WO2009049397A1 - Dispositif de gestion thermique utilisant de la mousse inorganique - Google Patents

Dispositif de gestion thermique utilisant de la mousse inorganique Download PDF

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Publication number
WO2009049397A1
WO2009049397A1 PCT/CA2007/001874 CA2007001874W WO2009049397A1 WO 2009049397 A1 WO2009049397 A1 WO 2009049397A1 CA 2007001874 W CA2007001874 W CA 2007001874W WO 2009049397 A1 WO2009049397 A1 WO 2009049397A1
Authority
WO
WIPO (PCT)
Prior art keywords
heat pipe
porous structure
metallic
mixture
range
Prior art date
Application number
PCT/CA2007/001874
Other languages
English (en)
Inventor
Dominic Pilon
Alain Harvey
Mario Patry
Original Assignee
Metafoam Technologies Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Metafoam Technologies Inc. filed Critical Metafoam Technologies Inc.
Priority to PCT/CA2007/001874 priority Critical patent/WO2009049397A1/fr
Priority to CA2702997A priority patent/CA2702997A1/fr
Priority to EP08839074A priority patent/EP2214851A1/fr
Priority to CA2703020A priority patent/CA2703020A1/fr
Priority to KR1020107011000A priority patent/KR20100098507A/ko
Priority to PCT/CA2008/001863 priority patent/WO2009049427A1/fr
Priority to CN2008801214744A priority patent/CN101903125A/zh
Publication of WO2009049397A1 publication Critical patent/WO2009049397A1/fr

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Classifications

    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
    • B21C37/06—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of tubes or metal hoses; Combined procedures for making tubes, e.g. for making multi-wall tubes
    • B21C37/08—Making tubes with welded or soldered seams
    • B21C37/09—Making tubes with welded or soldered seams of coated strip material ; Making multi-wall tubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/11—Making porous workpieces or articles
    • B22F3/1121—Making porous workpieces or articles by using decomposable, meltable or sublimatable fillers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/10—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of articles with cavities or holes, not otherwise provided for in the preceding subgroups
    • B22F5/106—Tube or ring forms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • B22F7/002—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of porous nature
    • B22F7/004—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of porous nature comprising at least one non-porous part
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F2005/005—Article surface comprising protrusions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

  • TITLE Heat management device using inorganic foam
  • the present invention relates to heat management devices such as a heat pipe that uses a component made of inorganic porous material.
  • the heat pipe can be used to provide cooling in a wide range of applications through repeated evaporation and condensation cycles of a working liquid.
  • the heat pipe can be used to provide cooling to electronic devices such as Central Processing Units (CPUs) .
  • CPUs Central Processing Units
  • the invention also extends to a method for making metallic porous material and to the resulting product thereof.
  • a heat pipe is capable of transferring thermal energy very effectively allowing to maintain the surface of an electronic component, such as a CPU, relatively cool.
  • a typical heat pipe has a closed chamber with a hot side and a cold side.
  • the hot side is the side that receives the heat to be removed while the cold side transfers that heat to an adjoining medium acting as a heat sink.
  • Working fluid such as water is provided in the closed chamber.
  • the hot side receives thermal energy, that energy vaporizes the working fluid that is in the vicinity of the hot side.
  • the vapor naturally flows in the chamber to the cold side where it condenses.
  • the latent heat of vaporization that is released during the condensation process is transmitted to the cold side and to the adjoining medium.
  • a wick is provided between the cold and the hot sides such that condensed liquid is continuously supplied to the hot side where it can be vaporized again.
  • the wick can be made from sintered metallic material that owing to its porous structure pulls the liquid by capillary action toward the hot side.
  • Alternative arrangements can also be used such as an array of fine channels machined on the bottom wall of the chamber that also develop capillary pressure capable of transporting the working liquid.
  • the geometry and orientation of the heat pipe may be such that liquid is allowed to flow back to the hot side by gravity. In such case, a wick structure to transport the liquid may not be required.
  • the continuous phase change cycle of the working liquid from liquid to vapor and then back to liquid confers a very good heat transport characteristics to the heat pipe.
  • the key factors are (1) the ability of the structure to allow the vaporized liquid to escape from the boiling liquid and (2) the ability to supply continuously sufficient amounts of working liquid to the hot side for the evaporation to be maintained. If any one of these two mechanisms is interrupted the heat transport cycle stops and in the case of key factor (1) the heat pipe reaches the so called critical heat flux value and in case of key factor (2) the heat pipe reaches the so called dry out state. At the critical heat flux value water vapor is essentially- trapped under the pool of working liquid and the heat pipe essentially ceases to function. In the dry out state, there is no more working liquid to be evaporated and the heat pipe essentially ceases to function.
  • the invention provides a heat pipe having an enclosed chamber with a hot side and a cold side and an inorganic porous structure between the hot side and the cold side.
  • the inorganic porous structure transports working liquid by capillary action from the cold side toward the hot side and having a wicking speed in excess of about 0.005m/s.
  • the invention provides a heat pipe having an enclosed chamber with a hot side and a cold side and an inorganic porous structure between the hot side and the cold side.
  • the inorganic porous structure transports working liquid by capillary action from the cold side toward the hot side and having an absorption capacity of at least 200kg/m 3 .
  • the invention provides a heat pipe having an enclosed chamber with a hot side and a cold side.
  • the heat pipe also has an inorganic porous structure between the hot side and the cold side for transporting working liquid by capillary action from the cold side toward the hot side, the inorganic porous structure having a porosity distribution, characterized by: i) a first pore group:
  • a second pore group having:
  • the invention provides a heat pipe having an enclosed chamber having a hot side and a cold side.
  • An inorganic porous structure is provided between the hot side and the cold side for transporting working liquid by capillary action from the cold side toward the hot side.
  • the inorganic porous structure has a porosity distribution, characterized by: i) a first pore group:
  • the invention provides a heat pipe having an enclosed chamber with a hot side and a cold side and an inorganic porous structure for receiving working fluid that is evaporated on the hot side and condensed on the cold side.
  • the inorganic porous structure having a specific surface area in the range from about 10,000 m 2 /m 3 to about 100,000 m 2 /m 3 .
  • the invention provides a heat pipe having an enclosed chamber with a hot side and a cold side, at least a portion of the enclosed chamber defining a conduit for conveying working fluid.
  • the conduit has a direction of longitudinal extent and having walls defining in cross section a figure having a closed boundary.
  • An insert made of inorganic porous material is provided within the conduit, the insert being in contact with the wall and in cross-section having a shape that follows a shape of the wall at least along a portion thereof.
  • the invention provides a process for manufacturing a component for use in a heat management device, the process comprising: a) providing a sheet of heat conductive material having: iii) a pair of generally opposite main faces; iv) a pair of opposite edge portions; b) placing on one of the main faces a body of inorganic porous material; c) rolling the sheet into a tube while the body of metallic material is located on the one of the main faces, the rolling bringing the opposite edge portions in a face-to-face relationship; d) joining the opposite edge portions.
  • the invention provides a heat pipe having an enclosed chamber having a hot side and a cold side.
  • the heat pipe also having: a) working fluid in the enclosed chamber; b) an inorganic porous structure for receiving thermal energy input at the hot side and for boiling the working fluid, the inorganic porous structure: i) having a porosity distribution, characterized by: (1) a first pore group having an average pore size in excess of about 20 ⁇ m; (2) a second pore group having:
  • the invention provides a heat pipe having an enclosed chamber having a hot side and a cold side.
  • the heat pipe also having: a) working fluid in the enclosed chamber; b) an inorganic porous structure for receiving thermal energy input at the hot side and for boiling the working fluid, the inorganic porous structure having: i) a base layer; ii) a plurality of projections extending from the base layer and being integrally formed with the base layer, the projections being spaced apart and defining valleys therebetween; iii) the projections and the base layer being porous; iv) the pores in the projections having an average pore size that is larger than an average pore size of portions of the base layer that register with the valleys.
  • the invention provides a method for manufacturing a metallic porous structure for boiling working fluid in a heat pipe, the method including providing a metallic porous blank having a pair of main faces opposite to one another and embossing one of the main faces to create a plurality of spaced apart projections.
  • the invention further includes method for making an open cell porous body, the method comprising the steps of: a. providing a dry flowable powder mixture comprising: l. a first predetermined amount of inorganic particles having a first melting temperature; li. a second predetermined amount of a binding agent having a decomposition temperature, the decomposition temperature being lower than the first melting temperature; b.
  • the invention further provides a dry flowable powder mixture for making open cell porous bodies.
  • the mixture comprising a first predetermined amount of inorganic particles having a first melting temperature and a second predetermined amount of a binding agent having a decomposition temperature, the decomposition temperature being lower than the first melting temperature.
  • Figure 1 a longitudinal cross-sectional view of heat pipe constructed according to a non-limiting example of implementation of the invention
  • Figure 2 a transverse cross-sectional view of the heat pipe of the example shown in Figure 1;
  • Figure 3 is cross-sectional view of a heat-pipe according to another non-limiting example of implementation of the invention.
  • Figure 4 illustrates a flat sheet of metallic porous material for use in making the wicking structure of a heat pipe
  • Figure 5 shows the flat sheet of the metallic porous material of Figure 4 formed into a tube for insertion in a heat pipe;
  • Figure 6 shows the rolled tube of metallic porous material placed inside a heat pipe
  • Figure 7 shows a flat sheet including several layers for use in making a heat pipe
  • Figure 8 illustrates the tube structure obtained by rolling the flat sheet of Figure 7;
  • Figure 9 is a cross-sectional shape of a heat pipe according to yet another non-limiting example of implementation of the invention.
  • Figure 10 is perspective view of the heat pipe shown in Figure 9, some elements being shown only partially to expose underlying structures;
  • Figure 11 is a perspective view of a metallic porous structure for use in boiling working liquid in a heat pipe
  • Figure 12 is an enlarged cross-sectional view of the metallic porous structure shown in Figure 11;
  • Figure 13 illustrates in cross-section yet another non-limiting example of implementation of a heat pipe
  • FIG. 1 is a longitudinal cross-sectional view of a heat pipe, according to a non-limiting example of implementation of the invention.
  • the heat pipe 10 is used to provide cooling to a heat generating component (not shown) .
  • a heat generating component is an electronic component such as a Central Processing Unit (CPU) .
  • Heat pipes are effective cooling devices since they rely on the vaporization and condensation of a working fluid, as a heat transport vehicle.
  • the heat pipe 10 has an enclosed chamber 12, which in this example is in the form of an elongated cylinder.
  • the enclosed chamber has, therefore cylindrical walls closed by end caps 14.
  • Inside the enclosed chamber 12 is provided a wick structure in the form of tubular liner 16.
  • the tubular liner 16 is an inorganic porous structure that will be described in greater detail later. As shown in the drawings, the tubular liner 16 extends almost the full length of the heat pipe. It should be expressly noted that this is merely an example of implementation and many variations as to the placement, structure, shape and
  • the heat pipe 12 contains working fluid.
  • the working fluid is capable to accumulate thermal energy by undergoing phase transition (from liquid to vapor) and then releases that energy to an external medium. The energy release causes the vapor to condensate. This cycle repeats itself as long as there is heat to dissipate.
  • the heat pipe 12 has a hot section at which the thermal energy is received and a cold section from which the thermal energy is dissipated.
  • the hot section and the cold section can be located on any area of the heat pipe structure 12 as long as they are sufficiently spaced apart to allow the phase transitions in the working liquid to take place.
  • the hot section can be designated as the end portion 18 while the cold section can be designated as the end portion 20.
  • the hot section 18 will, in use be in contact with the component to be cooled, while the cold section 20 will release heat to the surrounding medium.
  • This surrounding medium may be air, water or any other suitable material that acts as a heat sink.
  • the cold side 20 may be provided with any suitable heat dissipation structure such as fins, for instance (not shown in the drawings) .
  • the heat pipe 12 contains working fluid. That fluid is in a liquid phase in the area of the hot section 18. As a result of heat received at the hot section 18 the working liquid boils and converts to vapor, the phase change storing a significant amount of thermal energy.
  • the working vapor is allowed to flow toward the cold section 20 via the lumen of the tubular liner 16. As the vapor reaches the cold section 20 it condensed and released heat to the surrounding medium.
  • the condensation effect reduces the vapor pressure in the cold section 20 and as a result creates a lower pressure which has the effect of pulling vapor near the hot section 18 toward the cold section 20. Accordingly, the boiling and the condensation of the working fluid creates a pressure gradient in the heat pipe 12 that naturally causes the vapor to flow from the hot section 18 toward the cold section 20.
  • the tubular liner 16 is a porous structure.
  • the porous structure that will be discussed in greater detail later defines a certain void volume within the "solid" area of the tubular liner 16 (the lumen 22 is not considered to be part of the solid area) .
  • the void volume is capable to take-up the condensed liquid and to carry that liquid toward the hot section 18.
  • the liquid transport is the result of capillary pressure in the porous structure. Since the liquid in the tubular liner 16 is boiled out at the hot section 18, the void volume or pores in that area are dry.
  • the liquid migrates from the cold section 20 to the hot section 18, in a direction opposite the flow of vapor, such as to sustain the phase transitions of the working fluid.
  • Gravity will have a more pronounced effect when the geometry of the heat pipe 12 is such that the hot section 18 is at a different elevation than the cold section 20 (not shown in the drawings) .
  • the cold section 20 is located at a higher elevation than the hot section 18, then gravity will assist the movement of working liquid toward the hot section 18.
  • the capillary effect will have to combat gravity in order to transport the liquid toward the hot section 18 .
  • the amount and type of working liquid in the heat pipe 12 will vary according to the intended application. Since the heat transport mechanism is based on phase transition, it is not necessary to form in the heat pipe 12 a pool of liquid that will submerge a portion of the tubular liner 16. It is usually sufficient to provide enough liquid such as to create within the tubular liner a continuum of liquid that extends from the cold section 20 to the hot section 18. As to the type of working liquid used, it depends on the temperature range within which the cooling is to be provided and also the compatibility of the liquid and the materials used to make the heat pipe 12, including the tubular liner 16. In one specific example, the working liquid is water and the enclosed chamber 12 and the tubular liner 16 are both made of copper. Other possibilities exist. In operating temperature under water's freezing point, ammonia (NH3) is used as the working liquid and nickel as the constituting material for the enclosed chamber 12 and the tubular liner 16.
  • NH3 ammonia
  • the tubular liner 16 is bonded to the inner wall of the enclosed chamber 12 in order to provide a good thermal conductivity. Such thermal conductivity is important to allow heat to easily enter the hot section 18 and boil the liquid and also easily egress the cold section 20. Good thermal conductivity is created by forming an intimate physical contact between the tubular liner 16 and the inner wall of the enclosed chamber 12. Examples of bonding techniques which would work well when the tubular liner 16 is made of metal and that would provide an intimate physical contact include sintering or soldering connections between the tubular liner 16 and the enclosed chamber 12.
  • Soldering is a bonding process whereby a filler metal or alloy is heated to or above its melting temperature, which is generally referred to its liquidus temperature and below the melting temperature or solidus temperature of the base material to be joined.
  • the molten filler metal or alloy flows between two or more close-fitting parts of the material to be joined by capillary action.
  • the molten filler metal or alloy wets the base material and interacts with a thin layer of the base material, cooling to form a sealed joint.
  • soldering encompasses brazing techniques which use non-ferrous filler materials that have a relatively high melting point, generally above 450 degrees Celsius.
  • Sintering is a method for making objects, generally from powdered material, by heating the material until its particles adhere to each other. Sintering does not melt the material particles to create the bond between them: the material particles adhere to each other through a bond mainly created by solid-state diffusion. Effective solid- state diffusion occurs between material particles when they are heated, for a certain time, at temperatures slightly under the melting temperature of the material particles .
  • the efficiency of the heat pipe 12 is determined largely by the rate at which it can pump heat out of the hot section 18.
  • One way to increase the efficiency of the heat pipe 12, without altering its size, is to design the heat pipe 12 such as the phase transitions occur at a faster rate. In other words, more working fluid is boiled and condensed per unit of time such as to carry more heat.
  • One factor that limits the rate at which working liquid can be boiled is the ability of the tubular liner 16 to replenish the hot section 18 with sufficient amounts of liquid. When the amount of heat applied at the hot section 18 is such that the rate at which the working liquid is boiled exceeds the rate at which the tubular liner can replenish the hot section 18, a dry-out occurs and the heat pipe 12 ceases to function.
  • the material used for making the tubular liner 16 is designed such that its porosity induces liquid to travel relatively quickly such as to be able to feed the hot section 14 adequately.
  • the tubular liner has a wicking speed in excess of about 0.0005m/s, more preferably in excess of about 0.00075m/s, even more preferably in excess of about 0.001m/s, yet even more preferably in excess of about 0.0015m/s and most preferably in excess of about 0.002m/s.
  • a test for determining the wicking speed is provided later in this specification.
  • the tubular liner has an absorption capacity of at least about 200kg/m 3 , more preferably of at least 300kg/m 3 , even more preferably of at least about 400kg/m 3 , and most preferably of at least about 500kg/m 3 .
  • a test for determining the absorption capacity is provided later in this specification.
  • the tubular liner 16 is made of inorganic material.
  • the inorganic material comprises metallic material, metallic alloy material, ceramic material, carbon based material, coated material and/or a combination thereof. Note that among the inorganic materials that are best suited for heat management applications, metals are usually the best candidates because they have a good thermal conductivity. Carbon based inorganic materials are also a possibility since they tend to conduct heat also well.
  • metal in “metallic porous structure”, “metallic porous material” or any other similar expression is meant that the porous structure or material includes at least 50% of metallic component.
  • the metallic component can be a pure metal or an alloy or an amalgamation of pure metal and alloy.
  • the metal or metals are preferably transition metals (e.g. copper, nickel, iron) as defined by the periodic table of elements) .
  • a high metal concentration is preferred in heat management applications since metal has a good thermal conductivity, hence it will transmit heat readily between the interior or the heat pipe 12 and the external environment .
  • the resulting material has a porosity distribution which is characterized by at least two pore groups.
  • the metallic porous material has three pore groups, namely a first pore group, a second pore group and a third pore group.
  • the first pore group has an average pore size in the range from about 200 ⁇ m to about lOOO ⁇ m, preferably in the range from about 200 ⁇ m to about 750 ⁇ m and most preferably from about 200 ⁇ m to about 500 ⁇ m. In each case the standard deviation is in the range from about lOO ⁇ m to about 500 ⁇ m.
  • the first pore size group constitutes from about 30% to about 80% of the void volume of the metallic porous structure .
  • the second pore group has an average pore size in the range from about 40 ⁇ m to about 120 ⁇ m, preferably in the range from about 40 ⁇ m to about 90 ⁇ m and most preferably from about 40 ⁇ m to about 60 ⁇ m. In each case the standard deviation is in the range from about 30 ⁇ m to about 80 ⁇ m.
  • the second pore size group constitutes at least 20% of the void volume of the metallic porous structure.
  • the third pore group has an average pore size in the range from about 250nm to about 20 ⁇ m, preferably in the range from about 500nm to about 15 ⁇ m and most preferably from about 500nm to about lO ⁇ m. In each case the standard deviation is in the range from about 200nm to about lO ⁇ m.
  • the third pore size group constitutes from about 10% to about 40% of the void volume of the metallic porous structure.
  • the first pore group which has the largest pores is the result of the foaming agent used during the manufacturing of the metallic porous structure, as it will be discussed later.
  • the second pore group which contains smaller pores, are created by inter-pore interstices or voids in the structure between large pores that belong to the first group.
  • the pores of the first group communicate between them via inter-pore interstices, which behave from the perspective of interaction between the material and liquid, as smaller pores.
  • the inter-pore interstices can store liquid and also can induce liquid to migrate through the porous structure via capillary action.
  • the third pore group contains the finest pores of the material. Those pores are defined between the individual metal particles that are bonded via sintering. Since the sintering process does not actually melt the metal particles, those particles bond to adjoining particles at the respective physical contact points, leaving some void spaces between them.
  • the metallic porous material has two pore groups, namely a first pore group and a second pore group.
  • the first pore group has an average pore size in the range from about 20 ⁇ m to about 200 ⁇ m, preferably in the range from about 40 ⁇ m to about 150 ⁇ m and most preferably from about 60 ⁇ m to about lOO ⁇ m. In each case the standard deviation is in the range from about lO ⁇ m to about lOO ⁇ m.
  • the first pore size group constitutes from about 50% to about 80% of the void volume of the metallic porous structure .
  • the second pore group has an average pore size in the range from about 250nm to about 15 ⁇ m, preferably in the range from about 500nm to about 15 ⁇ m and most preferably from about 500nm to about lO ⁇ m. In each case the standard deviation is in the range from about 200nm to about lO ⁇ m.
  • the second pore size group constitutes from about 20% to about 50% of the void volume of the metallic porous structure .
  • a metallic porous structure in the form of a flat sheet 400 is manufactured according to the method described later.
  • the flat sheet 400 has a pair of main faces 402 and 404, end edges 406 and 408 and side edges 410 and 412.
  • the flat sheet 400 is then rolled into a tube, as shown in Figure 5.
  • the rolling operation can be performed by using any appropriate method. For instance a mandrel can be provided (not shown) shaped as a rod and having a diameter that corresponds to the lumen of the tubular liner to be formed.
  • the flat sheet 400 is then rolled over the mandrel to obtain the tube 414 of Figure 5.
  • the rolling operation causes the metallic porous structure to bend permanently and acquire the tubular shape.
  • the side edges 410 and 412 are brought in a face-to-face relationship.
  • the side edges 410 and 412 can be secured to one another by sintering or soldering. Note that this operation is not strictly necessary since the tube 414 is housed in an enclosed chamber, as described below.
  • the tube 414 forms an insert that is placed in an outer conduit 600, as shown in Figure 6.
  • the conduit 600 has walls which in cross-section define a closed figure, namely a circle.
  • the tube 414 is simply inserted in the cylindrical conduit 600.
  • the conduit 600 is shown as having a significantly larger diameter than the tube 414. This is shown for clarity only.
  • the tube 414 is designed to be tight fitting and as such it contacts the internal wall of the cylindrical conduit 600.
  • the tube 414 is constructed such as to leave a small gap between the side edges 410 and 412.
  • the diameter is selected such as to be slightly larger than the inner diameter of the cylindrical conduit 600.
  • the inner tube 414 can be bonded to the inner wall of the cylindrical conduit 600 by using any appropriate technique such as sintering or soldering.
  • the resulting heat pipe structure has a tubular liner formed by the tube 414.
  • the tube 414 is in contact and follows the shape of the conduit 600 wall.
  • the insert may shaped in cross- section as a half-circle or as a quarter of a circle, thus establishing contact with the conduit 600 wall over a smaller area.
  • conduits having other shapes can be used.
  • the conduit can be rectangular in cross-section and the insert of porous material can be made as a rectangular tube as well to allow a full perimeter contact with the conduit.
  • the insert can be made as a portion of a rectangle in cross-section when such full perimeter contact is not desired or necessary.
  • Figure 7 illustrates a variant.
  • a flat sheet 700 is provided that is made from metallic porous material.
  • the flat sheet 700 is similar to the flat sheet 400 described earlier.
  • the flat sheet 700 has a pair of main faces 702 and 704, end edges 706 and 708 and side edges 710 and 712.
  • the flat sheet 700 is laminated with a layer 714 that after a forming operation will constitute the enclosed chamber of the heat pipe.
  • the layer 714 is made of solid copper.
  • the layer 714 has side edges 716 and 718, opposite to one another.
  • the flat sheet 700 and the layer 714 are laminated by using any suitable technique. Preferably, sintering or soldering is used to create a physically strong bond and also enhance the thermal conductivity between the two layers .
  • the laminate is then rolled into a tube using a mandrel, as discussed above.
  • the resulting tube is shown in Figure 8 and designated by the reference numeral 800.
  • the outer surface of the tube 800 is formed by the layer 714 whose side edges 716 and 718 meet face-to-face along a joint area 802 that extends along the longitudinal axis of the tube 800.
  • the inside of the tube is formed by the metallic porous structure whose side edges 710 and 712 also meet at the joint area 802.
  • the side edges 716 and 718 are joined to one another. This can be done by welding or soldering, for example.
  • a layer of inorganic porous material such as metallic porous material is provided on the outer wall of the enclosed chamber. This is shown in Figures 9 and 10. More specifically, an outer jacket 900 made of metallic porous material is applied on the outer wall of the enclosed chamber 12. In this fashion, the wall of the enclosed chamber is sandwiched between two metallic porous layers.
  • the purpose of the outer porous layer 900 is to enhance the heat transfer to and from the heat pipe.
  • the metallic porous layer 900 can have a porosity that is identical to the porosity of the tubular liner 16 or it can be different. It is advantageous to provide a porosity which has a high specific area and at the same time is open enough to allow a cooling medium to readily flow though the outer porous layer 900. This allows increasing the heat transfer between the surrounding medium and the heat pipe.
  • the outer metallic layer 900 should be bonded to the outer wall of the enclosed chamber such as to create a bond allowing a good thermal conductivity. Examples of bonding methods include sintering or soldering, among others.
  • the sandwich structure can be made in a similar fashion as the rolled structures described earlier. Specifically, the two flat layers of porous materials are bonded to the central non- porous sheet that is also flat. The resulting laminate is rolled and the meeting ends jointed to one another as deemed appropriate.
  • FIG. 3 illustrates another example of implementation of a heat pipe.
  • the heat pipe 300 functions conceptually in the same fashion as the heat pipe 10, except that it uses a larger amount of working fluid that forms a pool at the bottom of the heat pipe 300 and that is boiled to provide the heat transfer effect .
  • the heat pipe 300 defines an enclosed chamber 302 having a hot section 304 at the bottom and a cold section
  • the cold section 306 is formed integrally with cooling fins 308 to facilitate the transfer of heat from the cold section 306 to the surrounding medium. If desired a cooling aid can also be provided, such a fan to force air to pass through the cooling fins 308 and thus further enhance the heat transfer.
  • the lower part of the enclosed chamber 302 is provided with a metallic porous structure 310 that is in contact with a pool of working liquid.
  • the amount of working liquid present can vary according to the application but in most cases the metallic porous structure will either be entirely submerged or partially submerged such that in use a pool of liquid is always in contact with the metallic porous structure 310.
  • the purpose of the metallic porous structure is generally two fold. First it enhances the heat transfer to the liquid body in order to facilitate the boiling process. Second it also acts as a wick to receive and distribute the condensed liquid that returns to the hot section.
  • the metallic porous structure is characterized by a high specific surface area to increase the contact surface between the metallic porous structure and the body of liquid.
  • the specific surface area is in the range from about 10,000 m 2 /m 3 to about 100,000 m 2 /m 3 , preferably of about 15,000 m 2 /m 3 to about 80,000 m 2 /m 3 , even more preferably from about 18,000 m 2 /m 3 to about 70,000 m 2 /m 3 , yet even more preferably from about 20,000 m 2 /m 3 to about 60,000 m 2 /m 3 and most preferably from about 20,000 m 2 /m 3 to about 50,000 m 2 /m 3 .
  • the specific surface area is defined as the available contact surface the metallic porous structure with the body of liquid with relationship to the bulk volume of the metallic porous structure.
  • the metallic porous structure has a pore distribution that is characterized by at least two pore groups, namely a first pore group and a second pore group.
  • the first pore group has an average pore size in excess of 20 ⁇ m.
  • the second pore group has an average pore size in the range from about 250nm to about 15 ⁇ m.
  • the second pore group has an average pore size in the range from about 500nm to about 15 ⁇ m, and most preferably an average pore size in the range from about 500nm to about lO ⁇ m. In each case the standard deviation is in the range from about 200nm to about lO ⁇ m.
  • the second pore size group constitutes from about 20% to about 50% of the void volume of the metallic porous structure .
  • the first pore group has an average pore size in the range from about
  • the first pore size group constitutes from about 50% to about 80% of the total void volume of the metallic porous structure .
  • the metallic porous structure has, in addition to the first and second pore groups a third pore group.
  • the first pore group has an average pore size in the range from about 40 ⁇ m to about 120 ⁇ m, preferably from about 40 ⁇ m to about 90 ⁇ m and most preferably from about 40 ⁇ m to about 60 ⁇ m. In each case the standard deviation is in the range from about 30 ⁇ m to about 80 ⁇ m.
  • the first pore size group constitutes from about 5% to about 30% of the total void volume of the metallic porous structure.
  • the third pore group contains the largest pores and it has an average pore size in the range from about 200 ⁇ m to about lOOO ⁇ m, preferably from about 200 ⁇ m to about 750 ⁇ m and most preferably from about 200 ⁇ m to about 500 ⁇ m. In each case the standard deviation is in the range from about lOO ⁇ m to about 500 ⁇ m.
  • the third pore group constitutes from about 30% to about 80% of the total void volume of the metallic porous structure.
  • Figure 11 illustrates a possible variant of the metallic porous structure. More specifically, the metallic porous structure 1100 has a length dimension a, a width dimension B and a thickness dimension C. In this case the thickness C is significantly less than anyone of the length and width dimensions A and B. Note that since the metallic porous structure 1100 is shaped as a disk, the length dimension A is equal to the width dimension B.
  • disk shape is merely exemplary and many other shapes are possible without departing from the spirit of this invention.
  • the metallic porous structure 1100 has a pair of main faces 1102 that are opposite one another and a narrow side surface 1106.
  • the main face 1102 is bonded to a substrate 1108, which in this example is made of copper.
  • the purpose of the substrate is to provide a support for the metallic porous structure and allow the metallic porous structure to be handled during the manufacturing of the heat pipe, without breakage. Copper, or another metals in general would be the material of choice for manufacturing the substrate 1108 since it provides good thermal conductivity.
  • the substrate 1108 can also be made out of a carbon based material that could provide acceptable thermal conductivity.
  • the metallic porous structure 1100 is bonded to the top surface of the substrate 1108 via any suitable technique that would provide good thermal conductivity. Examples include sintering and soldering.
  • the metallic porous structure has a plurality of projections 1200 that extend upwardly from a base layer 1204.
  • the projections 1200 and the base layer 1204 are integrally formed.
  • the projections 1200 are spaced apart and define between them valleys 1202.
  • the projections have a density in the range of 9 to about 10,000 per square inch.
  • the projection density is in the range of about 25 to about 2,500 per square inch.
  • Most preferably the projection density is in the range of about 25 to about 1000 per square inch.
  • the projections may or may not be distributed uniformly on the top surface 1102.
  • the method for measuring the projection density is generally a two step approach. The first is to measure the surface area of the top surface 1102. This is done by using any standard measurement techniques. The second is to count the number of projections 1200 that are formed on the top surface 1102. Finally, the count is divided by the surface area in square inches to determine the number of projections 1200 in a single square inch.
  • an alternative method is to count the number of projections 1200 formed within an area of one square inch, instead of counting the total number of projections 1200 on the top surface 1102.
  • the average projection height is in the range of about 250 ⁇ m to about 10mm, preferably from about 500 ⁇ m to about 5mm and most preferably from about 750 ⁇ m to about 3mm.
  • the method for assessing the average height is to first count the number of projections 1200 on the top surface 1102 and then measure the height of each projection 1200. All the height values are summed and the result is divided by the total number of projections 1200. Note when the projections 1200 are all of the same height, then it suffices to measure the height of a single projection 1200 in order to determine the average projection height.
  • the height of a projection 1200 is the height as measured from the base of the projection up to its tip. This is dimension Z shown in Figure 12. In other words, the projection height does not include the thickness of the base layer 1204.
  • the average thickness of the base layer is in the range from about 50 ⁇ m to about 2mm, preferably from about 50 ⁇ m to about lmm and most preferably from about lOO ⁇ m to about lmm.
  • the average thickness is determined by measuring the dimension X, as shown in Figure 12, associated with each projection 1200, summing up the results and dividing by the number of projections 1200. If the thickness is constant across the metallic porous structure then a single measurement anywhere will suffice to determine the average thickness.
  • the projections 1200 are formed on the top surface 1102 by an embossing process.
  • the process starts by providing a metallic porous blank which has two opposite main faces and a constant thickness. In other words, the thickness dimension measured between the two main faces is the same across the blank.
  • the porous metallic blank is then embossed by using a die (not shown in the drawings) .
  • the die has a relief surface that is the exact opposite of the projections and valleys profile desired to be obtained. In other words, for each valley 1202 and projection 1200 to be formed, a corresponding projection and valley are provided on the die.
  • the die is then pressed against one of the main surfaces of the porous metallic blank in order to emboss the porous metallic blank and thus transfer over the surface the die relief.
  • the embossing operation alters somewhat the pore distribution profile of the metallic porous structure. More specifically, the localized compression of the structure that creates valleys has the effect of partially crushing the pores in the material in the areas at which that compression is applied. Accordingly, the pores that are found in the regions of the base layer 1204 between two adjacent projections 1200, which corresponds to the bases of the valleys 1202, are reduced in size. Those regions 1206 will therefore contain pores that have an average pore size that is somewhat smaller than the average size of the pores located in the projections 1200. This pore distribution profile is beneficial in terms of liquid evaporation characteristics.
  • liquid that submerges the metallic porous structure 1100 is boiled off primarily at the areas that correspond to the bottoms of the valleys 1202.
  • the bubbles that form in the bottoms of the valleys 1202 float up through the liquid and then reach the surface.
  • Some boiling also occurs on the sides of the projections 1200, however most of the liquid is boiled off at the bottoms of the valleys 1202. This is so because those areas are closer to the source of heat . Since the heat propagation path is short, enough thermal energy reaches the liquid residing at the valley bottoms to cause the liquid there to boil first.
  • Fresh liquid that replenishes the liquid being boiled off enters the metallic porous structure via the projections 1200. Since those projections are porous, that porosity allows liquid to migrate through the projections 1200 and then reach the base layer 1204 area where it is evaporated. In this fashion, the vapor released from the metallic porous layer and the fresh liquid that enters the metallic porous layer move along separate paths. This limits their interaction and allows vapor to be released more easily from the boiling liquid. Also, it limits the blocking effect that escaping bubbles may have on the liquid penetration in the metallic porous structure .
  • the pore distribution profile that manifests smaller pores at the valley bottoms assists the liquid transport from the projections 1200 to the valley bottoms.
  • the smaller pores in the areas 1206, by virtue of their increased capillary effect then to pull the liquid from the remainder of the metallic porous structure 1100 precisely in the regions where the boiling occurs.
  • the pore distribution profile is such as to modulate the capillary attraction exerted on the liquid by pulling the liquid in the areas from which the liquid is being dissipated by evaporation.
  • FIG 13 shows another variant of the heat pipe.
  • the heat pipe 1300 is generally similar to the heat pipe 300 discussed above with the difference that the metallic porous structure 1302 is located vertically.
  • This vertical structure can be used for cooling an electronic component that is vertical instead of being installed horizontally.
  • the electronic component such as a CPU 1304 is shown in dotted lines.
  • the metallic porous structure 1302 In light of the vertical orientation of the metallic porous structure 1302, it is only partially submerged in the pool of liquid. However in light of the porosity of the structure, which acts as a wick, liquid can be more effectively drawn from the pool and distributed throughout the metallic porous structure where it is evaporated.
  • Metallic porous structures according to the examples described earlier are produced by a method which involves dry-mixing inorganic particles, binder and optionally a foaming agent, removing a binder and then sintering the inorganic particles. Two specific examples of the method are provided.
  • Example 1 produces a metallic foam that has a porosity distribution characterized by two pore groups, while example 2 produces a porosity distribution characterized by three pore groups.
  • Example 1 produces a method which involves dry-mixing inorganic particles, binder and optionally a foaming agent, removing a binder and then sintering the inorganic particles.
  • Two specific examples of the method are provided.
  • Example 1 produces a metallic foam that has a porosity distribution characterized by two pore groups, while example 2 produces a porosity distribution characterized by three pore groups.
  • Example 1 produces a method which involves dry-mixing inorganic particles, binder and optionally a foaming agent, removing a binder and then sintering the in
  • the porous material according to one or more examples provided above can be produced from a dry flowable powder mixture comprising a base material and a binding agent, all provided in predetermined amounts.
  • the base material includes inorganic particles having a first melting temperature
  • the binding agent is preferably, but not exclusively, an organic binder having a decomposition temperature lower than the first melting temperature and having clean burn out characteristics.
  • the exact amount of each constituent of the mixture is determined, prior to the execution of the method of the present invention, based on the physical and chemical properties of the inorganic particles and of the binding agent, and based on the desired properties of the finished open cell porous body. Consequently, the exact composition of the mixture will vary according to the nature of the base material and of the binding agent .
  • the inorganic particles comprise metallic particles, metallic alloy particles, ceramic particles, coated particles and/or a combination thereof.
  • the metal or metals are preferably transition metals (e.g. copper, nickel, iron) as defined by the periodic table of elements.
  • the inorganic particles will have a first melting temperature.
  • the inorganic particles content may vary from about 10 to about 90 wt % of the total weight of the mixture (preferably from about 40 to about 90 wt % for metal particles and from about 10 to about 60 wt % for ceramic particles) , the exact amount of the inorganic particles and the choice thereof will be determined by the skilled addressee depending on the requirements of the application for which the open cell porous material is being manufactured.
  • the binder used in the mixture is preferably an organic binder provided in a dry flowable powdered form and with clean burn out characteristics.
  • the binder can be a thermoplastic polymer, a thermoset resin and/or a combination thereof.
  • the binder can also be an inorganic, a synthetic binder or a mixture of organic and/or inorganic and/or synthetic binders.
  • the binder may be provided in solid form (preferably powder particles), in semi-solid form, in liquid form, in gel form or in semi- liquid form.
  • the binder has a decomposition temperature lower than the first melting temperature of the inorganic particles in order to prevent premature melting of the inorganic particles during the decomposition step.
  • the binder content in the mixture may vary from about 10 to about 90 wt % of the total weight of the mixture and preferably from about 20 to about 70 wt %, the exact amount thereof will be determined by the skilled addressee depending on the nature of the inorganic particles and on the requirements of the application for which the open cell porous material is being manufactured. Most preferably, the binder should not leave decomposition products that may negatively affect the final properties of the porous structure. However, some residues can be accepted if they have no impact on the final product or if they improve some of its properties.
  • the mixture may comprise a cross-linking agent that may induce faster curing of the binder during or after the curing step and, by the way, improve the mechanical strength of the cured structure before the decomposition of the binder.
  • the mixture may also comprise other additives such as a lubricant to ease shaping, molding or demolding or flowing agents to improve the flowability of the powder when all the constituents are in powdered form.
  • the organic binder can be blended with the other constituent using various techniques such as but not limited to mixing, milling, mixing the binder in suspension or in solution in a liquid, blending the binder in molten, liquid, gel or semi-liquid form with the inorganic particles and the other additives. Whichever mixing technique is used, the resulting product should be a curable mixture.
  • spacing agents may be added to the mixture for providing additional porosity and to improve pore connectivity.
  • the spacing agents are removed after curing to leave voids in the structure after decomposition of the binder or after sintering.
  • the spacing agent can be removed by thermal decomposition after curing or by leaching after curing, decomposition of the binder or sintering.
  • the spacing agent can be particles or a scaffold. When particles are used, they are admixed with the rest of the mixture.
  • the spacing agent can be polymeric particles admixed with the mixture. In this case, the spacing agent concentration can vary from about 5 to 50 wt %, but preferably between 10 and 30 wt %.
  • the scaffold When a scaffold is used, its porous structure is filled with the mixture used to produce the porous material.
  • the scaffold can be, for example and in no limiting fashion, a porous structure, like a polymeric foam, that can be filled with the mixture and removed by thermal decomposition or by leaching.
  • additional binder in amount varying between 0.05 wt % to 5 wt %, but preferably between 0.05 wt % to 1 wt %, in the mixture.
  • This additional binder may be generally used to glue different constituents of the mixture together in such a way that the final product is less prone to segregation and/or dusting.
  • This additional binder can also be used to improve the flowability of the mixture should all the constituents be provided in powdered form.
  • the additional binder may be added at different steps of the mixing procedure, either before mixing the inorganic particles with the binder, after the binder addition, after the lubricant addition, after the flowing agent addition or after the addition of any combination of those constituents. Whichever mixing technique is used, the resulting product should be a curable mixture.
  • the resulting mixture may be shaped using methods such as molding, deposition, lamination or extrusion.
  • the product is then heated at a moderate temperature to melt the binder, if the latter is not already in liquid, gel or semi-liquid form, and to initiate the curing of the mixture.
  • pressure may be applied to the mixture before or during heating the mixture.
  • the resulting open cell porous material porosity and structure will depend on the particle size, shape, density and content of the inorganic particles; the content and viscosity of the binder, as well as the processing conditions .
  • Materials can be cured in a mold to provide three- dimensional porous structures.
  • the mixture can be cured on or in a substrate to produce a coating or to produce composite structures. Curing can be done for example on a plate, on a rod, in or outside a tube or cylinder, in or on other porous structure (mesh, beads, foam for example) or any other substrate.
  • the material can be machined after curing, decomposition of the binder or sintering.
  • Functionally graded materials can be produced using mixtures with variable composition.
  • Graded layered structures can be produced for example by deposing layers of mixtures with different composition.
  • Functionally graded materials can also be produced by controlling the thermal gradient during curing in order to control material curing and pore size distribution.
  • the mechanical strength of the cured structure may be further increased, before decomposition of the binder and sintering, by using externally assisted cross-linking techniques such as irradiation or light exposure .
  • the cured mixture is treated at higher temperature to decompose the binder.
  • the atmosphere (with or without the presence of oxygen) , duration and temperature of the thermal treatment should preferably allow a clean decomposition of the binder.
  • Binder decomposition should preferably not deteriorate the three-dimensional structure of the cured mixture. If gas pressure generated during binder decomposition is too important, cracking may occur in the still unsintered structure. Oxidizing or reducing conditions during the thermal treatments may be chosen to optimize binder decomposition.
  • the cured mixture is composed of open cell metal, and/or metal alloy, and/or ceramic material particles.
  • Sintering is done after the decomposition of the binder to create bonds between the inorganic particles of the cured mixture.
  • Sintering conditions temperature, time and atmosphere
  • conditions should be such that the inorganic particles do not melt to create the bond between them: conditions should be such that the material particles adhere to each other through a bond mainly created by solid-state diffusion to form a strong metallurgical joint between them.
  • Effective solid-state diffusion occurs between material particles when they are heated, for a certain time, at temperatures slightly under the melting temperature of the material particles.
  • Sintering is generally done in reducing atmosphere for metal particles to avoid the formation of surface oxides on the foam.
  • Mechanical strength may be adjusted for the application.
  • the choice, size, nature and/or physical state of the inorganic particles and of the binder content will have a substantial influence of the physical properties (e.g. mechanical strength) of the produced open cell porous material.
  • the internal surface of the foam can be modified for example by heat treatment, chemical treatment or deposition of coatings using various state of the art deposition techniques.
  • the external surfaces of the foam can be modified for example by a stamping, etching, embossing, or grooving technique and by state of the art surface coating techniques.
  • the foams can be integrated in other products and/or to other structures using different state of the art techniques such as diffusion bonding, press fitting, welding, brazing, sintering or gluing. The invention is not so limited.
  • a metallic porous structure with copper (Cu) as the base material, was produced with the formulation presented in Table 1.
  • the different constituents were dry-mixed together until the mixture became homogeneous. After mixing, the mixture was poured into a mould and cured at 110 0 C in air for 2 hours. After curing, the material was submitted to the decomposition of the binder in a furnace at 650 0 C for 4 hours in a dry air stream. Finally, the specimens were sintered in an Ar-25%H2 atmosphere for 2 hour at 1000 0 C.
  • Metallic porous structures with copper (Cu) as the base material were produced with the formulation presented in Table 2 and in accordance with the procedure described in U.S. Patent No. 6,660,224.
  • the different constituents were dry-mixed together until the mixture became homogeneous.
  • the mixture was poured into a mould and foamed at 110 0 C in air for 2 hours.
  • the material was submitted to the decomposition of the binder in a tube furnace at 650 0 C for 4 hours in a dry air stream.
  • the specimens were sintered in an Ar-25%H2 atmosphere for 2 hours at 1000°C.
  • example 2 differs primarily from example 1 in that foaming agent is used to form some of the pores of the material. In the case of example 1 no such foaming agent is used.
  • a disc shaped sample with a 2cm diameter and a lcm thickness (“Reference Sample”) is manufactured.
  • a solution made of 85% ethanol and 15% methanol is used as the wicking fluid. The measurements are done in standard atmosphere conditions, i. e. 23°C and 101.3 kPa.
  • Weighted to measure its dry weight • The bulk volume of the reference sample is computed.
  • the Reference Sample is then deposited in a large reservoir filled with the wicking fluid so that one of its main faces (disc shape surface) is in full contact with the bottom of the reservoir.
  • the Reference sample is not supported in any way by an external apparatus; it is directly deposited inside the reservoir.
  • the lateral dimensions of the reservoir are such that there is a 1 mm thick layer of wicking liquid inside the reservoir, with the total volume of wicking fluid inside the reservoir being sufficiently large so that the lmm thickness stays relatively constant throughout the wicking test.
  • one end of the Reference Sample is immersed in lmm of fluid.
  • the resulting average wicking speed value is therefore considered for the purpose of this specification to be the wicking speed of the sample.
  • the Reference Sample is then quickly removed and placed on a nonabsorbent surface to be weighted to measure the fluid saturated weight of the Reference Sample.
  • the difference in weight between the fluid saturated weight and the dry weight of the Reference Sample is divided by the computed volume of the Reference Sample. This ratio is used as a measure of the absorbent capacity of The Reference Sample.
  • the absorbent capacity is expressed as weight of the test liquid (kg) per volume (m 3 )

Abstract

Un caloduc comporte une chambre fermée comprenant un côté chaud et un côté froid, et une structure poreuse inorganique entre le côté chaud et le côté froid. La structure poreuse inorganique transporte un liquide de travail par capillarité du côté froid vers le côté chaud et a une vitesse de pénétration capillaire supérieure à environ 0,005 m/s.
PCT/CA2007/001874 2007-10-19 2007-10-19 Dispositif de gestion thermique utilisant de la mousse inorganique WO2009049397A1 (fr)

Priority Applications (7)

Application Number Priority Date Filing Date Title
PCT/CA2007/001874 WO2009049397A1 (fr) 2007-10-19 2007-10-19 Dispositif de gestion thermique utilisant de la mousse inorganique
CA2702997A CA2702997A1 (fr) 2007-10-19 2007-10-19 Dispositif de gestion thermique utilisant de la mousse inorganique
EP08839074A EP2214851A1 (fr) 2007-10-19 2008-10-20 Cellule ouverte, matériau poreux, et procédé pour, et mélange pour, fabriquer ceux-ci
CA2703020A CA2703020A1 (fr) 2007-10-19 2008-10-20 Cellule ouverte, materiau poreux, et procede pour, et melange pour, fabriquer ceux-ci
KR1020107011000A KR20100098507A (ko) 2007-10-19 2008-10-20 개포형 다공성 물질, 및 이의 제조를 위한 방법 및 혼합물
PCT/CA2008/001863 WO2009049427A1 (fr) 2007-10-19 2008-10-20 Cellule ouverte, matériau poreux, et procédé pour, et mélange pour, fabriquer ceux-ci
CN2008801214744A CN101903125A (zh) 2007-10-19 2008-10-20 开孔多孔材料、其制备方法及用于制备其的混合物

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WO2009049427A1 (fr) 2009-04-23

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