CN102184902B - Porous alloy heat pipe radiator with gradient composite structure - Google Patents

Abstract

The invention provides a porous alloy heat pipe radiator with a gradient composite structure, comprising a shell, wherein a working medium filling opening and an exhaust opening are arranged on the shell; the working medium filling opening is arranged at the bottom of the shell; the exhaust opening is arranged on the upper end face of the shell; an evaporation zone, an adiabatic zone and a condensing zone are arranged from bottom to top in the shell; and three zones are filled with porous alloys, the average pore size of the porous alloys in the evaporation zone is minimum, the average pore size of the porous alloys in the condensing zone is maximum and the average pore size of the porous alloys in the adiabatic zone is between the average pore size of the porous alloys in the evaporation zone and the average pore size of the porous alloys in the condensing zone. In the invention, the evaporation zone, the adiabatic zone and the condensing zone which are filled with the porous-alloys and arranged inside the radiator have different pore sizes and porosities; and therefore, the radiator has the characteristics of strong heat dissipation capability, good permeability and high heat conductivity and the heat dissipation effect can be effectively improved.

Description

A kind of porous alloy heat-pipe radiator with gradient composite construction

Technical field

The present invention relates to a kind of porous alloy heat-pipe radiator that is used for dissipation from electronic devices, belong to the dissipation from electronic devices technical field.

Background technology

Development along with digitlization and network informationization; Demand to microelectronic component performance and speed is increasingly high; At present, semiconductor technology has got into nanometer scale, can on the IC chip, make more transistor; Based on light and need the demand of integration function, also develop at present towards the system single chip direction.During active device computing such as transistor, produce great amount of heat, among the IC along with transistorized number in the chip is more and more; Caloric value is also increasing, and under the situation that chip area does not significantly increase thereupon, device heating density is increasingly high; Problems of excessive heat has become the bottleneck of present restriction electronic device technical development, is example with CPU, and its caloric value increases along with the raising of speed gradually; Reached at present more than the 115W, corresponding density of heat flow rate also increases considerably.Heat dissipation problem has become the biggest obstacle of restriction microelectronic component development, and has caused concern widely.

The microelectronic component caloric value improves constantly, and the heat dissipation technology that is complementary is not with it in time caught up with, and makes the development of CPU face great bottleneck gradually.Estimate according to ITRS, 2006 every DRAM (dynamic random access memory) caloric value will from about 1W, be increased to 2W.In order to enlarge the memory module capacity; Present many companies begin to adopt 3D to pile up the encapsulation of form, though improved the application efficiency of chip, also make heat dissipation problem seem more and more important; According to statistics, account for over half that electronic device lost efficacy by the caused inefficacy of heat.Temperature is too high to cause the damage of semiconductor device except meeting, also can cause electronic reliability to reduce and decreased performance, for the solution of heat dissipation problem, must seek comprehensive technical solution scheme.In addition, heat dissipation problem also is one of key technology difficult problem that influences the LED life-span.

Common porous core heat exchanger generally comprises evaporating area, adiabatic region and condensing zone; Each zone is to adopt compacted density, the aperture porous alloy heat pipe identical with porosity, in microstructure, when working medium undergoes phase transition; Its internal pressure can sharply increase; Cause poor permeability, thermal conductivity reduces, and influences radiating effect.

Summary of the invention

The present invention is directed to the problem that existing dissipation from electronic devices technology exists;, good penetrability strong according to heat-sinking capability that metal porous alloy had, the characteristics that thermal conductivity is high provide a kind of good heat dissipation effect, can satisfy the porous alloy heat-pipe radiator with gradient composite construction of the microminiaturized development of electronic product to the heat dissipation technology demand.

Porous alloy heat-pipe radiator with gradient composite construction of the present invention adopts following technical scheme:

This porous alloy heat-pipe radiator; Comprise housing, housing is provided with working medium filling mouth and exhaust outlet, and the bottom of housing is provided with working medium filling mouth; The upper surface is provided with exhaust outlet; Be divided into evaporating area, adiabatic region and three zones of condensing zone in the housing from bottom to top, all fill full porous alloy in three zones, the average pore size of porous alloy is minimum in the evaporating area; The average pore size of porous alloy is maximum in the condensing zone, and the average pore size of porous alloy is in evaporating area in porous alloy average pore size and the condensing zone between the porous alloy average pore size in the adiabatic region.Porous alloy can be the porous alloy of existing various structure types.

The evaporating area height H ₁, the condensing zone height H ₃With the adiabatic region height H ₂Distribution be:

With

H wherein ₁Be the height of evaporating area 7, H ₂Be the height of adiabatic region 5, H ₃Be the height of condensing zone, H is three region height sums; V _lBe liquid phase topping up volume, φ ₁Be the porosity of evaporating area porous alloy, V _gBe gaseous phase volume, φ ₃Be the porosity of condensing zone porous alloy, L is the length in arbitrary zone, and W is the width in arbitrary zone.

The mean pore size of porous alloy obtains by following formula in evaporating area, adiabatic region and the condensing zone: ln (p/p ₀(the 2 γ V of)=- _m/ rRT) cos θ, in the formula, in the formula, p ₀Saturated vapour pressure when being the plane for the working media liquid level, p are the saturated vapour pressure of liquid-working-medium in the porous alloy, V _mBe the molal volume of corresponding phase, γ is the surface tension of corresponding phase in each district, and R is a constant, and T is an absolute temperature, and θ is the contact angle of liquid-working-medium and porous alloy metal level wall; When correspondence is meant real work mutually, the situation of working media in radiator evaporating area, adiabatic region and the condensing zone, the evaporating area working media is a liquid phase, and the adiabatic region working media is vapour-liquid two phases, and the condensing zone working media is a vapour phase.

Inner porous alloy evaporating area, adiabatic region and the condensing zone of radiator of the present invention has different apertures and porosity, has that heat-sinking capability is strong, a good penetrability, characteristics that thermal conductivity is high, can effectively improve radiating effect.

Description of drawings

Accompanying drawing is a structural representation of the present invention.

Wherein, 1, housing, 2, exhaust outlet, 3, condensing zone, 4, adiabatic region and condensing zone critical surface, 5, adiabatic region; 6, evaporating area and adiabatic region critical surface, 7, evaporating area, 8, working medium filling mouth.

Embodiment

Shown in accompanying drawing, the porous alloy heat-pipe radiator with gradient composite construction of the present invention comprises housing 1, and the bottom of housing 1 is provided with working medium filling mouth 8, and the upper surface is provided with exhaust outlet 2.Be divided into evaporating area 7, adiabatic region 5 and 3 three zones of condensing zone in the housing 1 from bottom to top, be respectively evaporating area and adiabatic region critical surface 6 and adiabatic region and condensing zone critical surface 4 between the adjacent area.All filling full porous alloy in three zones steams.The average pore size of sending out porous alloys in the district 7 is minimum, and the aperture of porous alloys is on average maximum in the condensing zone 3, and the average pore size of porous alloys is in evaporating area 7 in porous alloy average pore size and the condensing zone 3 between the porous alloy average pore size in the adiabatic region 5.

In evaporating area 7, fill liquid phase working fluid (liquid phase working fluid mainly is in evaporating area 7) through the working medium filling mouth 8 of housing 1 bottom.Radiator is when real work, and working medium mainly is liquid phase in the evaporating area 7, and working medium is vapour-liquid two phases in the adiabatic region 5, and working medium mainly is vapour phase in the condensing zone 3.

According to radiator caloric receptivity (Q ₁) and heat dissipation capacity (Q ₂), the size of confirming the physical dimension of radiator of the present invention and rationally dividing evaporating area 7, adiabatic region 5 and condensing zone 3.According to the phase difference of working medium at evaporating area 7, adiabatic region 5 and condensing zone 3; Each regional porous alloy is designed to the complex gradient structure; That is: the aperture of porous alloy is minimum in the evaporating area 7; The aperture of porous alloys is maximum in the condensing zone 3, and the aperture of porous alloys is in evaporating area 7 in porous alloy aperture and the condensing zone 3 between the porous alloy aperture in the adiabatic region 5.

The heat dissipation environment of condensing zone 3 is generally relatively stable, and so, the heat that discharges at condensing zone also can keep relative stability.In design process, to consider:

1.Q ₁, P, v ₁Between logical relation;

When the heat of evaporating area 7 absorptions equaled the heat of condensing zone 3 releases, its internal pressure P changed little; And the heat that the heat that absorbs when evaporating area 7 discharges greater than condensing zone 3 constantly, and its internal pressure P must increase, and causes the medium elevation of boiling point, and phase transformation slows down, heat transfer rate v ₁Descend, the heat sink temperature rises, until influencing its operate as normal.

2. the influence of aperture, porosity and pressure P;

Owing to do not consider the change in volume that Working fluid phase changing causes; The increase of the heat that consequently absorbs along with evaporating area 7; The ratio of its inner vapour phase and liquid phase changes, for keeping the relatively stable of P, and will appropriate design evaporating area 7, the height H of adiabatic region 5 and condensing zone 3 ₁, H ₂And H ₃Relative size.Detailed process is held as follows:

Utilize the continuity equation of saturated porous alloy, Darcy's law, the energy equation of consideration gravitational effect that trizonal working medium transport process is carried out mathematical modeling:

$\frac{\∂\left(\mathrm{\φ\ρ}\right)}{\∂\mathrm{\τ}}+\▿\·\left(\mathrm{\ρv}\right)=0---\left(1\right)$

In the formula, φ is the porosity of porous alloy, and ρ is the density of fluid, and v is the superficial velocity of fluid.

$q_V=-\frac{\mathrm{kA}}{\mathrm{\μL}}[(p_1-p_2)+\mathrm{\ρgL}]---\left(2\right)$

In the formula, q _VBe volume flow, k is the permeability of porous alloy, and μ is the dynamic viscosity of fluid; A is that cell cross-section is long-pending, and L is a cell cube length.

${\left(\mathrm{\ρc}\right)}_m\frac{\∂T}{\∂\mathrm{\τ}}+{\left(\mathrm{\ρ}{c}_P\right)}_{f}V\·\▿T=\▿\·({\mathrm{\λ}}_m\▿T)+\mathrm{\φ}{q}_m^{\′\′\′}---\left(3\right)$

Wherein (ρ c) _m=(1-φ) (ρ c) _s+ φ (ρ c _p) _fλ _m=(1-φ) λ _s+ φ λ _fQ ' " _m=(1-φ) q ' " _s+ φ q ' " _f

In the formula, subscript s and f represent that respectively solid phase and fluid are mutually; C is the specific heat of solid; c _pSpecific heat at constant pressure for fluid; λ is a conductive coefficient; Q ' is " for the heat of the unit volume that endogenous pyrogen produced.

Use fractal theory then, set up the expression formula of porous alloy porosity and permeability:

$\mathrm{\φ}=\frac{V_p}{V_b}=\frac{\mathrm{AD\π}}{4A_0(3-D-D_T)}{L}_0^{D_T-1}{\mathrm{\λ}}_{\max }^{3-D-D_T}(1-{\mathrm{\τ}}^{3-D-D_T})---\left(4\right)$

$k=\frac{\mathrm{\&mu;}{L}_{0}Q}{\mathrm{\&Delta;p}{A}_0}=\frac{\mathrm{\&pi;}}{128}\frac{A}{A_0}\frac{\mathrm{<figure-callout\; id="3"\; label="D"\; filenames="HDA0000055392590000011.png"\; state="\{\{state\}\}">D</figure-callout>}}{3+D_T-D}{L}_0^{1-D_T}{\mathrm{\&lambda;}}_{\max }^{3+D_T-D}---\left(5\right)$

In the formula, D is a porous alloy distribution of pores fractal dimension, D _TBe the tortuous fractal dimension of porous alloy hole, Q then is the total flow through the unit section A.

The mean pore size that obtains pairing porous alloy in evaporating area, adiabatic region and the condensing zone according to the parameter expression of above acquisition is:

ln(p/p ₀)＝-(2γV _m/rRT)cosθ (6)

In the formula, p ₀Saturated vapour pressure when being the plane for the working media liquid level, p are the saturated vapour pressure of liquid-working-medium in the porous alloy, V _mBe the molal volume of corresponding phase, γ is the surface tension of corresponding phase in each district, and R is a constant, and T is an absolute temperature, and θ is the contact angle of liquid-working-medium and porous alloy metal level wall; When correspondence is meant real work mutually, the situation of working media in radiator evaporating area, adiabatic region and the condensing zone, the evaporating area working media is a liquid phase, and the adiabatic region working media is vapour-liquid two phases, and the condensing zone working media is a vapour phase.

Porosity according to obtaining obtains evaporating area 7, condensing zone 3 and adiabatic region 5 height profile:

and

H wherein ₁Be the height of evaporating area 7, H ₂Be the height of adiabatic region 5, H ₃Be the height of condensing zone, H is three region height sums; V _lBe liquid phase topping up volume, φ ₁Be the porosity of evaporating area porous alloy, V _gBe gaseous phase volume, φ ₃Be the porosity of condensing zone porous alloy, L is the length in arbitrary zone, and W is the width in arbitrary zone.

The most important condition that the working medium of filling in the housing is selected is that working temperature should be between the solidifying point and critical point of working medium.According to universal experience, centering, Cryo Heat Tube, the general rule of screening working medium is under minimum operating temperature, interior pressure should be greater than 0.1 atmospheric pressure; Under maximum operating temperature, interior pressure should be less than 10～20 atmospheric pressure.Working temperature preferably is selected near the normal boiling point, is pressed in about an atmospheric pressure in promptly.The influence of working medium rerum natura opposite heat tube heat-transfer capability reduces a number crowd, and following form can be arranged:

$N=\frac{\mathrm{\&sigma;}\&CenterDot;{\mathrm{\&rho;}}_l\&CenterDot;h_{\mathrm{fg}}}{{\mathrm{\&mu;}}_l}---\left(7\right)$

In the formula, N is the transmission factor; σ is the surface tension coefficient of liquid; ρ _lBe fluid density; h _FgThe latent heat of vaporization for liquid; μ _lDynamic viscosity for liquid.The transmission factor of working medium is high more, and then heat-transfer capability is strong more, can find out that from formula such working medium should have high surface tension, the high latent heat of vaporization, characteristics such as wetability is good, and viscosity is little.

Working medium filling weight M should be:

M＝ρ _lV _l+ρ _vV _v (8)

V in the formula _l---evaporating area (V _l) the volume V of receiving fluids ₁=ε A _wl

V _v---vapor space volume V _v=A _vl

So

$\frac{M}{V_v}=(\frac{V_l}{V_v}{\mathrm{\&rho;}}_l+{\mathrm{\&rho;}}_v)=(\frac{\mathrm{\&epsiv;}{A}_w}{A_v}{\mathrm{\&rho;}}_l+{\mathrm{\&rho;}}_v)---\left(9\right)$

It is only relevant with the structural parameters and the working medium rerum natura of heat pipe to be full of the working medium filling weight entirely.

The present invention has following technique effect and advantage:

1, be used for efficiently radiates heat to microelectronic components such as IC, LED, the porous alloy in its inner porous alloy evaporating area, adiabatic region and the condensing zone has different apertures and porosity, can effectively improve radiating effect.

2, utilize the notion of gradient composite construction porous alloy critical surface, and introduce analytic solutions fractal and numerical computations acquisition aperture, critical surface both sides and porosity.

3, distinguish clear and definite radiator overall height H and each region height H according to the phase difference and the physical parameter of working medium in the zones of different ₁, H ₂, H ₃Between logical relation, calculated hole diameters and porosity size, and can application directs the type Design of for heat sinks.

Claims (3)

1. porous alloy heat-pipe radiator with gradient composite construction; Comprise housing, it is characterized in that: housing is provided with working medium filling mouth and exhaust outlet, and the bottom of housing is provided with working medium filling mouth; The upper surface is provided with exhaust outlet; Be divided into evaporating area, adiabatic region and three zones of condensing zone in the housing from bottom to top, all fill full porous alloy in three zones, the average pore size of porous alloy is minimum in the evaporating area; The average pore size of porous alloy is maximum in the condensing zone, and the average pore size of porous alloy is in evaporating area in porous alloy average pore size and the condensing zone between the porous alloy average pore size in the adiabatic region.

2. the porous alloy heat-pipe radiator with gradient composite construction according to claim 1 is characterized in that: said evaporating area height H ₁, the condensing zone height H ₃With the adiabatic region height H ₂Distribution be:

With

H wherein ₁Be the height of evaporating area, H ₂Be the height of adiabatic region, H ₃Be the height of condensing zone, H is three region height sums; V _lBe liquid phase topping up volume, φ ₁Be the porosity of evaporating area porous alloy, V _gBe gaseous phase volume, φ ₃Be the porosity of condensing zone porous alloy, L is the length in arbitrary zone, and W is the width in arbitrary zone.

3. the porous alloy heat-pipe radiator with gradient composite construction according to claim 1 is characterized in that: the mean pore size of porous alloy obtains by following formula in said evaporating area, adiabatic region and the condensing zone: ln (p/p ₀(the 2 γ V of)=- _m/ rRT) cos θ, in the formula, p ₀Saturated vapour pressure when being the plane for the working media liquid level, p are the saturated vapour pressure of liquid-working-medium in the porous alloy, V _mBe the molal volume of corresponding phase, γ is the surface tension of corresponding phase in each district, and R is a constant, and T is an absolute temperature, and θ is the contact angle of liquid-working-medium and porous alloy metal level wall; When correspondence is meant real work mutually, the situation of working media in radiator evaporating area, adiabatic region and the condensing zone, the evaporating area working media is a liquid phase, and the adiabatic region working media is a gas-liquid two-phase, and the condensing zone working media is a gas phase.

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