COOLING APPARATUS AND METHOD
20240019214 ยท 2024-01-18
Assignee
Inventors
Cpc classification
F28C1/16
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F28C1/16
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
An apparatus including: (a) a liquid conduit with sealable connectors at opposite ends thereof and air conduits passing vertically therethrough; (b) one or more mist generators positioned to deliver mist to said air conduits; and (c) an airflow generator positioned and configured to move said mist through said air conduits.
Claims
1.-18 (canceled)
19. An apparatus comprising: a central conduit comprising one of: a plurality of tubes, and a plurality of plates, wherein each one of the plurality of tubes or the plurality of plates has a first surface that comes in contact with a flowing liquid and a second opposite surface that comes in contact with air comprising droplets; an airflow generator positioned at a first end of said central conduit, and configured to produce an air flow and introduce said air flow to said second side; and one or more misters positioned at a second end of said central conduit, and configured to deliver mist to said air flow, thereby forming a thin water-film on said second side.
20. The apparatus of claim 19, wherein the air flow is produced at Reynolds number larger than 10000.
21. The apparatus of claim 19, wherein the thin flowing liquid film is between 10 to 100 microns thick.
22. The apparatus of claim 19, wherein the misters are configured to produce between to 4 liter of flowing liquid mist per minute.
23. The apparatus of claim 19, wherein the misters are configured to produce droplets of flowing liquid in a size range of 10 m to 100 m.
24. The apparatus of claim 19, wherein the first surface is an inner surface of the tubes, and wherein the misters and air flow generator are configured to deliver the mist into the inner surface of the tube.
25. The apparatus of claim 19, wherein the first surface is an outer surface of the plurality of plates and wherein the misters and air flow generator are configured to deliver the mist onto the outer surface of the tube.
26. The apparatus of claim 19, further comprising a hot liquid inlet tube for introducing hot liquid into the central conduit.
27. The apparatus of claim 19, wherein the central conduit comprises the plurality of tubes and wherein the apparatus further comprises a plurality of baffles arranged in alternation from on an inner surface of the central conduit.
28. The apparatus of claim 19, further comprising two disks for sealing the central conduit.
29. A method of cooling a hot liquid, comprising: introducing hot liquid into a central conduit of a cooling device, via an inlet, wherein the central conduit comprises one of: a plurality of tubes and plates, wherein each one of the plurality of tubes or plates has a first surface that comes in contact with a flowing liquid and a second opposite surface that comes in contact with an air comprising droplets; producing an airflow and introducing said air flow to said second side; producing and delivering mist to said air flow, thereby forming a thin water-film on said second side.
30. The method of claim 29, wherein the air flow is produced at Reynolds number larger than 10000.
31. The method of claim 29, wherein the thin flowing liquid film is between 10 to 100 microns thick.
32. The method of claim 29, wherein the mist is produced at a capacity of between 0.05 to 4 liter of flowing liquid mist per minute.
33. The method of claim 29, wherein the mist has droplets of flowing liquid in a size range of 10 pm to 100 pm.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying figures. In the figures, identical and similar structures, elements or parts thereof that appear in more than one figure are generally labeled with the same or similar references in the figures in which they appear. Dimensions of components and features shown in the figures are chosen primarily for convenience and clarity of presentation and are not necessarily to scale. The attached figures are:
[0021]
[0022]
[0023]
[0024]
[0025]
[0026]
[0027]
DETAILED DESCRIPTION OF EMBODIMENTS
[0028] Embodiments of the invention relate to apparatus and methods for heat exchange. Specifically, some embodiments of the invention can be used to cool a fluid flowing through an apparatus.
[0029] The principles and operation of an apparatus and/or method according to exemplary embodiments of the invention may be better understood with reference to the drawings and accompanying descriptions.
[0030] Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details set forth in the following description or exemplified by the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.
[0031] As shown in
[0032] In the depicted embodiment, central portion 14 includes a cylindrical portion 42 (see
[0033] In the depicted embodiment, disks 22 and 24 have groups of holes 26 and 28 respectively formed therein. In the depicted embodiment, there are nineteen holes in each disk, although in practice this number varies. Regardless of the number of holes employed, the number of holes in each disk is the same. As shown in the figures, the holes all have the same diameter (e.g. about 2.5 cm). In other exemplary embodiments of the invention, hole diameters vary from about 1 cm to about 5 cm. In the depicted embodiment, holes 26 and 28 are aligned with each other, with aligned holes having the same diameter, and sealingly attached to upper surface 22 of disk 22 and the lower surface 24 of disk 24 around each of holes are a series of tubes 30. In some exemplary embodiments of the invention, tubes 30 are formed of a metal, for example a non-corrosive metal having heat conductivity over 100 watt/meter kelvin. Examples of metals with suitable heat conductivity include (but are not limited to) copper (>400 w/m k) and aluminum (>200 w/m k). It is also possible to use stainless steel (>10 w/m k) in some cases. In the depicted embodiment, each of tubes 30 has the same length. In some exemplary embodiments of the invention, a length of tubes 30 is from 50 cm to 150 cm. In some embodiments, a length of tubes 30 is about 100 cm. Alternatively or additionally, according to various exemplary embodiments of the invention an inner diameter of tubes 30 ranges from 1 cm to 5 cm, optionally about 2.5 cm, in accordance with the size of holes 26 and 28.
[0034] In the depicted embodiment, tubes 30 also run through a series of roughly semi-circular baffles 32, which are arranged at set distances from disk 22 and 24, and are oriented approximately perpendicularly to the axes of the tubes 30. As depicted, each baffle has 12 holes formed therein, and the baffles are oriented in alternating fashion, so that a middle set A of five tubes runs through all the baffles, whereas the remaining groups of 7 tubes, B and C, on each side of A run through alternating baffles. The baffles serve not only to help secure the tubes 30 in place, but also to direct the flow of a liquid to be cooled through the central portion, from inlet tube 34 down through outlet tube 36. In the depicted embodiment, inlet tube 34 and outlet tube 36 are mounted over apertures 38 and 40 respectively formed in cylinder 42 (not visible in
[0035] In the depicted embodiment, a group of misters 52 is positioned at the lower surface 22 of disk 22. In the depicted embodiment, each mister is aligned with one of the holes in disk 22. Commercially available examples of misters are the MicroWhirl, the P, and the PJ, available from BETE Fog Nozzle, Inc., Greenfield, Massachusetts, USA, www.bete.com. As depicted in the figures, the misters are held in place by a series of bars 54. In some exemplary embodiments of the invention, the bars are affixed to lower surface 22. In some embodiments, fixation of the bars is removable affixation. According to the depicted arrangement, mist from each mister 52 enters directly into a corresponding tube 30. In other exemplary embodiments of the invention, misters 52 are located at a distance from lower surface 22 (e.g. 15-40 cm from the holes, for example by affixation of bars 54 to the interior of lower portion 12, between slits 18 and lower surface 22). Water is provided to the misters via a tube or conduit (not depicted).
[0036] According to various exemplary embodiments of the invention misters 52 produce droplets in a size range of about 10 m to 100 m, or in a range of 40 m to 60 m, with an average size of 50 m as determined by volume. Alternatively or additionally, in some embodiments each mister emits a volume of between about 0.05 L and 0.5 L of water per minute. Although
[0037] In the depicted embodiment, upper portion 16 is also cylindrical. In the depicted embodiment, upper portion 16 has the same inner diameter as cylinder 42, and is sealingly secured to the upper surface 24 of disk 24 along lower rim 55 of upper portion 16, which defines an aperture 55. In the depicted embodiment, a fan 56 is mounted in upper portion 16, which in operation generates an air stream which pulls air through slits 18, past the misters 52, through tubes 30 and out through aperture 60 formed by the upper rim 58 of upper portion 16.
[0038] The exemplary apparatus shown in the figures is typically be used as part of a circulating liquid cooling system. In operation, a hot liquid, generally water, is introduced into central portion 14 via inlet tube 34. The hot liquid will be hot as a result of absorbing heat from a system to be cooled, for example a liquid cooled Data Center Rack, and will be pumped into the central portion by a pump (not shown). Fan 56 creates an upward draft, pulling air through slits 18 into lower portion 12 and up through tubes 30. Misters 52 create a mist, which is dispersed in the air pulled through the tubes 30. In the arrangement in which the misters are positioned a distance from the holes, partial evaporation of this mist as it rises prior to entering tubes 30 helps cool the air prior to entry into tubes. Evaporation of the mist as it rises through the tubes 30 further cools the air. Thus the air in the tubes will generally be cooler than air entering the slots 18, and upon entry into each tube will be cooler than the hot liquid passing through central portion 14. Additionally, water in the mist will also coat the inner surfaces of tubes 30 with which the mist comes into contact. As heat transfers from the hot liquid through the bodies of the tubes to the inner surfaces of the tubes, the water on the inner tube surfaces absorbs the heat and evaporates, being carried up in the stream of air running through the tube.
[0039] The presence of the baffles 32 helps ensure that hot liquid does not take a direct path from inlet 34 to outlet 36, or that some portions of the liquid moving through central portion 14 resides there for significantly longer than other portions of the liquid, but instead that the liquid traverses the outer surfaces of tubes 30 several times on its way to outlet 36. This improves both the overall flow, and improves the contact of the liquid with the outer surfaces of the rods, thus improving the overall heat transfer from the liquid to the air/water mixture passing through the rods.
[0040] The liquid exiting via outlet 36 is thus significantly cooler than the liquid entering via inlet 34. In some exemplary embodiments of the invention, the liquid exiting via outlet 36 is recycled directly back to the system to be cooled, where it will absorb heat and then be directed again through inlet 34. Alternatively, in some embodiments, more than one apparatus 10 is employed in series, to effect further cooling of the liquid to be cooled before recycling it back into the system. In some exemplary embodiments of the invention, two or more apparatus 10 are employed in parallel, to increase the overall throughput of liquid to be cooled.
[0041] The embodiment shown in the figures is contemplated for a system in which 90 liters of liquid to be cooled is circulated through central portion 16 per minute. It will be appreciated, however, that the apparatus may be adapted to cool larger or smaller volumes of liquid per unit time, for example by increasing the number of tubes 30 running from the lower portion to the upper portion, and/or increasing or decreasing the length of the tubes, and/or by changing the inner diameter of the tubes, or by a combination of such factors.
[0042] In some exemplary embodiments of the invention, the Reynolds number (Re) contributes to cooling. Based on studies and experimental data, a Re value >10000 provides good cooling. The principle of effective cooling in the system is establishing a stable thin film (10-100 micron) of water at the air/droplet side (i.e. inner surface of tubes 30 or outer surface of plates 130). The Volume of mist is used to replenish this film. If there are not enough droplets in the air flow, the film will break and heat conductivity will go down dramatically. High air temperature can contribute to acceleration of evaporation but has a negative effect on the temperature gradient. Water which evaporates from the film is lost to the environment and dissipates heat from the apparatus to the environment.
[0043]
[0044] As shown in
[0045] In contrast to apparatus 10, however, the central portion 114 of apparatus 110, which is surrounded by an enclosure 115 having sidewalls 141, contains a series of hollow, rectangular plates 130, which are arranged with the faces of largest area parallel to each other and the plates being in fluid connection with each other. Plates 130 are made of a metal, e.g. a non-corrosive metal having heat conductivity over 100 watt/meter kelvin. Examples of metals with suitable heat conductivity include (but are not limited to) copper (>400 w/m k) and aluminum (>200 w/m k). It is also possible to use stainless steel (>10 w/m k) in some cases. The liquid to be cooled enters the plates via top inlet tube 134. The liquid then travels downward through the plates and exits via outlet tube 136. As is shown in
[0046] As shown in
[0047] In the depicted embodiment, misters 152 create a mist, which is dispersed in the air pulled through the spaces between and around plates 130. In the arrangement in which the misters are positioned a distance from the plates, partial evaporation of this mist as it rises prior to entering the central portion 114 helps cool the air prior to entry into the spaces between and around the plates 130. Evaporation of the mist as it rises around the plates 130 further cools the air. Thus the air around the plates 130 will generally be cooler than air entering the slots 118, and upon entry into the spaces between and around the plates 130 will be cooler than the hot liquid passing through the plates. Additionally, water in the mist will also coat the outer surfaces of plates 130 with which the mist comes into contact. As heat transfers from the hot liquid through the bodies of the plates to the outer surfaces of the plates, the water on the outer plate surfaces absorbs the heat and evaporates, being carried up in the stream of air running between and around the plates.
[0048] As noted above, in the embodiment shown in
[0049] It will also be appreciated that alternative arrangements are possible. For example, the apparatus could be arranged so that the liquid to be cooled runs through a series of pipes, and the mist is formed outside these pipes, so that the air/water mixture is drawn upward along the exterior of the pipes through which the liquid to be cooled runs.
[0050] According to various exemplary embodiments of the invention tap water and/or deionized water and/or distilled water are used to feed the misters.
[0051] In some exemplary embodiments of the invention, the liquid to be cooled enters the chamber at a temperature in the range of 20 C. to 90 C., for example in the range of 35 C. to 60 C. Depending on the particular apparatus configuration used, the misting rate, the temperature of the water upon misting, the mist droplet size, and the ambient air temperature, the liquid flowing through the conduit is cooled by as much as 20 C. before exiting the chamber through the outlet. Additionally, the ambient air temperature is, in some embodiments, as high 40 C.
Exemplary Apparatus
[0052] Referring again to the figures, an apparatus according to various exemplary embodiments of the invention includes a liquid conduit (e.g. central portion 14 in
[0053] In the depicted embodiments, the apparatus includes baffles (e.g. 32
Exemplary Method
[0054] Some exemplary embodiments of the invention relate to a method including directing a flow of heated liquid through a conduit with a wall (e.g. central portion 14 in
Additional Exemplary Apparatus
[0055] In some exemplary embodiments of the invention there is provided a heat exchanger characterized by: a heat transfer coefficient of 500 w/m.sup.2 k to 1000 w/m.sup.2 k and a cooling water (i.e. mist) requirement of 5.0 L/kW of removed heat energy. According to various exemplary embodiments of the invention the cooling water requirement is 4.5 L/kW of removed heat energy; 4.0 L/kW of removed heat energy; 3.5 L/kW of removed heat energy; 3.0 L/kW of removed heat energy; 2.5 L/kW of removed heat energy; 2.0 L/kW of removed heat energy or intermediate or lower L/kW of removed heat energy. In some exemplary embodiments of the invention, the heat exchanger is further characterized by a logarithmic mean temperature difference (LMTD) (k) of about 5.
[0056] It is expected that during the life of this patent many new mister types will be developed and the scope of the invention is intended to include all such new technologies a priori.
[0057] As used herein the term about refers to 10%.
[0058] Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.
[0059] Specifically, a variety of numerical indicators have been utilized. It should be understood that these numerical indicators could vary even further based upon a variety of engineering principles, materials, intended use and designs incorporated into the various embodiments of the invention. Additionally, components and/or actions ascribed to exemplary embodiments of the invention and depicted as a single unit may be divided into subunits. Conversely, components and/or actions ascribed to exemplary embodiments of the invention and depicted as sub-units/individual actions may be combined into a single unit/action with the described/depicted function.
[0060] Alternatively, or additionally, features used to describe a method can be used to characterize an apparatus and features used to describe an apparatus can be used to characterize a method.
[0061] It should be further understood that the individual features described hereinabove can be combined in all possible combinations and sub-combinations to produce additional embodiments of the invention. The examples given above are exemplary in nature and are not intended to limit the scope of the invention which is defined solely by the following claims.
[0062] Each recitation of an embodiment of the invention that includes a specific feature, part, component, module or process is an explicit statement that additional embodiments of the invention not including the recited feature, part, component, module or process exist.
[0063] Alternatively or additionally, various exemplary embodiments of the invention exclude any specific feature, part, component, module, process or element which is not specifically disclosed herein.
[0064] Specifically, the invention has been described in the context of apparatus and methods to cool water but might also be used to cool other liquids.
[0065] All publications, references, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.
[0066] The terms include, and have and their conjugates as used herein mean including but not necessarily limited to.