermal element and the energy collecting panel.
Heat exchanger system.
The method according to claim 1,
Wherein the graphite sheet is selected from the group consisting of at least one sheet of compressed particles of exfoliative graphite, at least one sheet of graphitized polyimide, or a combination of both.
Heat exchanger system.
The method according to claim 1,
Further comprising a structural element comprising a surface in thermal communication with a portion of the surface of the thermal element,
The structural element comprises one or more synthetic graphite layers.
Heat exchanger system.
delete The method according to claim 1,
And a protective layer having a first surface and a second surface,
Wherein a first surface of the protective layer is positioned between an energy source and the thermal element,
Heat exchanger system.
The method according to claim 1,
Including solar energy receptors,
Heat exchanger system.
A heat exchanger system comprising:
(a) a first synthetic graphite layer having a first surface and a second surface;
(b) a second synthetic graphite layer positioned below a second surface of said first synthetic graphite layer;
(c) a thermal element positioned between said first synthetic graphite layer and said second synthetic graphite layer; And
(d) a heat spreader comprising at least one sheet of compressed particles of exfoliated graphite having a density of at least 0.6 g / cc and an in-plane thermal conductivity of at least 140 W / mK, wherein the first synthetic graphite layer, A graphite layer, and a heat spreader positioned to be in heat transfer relationship with the thermal element; / RTI >
Heat exchanger system.
12. The method of claim 11,
Wherein at least one sheet of compressed particles of said peelable graphite has an in-plane thermal conductivity of at least 220 W / mK,
Heat exchanger system.
12. The method of claim 11,
Wherein the first synthetic graphite layer has an in-plane thermal conductivity of at least 120 W / mK,
Heat exchanger system.
A heat exchanger system comprising:
(a) at least one synthetic graphite layer;
(b) at least one thermal passageway for retaining heat transfer fluid therein, the thermal passageway crossing the at least one synthetic graphite layer; And
(c) a heat spreader comprising at least one sheet of compressed particles of exfoliated graphite having a density of at least 0.6 g / cc and an in-plane thermal conductivity of at least 140 W / mK, wherein the at least one synthetic graphite layer and the thermal passageway A heat spreader in contact with all; / RTI >
Heat exchanger system.
15. The method of claim 14,
And a protective layer having a first surface and a second surface,
Wherein the first surface of the protective layer is positioned between the energy source and the thermal path,
Heat exchanger system.

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