Carbon nano fiber vacuum super heat conductive tube and processing method thereof
Technical field
The present invention relates to a kind of technical field of high-efficiency heat pipe, be particularly related to a kind of carbon nano fiber vacuum super heat conductive tube and processing method thereof, can be widely used in various heat transfers and Related product, as solar energy (water heater, heating equipment etc.), oil, chemical industry, metallurgy, electric power, electronics, building materials, the renewable sources of energy, frozen soil control, road defrost etc.
Background technology
Conventional heat pipe is comprised of shell, liquid-sucking core and end cap, will after the negative pressure being extracted in shell, fill with appropriate hydraulic fluid, makes to be close in the liquid-sucking core capillary porous material of inside pipe wall to be full of after liquid, then is sealed.One end of shell is evaporator section (bringing-up section), and the other end is condensation segment (cooling section), as required can be two sections of intermediate arrangement adiabatic sections.The heat transfer medium of conventional heat pipe adopts the liquid that boiling point is lower mostly, as water or other organic substances.Conventional heat pipe is the phase transformation transferring heat energy of the liquid gentle state of medium in tube.
When one end of heat pipe is heated, after liquid absorption heat in capillary wick, can rapid explosive evaporation vaporize, during this transfer, absorbed large calorimetric, steam flows to the other end under small pressure reduction, when these gases that are heated are dispersed into the condensation segment of heat pipe, will discharge a large amount of heats, regelation becomes liquid, and liquid flows back to evaporator section along porous material by the effect of capillary force again.So endlessly, heat just reaches the other end by one end of heat pipe in circulation.
Heat pipe is a kind of heat transfer element with high heat conductivility, conventional heat pipe carrys out transferring heat by the evaporation and condensation (phase transformation) of the liquid in Totally enclosed vacuum pipe, utilize the fluid principles such as capillary imbibition effect, play the effect of similar freezer compressor refrigeration.Because heat transfer medium main component is liquid and additive, heat transfer medium is subject to the attribute limits of itself, and shell is subject to the restriction of temperature and circulating phase-change speed, so, the heat transfer efficiency of conventional heat pipe is only slightly larger than 60%, and heat waste is high, and heat pipe is very easy to tired, tube wall easily corrodes, and the life-span is not long yet.Most of heat pipes were used after one or two years, and heat transfer efficiency can obviously decline.
Summary of the invention
The object of the present invention is to provide a kind of carbon nano fiber vacuum super heat conductive tube and processing method thereof, its heat transfer medium is comprised of carbon nano-fiber, utilizes atomic high-frequency vibration transferring heat, without phase transformation under the exciting of the extraneous temperature difference, thermal resistance is minimum, and the life-span is long.
To achieve these goals, technical scheme of the present invention is:
A kind of carbon nano fiber vacuum super heat conductive tube, comprises the superconductive medium that vacuum tube and carbon nano-fiber are prepared into, and vacuum tube is formed by shell and end cap seal, and superconductive medium is implanted in airtight vacuum tube.
Described carbon nano-fiber refers to the carbon fiber of fibre diameter at the solid construction of 50~200nm.
Described vacuum tube adopts metal, nonmetal or board-like material to make.
Described metal is copper, carbon steel or stainless steel.
Described nonmetal be glass or pottery.
Described heat pipe structure is " n " type, " ∏ " type, " H " type or " one " type.
A processing method for carbon nano fiber vacuum super heat conductive tube, its step is as follows:
The first step, machining is made shell and the end cap of vacuum tube, and adopts carbon nano-fiber to make superconductive medium;
Second step, cleans scrubbing dedusting to shell and end cap, superconductive medium;
The 3rd step, implants superconductive medium in shell, then adds a cover end cap;
The 4th step, welding shell and end cap, check whether vacuum tube leaks gas, and get rid of the air in vacuum tube, completes the sealing-in of vacuum tube;
The 5th step, vacuum bakeout, under the environment of 200 ± 10 ℃ of high temperature, vacuum, opposite heat tube assembly is made capillary surface dehydration, deoxidation treatment, gets product.
Described the 4th step is before welding, first to carry out application of vacuum, adopts heating to displace the modes such as (liquid state), gaseous liquefied (gaseous state), vacuum benefit mercury and gets rid of the air in vacuum tube, and adopt the pure gas welding sealing of tungsten electrode.
Adopt after such scheme, super heat-conductive pipe of the present invention claims again medium heat conduction pipe, " carbon nano fiber vacuum super heat conductive tube technology " is the upgrading of vacuum heat-pipe technology, and this carbon nano-fiber new material is applied to superconductive heat transfer and high efficient heat exchanging technology, is a kind of Novel hot transport element.It has broken traditional heat transfer type take liquid such as water as medium, conduct heat and do not need working media phase transformation, the elastic wave producing by the vibration of lattice structure, can realize remote fast transport by minimum sectional area by amount of heat, can in diabatic process, realize efficient and low energy consumption.Its principle is that carbon nano-fiber is prepared into superconductive medium, implants in airtight vacuum tube, and the two ends of vacuum tube (being respectively bringing-up section and condensation segment), once have temperature difference, superconductive medium can be intensified, with supersonic speed transferring heat energy.In other words, by atom, near the Vibration on Heat Transfer of molecule its equilbrium position), conduct heat fast, heat transfer efficiency is high.In diabatic process, thermal resistance is very little, and heat transfer efficiency is up to 98%~99%, and due to the constitutionally stable molecular characterization of carbon nano-fiber, fatigue phenomenon can not occur this super heat-conductive pipe, under the state that heat transfer efficiency is not revealed at heat pipe, declines never.
The present invention adopts carbon nano-fiber as heat-conducting medium, mainly has the following advantages:
One, startup is rapid, heat transfer rate is fast
Heat is delivered to condensation segment from the bringing-up section of heat-pipe elements only needs the several seconds to complete.
Two, thermal resistance is little, uniform temperature good
Carbon nano-fiber high-efficiency heat pipe is mainly to realize heat transfer process by the carbon nano-fiber medium of seal chamber inside, heat-transfer capability is far away higher than metal material, along high-efficiency heat pipe axial temperature difference, level off to zero, thereby the surface temperature of high-efficiency heat pipe is reached unanimity.
Three, thermal conductivity factor is high, and heat-transfer capability is large
Equivalent heat conductivity is 20MW/m ℃, is 4.6 ten thousand times of fine silver.
Four, under the low temperature environment of 40 degrees below zero, do not freeze, do not freeze hidden danger.The heat transfer medium of conventional heat pipe easily freezes at low temperatures, particularly adopts the conventional heat pipe of water as heat transfer medium.
Five, Applicable temperature scope is wide: medium Applicable temperature scope-35~1000 ℃.
Six, operating pressure is low
During work, carbon nano-fiber high-efficiency heat pipe chamber pressure is low, and high temperature booster can not occur.In conventional heat pipe cavity, there is air pressure, at high temperature easily blast.
Seven, compatibility is good
There is not chemical reaction in carbon nano-fiber high-efficiency heat pipe medium and common metal material.The heat transfer medium of conventional heat pipe is mainly organic element, with the metal material of cavity, chemical reaction easily occurs.
Eight, the long-acting life-span
Carbon nano-fiber high-efficiency heat pipe medium self the reduction of speed rate that disappears continues 100,000 hours, can make the operation steady in a long-term of carbon nano-fiber high-efficiency heat pipe.Through facts have proved in a large number, carbon nano-fiber high-efficiency heat pipe medium and various metals are as copper, aluminium, carbon steel and stainless steel and nonmetally have good compatibility, a long service life.
Nine, safe and reliable
Carbon nano-fiber high-efficiency heat pipe medium consists of carbon nano-fiber, and medium itself is nontoxic, pollution-free, non-corrosiveness.
Ten, carbon nano-fiber high-efficiency heat pipe, no matter in excited state or the inactive state of being heated, all can not produce the radioactive substance of any harmful human body.
Accompanying drawing explanation
Fig. 1 is structural representation of the present invention;
Fig. 2 is schematic flow sheet of the present invention.
Below in conjunction with accompanying drawing, the invention will be further described:
The specific embodiment
As shown in Figure 1, a kind of carbon nano fiber vacuum super heat conductive tube that the present invention discloses, comprises the superconductive medium 2 that vacuum tube 1 and carbon nano-fiber are prepared into.
Wherein, vacuum tube 1 is formed by shell and end cap seal, can adopt the non-metal tubulars such as the metals such as copper, carbon steel, stainless steel or glass, pottery or board-like material to make; Superconductive medium 2 is mixtures of carbon nano-fiber, and superconductive medium 2 is injected in vacuum tube 1, forms high-efficiency heat pipe after sealing moulding.
This super heat-conductive pipe specifically add man-hour, as shown in Figure 2, first by machining, make shell and the end cap of vacuum tube, the selection of shell material will be noted the characteristics such as heat conductivity, vacuum degree of maintaining, withstand voltage, fluid compatibility (burn into chemical reaction), and adopts carbon nano-fiber to make superconductive medium; Then, shell and end cap, superconductive medium are cleaned to scrubbing dedusting; Again superconductive medium is implanted in shell, then added a cover end cap; Then, welding shell and end cap, check whether vacuum tube leaks gas, and get rid of the air in vacuum tube, complete the sealing-in of vacuum tube, concrete operations are before welding, first to carry out application of vacuum, adopt heating to displace the modes such as (liquid state), gaseous liquefied (gaseous state), vacuum benefit mercury and get rid of the air in vacuum tube, and adopt the pure gas welding sealing of tungsten electrode; Vacuum bakeout again, under the environment of 200 ± 10 ℃ of high temperature, vacuum, opposite heat tube assembly is made capillary surface dehydration, deoxidation treatment, dries the cleaning fluid on vacuum tube hollow billet, makes tube wall not stay impurity and watermark, stopped the hidden danger such as demoulding, vacuum reduction, finally got product.
Carbon fiber be a kind ofly there is good heat resistance, quality is light, intensity is high and the high-performance fiber of high-modulus, has been widely used in each fields such as space flight, sports equipment articles for use, medical equipment and weaving.The development early start of carbon fiber, in nineteen fifty-nine, is produced by U.S. combinating carbide company.Carbon fiber diameter is generally in the scope of 7~20mm.
And carbon nano-fiber (Carbon nanofibers, CNFs) refers to the carbon fiber of fibre diameter at the solid construction of 50~200nm.The draw ratio of carbon nano-fiber is 100~500.It is a kind of form of chemical meteorological grown carbon fiber, by the discontinuous graphite fibre of preparing by cracking gaseous hydrocarbon, to form take richness to strangle (Fullerene) alkene (C60) single wall and multiple-wall carbon nanotube as one end, take continuous carbon fibre as the other end, the ring in chain link.Diameter, the doughnut below 100nm is referred to as CNT at present many researchers, be the diameter of carbon nano-fiber between CNT and gas-phase growth of carbon fibre, the preparation of carbon nano-fiber is easier to realize suitability for industrialized production compared with CNT.It has filled up conventional carbon fiber, and (diameter is the breach of 7~10 μ m) and in SWCN (SWNTs) (diameter is about 1nm) and multi-walled carbon nano-tubes (MWNTs) (diameter is 1~50nm) size, has the features such as higher intensity, modulus, draw ratio, heat endurance, chemism, electric conductivity.
Carbon fiber can be divided into the three major types such as cellulose base carbon fiber, polyacrylonitrile-based carbon fibre and asphalt base carbon fiber according to raw material used, is all with wet spinning or melt spinning method spinning fibre stabilized, carbonization or graphited heat treatment process and obtain again.Carbon nano-fiber need to adopt the Advanced Manufacturing Technologies such as chemical vapour deposition, polymer blending melt spinning method and electric discharge spin processes to produce.For example, chemical vapour deposition, also claim chemical vapour deposition technique, when high temperature, make alkanes gas on catalyst, carry out thermal decomposition and can form carbon nano-fiber, this carbon nano-fiber has extremely low thermal coefficient of expansion, very high heat conductivility (under room temperature, its thermal conductivity factor can compare favourably with diamond, about 2320W/mK) and approaches the strength modulus of carbonized polyacrylonitrile fibre.
In metal, what thermal conductivity factor was the highest is silver, about 429W/mK, then be copper, about 401W/mK, and the thermal conductivity factor of carbon nano-fiber is 5 times of silver, is 4300 times (thermal conductivity factor of water is 0.54W/mK) of water, 92800 times of water vapours, (thermal conductivity factor of water vapour is 0.0235~0.025W/mK).
Therefore, carbon nano-fiber medium is a kind of energy saving and environment friendly cooling, heat transfer and heat-storage medium.
The difference on effect that super heat-conductive pipe produces from conventional heat pipe is mainly due to different the produced different heat-transfer effects of medium that adopt.Super heat-conductive pipe is completely different from current conventional heat pipe on the market.Conventional heat pipe is the phase transformation transferring heat energy of the liquid gentle state of medium in tube, and it is subject to the restriction of temperature and circulating phase-change speed, has heat waste, and the life-span is not high yet; And the heat transfer medium 2 of carbon nano-fiber super heat-conductive pipe is comprised of carbon nano-fiber, under the exciting of the extraneous temperature difference, utilize atomic high-frequency vibration transferring heat, without phase transformation, thermal resistance is minimum.
High-efficiency heat pipe medium is subject to along chamber wall, transmitted by bringing-up section heat energy to condensation segment after thermal excitation.The uniform temperature of element outer surface shows that element has good heat transfer property; The uniform temperature point of element surface shows: temperature is prolonged the characteristic that axially shows sinusoidal wave distribution.
Heat pipe structure can be according to service condition, corresponding frame for movement, and heat radiation requires to wait and is designed to difformity, for example, can be prepared into the shapes such as " n " type, " ∏ " type, " H " type, " one " type.
Super heat-conductive pipe of the present invention with respect to the superior function of general heat pipe is:
1) conventional heat pipe is to adopt the liquid organic compounds such as water or oil, ethanol as heat transfer medium; Due to series of problems such as vapour pressure, operation temperature area and the media compatibility of these media, the range of application of conventional heat pipe is very restricted, and super heat-conductive pipe adopt Nanometer material and solid inorganic compounds as heat transfer medium efficiently, it is different from the heat transfer medium of conventional heat pipe completely, possess pollution-free, "dead", nontoxic, corrosion-free, medium steam forces down, and operation temperature area is wide, long service life, the series of advantages such as cost is low, it possesses the unrivaled premium properties of conventional heat pipe.
2) while working due to general heat pipe, in pipe, produce larger pressure, and the size of pressure is closely related with temperature, and temperature one height will booster, in addition, also deposit at high temperature, in pipe, chemical reaction generation incoagulable gas occurs, tube wall is produced to corrosivity, easily cause general heat pipe to lose efficacy.And super heat-conductive pipe is owing to adopting Nanometer material, inorganic solid matter and liquid on a small quantity, intraductal pressure is little, thereby serviceability temperature scope is large, and booster phenomenon can not occur, and chemical reaction also can not occur in pipe, and generation incoagulable gas.
3) the heat conduction speed of the high metal of the conduction velocity of super heat-conductive pipe, nonmetallic materials itself depends on the thermal conductivity factor of material, and thermograde is orthogonal to the area of section of thermograde, and the highest with silver-colored thermal conductivity factor in metal, its value is in 415W/MK left and right.Through actual measurement, its axial heat flux density of super heat-conductive pipe is 8.4 × 106W/m
2, radial heat flows density is 4.3 × 104W/m
2, effective thermal conductivity is 3.2 × 106W/M.K, contrasts knownly, the heat-transfer rate of super heat-conductive pipe is thousands of times of silver heat-transfer rate.
4) long service life of super heat-conductive pipe is through the acceleration inefficacy measuring of carrier material (metal, nonmetal), about aging life-span 130,000 hours, the actual measurement of medium life-span is 110,000 hours, the compatibility of heat pipe medium and tube wall is good simultaneously, can make heat-transfer pipe steady operation under higher thermal load for a long time.
In a word, the heat transfer area that the present invention and super heat-conductive pipe have high thermal conductivity, good isothermal, cold and hot both sides can change arbitrarily, can remotely transferring, the series of advantages such as temperature controllable, and the heat exchanger being comprised of heat pipe has that heat transfer efficiency is high, compact conformation, fluid resistance damage the advantages such as little.