CN101010552A - Flat perforated pipe and heat exchanger - Google Patents

Abstract

A flat perforated pipe, comprising a flat outer pipe and a plurality of partition walls partitioning the inside of the outer pipe into a plurality of flow passages. The partition walls of the flat perforated pipe are formed in a cross sectional shape with a thickness of (ti) in a chevron form comprising two of a side with a length of (a), and disposed so that face-to-face distances between the partition walls on the inner surface of the outer pipe are (Li). The thickness (to) of the outer pipe meets the following requirement. By properly selecting a pressure to expand the flat perforated pipe, the outer surface of the pipe can be prevented from being deformed in a waveform shape or an irregular shape.

Description

Flat perforated pipe and heat exchanger

Technical field

The present invention relates to be used for the structure of the flat perforated pipe of heat exchanger.

Background technology

As the heat exchanger that is used for refrigerating plant or radiator etc., known have separate certain intervals and parellel arranged plate wing and run through the fin type heat exchanger of a plurality of pipes (pipe) of these fins configuration.A kind of method when making this fin type heat exchanger is, assemble pipe in the mode that runs through fin after, by pipe is carried out expander or expansion, thereby make pipe engage with fin.For these pipes are expanded, with the inside of rigid body rod or expander spare insertion pipe, from inboard pushing convergent divergent channel.By being expanded, pipe make pipe contact with fin.

In heat exchanger, be known that use has a plurality of next doors, will manage the inner flat perforated pipe that is partitioned into a plurality of parallel streams by these next doors in inside.

Open in the clear 62-19691 communique the spy and to disclose conduit with ellipse or rectangular cross section.This conduit utilizes the expansion pushing on the surface of the conduit between each butt joint to cool off the fin of usefulness.When conduit expanded, the chevron shape at the initial stage of joint flattened, and prevented that the wall of conduit from shrinking to its original position.

Summary of the invention

An embodiment of the invention are the flat perforated pipes that have flat outer tube and the inside of this outer tube is divided into a plurality of next doors of a plurality of streams.It is that ti, length on one side are the cross sectional shape that bends to chevron that two limits of a constitute that each next door has thickness, and being configured to becomes distance L i between the face in next door of outer tube inner face, and the thickness t o of outer tube satisfies the shown condition of following formula (1).

[formula 1]

$\sqrt{\frac{\mathrm{Li}\·\mathrm{ti}\·\sqrt{a^2-t{i}^2}}{3a}}\≤\mathrm{to}---\left(1\right)$

Have expander spare is inserted into the method for expanding in the stream of flat perforated pipe.In addition, studying inject fluid into flat perforated pipe (pipe) thus in to improve the method that interior pressure stretches the next door.For the method for the interior pressure that improves this pipe (following also have the occasion that is called the expander that pressurize), by the expansion that expander spare is implemented, the outer tube between next door and the next door (being outer wall later on) expands and makes that this situation of tube outside distortion becoming waveform or concaveconvex shape is not very desirable.The contact area of tube outside and fin reduces, and heat conductivility reduces.Yet, if next door stops to expand the performance that can not obtain to expect before being stretched over desired size.

When the phenomenon that stretch in the next door of considering to be bent to chevron (Japanese hiragana " く " font), by tensile force angle between the both sides that constitute chevron is opened (becoming big) at first and be out of shape from the effect of two ends, next door.And when angle that both sides were reached to a certain degree big or small, angle became big distortion (distortion of the tilt variation in next door) and just almost disappears, and the inclination in next door no longer changes the state of the full extension ().And then the tensile force owing to the two ends from the next door act on becomes the distortion (stretcher strain) of the reduced thickness in next door.The stress that makes next door stretcher strain and cause wall thickness reduction is different from the stress of the inclination that is used to change the next door, and stress one side of inclination who changes the next door is less.

For the flat perforated pipe of outer tube, in the pressure limit of the degree of the inclination that changes the next door, do not deform as the outer wall of the part between the next door of outer tube with the thickness that satisfies above-mentioned condition (1).Therefore, satisfy the distortion that can prevent outer wall before the flat perforated pipe next door full extension of above-mentioned condition (1).Thereby this flat perforated pipe can carry out expander to prevent the state that the tube outside is deformed into waveform or concaveconvex shape by the interior pressure of the scope of the inclination and distortion in next door.

The deflection of the inclination in next door is subjected to the influence of the tolerance of flat perforated pipe or plus-pressure inequality and change to some extent.Thereby, preferably utilize maximum pressure (interior pressure) or its above pressure in the inclination and distortion scope in next door to carry out expander.By carrying out expander, can carry out expander up to the inclination in the next door state opened of full extension roughly with such pressure.Therefore, when carrying out expander, do not carry out the state that careful pressure control just can be expanded to flat perforated pipe expectation.Otherwise,, then exist outer tube before the full extension of next door just to begin the possibility of being out of shape if the thickness t o of outer tube breaks away from the scope of condition (1), the thickness t o of outer tube diminishes.Therefore, the pressure during expander is difficult to control.

Another embodiment of the invention is to have a plurality of flat perforated pipes of satisfying above-mentioned condition (1) and the heat exchanger of a plurality of fins of installing with the state that runs through these a few flat perforated pipes.Such as mentioned above, if the flat perforated pipe of satisfy condition (1) utilizes the pressurization expander of fluid, the expander by expander spare carries out stretches the next door while can both suppress the distortion of outer wall.Thereby behind expander, the contacting efficiency of a plurality of flat perforated pipes and the plate wing installed with the state that is penetrated with them is improved.Therefore, can improve the heat exchanger effectiveness of heat exchanger.Especially,, can not insert expander spare, be suitable for roughly expanding equably all trickle streams of flat perforated pipe if utilize the pressurization expander of fluid.

Another embodiment of the present invention is such flat perforated pipe, that is, on the basis of above-mentioned condition (1), the thickness t o of outer tube also satisfies following condition (2).

[formula 2]

$2\sqrt{\frac{\mathrm{Li}\·\mathrm{ti}\·\sqrt{a^2-t{i}^2}}{3a}}\≥\mathrm{to}---\left(2\right)$

The method of establishing greatly the thickness of the desired outer tube of flat tube that does not possess the next door as the thickness of the outer tube of the flat perforated pipe that will possess a plurality of next doors considers not to be very economical from aspects such as the miniaturization of product and lightweights.Use an advantage of flat perforated pipe to be, can guarantee the intensity of flat tube by the next door being set, so can make outer wall or outer tube thin-walled property in inside.

Another embodiment of the invention is such flat perforated pipe, that is, on the basis of above-mentioned condition (1), the thickness t o of outer tube also satisfies following condition (3).

[formula 3]

$\sqrt{\frac{\mathrm{Li}\·\mathrm{ti}}{2}}\≥\mathrm{to}---\left(3\right)$

The above pressure of pressure is not the wirking pressure of flat perforated pipe during expander.When applying such pressure often, there is the further possibility of distortion of flat perforated pipe, such design is impracticable.Therefore, the pressure during expander need reach the upper limit of withstand voltage condition commonly used or more than it.In addition, the pressure during expander for reach the next door full extension by it the degree of state, the such pressure of stretcher strain that begins to be attended by wall thickness reduction is not set.Thereby, only the thickness of outer tube to be set and made that outer wall also is out of shape under the such pressure effect of the stretcher strain that begins to follow wall thickness reduction, this is both economical, heat transfer efficiency also improved when outer tube was thin.

In addition, if the flat perforated pipe of satisfy condition (3) in the occasion of pressurization expander, when applying when making such excessive interior pressures of next door stretcher strain, exists outer wall also to expand and possibility that the tube outside is out of shape.Therefore, the state of tube outside just can become a key factor of the pressure state when checking expander.

Description of drawings

Fig. 1 has schematically shown heat exchanger.

Fig. 2 shows the flat perforated pipe of heat exchanger shown in Figure 1 and the state that fin is bonded together.

Fig. 3 (a) represents the state of the flat perforated pipe before the expander with the cross section of long axis direction, and Fig. 3 (b) represents with the cross section of its short-axis direction.

Fig. 4 (a) represents the state of the flat perforated pipe behind the expander with the cross section of long axis direction, and Fig. 4 (b) represents the end of this flat perforated pipe with the cross section of short-axis direction, and Fig. 4 (c) represents other parts of this flat perforated pipe with the cross section of short-axis direction.

The sample attitude of angular distortion takes place in Fig. 5 (a) expression next door, and the sample attitude of stretcher strain takes place in Fig. 5 (b) expression next door.

Fig. 6 amplifies the cross section of expression flat perforated pipe.

Fig. 7 has represented to increase the variation of the internal diameter of the flat perforated pipe after the interior pressure.

Fig. 8 shows because tolerance etc. cause the expander volume production of flat perforated pipe to give birth to the sample attitude of deviation.

Fig. 9 shows the upper limit of thickness of outer tube of flat perforated pipe and an example of lower limit.

The specific embodiment

Fig. 1 shows the overview of the heat exchanger that has adopted flat perforated pipe.In addition, Fig. 2 amplifies the state of flat perforated pipe after by expander that show by stereogram.Heat exchanger 1 is the fin type heat exchanger, has: parellel arranged at regular intervals a plurality of tabular fins 2 and be engaged, be the many flat perforated pipes 3 of form arranged side by side with the state that runs through these fins 2.These flat perforated pipes 3 are the pipes that the inside of flat outer tube 21 are divided into a plurality of parallel streams 14 by a plurality of next doors 15.The end 4 of flat perforated pipe 3 both sides is connected with conjugate foramen 19 on the sidewall 9 that is formed on the head 6 that is positioned at heat exchanger about 1 and 7.The thermal medium (internal flow) of 6 supply port 11 importings is directed to the delivery outlet 12 of head 7 through the stream 14 of flat perforated pipe 3 from the head.In heat exchanger 1, when external fluid such as air were passed through, external fluid B contacted with flat perforated pipe 3 and fin 2, carries out heat exchange between thermal medium and external fluid, and thermal medium and/or external fluid are cooled or heat.

Fig. 3 (a) shows flat perforated pipe 3 by the state before the expander.When making heat exchanger 1, flat perforated pipe 3 is inserted into is located at the dashing in the marginal pore 18 of fin 2 in advance, assemble fin 2 and flat perforated pipe 3 temporarily.

Fig. 3 (b) amplifies the cross section that shows flat perforated pipe 3.The outer tube 21 of flat perforated pipe 3 possesses the right outer wall 21w in top and bottom.Flat perforated pipe 3 is to be shaped to the outer wall 21w of the upper wall that constitutes outer tube 21 or roof and the flat pipe of the outer wall 21w almost parallel that constitutes lower wall or diapire.This flat perforated pipe 3 portion within it possesses a plurality of next doors 15, and next door 15 connects outer wall 21w up and down, and their cross sectional shape is chevron, the long axis direction X bending in the cross section of flat perforated pipe 3.The inside of flat perforated pipe 3 is cut apart by these next doors 15, forms a plurality of parallel streams 14.

The end 4 of the flat perforated pipe of temporarily being assembled in the mode that runs through fin 23 is inserted in the conjugate foramen 19 of being located at head 6 and 7.These ends 4 engage with head 6 and 7 by soldering or other proper methods.The parallel stream 14 of each flat perforated pipe 3 forms the pipe inner looping that heating medium flows via head 6 and 7 and be communicated with.

Fig. 4 (a), Fig. 4 (b) and Fig. 4 (c) show the state of the flat perforated pipe 3 of pressurization behind the expander with the cross section.In addition, Fig. 5 (a) and Fig. 5 (b) show the sample attitude that the next door 15 of flat perforated pipe 3 is stretched.Can compressed fluid be supplied in the flat perforated pipe 3 via head 6 and 7.Can improve the interior pressure of parallel stream 14 by compressed fluid, can carry out expander (pressurization expander) flat perforated pipe 3.Such shown in Fig. 4 (a), by carrying out expander, flat perforated pipe 3 and each fin 2 fluid-tight engagement.In heat exchanger 1, in advance head 6 and 7 is engaged with the end 4 of flat perforated pipe 3.Thereby like that, in the end 4, does not stretch in crooked next door 15 shown in Fig. 4 (b).Comprising other part of the part that runs through fin 2, like that, crooked next door 15 is stretched shown in Fig. 4 (c).

The next door 15 of heat exchanger 1 employed flat perforated pipe 3 possesses thickness t i, possesses length a one side be in the both sides of chevron.(between face) is distance L i between the next door 15 in the inner face of the outer wall 21w of outer tube 21.In addition, the thickness t o of outer tube 21 satisfies the condition of following formula (1).

[formula 1]

$\sqrt{\frac{\mathrm{Li}\·\mathrm{ti}\·\sqrt{a^2-t{i}^2}}{3a}}\≤\mathrm{to}---\left(1\right)$

About possessing on one side length is that the both sides 27 of a are angle 2 θ, the flat perforated pipe 3 in next door 15 that bends to the cross sectional shape of chevron carries out expander, and this situation is studied.Shown in Fig. 5 (a) like that, when in improving, pressing, the power of the wall 21w by acting on outer tube 21, the next door 15 that bends to chevron is stretched at above-below direction, the tilt angle theta that is deformed into the limit 27 of a side is spent near 90.This distortion is called distortion or the angular distortion that the inclination in next door changes.This angular distortion is considered to: the angle (foundation) of the part that next door 15 is connected with the wall 21w of outer tube 21 26 and form the full extension sample attitude of state that summit 25 that two limits 27 of chevron intersect becomes the thickness t i in the next door 15 of roughly having setovered, end then.This state is shown in Figure 6.

Like that, distortion afterwards is considered to the distortion (stretcher strain) that is caused by stretching of the wall thickness reduction in next door 15 shown in Fig. 5 (b).Therefore, because the interior pressure of being implemented, the mechanical performance of the distortion in next door 15 changes to some extent.Thereby, think:,, can both carry out stable distortion up to making next door 15 greatly to the states of full extension by applying the pressure that finishes the scope that begins to stretcher strain from angular distortion.

Fig. 7 shows the result that reality is tested the relation of the height of the inboard of pipe (internal diameter of short-axis direction Y or inside dimension) Hi and interior pressure (moulding pressure).This solid line A1 illustrated in fig. 7 is the measured value of the thickness of slab ti with next door 15 when being set at 0.19mm, and chain-dotted line A2 calculates the value that tangent (tan) gets according to the measured value of the angle of bend θ in next door 15.As by solid line A1 as can be known, if the thickness t i in next door 15 is 0.19mm, when interior pressure surpassed roughly 2MPa, pipe height H i sharply increased, angular distortions take place in next door 15.In the time of near interior pressure is in 7.2MPa, the deflection in next door 15 begins to diminish, and when interior pressure was the 7.5MPa left and right sides, next door 15 was out of shape hardly.Think: by applying the pressure about 7.5MPa, next door 15 becomes the state of full extension, does not also deform even apply its above pressure next door 15, and the angular distortion in next door 15 finishes.

To comparing by the calculated value shown in the chain-dotted line A2 with by the measured value shown in the solid line A1 among Fig. 7, as shown in FIG., on the point of " tan θ=Hi/ (2ti) ", the angular distortion of pipe finishes basically.Thus, such as mentioned above, infer: the summit 25 of next door 15 is positioned at when foundation part 26 has been offset the position of thickness t i in next door 15, next door 15 become full extension state, angular distortion finishes.When judging according to measured value A1, it is to be occasion about 7-8MPa in interior pressure that angular distortion finishes.Therefore, if the pressure can be with expander the time is set at about 7-8MPa or more than it, then can make next door 15 become the state that full extension is opened.

As shown in Figure 8, there is tolerance in the thickness t i in next door 15 etc.Because this tolerance makes deflection (height of pipe) Hi internally press the relation of P to change to some extent mutually.When the desired value of the height H i when with expander is set the such unclosed position of angular distortion of in the drawings H2, must internally press P to control according to each pipe, so that height H i becomes desired value H2.Such expander operation is not a very economical, and because the dimensional accuracy behind the expander reduces, institute is so that the productivity ratio of the heat exchanger of employing flat perforated pipe also reduces.To this, when the desired value of the height H i when with expander was set the position that the such angular distortion of H3 in the drawings is through with, the interior pressure in the time of can be with expander was set at the value of the pressure that the such angular distortion of P3 finishes among the figure or the value more than it.Thereby, can be irrelevant with the tolerance of each pipe, by carrying out expander, can arrive identical height H i by expander with identical pressure.Therefore, because the dimensional accuracy of the pipe 3 behind the expander is stable, so adopt the productivity ratio and the quality of the heat exchanger 1 of flat perforated pipe 3 to be improved.

Like this, in flat perforated pipe 3,, can realize stable expander by carrying out the expander state that 15 full extension are opened up to the next door, being desired value H3 shown in Figure 8.Carrying out the required pressure of such expander is pressure P 3 shown in Figure 8, this pressure P 3 times, sets the thickness t o of the outer wall section 21w of outer tube 21, makes almost to can't see distortion in the tube outside.

Next door 15 take place the required power (interior pressure) of angular distortions can be according to next door shown in Figure 6 15 during for the state of full extension applied force calculate.When pressing in applying this, the outer wall 21w of outer tube 21 is not deformed becomes a condition.In Fig. 6, the length on the one side 27 in next door 15 is made as a, its inclination (inclination angle) is made as θ, the interplanar distance in the next door 15 in the inner face of the outer wall section 21w of outer tube 21 is made as Li from (face in opposite directions in the next door 15 and distance between the face), the height (internal diameter or the inside dimension of the short-axis direction X of outer tube 21) of flat perforated pipe (pipe) 3 is made as Hi, the stress σ o that is created in outer wall section 21w when pressing P at this moment, effect has becomes following such.At first, because outer wall 21w can specialize as the beam with both ends built-in that waits distribution load of accepting pressure P between next door apart from Li, so maximum bending moment Mmax and section factor Z become formula (4) and (5) respectively.Therefore, the maximum stress σ o that is applied on the outer wall 21w becomes formula (6).

[formula 4]

$M\max =\frac{P\·L{i}^2}{12}---\left(4\right)$

[formula 5]

$Z=\frac{t{o}^2}{6}---\left(5\right)$

[formula 6]

$\mathrm{\σo}=\frac{M\max }{Z}=\frac{P\·L{i}^2}{12}\×\frac{6}{t{o}^2}=\frac{P\·L{i}^2}{2t{o}^2}---\left(6\right)$

Next door 15 is created within the power up-down stretch of foundation 26.Foundation 26 is because of interior pressure P holding capacity (load) W (W=plus-pressure P * pressure-bearing surface length L i).Think: next door 15 produces bending moments and deforms in foundation 26 and the central apex portion 25 that connects two limits 27.At this moment, next door 15 can be specialized as bear beam with both ends built-in point-load W ', physical length 2a and height t i in central authorities 25.Because the point-load W ' that puts on next door 15 becomes minimum when certain and tan θ is maximum at power W, so under point-load W ' carries out the condition of angular distortion during for minimum of a value, calculate.Become maximum occasion at tan θ, the full extension that finishes for the angular distortion in next door 15 state, cant angle theta can be represented by formula (7).Therefore, point-load W ' tries to achieve as formula (8).

[formula 7]

$\tan \mathrm{\θ}=\frac{\mathrm{Hi}/2}{\mathrm{ti}}=\frac{\mathrm{Hi}}{2\mathrm{ti}}---\left(7\right)$

[formula 8]

$W^{\′}=\frac{W}{\tan \mathrm{\θ}}=\frac{P\·\mathrm{Li}}{\frac{\mathrm{Hi}}{2\mathrm{ti}}}=\frac{2\mathrm{ti}\·P\·\mathrm{Li}}{\mathrm{Hi}}---\left(8\right)$

It is such that maximum bending moment when angular distortion takes place in next door 15 becomes formula (9).By using the section factor Z of formula (10), the maximum stress σ i that is created in the next door 15 becomes formula (11) like that.In addition, specialize, ask calculation stress by the one dimension mode for cross sectional shape based on flat perforated pipe.

[formula 9]

$M\max =\frac{W^{\&prime;}\&CenterDot;2\mathrm{<figure-callout\; id="8"\; label="a"\; filenames="A20058002911900211.png"\; state="\{\{state\}\}">a</figure-callout>}}{8}=\frac{2\mathrm{ti}\&CenterDot;P\&CenterDot;\mathrm{Li}\&CenterDot;2\sqrt{{(\mathrm{Hi}/2)}^2+t{i}^2}}{8\mathrm{Hi}}=\frac{\mathrm{ti}\&CenterDot;P\&CenterDot;\mathrm{Li}\sqrt{{(\mathrm{Hi}/2)}^2+t{i}^2}}{2\mathrm{Hi}}---\left(9\right)$

[formula 10]

$Z=\frac{\mathrm{<figure-callout\; id="2"\; label="t\; i"\; filenames="A20058002911900161.png,A20058002911900171.png"\; state="\{\{state\}\}">t</figure-callout>}{i}^{}{}^2}{6}---\left(10\right)$

[formula 11]

$\mathrm{\&sigma;i}=\frac{M\max }{Z}=\frac{\mathrm{ti}\&CenterDot;P\&CenterDot;\mathrm{Li}\sqrt{{(\mathrm{Hi}/2)}^2+\mathrm{<figure-callout\; id="2"\; label="t\; i"\; filenames="A20058002911900161.png,A20058002911900171.png"\; state="\{\{state\}\}">t</figure-callout>}{i}^{}{}^2}}{2\mathrm{Hi}}\&times;\frac{6}{\mathrm{<figure-callout\; id="2"\; label="t\; i"\; filenames="A20058002911900161.png,A20058002911900171.png"\; state="\{\{state\}\}">t</figure-callout>}{i}^{}{}^2}=\frac{3P\&CenterDot;\mathrm{Li}\sqrt{{(\mathrm{Hi}/2)}^2+\mathrm{<figure-callout\; id="2"\; label="t\; i"\; filenames="A20058002911900161.png,A20058002911900171.png"\; state="\{\{state\}\}">t</figure-callout>}{i}^{}{}^2}}{\mathrm{Hi}\&CenterDot;\mathrm{ti}}---\left(11\right)$

In order to carry out expander, as long as do not make outer wall 21w distortion in the pressure limit of next door 15 generation angular distortions according to above-mentioned condition.Therefore, when the minimum pressure Pmin that expander is used is applied on the flat perforated pipe 3, maximum stress σ i when the material that constitutes outer wall 21w and next door 15 for example comprises limit stress σ lim, next door 15 angular distortions of the metal material of aluminium or copper etc. and being applied between the maximum stress σ o on the outer wall 21w, as long as formula (12) is set up.

[formula 12]

σo?≤σlim≤σi…(12)

According to formula (12), can derive above-mentioned condition (1).In addition, the length a on the one side 27 in next door 15 is such shown in following formula (13).

[formula 13]

$a=\sqrt{{(\mathrm{Hi}/2)}^2+t{i}^2}---\left(13\right)$

An advantage of flat perforated pipe is, owing to can guarantee the intensity of flat tube by being arranged on inner next door, so can attenuate outer wall 21w, be outer tube 21.At this, be considered as the two holes pipe that possesses two streams 14 of the least unit of flat perforated pipe.The maximum stress σ o that is created among the outer wall 21w when pressing P in applying becomes formula as described above (6).Manage identical flat tube with two holes, be that distance is the flat tube of Hi for 2Li and tube interior size (highly) between the next door for area of section in the pipe,, the thickness t o of outer wall 21w need be set as two times in order to obtain and the same intensity of two holes pipe.Therefore, when the thickness of outer wall 21w surpasses two times of the minimum of a value of being tried to achieve by formula (1), this advantage of flat perforated pipe will disappear.Therefore, the thickness t o that it is desirable for outer wall 21w satisfy condition (2).

[formula 2]

$2\sqrt{\frac{\mathrm{Li}\&CenterDot;\mathrm{ti}\&CenterDot;\sqrt{a^2-\mathrm{<figure-callout\; id="2"\; label="t\; i"\; filenames="A20058002911900161.png,A20058002911900171.png"\; state="\{\{state\}\}">t</figure-callout>}{i}^{}{}^2}}{3a}}\&GreaterEqual;\mathrm{to}---\left(2\right)$

On the other hand, in Fig. 8, when further raising pressure P, stretcher strains take place in next door 15, on one side next door 15 on one side attenuates continue to be stretched.At this moment, want to judge that the time of next door 15 fractures is not to be easy to.Thereby, do not wish to use to begin to take place the such pressure P of stretcher strain and carry out expander.In addition, the pressure during expander is the withstand voltage upper limit of flat perforated pipe or more than it, with respect to beginning the such pressure P of stretcher strain takes place, and the outer wall 21w that the does not require outer tube 21 ground pressure-bearing that do not deform.And from the viewpoint of economy and heat exchanger effectiveness, the thickness t o of preferred outer tube 21 is thinner.Therefore, the thickness t o of outer tube 21 also can be the value that deforms under the such pressure effect of next door 15 stretcher strains making.And, if outer wall 21w deforms when making next door 15 that the such pressure P of stretcher strains take place having applied, then applied excessive pressure from can recognizing in appearance of flat perforated pipe 3, so, can be used as and be used to confirm flat perforated pipe 3 and use its one of quality of heat exchanger 1 to judge that key element is used.

When stretcher strain took place next door 15, the tensile stress σ s that acts on next door 15 became formula (14) like that.

[formula 14]

$\mathrm{\&sigma;s}=\frac{P\&CenterDot;\mathrm{Li}}{\mathrm{ti}}---\left(14\right)$

Outer wall 21w can be out of shape before considering next door 15 generation stretcher strains.Therefore, when the maximum pressure Pmax that expander is used was applied on the flat perforated pipe 3, formula (15) can be set up at the limit stress σ lim of the material of flat perforated pipe 3, stress σ s and being applied between the maximum stress σ o on outer wall 21w when stretcher strains take place in next door 15.

[formula 15]

σs≤σlim≤σo…(15)

Can wish that the thickness t o of outer wall 21w satisfies this condition according to this formula (15) derivation condition (3).

[formula 3]

$\sqrt{\frac{\mathrm{Li}\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="ti"\; filenames="A20058002911900161.png,A20058002911900171.png"\; state="\{\{state\}\}">ti</figure-callout>}}{2}}\&GreaterEqual;\mathrm{to}---\left(3\right)$

The desired value of the inside dimension Hi of Fig. 9 when showing expander apart from Li and next door thickness of slab ti between the next door is the thickness t o of outer wall 21w of the flat perforated pipe 3 of 1.5mm.Face Cu shown in Figure 9 represents the upper limit according to the thickness t o of condition (3), and face Cl represents the lower limit according to the thickness t o of condition (1).If possess the flat perforated pipe 3 of outer tube 21 of the thickness t o of this scope, then can set the pressure P that is suitable for expander 3 shown in Fig. 8, can carry out expander with productivity ratio preferably.In addition, outer wall 21w deforms in the time of can preventing expander, can by the stable flat perforated pipe 3 of outer shape be manufactured on good productivity ratio and fin 2 between possess heat exchanger 1 sufficient contact area, that heat exchanger effectiveness is high.Be suitable in the angular distortion scope that does not cause next door 15 generation stretcher strains, inside dimension Hi expander being reached the occurrence of the pressure P 3 of desired destination value, can set based on the limit stress σ lim of the material that constitutes flat perforated pipe 3.If with reference to formula (12) and formula (15), the preferred as can be known pressure P 3 that the setting expander is used in following scope.

[formula 16]

$\frac{2\&CenterDot;\sqrt{a^2-\mathrm{<figure-callout\; id="2"\; label="t\; i"\; filenames="A20058002911900161.png,A20058002911900171.png"\; state="\{\{state\}\}">t</figure-callout>}{i}^{}{}^2}}{3\mathrm{Li}\&CenterDot;a}\mathrm{\&sigma;lim}\&le;\mathrm{<figure-callout\; id="3"\; label="P"\; filenames="A20058002911900161.png,A20058002911900171.png"\; state="\{\{state\}\}">P</figure-callout>}3\&le;\frac{\mathrm{ti}}{\mathrm{Li}}\mathrm{\&sigma;lim}---\left(16\right)$

In addition, in the above description, though understand the process of making the heat exchanger 1 that possesses tabular fin 2, the shape of fin is not limited to tabular, also can be corrugated fin in wave shape.In the heat exchanger that uses corrugated fin, only expand the part that is installed in head within the flat perforated pipe and get final product, and need not basically the part that is connected with fin is expanded.Yet, after having engaged fin, can carry out expander to flat perforated pipe and increase contact area.When in the pipe of flat perforated pipe, being divided into trickle stream by a plurality of next doors, because the area of section of each stream is less, so, by fluid is injected flat perforated pipe and improve in press the next door that stretches method more more suitable than inserting the method that expander spare expands.Satisfy the flat perforated pipe of above-mentioned condition (1) by employing, the method (occasion that is called the expander that pressurizes is also arranged) of pressing in improving might as well, might as well by the expansion that expander spare carries out, next door is stretched over before the size of hope, can prevent: because the interior pressure that fluid or expander spare produced makes the outer wall of outer tube be out of shape, the state that outside distortion the becoming fluctuation of outer wall rises and falls.That is, when opening flat perforated pipe by interior companding,, become desired size on one side, can both be controlled the profile of pipe up to flat perforated pipe on one side the next door is stretched in the distortion of killer tube outer wall by pressurization expander etc.By preventing to manage the shape of the non-expectation of outer wall distortion becoming, can between tube outside and fin, guarantee sufficient contact area can improve heat conductivility.Therefore, can provide heat exchanger effectiveness height and reliability high heat exchanger.

Claims (4)

1. flat perforated pipe has:

Flat outer tube and

The inside of this outer tube is divided into a plurality of next doors of a plurality of streams;

It is that ti, length on one side are the cross sectional shape that bends to chevron that two limits of a constitute that each next door has thickness, and is configured to become distance L i between the face in the next door in the inner face of described outer tube, and the thickness t o of described outer tube meets the following conditions,

[formula 1]

$\sqrt{\frac{\mathrm{Li}\&CenterDot;\mathrm{ti}\&CenterDot;\sqrt{a^2-{\mathrm{ti}}^2}}{3a}}\&le;\mathrm{to}.$

2. flat perforated pipe as claimed in claim 1 is characterized in that the thickness t o of described outer tube also meets the following conditions,

[formula 2]

$2\sqrt{\frac{\mathrm{Li}\&CenterDot;\mathrm{ti}\&CenterDot;\sqrt{a^2-{\mathrm{ti}}^2}}{3a}}\&GreaterEqual;\mathrm{to}.$

3. flat perforated pipe as claimed in claim 1 is characterized in that the thickness t o of described outer tube also meets the following conditions,

[formula 3]

$\sqrt{\frac{\mathrm{Li}\&CenterDot;\mathrm{ti}}{2}}\&GreaterEqual;\mathrm{to}.$

4. heat exchanger has: a plurality of flat perforated pipes as claimed in claim 1 and

The a plurality of fins that are mounted by the state that is penetrated with described a plurality of flat perforated pipes.

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