Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F22—STEAM GENERATION
  • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
  • F22B1/00—Methods of steam generation characterised by form of heating method
  • F22B1/28—Methods of steam generation characterised by form of heating method in boilers heated electrically
  • F22B1/284—Methods of steam generation characterised by form of heating method in boilers heated electrically with water in reservoirs
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B39/00—Evaporators; Condensers
  • F25B39/02—Evaporators
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
  • F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
  • F28D15/0233—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes the conduits having a particular shape, e.g. non-circular cross-section, annular
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
  • F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
  • F28D15/04—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure
  • F28D15/046—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure characterised by the material or the construction of the capillary structure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
  • F28F13/18—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by applying coatings, e.g. radiation-absorbing, radiation-reflecting; by surface treatment, e.g. polishing
  • F28F13/185—Heat-exchange surfaces provided with microstructures or with porous coatings
  • F28F13/187—Heat-exchange surfaces provided with microstructures or with porous coatings especially adapted for evaporator surfaces or condenser surfaces, e.g. with nucleation sites

Definitions

• This invention relates to design and building of low cost boiling coolers that utilize nucleate boiling heat transfer for a plurality of cooling applications.
• One current electronic cooling apparatus employs an air-conditioning manifold to distribute chilled air to the heating electronic assembly through a plurality of orifices or vortex tubes within the enclosure of the apparatus.
• power consuming air circulating system and its complicated structure make such apparatus expensive, bulky, and not flexible for various electronic system designs.
• Another cooling apparatus for electronic apparatus utilizes combination of liquid cooling and convection.
• the boiling cooler described in this invention overcomes many drawbacks of those conventional electronic cooling apparatus in terms of zero-power consumption, high heat- transfer efficiency, low cost, flexibility in physical shapes and ability to miniaturize, making it very suitable for a plurality of cooling applications including electronic component/system cooling.
• the boiling cooler that utilizes boiling two-phase cooling in accordance with the
• the boiling cooler comprises a vessel that is partially filled with a liquid coolant, enclosed by a body-shell mainly made of non-metal materials with extra open spaces within the vessel for liquid vapor to spread heat around and an extended surface area for additional cooling by natural convection or, if necessary, by forced-air convection.
• a part of the body-shell is thermally conductive and used to couple the heat-generating component so that the neat flux is transferred to the liquid and nucleate boiling is induced on the surface where a plurality of boiling enhancement treatments (such as mechanical roughening or microporous coating) are applied.
• This thermally conductive side may be a part of the body surface itself of the heat-generating device component, making an integrated device cooler.
• the plastic body- shell of the vessel can be easily molded to form a plurality of desired shapes, complex or asymmetric, which would otherwise be impossible or too expensive to make with metal, hi yet another embodiment of the invention, for some device/system with bigger thermal load the cooler can have a molded vessel molded by baked copper powder with extruded shapes or fins, which provides much better thermal conductivity than those modules using all-plastic materials but still costs less than those using all-machined metals,
• An alternative structure of the cooler can have plastic end-caps or top/bottom for the vessel with metal body-shell.
• a low cost liquid coolant such as water can be
• FIG. IA illustrates a cross-sectional view, as a preferred embodiment of this
• FIG. IB is a SEM image of the coating structure comprising particles of sizes of
• FIG. 2 illustrates a cross-sectional view of a boiling cooler as an enclosed vessel comprising a base chamber and one (or more) upper chamber with extended plates and extruded fins in combination with a boiling enhancement coating at the bottom of the base chamber with a liquid coolant partially filling the chamber
• FIG. 3 is a cross-sectional view showing schematically a boiling cooler with a vessel comprising a relatively complex, asymmetric shell shape and extended surface area, according to another embodiment of the invention.
• FIG. 4 is a cross-sectional view showing schematically a boiling cooler with a vessel partially wrapping around a heating electronic component whose part of thermally conductive body-shell, is also a part of the body-shell of the cooler vessel.
• the microporous coating is applied on said thermally conductive surface, which is at least partially submerged in the liquid in the ⁇ cssel. to enhance the nucleate boiling heat
• the current invention presents a boiling cooler with a vessel in a simplified design using inexpensive non-metal material or low cost liquid coolant in combination with boiling enhancement vessel surface treatment comprising mechanical roughening, sintering, and/or microporous coating.
• a preferred embodiment of the invention uses a Thermally-Conductive Microporous Coating (TCMC) developed by You and Kim (2005), described in co-pending U.S. Patent Application Serial No. 1 1/272,332. This coating technique combines the advantages of a mixture batch type and thermally- conductive microporous structures.
• TCMC Thermally-Conductive Microporous Coating
• the microporous surface is created using panicles of various sizes comprising any metal which can be bonded by the soldering process including nickel, copper, aluminum, silver, iron, brass, and various alloys in conjunction with a thermally conductive binder.
• the coating 40 is applied on the surface of a substrate 30 while mixed wirh a solvent.
• the solvent is vaporized after the application prior to heating the surface sufficiently to melt the binder to bind the particles, FlG.
• I A shows a cross-sectional view of the coating structure full of cavities and particles formed on top of the substrate plate
• the mixture batch type application is an inexpensive and easy process, not requiring extremely high operating temperatures.
• the coating surface created by this process is insensitive to its thickness due to high thermal conductivity of the binder.
• FIG. IB shows a SEM picture of a coating surface containing nickel particle of sizes around 30- 50 ⁇ m using -100+325 mesh nickel powder mixed with solder pastes.
• the solder pastes
• the coating with particles in such a size range of 30-50 ⁇ m has
• a boiling cooler is illustrated in Figure 2 as an enclosed vessel comprising a base chamber 120 with a thermally conductive side 130, and one or more upper chambers 110 according to one embodiment of the invention.
• the Ihermally-Conductive Microporous Coating (TCMC) 140 is applied to the surface of conductive side 130 within the base chamber 120 with which a heating electronic component S 00 is coupled from outside the base chamber i 20.
• the liquid coolant 150 partially fills the base chamber 120, at least partially covering the
• the liquid boiling cooler in this invention includes that it does not need a radiator or other complicated heat exchanger within the apparatus, making it very suitable to be miniaturized for electronics cooling applications.
• the boiling cooler can have a height of h and/or a lateral dimension of Z, less than or equal to
• the cooler in Fig. 2 can also be elongated
• body-shell of the cooling vessel can be made of non-metal material to save cost.
• the heat transfer in this boiling cooler is basically taking place within the cooler vessel by TCMC enhanced liquid boiling and additional vapor heat-spreading throughout the open space 160 of the cooling vessel. Therefore, it is not critical for the boiling cooler to have highly conductive metal body-shell as in many conventional coolers including heat sinks for various heating electronics element/device.
• Highly thermally conductive materia! usually metal such as copper or aluminum, must be used for the body-shells of those conventional coolers because conducting heat through the shell to the surface, then cooling by using forced air convection, is their prominent way of cooling.
• vessel chambers 110 and 120 including those extruded fins 170 and extended plate 180 can be made of non-metal material comprising plastic, vinyl, or paper, which is much less expensive than any metal. Not only the material cost is lower, capability of plastic molding for those extruded fin structure also reduces the manufacturing cost comparing to processing metal.
• these non-metal body-shells can also be electrically insulating which provides an important advantage over the conventional cooler with electrically conducting metal shells for certain electronics cooling applications.
• Additional advantage of the boiling cooler using TCMC is that the TCMC boiling enhancement coating can be optimized in terms of cavity-generating particle size using easy process modifications so that it can ensure no degradation in nucleate heal transfer rate and critical heat flux specification for a wide selection of liquid coolant types. This naturally translates to lower cost boiling cooler if the cheap liquid, such as water, instead of specially developed refrigerant or chemical fluid, can be used, As mentioned earlier a
• TCMC boiling enhancement surface treatment is a preferred embodiment of this invention, a plurality of other boiling enhancement technologies such as mechanical roughening, sintering and/or conventional microporous coating shall be utilized to be integrated in the boiling cooler according to current invention.
• the chamber shells including fins can be constructed by utilizing molded and baked copper powder, which provides better thermal conductivity than those modules using ail-plastic materials but still costs less than those using all-machined metals.
• thermally conductive plastic composite material can be another candidate for constructing the boiling cooler according to current invention.
• the body-shell made of plastic can be molded into a relatively complex structure with asymmetric shape or small detailed features, which is usually much more expensive, if not impossible, to be manufactured using metal.
• FIG. 3 illustrates an example of such a boiling cooler with a vessel 220 enclosed by a body-shell 271 comprising multiple upper chambers 221 and 222 in irregular shapes and different heights, for example, h ⁇ and Zz 2 on top of a common base chamber with dimension L x (dimension along perpendicular direction is not shown)
• the boiling cooler also comprises a boiling enhancement surface 241 on a thermally conductive side shell 231 (a part of the body-shell 271), partially filled liquid coolant 251. Vapor generated from boiling helps spread heat over all extended space 261 adding extra pathway for cooling through convection.
• the cooler utilizing boiling enhancement surface achieves efficient cooling within the vessel, making the forced air convection not critical for the system.
• natural or forced-air convection can still provide extra heat exchange through the extended exterior surface of the vessel of this boiling cooler.
• the boiling cooler vessel has been transformed to a built-m part of the heat-generating component, in other words, the cooler and the heat-generating component are built together as a coherent or integrated unit.
• Fig. 4 shows an example of such a boiling cooler whose thermally conductive side 330 essentially is the body-shell (at least covering partial surface) of the heat-generating component 300.
• Surface boiling enhancement treatment 340 is applied at least partially on side 330 at a surface within the vessel.
• Other parts of the body-shell 320 can be made of less-expensive materials comprising plastic, vinyl, paper, or molded and baked copper powder, which is sealed with side 330 to form an enclosed vessel holding partially- filled liquid coolant 350. As shown in Fig.
• the shape of the body-shell 320 is intentionally made to have an extended surface area for extra benefit of convection cooling.
• the shape of the body-shell 320 is relatively irregular it can be done easily and inexpensively because of the material selection such as plastic.
• the dimensions of /? 3 and Z 3 in this case basically depend on that of the heat-generating component 300 itself.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Cooling Or The Like Of Electrical Apparatus (AREA)
• Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)

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• 2007
  • 2007-03-31 JP JP2009503330A patent/JP2009532886A/ja active Pending
  • 2007-03-31 EP EP07759921A patent/EP2002194A2/de not_active Withdrawn
  • 2007-03-31 CN CNA2007800191933A patent/CN101568791A/zh active Pending
  • 2007-03-31 WO PCT/US2007/065743 patent/WO2007115241A2/en active Application Filing

Non-Patent Citations (1)

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