US20030141045A1 - Heat pipe and method of manufacturing the same - Google Patents

Heat pipe and method of manufacturing the same Download PDF

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US20030141045A1
US20030141045A1 US10/163,831 US16383102A US2003141045A1 US 20030141045 A1 US20030141045 A1 US 20030141045A1 US 16383102 A US16383102 A US 16383102A US 2003141045 A1 US2003141045 A1 US 2003141045A1
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wick
heat pipe
wick structure
heat
section
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Se Min Oh
Leonard Vasiliev
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Samsung Electro Mechanics Co Ltd
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Samsung Electro Mechanics Co Ltd
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00Heat-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
    • F28D15/02Heat-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
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00Heat-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
    • F28D15/02Heat-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
    • F28D15/04Heat-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
    • F28D15/046Heat-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

Definitions

  • the invention relates to a heat pipe in use for heat transfer, cooling and heat radiation, and more particularly, to an internal structure of a Miniature Heat Pipe (MHP) and a method of manufacturing the same.
  • MHP Miniature Heat Pipe
  • a heat pipe functioning to efficiently transfer heat from one place to another is used as a critical part of a heat transporting apparatus.
  • an MHP can be effectively used for heat transport and thermal diffusion for cooling a high density electronic circuit or an electronic chip.
  • FIG. 1 is a sectional view illustrating an internal structure of a heat pipe.
  • the heat pipe is constituted of a wall in the outer side thereof, a channel for flowing a working fluid for performing heat transport and a porous wick structure provided between the wall and the channel for regulating the working fluid to continuously perform heat transport.
  • the heat pipe is divided into an evaporating section, a heat insulating section and a condensing section in length as shown in FIG. 1.
  • the operational principle of the heat pipe is as follows: When the working fluid saturated in the wick in the evaporating section evaporates due to heat from an external heat source, vapor moves toward the condensing section due to the difference of vapor pressure to perform heat transport, and then cools and condenses in the condensing section again to perform heat radiation. In this case, condensed the working fluid is absorbed into the condensing wick and then returns to the condensing section due to the difference of capillary pressure between the condensing and evaporating sections. Such motion and returning processes are so repeated that heat continuously transfers from the evaporating section into the condensing section.
  • movement of the working fluid mainly depends on the amount of heat transfer, the capillary pressure of the wick and permeability as resistance against flow of the working fluid in the wick.
  • d 0 is mean hydraulic diameter
  • is surface tension coefficient
  • is wetting angle of the wick.
  • the capillary pressure has the following relation as in Equation 2:
  • P l , P v and P g mean pressure loss of liquid channel, pressure loss of vapor channel and gravity resistance, respectively.
  • Equation 5 the pressure loss due to gravity resistance is expressed as in Equation 5:
  • D means particle diameter
  • Characteristic parameters of the wick in the heat pipe are uniform, the sintered powder wick is saturated with the working fluid, the evaporating and condensing sections have uniform heat flux, saturated vapor having a temperature T s moves through a vapor channel, liquid and gas have non-compressive fluid flow expressed with the Navier-Stocks equation, vapor has no heat source or cooling source, liquid flow within the porous wick follows the Darcy's Law, frictional force at the vapor-liquid interface is very small compared to liquid pneumatic resistance within the wick so as to be disregarded, and the working fluid evaporates at the surface of the evaporating section.
  • the heat pipe is restricted in the performance thereof by viscous limit, capillary limit, entrain or flooding limit, sonic limit and boiling limit.
  • design parameters are determined considering the foregoing working limits in designing the heat pipe.
  • the viscous limit and the boiling limit are considered, in particular, in a low temperature heat pipe used at or under 200° C.
  • ability and time of the heat pipe for recovering from the dry out are also considered.
  • drying out means that the amount of heat inputted into the heat pipe exceeds the maximum heat transport Q max so that the amount of the working fluid evaporating at the evaporating section exceeds the amount of the working fluid returning to the evaporating section from the condensing section, thereby leaving the evaporating section completely dry for a certain time.
  • the temperature of the evaporating section rises rapidly and drops again as the working fluid returns to the wick so that the heat pipe recovers the ability thereof.
  • the temperature controlling ability of the heat pipe is disabled. Then, the corresponding heat pipe cannot be used at or over the amount of heat which is being inputted.
  • the heat pipe has a longitudinal section divided into a evaporating section, a heat insulating section and a condensing section.
  • the heat pipe has the first partial wick structure which may elevate capillary pressure and thermal conductivity
  • the heat insulating section has the second partial wick structure having high permeability
  • the condensing section has the third partial wick structure which may elevate the permeability and the thermal conductivity.
  • a typical heat pipe has a wick structure constituted into the following four configurations, or combined configurations or variations thereof.
  • the configurations have the following characteristics together with advantages and disadvantages.
  • Metal sintered powder wicks have an excellent fluid transport ability against gravitational resistance due to a large value of capillary head, excellent thermal conductivity due to a fin effect of porous metal sintered powder. Further, rapid temperature elevation rarely takes place since the viscous limit gradually takes place. However, the metal sintered powder wicks have a large amount of pressure loss occurring in movement of the working fluid due to a small value of permeability.
  • Grooved wicks have a small pressure loss in movement of the working fluid due to a large permeability.
  • the simple groove wick has drawbacks that capillary pressure is small due to a large capillary diameter, working ability is inferior in a partially superheated-dry state, and viscous limit occurs abruptly thereby resulting in rapid temperature growth.
  • Fine fiber bundle wicks have characteristics that capillary pressure is large, but permeability is small and thus pressure loss is large in movement of the working fluid, and working ability is inferior in a partially superheated-dry state.
  • the foregoing basic wick structures cannot be compared on the basis of a single criterion since they have their own advantages and disadvantages and can be modified into structures which can complement the disadvantages.
  • the sintered powder wicks are preferred to other wicks with regard to heat transport ability and ability against gravitational resistance which are the basic performances of the heat pipes.
  • the sintered powder wicks have a very dense inter-particle structure causing the capillary pressure thereof to be larger than that of the grooved wicks or the mesh screen wicks and the thermal conductivity to be higher than that of the mesh screen wicks thereby to show a relatively large heat flux.
  • the sintered powder wicks have a more excellent working ability against gravitational resistance compared to other wick structures such as the grooved or mesh screen wicks. However, the sintered powder wicks are not superior in the maximum heat transfer due to a large amount of liquid pneumatic resistance.
  • those structures applied to the conventional sintered powder wicks generally have a single porous structure. Therefore, the MHP requires metal powder having a relatively large particle size in order to increase the permeability of the wick.
  • the pore size of the wick is not optimized due to problems of the internal structure and a manufacturing process of the wick so that the basic relative superiority of the sintered powder wick is not sufficiently utilized.
  • the U.S. Pat. No. 6,056,044 proposes a wick structure which uses microscopic multi-capillary tubes via the MEMS to have different particle sizes so as to improve the capillary pressure and the permeability.
  • wick structures belonging to functional components have difficulties from one another with pore size, pore shape, thermal conductivity and absorbing ability of the working fluid.
  • a powder mixture having different particle sizes is hardly constructed into a biporous wick in practice.
  • the present invention is proposed to solve the foregoing problems in regard to a conventional MHP having a single wick or a multi-capillary tube structure, and it is an object of the invention to provide a porous sintered powder wick structure having sub-structures, which are different in material, shape or particle size from one another adequate to requirements of evaporating, heat insulating and condensing sections, so as to increase porosity and permeability of the wick structure. Therefore, in order to arrange the wick sub-structures different in material, shape or particle size from one another, a mixture of such powder undergoes sintering to have a biporous structure thereby providing a heat pipe of an eccentric structure having a radially asymmetric sectional shape.
  • the invention proposes a method for improving ability and time for recovering from dry out due to overheating in an evaporating section of the heat pipe in order to improve working ability in occurrence of thermal limit conditions.
  • the invention proposes a method for minimizing the pore size of the sintered powder wick by rapidly recovering the heat pipe function from such an superheated dry state and forming an absorptive coating on the surface of the wick in the evaporating section by adding a hydrate into the working fluid.
  • FIG. 1 illustrates the structure of a heat pipe in the related art
  • FIG. 2 is a graph illustrating the mean hydraulic pore diameter and permeability
  • FIG. 3 is a graph illustrating the optimum size of wick pores in respect to the working temperatures of a heat pipe for a fixed amount of heat transport thereof;
  • FIG. 4 is a graph illustrating the relation between vapor channel diameters D ch and working temperatures
  • FIG. 5 is a graph illustrating the relation between the maximum amounts of heat transport Q max and working temperatures
  • FIG. 6 is a graph illustrating the relation between the mean pore size and the wick pore diameter
  • FIG. 7 is a graph illustrating a wick structure having an asymmetric radial cross section
  • FIG. 8 is a graph illustrating thermal conductivities radially measured in the outer diameter surface of the heat pipe having the wick structure of the asymmetric cross section shown in FIG. 7;
  • FIG. 9 illustrates a biporous structure of main pores
  • FIG. 10 illustrates a wick structure in which a liquid or solid compound is added into copper powder having fine particle size
  • FIG. 11 illustrates a wick structure made of metal powder and carbon fiber
  • FIG. 12 illustrates a hydrate which is coated on surface particles of an evaporating section wick of a heat pipe having a rectangular cross section
  • FIG. 13 illustrates a sintered wick structure made of a powder mixture in which copper powder is mixed with crystal powder of nickel, graphite or diamond;
  • FIG. 14 is a sectional view illustrating a heat pipe having sections with their own wick structures different from one another in length;
  • FIG. 15 illustrates a planar wick structure
  • the present invention proposes a heat pipe comprising an evaporating section, a heat insulating section, a condensing section and a porous sintered powder wick structure, in which the wick structure comprises sub-structures different from one another in at least one selected from group including material, shape and particle size, each of the sub-structures being arranged into each of the evaporating, heat insulating and condensing sections, in which the wick structure has a biporous distribution made through sintering of a powder mixture having various particle sizes to increase porosity and permeability of the wick structure, and in which the heat pipe has an asymmetric cross sectional shape in a radial direction.
  • the application will design and analyze the relation between the capillary head, permeability and pore capacity of a porous medium and the thermal flow of a working fluid in order to improve the performance of the sintered powder wick, and accordingly derive the optimum pore size and the particle size of the metal powder for realizing the optimum pore size.
  • the optimum design policy will be described as follows for the optimum conditions for carrying out wick sintering of each functional component of the heat pipe.
  • the sintered powder wick advantageously has a capillary pressure larger than that of a grooved wick or mesh screen wick and a thermal conductivity higher than that of the mesh screen wick thereby showing a relatively large heat flux, it is necessary to optimize working parameters of the wick in order to design a heat pipe with excellent performance by utilizing those advantages while compensating disadvantages such as a lower permeability.
  • Examples of pore parameters for constructing the optimized porous wick may include the size and shape of particles, the specific volume, pore diameter and porosity of the porous wick, which cooperate with one another to influence the design of the heat pipe.
  • Equation 6 the permeability k in Equation 6, which is an important design parameter of the heat pipe, can be experimentally obtained according to Equation 8:
  • the capillary pressure can be obtained through a test of a porous medium specimen of an equivalent pore diameter.
  • the liquid hydraulic head can be obtained through measurement in the wick.
  • the permeability can be obtained through the liquid hydraulic head measurement and the Darcy's Law.
  • the heat flux can be obtained by evaluating mass flux in an evaporating process through calculation of two-phase pressure loss.
  • the wick porosity can be obtained through measurement/evaluation of the thermal conductivity of the wick saturated with liquid.
  • the heat flux determining the amount of heat transport of the heat pipe mainly depends on conditions for applying the heat pipe as follows. Examples of the conditions may include the distance between the evaporating section and the condensing section, superheating of a wall of the heat pipe, subcooling of a working fluid, a thermal contact status between a heat source and the wick.
  • working parameters of a specific heat pipe can be designed on the basis of the working parameters of the wick and information about the conditions for applying the heat pipe.
  • the amount of heat transport Q of the invention mainly depends on the vapor channel diameter D ch in a vapor channel of the actual heat pipe and the mean hydraulic pore diameter in a liquid channel
  • the maximum heat transport Q max is varied according to a temperature in the heat insulating section of the heat pipe T sat (or working temperature) due to temperature dependency of thermal-physical characteristics of the working fluid. Further, Q max is varied by a large amount in respect to the inclination angle of the heat pipe installed about the gravitational field.
  • design/analysis results about main design parameters of a sintered copper powder wick about the MHP can be expressed as in FIGS. 2 to 6 .
  • the invention employs a wick structure using a metal powder having a biporous distribution or different particle shapes or mixed with fiber in order to prevent degradation of the capillary head.
  • FIG. 3 is a graph illustrating the optimum size of the wick pores in respect to the working temperatures of the heat pipe for a fixed amount of heat transport thereof. It can be understood that the optimum pore size is 100 to 160 ⁇ m from FIG. 3.
  • FIG. 4 is a graph illustrating the relation between the vapor channel diameters D ch and the working temperatures
  • FIG. 5 is a graph illustrating the relation between the maximum amounts of heat transport Q max and the working temperatures.
  • FIG. 6 is a graph illustrating that the wick pores sized as above can be made through sintering of copper powder having particle sizes of 300 to 500 ⁇ m.
  • copper powder having such a large particle size can be hardly filled between a copper envelope or container having an outer diameter of 4 mm and an iron core having an outer diameter of 2 mm installed in the center of the copper envelope in manufacture of the heat pipe. Therefore, it has been difficult to optimize the pores in the porous sintered powder wick applied to the MHP in the related art.
  • the invention proposes the first method for realizing the optimum hydraulic diameter of the wick pore, in which the iron core is asymmetrically installed from the radial center of the hollow copper pipe and copper powder filled therebetween undergoes sintering.
  • the radial cross section is provided asymmetric, as shown in FIG. 7, to optimize the wick pore.
  • FIG. 8 is a graph illustrating thermal conductivities radially measured in the outer diameter surface of the heat pipe having the wick structure as above. As shown in FIG. 8, it can be seen that heat transfer heavily takes place at a portion having a relatively smaller wick thickness. When applied to the heat pipe, this selectively applies a contact surface between the heat source and a heat sink in the evaporating section and the condensing section thereby providing an additional function of raising a heat transfer efficiency.
  • the invention proposes a wick having biporous structure which is obtained through sintering of mixed copper powders having different particle sizes.
  • FIG. 9 illustrates a biporous structure of main pores.
  • the invention proposes a method for adding a liquid or solid additive into particulate copper powder and enlarging the pore size among copper powder particles by using a gas which is generated when the additive undergoes thermal reaction or thermal decomposition at a temperature lower than a sintering temperature of copper powder in a sintering process of the wick.
  • the additive for enlarging the permeability of the wick is sufficiently melted and cleared but may reside by a very small amount. Therefore, it is required that the additive does not generate gas through thermal reaction with components of the wick and the working fluid.
  • Examples of the additive satisfying the above characteristic may include Co(NH 2 ) 2 .
  • the shape of the wick manufactured according to the above method is shown in FIG. 10.
  • the invention proposes a wick structure which is manufactured by using a powder mixture made of copper powder and smashed copper (graphite) or cellulose (coconut shells, peach pits and the like) or a powder mixture of copper powder and Polyvinylidene Chloride (PVDC) as a kind of non-cellulose.
  • a powder mixture made of copper powder and smashed copper (graphite) or cellulose (coconut shells, peach pits and the like) or a powder mixture of copper powder and Polyvinylidene Chloride (PVDC) as a kind of non-cellulose.
  • PVDC Polyvinylidene Chloride
  • FIG. 11 illustrates a wick structure made of metal powder and carbon fiber. As shown in FIG. 11, various sizes of pores are distributed in the wick thereby improving the capillary pressure and the permeability of the wick while the carbon fiber enhancing the thermal conductivity.
  • the invention proposes a method for adding an absorptive or absorbent material into the working fluid for absorbing the same.
  • the working fluid is water
  • examples of the material having the above capability may include hydrate such as MnCl 2 , NiCl 2 , CaCl 2 , BaCl 2 and LiBr.
  • hydrate exists in the form of a water solution of the working fluid such as water at a room temperature until the wick in the evaporating section is heated.
  • the hydrate When the wick in the evaporating section is heated, the hydrate is separated from the water solution and coated on the particle surface of the evaporating section wick as shown in FIG. 12. Then, the hydrate absorbs water again to assist return or supply of the working fluid into the evaporating section wick. As described above, almost of the hydrate ingredient added into the working fluid is coated on the surface of the evaporating wick thereby to accelerate reflow of the working fluid toward the evaporating section from the condensing section.
  • FIG. 12 illustrates a hydrate which is coated on surface particles of the evaporating section wick of the heat pipe having a rectangular cross section. Such an additive accelerates a recovery time of the evaporating section from a dried status due to overheating, thereby to enhance temperature controlling features and working limits of the heat pipe.
  • the wick can undergo sintering by using a powder mixture of different metals in order to raise the thermal conductivity of the wick.
  • FIG. 13 illustrates a sintered wick structure made of a powder mixture in which copper powder is mixed with crystal powder of nickel, graphite or diamond.
  • the evaporating and condensing sections have thermal conductivities elevated in the radial direction thereby improving the heat exchange performance of the heat pipe.
  • the invention optimizes the characteristics of the heat pipe by applying a wick having different sub-structures, each of which is adequate to a function of each functional component of the heat pipe. Therefore, the invention applies the first sub-structure for elevating the capillary pressure and the thermal conductivity to the evaporating section, the second sub-structure having a high permeability to the heat insulating section and the third sub-structure for elevating the permeability and thermal conductivity to the condensing section as shown in FIG. 14.
  • the above structures can apply the metal powder mixtures having different particle sizes or different kinds such as copper and nickel or carbon fiber to the each functional component of the heat pipe through sintering while utilizing the above characteristics.
  • wick structures and coats can employ any of planar and cylindrical structures.
  • FIG. 15 illustrates a planar wick structure which has a rectangular cross section.
  • the inventive heat pipe has the biporous structure which is optimized to the sintered powder wick so that the maximum heat transport is improved by a large amount.
  • the heat transport ability is improved for 1.3 times over a conventional sintered powder wick and two times over a conventional grooved wick.

Abstract

Disclosed is a heat pipe comprising: an evaporating section, a heat insulating section, a condensing section and a porous sintered powder wick structure, in which the wick structure comprises sub-structures different from one another in at least one selected from group including material, shape and particle size, each of the sub-structures being arranged into each of the evaporating, heat insulating and condensing sections, in which the wick structure has a biporous distribution made through sintering of a powder mixture having various particle sizes to increase porosity and permeability of the wick structure, and in which the heat pipe has an asymmetric cross sectional shape in a radial direction. Powder having a large particle size is readily inserted into the heat pipe to simplify manufacture of the heat pipe while thermal conductivity of the heat pipe is not degraded compared to a conventional structure which is not eccentric.

Description

    BACKGROUND OF THE INVENTION
  • 1. Field of the Invention [0001]
  • The invention relates to a heat pipe in use for heat transfer, cooling and heat radiation, and more particularly, to an internal structure of a Miniature Heat Pipe (MHP) and a method of manufacturing the same. [0002]
  • 2. Description of the Related Art [0003]
  • Well known to those skilled in the art, a heat pipe functioning to efficiently transfer heat from one place to another is used as a critical part of a heat transporting apparatus. In particular, an MHP can be effectively used for heat transport and thermal diffusion for cooling a high density electronic circuit or an electronic chip. [0004]
  • FIG. 1 is a sectional view illustrating an internal structure of a heat pipe. As shown in FIG. 1, the heat pipe is constituted of a wall in the outer side thereof, a channel for flowing a working fluid for performing heat transport and a porous wick structure provided between the wall and the channel for regulating the working fluid to continuously perform heat transport. [0005]
  • Further, the heat pipe is divided into an evaporating section, a heat insulating section and a condensing section in length as shown in FIG. 1. [0006]
  • The operational principle of the heat pipe is as follows: When the working fluid saturated in the wick in the evaporating section evaporates due to heat from an external heat source, vapor moves toward the condensing section due to the difference of vapor pressure to perform heat transport, and then cools and condenses in the condensing section again to perform heat radiation. In this case, condensed the working fluid is absorbed into the condensing wick and then returns to the condensing section due to the difference of capillary pressure between the condensing and evaporating sections. Such motion and returning processes are so repeated that heat continuously transfers from the evaporating section into the condensing section. [0007]
  • In general, movement of the working fluid mainly depends on the amount of heat transfer, the capillary pressure of the wick and permeability as resistance against flow of the working fluid in the wick. [0008]
  • The capillary pressure P[0009] c is determined according to Equation 1: P c = 4 σ cos θ d 0 , Equation 1
    Figure US20030141045A1-20030731-M00001
  • wherein d[0010] 0 is mean hydraulic diameter, σ is surface tension coefficient and θ is wetting angle of the wick.
  • The capillary pressure has the following relation as in Equation 2:[0011]
  • P c =P v +P l +P g  Equation 2,
  • wherein, P[0012] l, Pv and Pg mean pressure loss of liquid channel, pressure loss of vapor channel and gravity resistance, respectively.
  • The pressure loss of liquid channel and the pressure loss of vapor channel are expressed, respectively, as in [0013] Equations 3 and 4 according to the Darcy's Law and the Equation of Poiselle: P l = Q μ l l ef ρ l LS ξ d 0 v , and Equation 3 P v = 128 Q μ v l ef π D ch 4 ρ v L . Equation 4
    Figure US20030141045A1-20030731-M00002
  • Further, the pressure loss due to gravity resistance is expressed as in Equation 5:[0014]
  • P gl gl sin φ  Equation 5,
  • wherein g means gravitational constant. [0015]
  • Further, permeability k determining the migration resistance of the working fluid in the wick has the following relation with the porosity of the wick as in Equation 6: [0016] k = f ( Π ) β D 2 , Equation 6
    Figure US20030141045A1-20030731-M00003
  • wherein D means particle diameter. [0017]
  • Further, the quantity of thermal transport Q[0018] max due to flow of thermal fluid is obtained on the following assumption.
  • Characteristic parameters of the wick in the heat pipe are uniform, the sintered powder wick is saturated with the working fluid, the evaporating and condensing sections have uniform heat flux, saturated vapor having a temperature T[0019] s moves through a vapor channel, liquid and gas have non-compressive fluid flow expressed with the Navier-Stocks equation, vapor has no heat source or cooling source, liquid flow within the porous wick follows the Darcy's Law, frictional force at the vapor-liquid interface is very small compared to liquid pneumatic resistance within the wick so as to be disregarded, and the working fluid evaporates at the surface of the evaporating section.
  • On the basis of the foregoing assumption, the amount of heat transport Q is calculated as in Equation 7: [0020] Q = π L 4 l ef 4 σ cos θ d 0 - ρ g l sin φ μ l ρ l ( D p 2 - D ch 2 ) ξ d 0 v + 32 μ v D 4 ρ v . Equation 7
    Figure US20030141045A1-20030731-M00004
  • In the meantime, the heat pipe is restricted in the performance thereof by viscous limit, capillary limit, entrain or flooding limit, sonic limit and boiling limit. [0021]
  • Therefore, design parameters are determined considering the foregoing working limits in designing the heat pipe. The viscous limit and the boiling limit are considered, in particular, in a low temperature heat pipe used at or under 200° C. When the evaporating section of the heat pipe undergoes dry out due to overheating in order to improve working ability at thermal limit conditions of the heat pipe, ability and time of the heat pipe for recovering from the dry out are also considered. [0022]
  • The foregoing “dry out” means that the amount of heat inputted into the heat pipe exceeds the maximum heat transport Q[0023] max so that the amount of the working fluid evaporating at the evaporating section exceeds the amount of the working fluid returning to the evaporating section from the condensing section, thereby leaving the evaporating section completely dry for a certain time. The temperature of the evaporating section rises rapidly and drops again as the working fluid returns to the wick so that the heat pipe recovers the ability thereof. However, if a function for recovering this ability is slow, the temperature controlling ability of the heat pipe is disabled. Then, the corresponding heat pipe cannot be used at or over the amount of heat which is being inputted.
  • As shown in FIG. 1, the heat pipe has a longitudinal section divided into a evaporating section, a heat insulating section and a condensing section. In this case, it is preferred that the heat pipe has the first partial wick structure which may elevate capillary pressure and thermal conductivity, the heat insulating section has the second partial wick structure having high permeability, and the condensing section has the third partial wick structure which may elevate the permeability and the thermal conductivity. [0024]
  • In order to satisfy the foregoing requirements, a typical heat pipe has a wick structure constituted into the following four configurations, or combined configurations or variations thereof. The configurations have the following characteristics together with advantages and disadvantages. [0025]
  • Metal sintered powder wicks have an excellent fluid transport ability against gravitational resistance due to a large value of capillary head, excellent thermal conductivity due to a fin effect of porous metal sintered powder. Further, rapid temperature elevation rarely takes place since the viscous limit gradually takes place. However, the metal sintered powder wicks have a large amount of pressure loss occurring in movement of the working fluid due to a small value of permeability. [0026]
  • Grooved wicks have a small pressure loss in movement of the working fluid due to a large permeability. In particular, it is advantageous in price since a simple grooved wick can be integrally manufactured in manufacture of a heat pipe envelope or container. However, the simple groove wick has drawbacks that capillary pressure is small due to a large capillary diameter, working ability is inferior in a partially superheated-dry state, and viscous limit occurs abruptly thereby resulting in rapid temperature growth. [0027]
  • Fine fiber bundle wicks have characteristics that capillary pressure is large, but permeability is small and thus pressure loss is large in movement of the working fluid, and working ability is inferior in a partially superheated-dry state. [0028]
  • In mesh screen wicks, capillary pressure is about in the middle and permeability is small so that pressure loss is large in movement of the working fluid as well as thermal resistance is large. [0029]
  • The foregoing basic wick structures cannot be compared on the basis of a single criterion since they have their own advantages and disadvantages and can be modified into structures which can complement the disadvantages. However, the sintered powder wicks are preferred to other wicks with regard to heat transport ability and ability against gravitational resistance which are the basic performances of the heat pipes. The sintered powder wicks have a very dense inter-particle structure causing the capillary pressure thereof to be larger than that of the grooved wicks or the mesh screen wicks and the thermal conductivity to be higher than that of the mesh screen wicks thereby to show a relatively large heat flux. [0030]
  • The sintered powder wicks have a more excellent working ability against gravitational resistance compared to other wick structures such as the grooved or mesh screen wicks. However, the sintered powder wicks are not superior in the maximum heat transfer due to a large amount of liquid pneumatic resistance. [0031]
  • Further, those structures applied to the conventional sintered powder wicks generally have a single porous structure. Therefore, the MHP requires metal powder having a relatively large particle size in order to increase the permeability of the wick. However, the pore size of the wick is not optimized due to problems of the internal structure and a manufacturing process of the wick so that the basic relative superiority of the sintered powder wick is not sufficiently utilized. [0032]
  • Therefore, for the purpose of obtaining the optimized shape of the wick as above, the U.S. Pat. No. 6,056,044 proposes a wick structure which uses microscopic multi-capillary tubes via the MEMS to have different particle sizes so as to improve the capillary pressure and the permeability. [0033]
  • However, in the foregoing structure, the manufacturing process is sophisticated and accordingly the manufacturing cost is elevated. In other words, after a bonding agent is coated on underlying mesh screens, another mesh screens are scrolled into the multiple pipes thereby making the manufacture of the multiple pipes difficult. [0034]
  • In order to overcome the foregoing problems, it is proposed that wick structures belonging to functional components have difficulties from one another with pore size, pore shape, thermal conductivity and absorbing ability of the working fluid. However, a powder mixture having different particle sizes is hardly constructed into a biporous wick in practice. [0035]
  • The above problem is caused due to the fact that powder having a large particle size can be hardly inserted into the MHP considering that the inside diameter of the outer wall of the conventional MHP is limited with size. [0036]
  • SUMMARY OF THE INVENTION
  • Accordingly the present invention is proposed to solve the foregoing problems in regard to a conventional MHP having a single wick or a multi-capillary tube structure, and it is an object of the invention to provide a porous sintered powder wick structure having sub-structures, which are different in material, shape or particle size from one another adequate to requirements of evaporating, heat insulating and condensing sections, so as to increase porosity and permeability of the wick structure. Therefore, in order to arrange the wick sub-structures different in material, shape or particle size from one another, a mixture of such powder undergoes sintering to have a biporous structure thereby providing a heat pipe of an eccentric structure having a radially asymmetric sectional shape. [0037]
  • Further, the invention proposes a method for improving ability and time for recovering from dry out due to overheating in an evaporating section of the heat pipe in order to improve working ability in occurrence of thermal limit conditions. [0038]
  • Moreover, the invention proposes a method for minimizing the pore size of the sintered powder wick by rapidly recovering the heat pipe function from such an superheated dry state and forming an absorptive coating on the surface of the wick in the evaporating section by adding a hydrate into the working fluid.[0039]
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 illustrates the structure of a heat pipe in the related art; [0040]
  • FIG. 2 is a graph illustrating the mean hydraulic pore diameter and permeability; [0041]
  • FIG. 3 is a graph illustrating the optimum size of wick pores in respect to the working temperatures of a heat pipe for a fixed amount of heat transport thereof; [0042]
  • FIG. 4 is a graph illustrating the relation between vapor channel diameters D[0043] ch and working temperatures;
  • FIG. 5 is a graph illustrating the relation between the maximum amounts of heat transport Q[0044] max and working temperatures;
  • FIG. 6 is a graph illustrating the relation between the mean pore size and the wick pore diameter; [0045]
  • FIG. 7 is a graph illustrating a wick structure having an asymmetric radial cross section; [0046]
  • FIG. 8 is a graph illustrating thermal conductivities radially measured in the outer diameter surface of the heat pipe having the wick structure of the asymmetric cross section shown in FIG. 7; [0047]
  • FIG. 9 illustrates a biporous structure of main pores; [0048]
  • FIG. 10 illustrates a wick structure in which a liquid or solid compound is added into copper powder having fine particle size; [0049]
  • FIG. 11 illustrates a wick structure made of metal powder and carbon fiber; [0050]
  • FIG. 12 illustrates a hydrate which is coated on surface particles of an evaporating section wick of a heat pipe having a rectangular cross section; [0051]
  • FIG. 13 illustrates a sintered wick structure made of a powder mixture in which copper powder is mixed with crystal powder of nickel, graphite or diamond; [0052]
  • FIG. 14 is a sectional view illustrating a heat pipe having sections with their own wick structures different from one another in length; and [0053]
  • FIG. 15 illustrates a planar wick structure.[0054]
  • DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
  • In order to obtain the foregoing objects, the present invention proposes a heat pipe comprising an evaporating section, a heat insulating section, a condensing section and a porous sintered powder wick structure, in which the wick structure comprises sub-structures different from one another in at least one selected from group including material, shape and particle size, each of the sub-structures being arranged into each of the evaporating, heat insulating and condensing sections, in which the wick structure has a biporous distribution made through sintering of a powder mixture having various particle sizes to increase porosity and permeability of the wick structure, and in which the heat pipe has an asymmetric cross sectional shape in a radial direction. [0055]
  • Further, the optimum condition for improving performance within the wick will be presented to preferably carry out the invention and a method thereof will be described. [0056]
  • The application will design and analyze the relation between the capillary head, permeability and pore capacity of a porous medium and the thermal flow of a working fluid in order to improve the performance of the sintered powder wick, and accordingly derive the optimum pore size and the particle size of the metal powder for realizing the optimum pore size. The optimum design policy will be described as follows for the optimum conditions for carrying out wick sintering of each functional component of the heat pipe. [0057]
  • In other words, although the sintered powder wick advantageously has a capillary pressure larger than that of a grooved wick or mesh screen wick and a thermal conductivity higher than that of the mesh screen wick thereby showing a relatively large heat flux, it is necessary to optimize working parameters of the wick in order to design a heat pipe with excellent performance by utilizing those advantages while compensating disadvantages such as a lower permeability. [0058]
  • Examples of pore parameters for constructing the optimized porous wick may include the size and shape of particles, the specific volume, pore diameter and porosity of the porous wick, which cooperate with one another to influence the design of the heat pipe. [0059]
  • The present invention represents that the permeability k in Equation 6, which is an important design parameter of the heat pipe, can be experimentally obtained according to Equation 8:[0060]
  • k=0.00144d 0 179  Equation 8,
  • wherein d[0061] 0 indicates mean hydraulic diameter.
  • Other thermal fluid parameters can be obtained through experiments as follows. [0062]
  • The capillary pressure can be obtained through a test of a porous medium specimen of an equivalent pore diameter. [0063]
  • The liquid hydraulic head can be obtained through measurement in the wick. [0064]
  • The permeability can be obtained through the liquid hydraulic head measurement and the Darcy's Law. [0065]
  • The heat flux can be obtained by evaluating mass flux in an evaporating process through calculation of two-phase pressure loss. [0066]
  • The wick porosity can be obtained through measurement/evaluation of the thermal conductivity of the wick saturated with liquid. [0067]
  • The heat flux determining the amount of heat transport of the heat pipe mainly depends on conditions for applying the heat pipe as follows. Examples of the conditions may include the distance between the evaporating section and the condensing section, superheating of a wall of the heat pipe, subcooling of a working fluid, a thermal contact status between a heat source and the wick. [0068]
  • As described above, working parameters of a specific heat pipe can be designed on the basis of the working parameters of the wick and information about the conditions for applying the heat pipe. [0069]
  • For example, when a cylindrical MHP has a length l, an outer diameter D[0070] p of 4 mm, an inner diameter or vapor channel diameter Dch of 2 mm and a sintered wick cross section of S, in which the length of an evaporating section is le, the length of a heat insulating section is lt, and the length of a condensing section is lc, the maximum heat transport Qmax can be obtained according to Equation 7.
  • Although the amount of heat transport Q of the invention mainly depends on the vapor channel diameter D[0071] ch in a vapor channel of the actual heat pipe and the mean hydraulic pore diameter in a liquid channel, the maximum heat transport Qmax is varied according to a temperature in the heat insulating section of the heat pipe Tsat (or working temperature) due to temperature dependency of thermal-physical characteristics of the working fluid. Further, Qmax is varied by a large amount in respect to the inclination angle of the heat pipe installed about the gravitational field.
  • In general, on the basis of horizontal installation (Φ=0°), Φ is expressed—when the evaporating section is arranged over the condensing section but+ when the former is arranged under the latter. When Φ is −90°, Q[0072] max is restricted by the largest amount from gravitational resistance.
  • Based upon the foregoing principles, design/analysis results about main design parameters of a sintered copper powder wick about the MHP can be expressed as in FIGS. [0073] 2 to 6.
  • From the relation between the mean hydraulic pore diameter and the permeability in FIG. 2, it can be seen that the permeability increases due to increase in the pore size of the wick. However, since the capillary pressure decreases due to increase in the pore size, the invention employs a wick structure using a metal powder having a biporous distribution or different particle shapes or mixed with fiber in order to prevent degradation of the capillary head. By using the method as above, reduction of the capillary pressure can be minimized while the permeability of the wick is enlarged. [0074]
  • FIG. 3 is a graph illustrating the optimum size of the wick pores in respect to the working temperatures of the heat pipe for a fixed amount of heat transport thereof. It can be understood that the optimum pore size is 100 to 160 μm from FIG. 3. [0075]
  • FIG. 4 is a graph illustrating the relation between the vapor channel diameters D[0076] ch and the working temperatures, and FIG. 5 is a graph illustrating the relation between the maximum amounts of heat transport Qmax and the working temperatures.
  • FIG. 6 is a graph illustrating that the wick pores sized as above can be made through sintering of copper powder having particle sizes of 300 to 500 μm. However, copper powder having such a large particle size can be hardly filled between a copper envelope or container having an outer diameter of 4 mm and an iron core having an outer diameter of 2 mm installed in the center of the copper envelope in manufacture of the heat pipe. Therefore, it has been difficult to optimize the pores in the porous sintered powder wick applied to the MHP in the related art. [0077]
  • Therefore, the invention proposes the first method for realizing the optimum hydraulic diameter of the wick pore, in which the iron core is asymmetrically installed from the radial center of the hollow copper pipe and copper powder filled therebetween undergoes sintering. In particular, the radial cross section is provided asymmetric, as shown in FIG. 7, to optimize the wick pore. [0078]
  • FIG. 8 is a graph illustrating thermal conductivities radially measured in the outer diameter surface of the heat pipe having the wick structure as above. As shown in FIG. 8, it can be seen that heat transfer heavily takes place at a portion having a relatively smaller wick thickness. When applied to the heat pipe, this selectively applies a contact surface between the heat source and a heat sink in the evaporating section and the condensing section thereby providing an additional function of raising a heat transfer efficiency. [0079]
  • As the second method of realizing the optimum hydraulic diameter of the wick pore, the invention proposes a wick having biporous structure which is obtained through sintering of mixed copper powders having different particle sizes. [0080]
  • FIG. 9 illustrates a biporous structure of main pores. [0081]
  • As the third method for realizing the optimum hydraulic diameter of the wick pore, the invention proposes a method for adding a liquid or solid additive into particulate copper powder and enlarging the pore size among copper powder particles by using a gas which is generated when the additive undergoes thermal reaction or thermal decomposition at a temperature lower than a sintering temperature of copper powder in a sintering process of the wick. The additive for enlarging the permeability of the wick is sufficiently melted and cleared but may reside by a very small amount. Therefore, it is required that the additive does not generate gas through thermal reaction with components of the wick and the working fluid. Examples of the additive satisfying the above characteristic may include Co(NH[0082] 2)2. The shape of the wick manufactured according to the above method is shown in FIG. 10.
  • As a method for increasing the permeability, the capillary pressure and the heat transfer rate of the heat pipe wick, the invention proposes a wick structure which is manufactured by using a powder mixture made of copper powder and smashed copper (graphite) or cellulose (coconut shells, peach pits and the like) or a powder mixture of copper powder and Polyvinylidene Chloride (PVDC) as a kind of non-cellulose. [0083]
  • FIG. 11 illustrates a wick structure made of metal powder and carbon fiber. As shown in FIG. 11, various sizes of pores are distributed in the wick thereby improving the capillary pressure and the permeability of the wick while the carbon fiber enhancing the thermal conductivity. [0084]
  • As a method for reducing a recovery time of the heat pipe from a partial dry out status of the wick due to increase of input heat into the evaporating section of the heat pipe, the invention proposes a method for adding an absorptive or absorbent material into the working fluid for absorbing the same. When the working fluid is water, examples of the material having the above capability may include hydrate such as MnCl[0085] 2, NiCl2, CaCl2, BaCl2 and LiBr. Such hydrate exists in the form of a water solution of the working fluid such as water at a room temperature until the wick in the evaporating section is heated. When the wick in the evaporating section is heated, the hydrate is separated from the water solution and coated on the particle surface of the evaporating section wick as shown in FIG. 12. Then, the hydrate absorbs water again to assist return or supply of the working fluid into the evaporating section wick. As described above, almost of the hydrate ingredient added into the working fluid is coated on the surface of the evaporating wick thereby to accelerate reflow of the working fluid toward the evaporating section from the condensing section.
  • FIG. 12 illustrates a hydrate which is coated on surface particles of the evaporating section wick of the heat pipe having a rectangular cross section. Such an additive accelerates a recovery time of the evaporating section from a dried status due to overheating, thereby to enhance temperature controlling features and working limits of the heat pipe. [0086]
  • The wick can undergo sintering by using a powder mixture of different metals in order to raise the thermal conductivity of the wick. [0087]
  • FIG. 13 illustrates a sintered wick structure made of a powder mixture in which copper powder is mixed with crystal powder of nickel, graphite or diamond. In such a wick, the evaporating and condensing sections have thermal conductivities elevated in the radial direction thereby improving the heat exchange performance of the heat pipe. [0088]
  • Further, in order to maximize the heat transport ability of the heat pipe while maximizing the heat transfer performance thereof with the outside, the invention optimizes the characteristics of the heat pipe by applying a wick having different sub-structures, each of which is adequate to a function of each functional component of the heat pipe. Therefore, the invention applies the first sub-structure for elevating the capillary pressure and the thermal conductivity to the evaporating section, the second sub-structure having a high permeability to the heat insulating section and the third sub-structure for elevating the permeability and thermal conductivity to the condensing section as shown in FIG. 14. [0089]
  • The above structures can apply the metal powder mixtures having different particle sizes or different kinds such as copper and nickel or carbon fiber to the each functional component of the heat pipe through sintering while utilizing the above characteristics. [0090]
  • Further, the above wick structures and coats can employ any of planar and cylindrical structures. [0091]
  • FIG. 15 illustrates a planar wick structure which has a rectangular cross section. [0092]
  • As described above, the inventive heat pipe has the biporous structure which is optimized to the sintered powder wick so that the maximum heat transport is improved by a large amount. For example, when the inventive structure is applied to a heat pipe having an outer diameter of 4 mm, the heat transport ability is improved for 1.3 times over a conventional sintered powder wick and two times over a conventional grooved wick. [0093]
  • Further, the maximum heat transport ability and the ability of resisting against gravity are enhanced to increase the difference from conventional products. [0094]

Claims (9)

What is claimed is:
1. A wick structure composed of a porous sintered powder wick and arranged into a heat pipe which has functional sections including an evaporating section, a heat insulating section and a condensing section, the wick structure comprising:
a method disposing sub-structures different from one another in at least one selected from group including material, shape and particle size, each of the sub-structures being arranged into each of the evaporating, heat insulating and condensing sections, in order to elevate thermal conductivity, amount of heat transport and temperature-controlling performance of the heat pipe.
2. The method in accordance with claim 1, further comprising adding an additive such as Co(NH2)2 inputted into sintering powder to generate a gas through thermal decomposition of the additive during sintering of a wick to increase porosity and permeability of the wick structure.
3. The method in accordance with claim 1, further comprising an arrangement of a biporous distribution in a radial direction of the heat pipe asymmetrically through sintering of a powder mixture having various particle sizes, to increase porosity and permeability of the wick structure.
4. The method in accordance with claim 1, further comprising manufacturing porous sintered powder wick composed of a powder mixture which contains materials including copper, nickel, graphite, carbon and diamond, each of the materials having shape and thermal conductivity different from one another, to improve a heat transfer ability of the heat pipe in a radial direction.
5. The method in accordance with claim 1, further comprising an absorptive coating applied to the surface of the wick structure or particles constituting the wick structure to increase an ability of the wick structure absorbing a working fluid.
6. The method in accordance with one of claim 1 to 5, further comprising an absorptive coating for increasing an ability of the wick structure for absorbing a working fluid, the absorptive coating is made of one selected from group including hydrates, hydroxides, carbonates and LiBr.
7. The method in accordance with one of claim 1 to 5, wherein the wick structure and a coating applied to the wick structure are planar or cylindrical.
8. The method in accordance with one of claim 1 to 5, further comprising an absorptive coating applied to the surface of the wick sub-structure of the evaporating section of the heat pipe or particles constituting the wick sub-structure of the evaporating section of the heat pipe.
9. A heat pipe comprising an evaporating section, a heat insulating section, a condensing section and a porous sintered powder wick structure,
wherein the wick structure comprises sub-structures different from one another in at least one selected from group including material, shape and particle size, each of the sub-structures being arranged into each of the evaporating, heat insulating and condensing sections,
wherein the wick structure has a biporous distribution made through sintering of a powder mixture having various particle sizes to increase porosity and permeability of the wick structure, and
wherein the heat pipe has an asymmetric cross sectional shape in a radial direction.
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Cited By (58)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040118553A1 (en) * 2002-12-23 2004-06-24 Graftech, Inc. Flexible graphite thermal management devices
US20050022976A1 (en) * 2003-06-26 2005-02-03 Rosenfeld John H. Heat transfer device and method of making same
US20050039889A1 (en) * 2003-08-08 2005-02-24 Yu-Nien Huang Phase transformation heat dissipation apparatus
US20050092467A1 (en) * 2003-10-31 2005-05-05 Hon Hai Precision Industry Co., Ltd. Heat pipe operating fluid, heat pipe, and method for manufacturing the heat pipe
US20050105274A1 (en) * 2003-11-19 2005-05-19 Shuttle Inc. Method for reducing the thermal resistance of a heat dissipating base and a heat dissipating base using the same
US20050155745A1 (en) * 2003-12-22 2005-07-21 Fujikura Ltd. Vapor chamber
US20050199374A1 (en) * 2004-03-15 2005-09-15 Hul-Chun Hsu End surface capillary structure of heat pipe
US20050219501A1 (en) * 2004-04-05 2005-10-06 Canon Kabushiki Kaisha Stage apparatus and exprosure apparatus
US20050247435A1 (en) * 2004-04-21 2005-11-10 Hul-Chun Hsu Wick structure of heat pipe
US20050269065A1 (en) * 2004-06-07 2005-12-08 Hon Hai Precision Industry Co., Ltd. Heat pipe with hydrophilic layer and/or protective layer and method for making same
US20060005960A1 (en) * 2004-07-06 2006-01-12 Hul-Chun Hsu End surface capillary structure of heat pipe
US20060011327A1 (en) * 2004-07-16 2006-01-19 Hsu Hul-Chun Wick structure of heat pipe
WO2006007721A1 (en) * 2004-07-21 2006-01-26 Xiao Huang Hybrid wicking materials for use in high performance heat pipes
US20060090884A1 (en) * 2004-11-02 2006-05-04 Sang-Wook Park Heat pipe and heat pipe structure
US20060162907A1 (en) * 2005-01-21 2006-07-27 Foxconn Technology Co., Ltd. Heat pipe with sintered powder wick
US20060162906A1 (en) * 2005-01-21 2006-07-27 Chu-Wan Hong Heat pipe with screen mesh wick structure
US20060175044A1 (en) * 2005-02-10 2006-08-10 Chin-Wei Lee Heat dissipating tube sintered with copper powders
US20060198753A1 (en) * 2005-03-04 2006-09-07 Chu-Wan Hong Method of manufacturing wick structure for heat pipe
US20060219391A1 (en) * 2005-04-01 2006-10-05 Chu-Wan Hong Heat pipe with sintered powder wick
US20070039718A1 (en) * 2005-08-17 2007-02-22 Ming-Chih Chen Heat pipe and manufacturing method for the same
US20070077165A1 (en) * 2005-09-16 2007-04-05 Foxconn Technology Co., Ltd. Method for making wick structure of heat pipe and powders for making the same
US20070193722A1 (en) * 2006-02-18 2007-08-23 Foxconn Technology Co., Ltd. Heat pipe with capillary wick
US20070193723A1 (en) * 2006-02-17 2007-08-23 Foxconn Technology Co., Ltd. Heat pipe with capillary wick
US20070204974A1 (en) * 2005-07-22 2007-09-06 Ramesh Gupta Heat pipe with controlled fluid charge
US20070267178A1 (en) * 2006-05-19 2007-11-22 Foxconn Technology Co., Ltd. Heat pipe
CN100370208C (en) * 2005-01-22 2008-02-20 富准精密工业(深圳)有限公司 Sintering type heat pipe and manufacturing method thereof
US20080148570A1 (en) * 2005-11-07 2008-06-26 3M Innovative Properties Company Structured thermal transfer article
CN100413063C (en) * 2004-07-21 2008-08-20 鸿富锦精密工业(深圳)有限公司 Heat pipe and manufacturing method thereof
US20090260793A1 (en) * 2008-04-21 2009-10-22 Wang Cheng-Tu Long-acting heat pipe and corresponding manufacturing method
US20100139885A1 (en) * 2008-12-09 2010-06-10 Renewable Thermodynamics, Llc Sintered diamond heat exchanger apparatus
US20100181048A1 (en) * 2009-01-16 2010-07-22 Furui Precise Component (Kunshan) Co., Ltd. Heat pipe
US7861768B1 (en) * 2003-06-11 2011-01-04 Apple Inc. Heat sink
US20110083835A1 (en) * 2009-10-08 2011-04-14 Ying-Tung Chen Heat-dissipating structure and method for fabricating the same
US20110127013A1 (en) * 2009-11-30 2011-06-02 Shinko Electric Industries Co., Ltd. Heat-radiating component and method of manufacturing the same
US8235096B1 (en) * 2009-04-07 2012-08-07 University Of Central Florida Research Foundation, Inc. Hydrophilic particle enhanced phase change-based heat exchange
US20120325439A1 (en) * 2011-06-27 2012-12-27 Raytheon Company Method and apparatus for heat spreaders having a vapor chamber with a wick structure to promote incipient boiling
US20120325440A1 (en) * 2011-06-27 2012-12-27 Toshiba Home Technology Corporation Cooling device
US20130032311A1 (en) * 2011-08-01 2013-02-07 Avijit Bhunia System for Using Active and Passive Cooling for High Power Thermal Management
US8434225B2 (en) 2009-04-07 2013-05-07 University Of Central Florida Research Foundation, Inc. Hydrophilic particle enhanced heat exchange and method of manufacture
US20130168052A1 (en) * 2011-12-30 2013-07-04 Celsia Technologies Taiwan, Inc. Heat pipe and composition of capillary wick thereof
US20130174577A1 (en) * 2012-01-10 2013-07-11 Spring (U.S.A.) Corporation Heating and Cooling Unit with Semiconductor Device and Heat Pipe
US20130240180A1 (en) * 2012-03-14 2013-09-19 Kist Europe-Korea Institute of Science and Technologie Europe Forschungsgesellschaft mbh System and method for superheating and/or supercooling of liquids and use of the system and/or method
US20160010927A1 (en) * 2014-07-14 2016-01-14 Fujikura Ltd. Heat transport device
US9416995B2 (en) 2012-01-10 2016-08-16 Spring (U.S.A.) Corporation Heating and cooling unit with semiconductor device and heat pipe
US20170167800A1 (en) * 2015-12-11 2017-06-15 California Institute Of Technology Silicon biporous wick for high heat flux heat spreaders
USD811802S1 (en) 2016-07-15 2018-03-06 Spring (U.S.A.) Corporation Food server
US9909789B2 (en) 2012-01-10 2018-03-06 Spring (U.S.A.) Corporation Heating and cooling unit with canopy light
CN108801015A (en) * 2017-05-05 2018-11-13 双鸿科技股份有限公司 Temperature equalizing plate
CN110736376A (en) * 2018-07-18 2020-01-31 实迈公司 Heat pipe having a wick structure with variable permeability
EP3815815A1 (en) * 2019-10-31 2021-05-05 Sunonwealth Electric Machine Industry Co., Ltd. Vapor chamber and capillary film thereof
US11015879B2 (en) 2016-06-16 2021-05-25 Teledyne Scientific & Imaging, Llc Interface-free thermal management system for high power devices co-fabricated with electronic circuit
WO2022040152A1 (en) * 2020-08-17 2022-02-24 Nuscale Power, Llc Heat pipes including composite wicking structures, and associated methods of manufacture
US20220136779A1 (en) * 2020-11-02 2022-05-05 California Institute Of Technology Systems and Methods for Thermal Management Using Separable Heat Pipes and Methods of Manufacture Thereof
US11415373B2 (en) * 2017-04-12 2022-08-16 Furukawa Electric Co., Ltd. Heat pipe
US11710577B2 (en) 2019-10-15 2023-07-25 Nuscale Power, Llc Nuclear reactors having liquid metal alloy fuels and/or moderators
US11728053B2 (en) 2019-10-15 2023-08-15 Nuscale Power, Llc Heat pipe networks for heat removal, such as heat removal from nuclear reactors, and associated systems and methods
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WO2017212646A1 (en) * 2016-06-10 2017-12-14 日本碍子株式会社 Wick
CN108458615A (en) * 2018-05-25 2018-08-28 中国科学院理化技术研究所 The evaporator of loop heat pipe
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CN113399669A (en) * 2020-03-17 2021-09-17 永源科技材料股份有限公司 Capillary structure
TW202140691A (en) * 2020-04-07 2021-11-01 日商昭和電工材料股份有限公司 Copper paste, wick formation method and heat pipe
JP6980081B1 (en) * 2020-11-13 2021-12-15 古河電気工業株式会社 heat pipe

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5534354B2 (en) * 1974-01-16 1980-09-05
JPS56138686A (en) * 1980-03-31 1981-10-29 Oki Densen Kk Heat pipe of large capacity
JPH08219668A (en) * 1995-02-15 1996-08-30 Mitsubishi Electric Corp Heat pipe
JPH09119789A (en) * 1995-10-24 1997-05-06 Mitsubishi Materials Corp Manufacture of heat pipe
JP3953184B2 (en) * 1998-04-13 2007-08-08 株式会社フジクラ Heat pipe manufacturing method
KR100497332B1 (en) * 1999-12-22 2005-06-29 한국전자통신연구원 Heat pipe having a sintered wick structure and method for manufacturing the same
JP2002303494A (en) * 2001-04-02 2002-10-18 Mitsubishi Electric Corp Evaporator and loop type heat pipe employing the same

Cited By (81)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090032227A1 (en) * 2002-12-23 2009-02-05 Graftech International Holdings Inc. Flexible Graphite Thermal Management Devices
US20040118553A1 (en) * 2002-12-23 2004-06-24 Graftech, Inc. Flexible graphite thermal management devices
US7861768B1 (en) * 2003-06-11 2011-01-04 Apple Inc. Heat sink
US20050022976A1 (en) * 2003-06-26 2005-02-03 Rosenfeld John H. Heat transfer device and method of making same
US20050039889A1 (en) * 2003-08-08 2005-02-24 Yu-Nien Huang Phase transformation heat dissipation apparatus
US20050092467A1 (en) * 2003-10-31 2005-05-05 Hon Hai Precision Industry Co., Ltd. Heat pipe operating fluid, heat pipe, and method for manufacturing the heat pipe
US7213637B2 (en) * 2003-10-31 2007-05-08 Hon Hai Precision Industry Co., Ltd. Heat pipe operating fluid, heat pipe, and method for manufacturing the heat pipe
US20050105274A1 (en) * 2003-11-19 2005-05-19 Shuttle Inc. Method for reducing the thermal resistance of a heat dissipating base and a heat dissipating base using the same
US20050155745A1 (en) * 2003-12-22 2005-07-21 Fujikura Ltd. Vapor chamber
US7137442B2 (en) * 2003-12-22 2006-11-21 Fujikura Ltd. Vapor chamber
US20050199374A1 (en) * 2004-03-15 2005-09-15 Hul-Chun Hsu End surface capillary structure of heat pipe
US7137441B2 (en) * 2004-03-15 2006-11-21 Hul-Chun Hsu End surface capillary structure of heat pipe
US7301602B2 (en) * 2004-04-05 2007-11-27 Canon Kabushiki Kaisha Stage apparatus and exposure apparatus
US20050219501A1 (en) * 2004-04-05 2005-10-06 Canon Kabushiki Kaisha Stage apparatus and exprosure apparatus
WO2005108897A3 (en) * 2004-04-21 2006-01-05 Thermal Corp Heat transfer device and method of making same
WO2005108897A2 (en) * 2004-04-21 2005-11-17 Thermal Corp Heat transfer device and method of making same
US20050247435A1 (en) * 2004-04-21 2005-11-10 Hul-Chun Hsu Wick structure of heat pipe
US7874347B2 (en) * 2004-06-07 2011-01-25 Hon Hai Precision Industry Co., Ltd. Heat pipe with hydrophilic layer and/or protective layer
US20050269065A1 (en) * 2004-06-07 2005-12-08 Hon Hai Precision Industry Co., Ltd. Heat pipe with hydrophilic layer and/or protective layer and method for making same
US20060005960A1 (en) * 2004-07-06 2006-01-12 Hul-Chun Hsu End surface capillary structure of heat pipe
US20060011327A1 (en) * 2004-07-16 2006-01-19 Hsu Hul-Chun Wick structure of heat pipe
US7134485B2 (en) * 2004-07-16 2006-11-14 Hsu Hul-Chun Wick structure of heat pipe
US20070084587A1 (en) * 2004-07-21 2007-04-19 Xiao Huang Hybrid wicking materials for use in high performance heat pipes
WO2006007721A1 (en) * 2004-07-21 2006-01-26 Xiao Huang Hybrid wicking materials for use in high performance heat pipes
CN100413063C (en) * 2004-07-21 2008-08-20 鸿富锦精密工业(深圳)有限公司 Heat pipe and manufacturing method thereof
US7828046B2 (en) 2004-07-21 2010-11-09 Xiao Huang Hybrid wicking materials for use in high performance heat pipes
US20060090884A1 (en) * 2004-11-02 2006-05-04 Sang-Wook Park Heat pipe and heat pipe structure
US20060162906A1 (en) * 2005-01-21 2006-07-27 Chu-Wan Hong Heat pipe with screen mesh wick structure
US20060162907A1 (en) * 2005-01-21 2006-07-27 Foxconn Technology Co., Ltd. Heat pipe with sintered powder wick
CN100370208C (en) * 2005-01-22 2008-02-20 富准精密工业(深圳)有限公司 Sintering type heat pipe and manufacturing method thereof
US20060175044A1 (en) * 2005-02-10 2006-08-10 Chin-Wei Lee Heat dissipating tube sintered with copper powders
US20060198753A1 (en) * 2005-03-04 2006-09-07 Chu-Wan Hong Method of manufacturing wick structure for heat pipe
US20060219391A1 (en) * 2005-04-01 2006-10-05 Chu-Wan Hong Heat pipe with sintered powder wick
US20070204974A1 (en) * 2005-07-22 2007-09-06 Ramesh Gupta Heat pipe with controlled fluid charge
US20070044308A1 (en) * 2005-08-17 2007-03-01 Ming-Chih Chen Heat pipe and manufacturing method for the same
US20070039718A1 (en) * 2005-08-17 2007-02-22 Ming-Chih Chen Heat pipe and manufacturing method for the same
US20070077165A1 (en) * 2005-09-16 2007-04-05 Foxconn Technology Co., Ltd. Method for making wick structure of heat pipe and powders for making the same
US20080148570A1 (en) * 2005-11-07 2008-06-26 3M Innovative Properties Company Structured thermal transfer article
US7594537B2 (en) * 2006-02-17 2009-09-29 Foxconn Technology Co., Ltd. Heat pipe with capillary wick
US20070193723A1 (en) * 2006-02-17 2007-08-23 Foxconn Technology Co., Ltd. Heat pipe with capillary wick
US7520315B2 (en) * 2006-02-18 2009-04-21 Foxconn Technology Co., Ltd. Heat pipe with capillary wick
US20070193722A1 (en) * 2006-02-18 2007-08-23 Foxconn Technology Co., Ltd. Heat pipe with capillary wick
WO2007112060A2 (en) * 2006-03-24 2007-10-04 Exxonmobil Research And Engineering Company Heat pipe with controlled fluid charge
WO2007112060A3 (en) * 2006-03-24 2007-11-22 Exxonmobil Res & Eng Co Heat pipe with controlled fluid charge
US20070267178A1 (en) * 2006-05-19 2007-11-22 Foxconn Technology Co., Ltd. Heat pipe
US20090260793A1 (en) * 2008-04-21 2009-10-22 Wang Cheng-Tu Long-acting heat pipe and corresponding manufacturing method
US8919427B2 (en) * 2008-04-21 2014-12-30 Chaun-Choung Technology Corp. Long-acting heat pipe and corresponding manufacturing method
US20100139885A1 (en) * 2008-12-09 2010-06-10 Renewable Thermodynamics, Llc Sintered diamond heat exchanger apparatus
US20100181048A1 (en) * 2009-01-16 2010-07-22 Furui Precise Component (Kunshan) Co., Ltd. Heat pipe
US8235096B1 (en) * 2009-04-07 2012-08-07 University Of Central Florida Research Foundation, Inc. Hydrophilic particle enhanced phase change-based heat exchange
US8434225B2 (en) 2009-04-07 2013-05-07 University Of Central Florida Research Foundation, Inc. Hydrophilic particle enhanced heat exchange and method of manufacture
US20110083835A1 (en) * 2009-10-08 2011-04-14 Ying-Tung Chen Heat-dissipating structure and method for fabricating the same
US20110127013A1 (en) * 2009-11-30 2011-06-02 Shinko Electric Industries Co., Ltd. Heat-radiating component and method of manufacturing the same
US20120325439A1 (en) * 2011-06-27 2012-12-27 Raytheon Company Method and apparatus for heat spreaders having a vapor chamber with a wick structure to promote incipient boiling
US20120325440A1 (en) * 2011-06-27 2012-12-27 Toshiba Home Technology Corporation Cooling device
US10018428B2 (en) * 2011-06-27 2018-07-10 Raytheon Company Method and apparatus for heat spreaders having a vapor chamber with a wick structure to promote incipient boiling
US20130032311A1 (en) * 2011-08-01 2013-02-07 Avijit Bhunia System for Using Active and Passive Cooling for High Power Thermal Management
US10006720B2 (en) * 2011-08-01 2018-06-26 Teledyne Scientific & Imaging, Llc System for using active and passive cooling for high power thermal management
US20130168052A1 (en) * 2011-12-30 2013-07-04 Celsia Technologies Taiwan, Inc. Heat pipe and composition of capillary wick thereof
US20130174577A1 (en) * 2012-01-10 2013-07-11 Spring (U.S.A.) Corporation Heating and Cooling Unit with Semiconductor Device and Heat Pipe
US9909789B2 (en) 2012-01-10 2018-03-06 Spring (U.S.A.) Corporation Heating and cooling unit with canopy light
US9416995B2 (en) 2012-01-10 2016-08-16 Spring (U.S.A.) Corporation Heating and cooling unit with semiconductor device and heat pipe
US20130240180A1 (en) * 2012-03-14 2013-09-19 Kist Europe-Korea Institute of Science and Technologie Europe Forschungsgesellschaft mbh System and method for superheating and/or supercooling of liquids and use of the system and/or method
US20160010927A1 (en) * 2014-07-14 2016-01-14 Fujikura Ltd. Heat transport device
US20170167800A1 (en) * 2015-12-11 2017-06-15 California Institute Of Technology Silicon biporous wick for high heat flux heat spreaders
US10746478B2 (en) * 2015-12-11 2020-08-18 California Institute Of Technology Silicon biporous wick for high heat flux heat spreaders
US11015879B2 (en) 2016-06-16 2021-05-25 Teledyne Scientific & Imaging, Llc Interface-free thermal management system for high power devices co-fabricated with electronic circuit
US11022383B2 (en) 2016-06-16 2021-06-01 Teledyne Scientific & Imaging, Llc Interface-free thermal management system for high power devices co-fabricated with electronic circuit
USD811802S1 (en) 2016-07-15 2018-03-06 Spring (U.S.A.) Corporation Food server
US11415373B2 (en) * 2017-04-12 2022-08-16 Furukawa Electric Co., Ltd. Heat pipe
US11828539B2 (en) 2017-04-12 2023-11-28 Furukawa Electric Co., Ltd. Heat pipe
CN108801015A (en) * 2017-05-05 2018-11-13 双鸿科技股份有限公司 Temperature equalizing plate
CN110736376A (en) * 2018-07-18 2020-01-31 实迈公司 Heat pipe having a wick structure with variable permeability
US11480394B2 (en) 2018-07-18 2022-10-25 Aavid Thermal Corp. Heat pipes having wick structures with variable permeability
US11710577B2 (en) 2019-10-15 2023-07-25 Nuscale Power, Llc Nuclear reactors having liquid metal alloy fuels and/or moderators
US11728053B2 (en) 2019-10-15 2023-08-15 Nuscale Power, Llc Heat pipe networks for heat removal, such as heat removal from nuclear reactors, and associated systems and methods
EP3815815A1 (en) * 2019-10-31 2021-05-05 Sunonwealth Electric Machine Industry Co., Ltd. Vapor chamber and capillary film thereof
WO2022040152A1 (en) * 2020-08-17 2022-02-24 Nuscale Power, Llc Heat pipes including composite wicking structures, and associated methods of manufacture
US20220136779A1 (en) * 2020-11-02 2022-05-05 California Institute Of Technology Systems and Methods for Thermal Management Using Separable Heat Pipes and Methods of Manufacture Thereof
US20240009869A1 (en) * 2021-09-13 2024-01-11 Jiangsu University Bionic sweat gland and bionic skin
CN116618275A (en) * 2023-06-08 2023-08-22 南昌航空大学 Composite foam copper liquid absorption core, preparation method and application thereof

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