EP2815197A2

EP2815197A2 - Pipe forming part of a heat exchanger and heat exchanger comprising such a pipe

Info

Publication number: EP2815197A2
Application number: EP13724363.0A
Authority: EP
Inventors: Mounir AMOKRANE; Pascal LAVIEILLE; Laetitia LEAL; Marc Miscevic; Bertrand Nogarede; Francois PIGACHE; Lounes TADRIST; Frederic TOPIN
Original assignee: Aix Marseille Universite
Current assignee: Aix Marseille Universite; Centre National de la Recherche Scientifique CNRS; Institut National Polytechnique de Toulouse INPT; Universite de Toulouse
Priority date: 2012-02-17
Filing date: 2013-02-14
Publication date: 2014-12-24
Anticipated expiration: 2033-02-14
Also published as: FR2987107A1; EP2815197B1; MY184061A; CN104220832B; WO2013121297A2; FR2987107B1; WO2013121297A3; CA2863885C; KR102185766B1; US20150362261A1; CA2863885A1; CN104220832A; KR20150033597A

Abstract

The subject matter of the invention is a pipe (2) forming part of a heat exchanger. The pipe (2) is delimited by at least one wall (4, 7) for separating a fluid (3) circulating in the pipe (2) and an external medium (6). The wall (4, 7) is equipped with means (8) of deforming the wall (4, 7). These arrangements are such that at least one of the walls (4, 7) of the pipe (2) is actively deformed, in a precise and controlled manner, by the deformation means (8) in order to precisely conform and configure said, wall (4, 7), the use of the deformation means (8) being in particular placed under the influence of control means in relationship with the deformation means (8).

Description

PIPE FORMING PART OF A HEAT EXCHANGER AND HEAT EXCHANGER

COMPRISING SUCH A PIPE

The invention relates to the field of constituent parts or arrangements of a heat transfer device, such as a heat, exchanger. Its subject matter is a pipe forming part of a heat exchanger. Another subject matter is a heat exchanger comprising at least one such pipe. Finally, it has as its subject matter a heat exchange loop comprising at least one heat exchanger.

The patent document FR 2,611,034 (Jean Buffet and ESAC) describes a heat exchanger affording heat transfer between a first fluid circulating inside a heat exchanger and a second fluid in which the heat exchanger is immersed. The heat exchanger comprises a pipe that channels the circulation of the first fluid. The pipe consists of two opposite walls that are fixed to each other at their respective ends. A first wall is thin and deformable under the effect of a first pressure of the first fluid circulating inside the pipe and/or a second pressure of the second fluid. In other words, the first wall deforms passively under the effect of a change in a difference between the first pressure and the second pressure. The result of this is that the first wall has a conformation determined passively by a change in said pressure difference. Moreover, the first wall constitutes a heat exchange surface through which the heat transfer takes place between the first fluid and the second fluid. The deformability of the first wall aims to increase said heat exchange surface between the first fluid and the second fluid, which are respectively situated on either side of the first wall. Thus a geometric configuration of the first wall is determined by, and passively subject to, the difference in pressure between the first pressure and the second pressure.

Such a pipe merits being improved in order to optimise said heat transfer, without for all that increasing the weight and size of the pipe and consequently of the heat exchanger. Moreover, the pipe and heat exchanger merit being improved in order to facilitate a flow of the first fluid inside the pipe and consequently inside the heat exchanger, in order in particular to optimise the general size and overall weight of a heat exchange loop on which such a heat exchanger is installed. Finally, in a context of greater and greater and more and more necessary miniaturisation of heat exchangers and/or heat exchange loops, such a pipe proves to be fragile, of low reliability and nevertheless complex and has appreciable disadvantages such as an increase in cost of raw materials necessary for manufacturing the heat exchanger, but also an increase in pressure drops caused by a flow of the first fluid and therefore mechanical power necessary for causing the first fluid to flow, such as a powerful and bulky pump. Such a pump is liable to be the cause of a plurality of problems including in particular an increase in pressure drops caused by a loop distance between the pump and the heat exchanger that is great, an uneven distribution of respective flows of first fluid inside the various pipes included in the heat exchanger and a complexity of the heat exchange loop associated with high costs of maintenance and raw material.

One aim of the present invention is to propose a pipe forming part of a heat exchanger that responds to the aforementioned drawbacks, in particular that is optimised to facilitate a transfer of a heat flow between a fluid circulating inside the pipe and an external medium, the pipe and the heat exchanger being as light as possible and as compact as possible, while facilitating and controlling a flow of fluid inside the pipe and heat exchanger in order in particular to optimise an overall size and total weight of a heat exchange loop on which such a heat exchanger is installed. Another aim of the present invention is to propose a heat exchanger that is effective and compact and meets various requirements in relation to flow of the first fluid while effectively ensuring said transfer of the heat flow. Another aim of the present invention is to propose a heat exchange loop that is particularly compact, while being effective, such a heat exchange loop being subject to minimised maintenance operations through a structural simplification of elements forming part of the heat exchange loop.

The first aspect of the invention concerns a pipe forming part of a heat exchanger, the pipe being delimited by at least a first separation wall for a fluid circulating inside the pipe and an external medium, a heat flow transfer occurring between said fluid and said external medium through said first wall, characterised in that said pipe is also delimited by a second wall not participating in the heat flow transfer between said fluid and said external medium, said second wall being equipped with means of deforming the wall.

Advantageously, - the first wall is not equipped with means of deforming the wall; - the first wall is also equipped with means of deforming the wall; the deformation means constitute a means of causing fluid to circulate inside the pipe; - the deformation means constitute a means of controlling the circulation of the fluid inside the pipe; - the deformation means constitute a means of intensification of the heat flow transfer; - the deformation means constitute a means of controlling the heat flow transfer; - the deformation means constitute a means of decoupling a control of the fluid flow and the heat flow transfer; - the deformation means constitute a means of reversing a direction of flow of the fluid inside the pipe; - the deformation means constitute a means of disturbing limit layers of the fluid inside the pipe; - the deformation means comprise at least one actuator that may be electromagnetic, pneumatic, hydraulic or piezoelectric; and/or - the actuator is able to apply a deformation wave to the wall, the deformation wave being progressive or standing in nature.

A second aspect concerns a heat exchanger comprising a pipe as defined above.

Advantageously, the heat exchanger comprises a plurality of pipes that are disposed parallel to one another in a general extension plane of the heat exchanger .

Finally, a third aspect concerns a heat exchange loop inside which a fluid circulates, the heat exchange loop comprising a means of setting the fluid in movement, characterised in that the means of setting the fluid in movement comprises a heat exchanger as defined above.

These arrangements are such that at least one of the walls of the pipe is actively deformed, in a precise and controlled manner, by the deformation means in order to precisely conform and configure said wall, the use of the deformation means being in particular placed under the influence of control means in relationship with the deformation means.

Other features and advantages of the present invention will emerge from a reading of the description that will be made of example embodiments, in relation to the figures in the accompanying drawings, in which:

Figure 1 is a schematic plan view of a heat exchanger according to a first embodiment of the present invention .

Figure 2 is a schematic view from below of the heat exchanger shown in figure 1.

Figure 3 is a schematic side view of the heat exchanger shown in the previous figures.

Figure 4 is a schematic front view of the heat exchanger shown in the previous figures.

Figure 5 is a schematic view in transverse section of a first variant embodiment of a pipe forming part of the heat exchanger shown in the previous figures.

Figure 6 is a schematic view in transverse section of a second variant embodiment of the pipe forming part of the heat exchanger shown in figures 1 to 4.

Figure 7 is a schematic view in perspective of a heat exchanger according to a third embodiment of the present invention.

Figure 8 is a schematic view of a longitudinal section of the pipe illustrated in figure 5.

Figure 9 is a schematic view of a deformation wave produced by deformation means equipping the pipe shown in figures 5 to 8. Figure 10 is a schematic view of a heat exchange loop comprising a heat exchanger shown in figures 1 to 4 or in figure 7.

Figure 11 is a curve illustrating a thermal coefficient gain as a function of a relative amplitude from the use of a heat exchanger shown in figures 1 to 4 or in figure 7.

Figure 12 is a curve illustrating a mass flow as a function of a relative amplitude from the use of a heat exchanger shown in figures 1 to 4 or in figure 7.

Figure 13 is a curve illustrating a thermal coefficient gain as a function of a mass flow from the use of a heat exchanger shown in figures -1 to 4 or in figure 7.

Figures 14 and 15 are plan views of variant embodiments of the pipe respectively illustrated in figure 5 and figure 6.

Figure 16 is a schematic view in perspective of a heat exchanger according to a third embodiment of the present invention.

Figures 17 and 18 are schematic views of successive steps of use of the pipe shown in figure 5 according to a particular operating mode of the deformation means.

In figures 1 to 5, a first embodiment of a heat exchanger 1 of the present invention is shown in which the heat exchanger 1 comprises a plurality of pipes 2 that are intended to channel a circulation of a fluid 3. Each pipe 2 has any conformation, in particular a tubular conformation, and comprises a transverse section S visible in figure 4, which is for example polygonal, in particular square or rectangular. The pipes 2 are preferentially contiguous with one another while being disposed in a general extension plane P of the heat exchanger 1. By way of non-limitative example, the pipe 2 is able to have a thickness E of between 0.2 mm and 4 mm, a length Ll of around 30 mm to within 10% and a length L2 of around 100 mm to within 10%. The pipe 2 is preferentially longitudinally extended along a symmetry axis Al that is substantially orthogonal to the transverse section S of the pipe 2. The pipe 2 comprises at least one first wall 4 that forms a heat exchange surface 5 between the fluid 3 and an external medium 6 in which the pipe 2 is at least partially immersed, and more particularly the first wall 4. The first wall 4 is a wall through which a transfer of a heat flow φ occurs between the fluid 3 and the external medium 6. The first wall 4 is a rigid wall, non-deformable under the action of a pressure of the first fluid. The first wall 4 is for example produced from a material that is a good heat conductor, such as a metal material or the like, and which in addition confers on the pipe 2 a satisfactory mechanical strength. The first wall 4 constitutes a separation between the fluid 3, which is either liquid or gaseous, and the external medium 6, which is either a solid medium, a liquid fluid or a gaseous fluid. According to various variant embodiments, the flow of heat φ between the fluid 3 and the external medium 6 is a positive heat flow in which the fluid 3 yields calories to the external medium 6, or conversely a negative heat flow in which the external medium 6 yields calories to the fluid 3. By way of non-limitative examples, and to illustrate a few applications of the present invention, the external medium 6 is in particular a solid medium comprising electronic components dissipating heat that the fluid 3 is able to discharge, such an application being for example encountered in the railway, aeronautical, automobile or space fields, in the field of chemistry and biochemistry in general, and chemical or biochemical reactors in particular, as well as stationary fields, such as dwellings, and heat exchange methods in general, as well as air conditioning in particular. Such applications are liable to cover varied fields in which the use of electronic or microelectronic components produces heat that is necessary to discharge or various components that it is necessary to heat. The external medium 6 is for example also formed by a gaseous fluid set in motion by a fan, or even a liquid fluid set in motion by a pump, to discharge heat, or cold, yielded by the fluid 3 to the external medium 6. In this case, the heat exchanger 1 of the present invention is a heat exchanger in particular forming an air-conditioning loop, or any type of heat exchange system between two circulating fluids. The fluid 3 preferentially consists of a heat-transfer fluid, such as glycol, carbon dioxide or any other similar heat-transfer fluid. The fluid constituting the external medium 6 is either a heat- transfer fluid of the fluid type 3, or even a flow of air in the case where the heat exchanger 1 is a radiator or an evaporator respectively intended to heat or cool the air flow.

According to the present invention, the pipe 2 is equipped with a second wall 7. This second wall 7 is a wall of the pipe 2 which faces the first wall 4. The second wall 7 is positioned in the pipe 2, opposite to the first wall 4. The second wall 7 does not contact the external medium 6. It does not participate in the transfer of the heat flow φ between the fluid 3 and the external medium 6. The second wall 7 is provided with deformation means 8. It is also possible to provide the first wall 4 with such deformation means 8. In other words, the deformation means 8 equip either the second wall 7, as illustrated in figure 5, or the first wall 4 and the second wall 7 as illustrated in figure 6. These arrangements are such that either the second wall 7 or the first wall 4 and the second wall 7 is (are) deformed under the effect of the deformation means 8. In other words, the deformation means 8 make flexible and deformable either the second wall 7, or the first wall 4 and the second wall 7, which change shape under the effect of the deformation means 8.

According to a first variant embodiment illustrated in figure 5, the second wall 7 that is equipped with the deformation means 8 does not participate in the transfer of the heat flow φ between the fluid 3 and the external medium 6.

According to a second variant embodiment illustrated in figure 6, the first wall 4 and the second wall 7, which are both equipped with the deformation means 8, respectively participate and do not participate in the transfer of the heat flow φ between the fluid 3 and the external medium 6.

It is noteworthy at this stage of the description that the heat exchange surface 5 is either completely or partially formed by the first wall 4 able to be equipped with the deformation means 8 according to a second variant embodiment of the invention. In other words, the heat exchange surface 5 may comprise or may consist of the first wall 4. The second wall 7 and the first wall 4 are in particular placed opposite each other while being situated at a distance D from each other. According to the various variants considered, the distance D and the ^' thickness E are features equivalent to or distinct from each other.

According to another variant embodiment, not shown, the second wall 7 and the first wall 4 are concurrent with each other.

According to a third embodiment of the present invention illustrated in figure 7, the heat exchanger 1 consists of a single pipe 2, which is for example cylindrical in conformation and comprises a first wall 4 corresponding for example substantially to a first portion of the cylindrical pipe 2 in contact with the external medium 6 and a second wall 7 corresponding for example substantially to a second portion of the ^' cylindrical pipe 2, substantially facing the first wall, which is not in contact with said external medium 6. In this case, for example, the two walls 4, 7 are equipped with the deformation means 8. In other words, all or part of the circumference of the pipe and its length may be equipped with such deformation means 8 but only the first wall 4 constitutes the heat exchange surface 5.

It will be understood that the pipe 2 is able to comprise any one at least of the aforementioned features, taken alone or in combination, provided that the pipe 2 satisfies the following condition of the present invention, which consists of the fact that the pipe 2 is provided with means 8 of deforming the second wall 7 at least, the pipe 2 and the heat exchanger 1 being able to have varied conformations and arrangements. Advantages of the present invention will be disclosed below while relying on the first variant of the first embodiment, in particular illustrated in figure 5, in which the first wall 4 constitutes the heat exchange surface 5 while the second wall 7 alone is equipped with the deformation means 8. It is nevertheless noteworthy that such advantages are valid mutatis mutandis for the other variants of the present invention.

Referring also to figure 8, these arrangements intensify the transfer of the heat flow φ between the fluid 3 and the external medium 6 by virtue of a disturbance of the first limit layers CI of the fluid 3 that are in contact with the first wall 4 and/or a disturbance of the second limit layers C2 that are^' in contact with the second wall 7. This is because the deformation of the second wall 7 disturbs a flow of the fluid 3 inside the pipe 2, which facilitates the transfer of the heat flow φ. The result is a destabilisation of the limit layers, either the first layers CI and/or second layers C2, which in the end facilitates the transfer of the heat flow φ. The deformation of the second wall 7, in the example illustrated, alternately brakes and accelerates a flow of the fluid 3 in the vicinity of the second wall 7. Thus the heat exchanger 1 of the present invention effects an optimised transfer of the heat flow φ between the fluid 3 and the external medium 6 from a disturbance of the flow of the limit layers, either first layers CI and/or second layers C2, of the fluid 3 in contact with the first wall 4 and/or the second wall 7. Such a disturbance enables the second limit layers C2, distant from the first wall 4, to even out in temperature with the first limit layers CI, in contact with the first wall 4, which improves the transfer of the total heat flow φ between the external medium 6 and the fluid 3. Finally, the deformation means 8 prevent the limit layers CI, C2 from thickening along the first wall 4 and second wall 7, until in the end destroying these limit layers CI, C2. By way of example, an increase of 600% in the transfer of the heat flow cp achieved by means ^" of a heat exchanger 1 of the present invention has in particular been observed compared with a heat exchanger of the prior art.

These arrangements make it possible also to integrate a function of pumping the fluid 3 by imposing a propagation speed on a deformation wave 9 that the second wall 7 undergoes. The deformation means 8 are able to subject the second wall 7 to a deformation wave 9, which is precise and controlled, so that the fluid 3 accompanies such a deformation and in the end flows inside the pipe 2 under the effect of such a deformation wave 9. The latter is for example periodic in nature, for example also sinusoidal, as illustrated in figure 9, but is able to have an amplitude A, fixed or variable, while being preferentially progressive but possibly standing. The deformation wave 9 is for example also able to be a deformation wave resulting from a superimposition of such deformation waves. Such an advantage is more particularly interesting for a heat exchange 1 comprising a section S with a small dimension, for example less than 1 mm². In this case, the amplitude A of the deformations of the second wall 7 may be great, for example around 80%, or even 90%, of the distance D between the first wall 4 and the second wall 7, ranging up to almost 100% of the distance D, in order to obtain a required fluid flow rate 3.

These arrangements also make it possible to control the pumping function in that, depending on the nature and characteristics of the deformation wave 9 applied to the second wall 7, the pumping of the fluid 3 is able to be modulated at each of the points on the second wall 7, so that the flow rate of the fluid 3 is able to be controlled vertically in line with each point on the second wall 7.

These arrangements also make it possible to control a residence time of the fluid 3 in the heat exchanger 1 and more particularly between the first wall 4 and the second wall 7. In the case where the fluid 3 consists of several compounds, these provisions make it possible in particular to improve a mixing of these compounds. Moreover, the heat exchanger 1 may also be used in the field of reactor exchangers for which the control of the residence time of the fluid 3 in the heat exchanger 1, for a constant transfer of heat flow cp, is advantageously obtained from a variation in flow rate but also able to be obtained more precisely on a particular embodiment of the present invention, which is described later in figure 16, in which a transportation of the fluid 3 in the deformation wave trains 9 conformed as eggshells having a path in the form of a spiral makes it possible to vary the residence time as required, which procures numerous advantages, in particular in the chemical field.

Finally, these arrangements make it possible to control the performance of the heat exchanger 1 independently of the fluid flow rate 3. This is because the performance of the heat exchanger 1, such as a transfer coefficient for the heat flow φ and a fluid flow rate 3, are functions of parameters of the deformation wave 9, namely the amplitude A, the frequency, the wavelength λ, and the number of waves that describes a deformation wave 9 sinusoidal in nature. Thus, for a required performance of the heat exchanger 1, a modulation of these parameters makes it possible to obtain the required fluid flow rate value 3. These arrangements are such that a thermal power exchanged through the first wall 4 can be fixed in the case where the flow rate, and/or an input temperature of the fluid 3 in the pipe 2, varies. The result is finally an ability to effect a transfer of the heat flow φ that is constant from a fluid source 3 having variable flow characteristics. Finally the result of this is an ability to vary either a flow rate in the pipe 2 or the heat flow φ, which enables regulation with a constant heat flow for a variable flow rate or a variable heat flow for a constant flow rate.

The result of these arrangements and advantages is a particularly advantageous adaptation of the present invention for heat exchangers 1 integrated in miniaturised systems of the microfluid type, such as a microreactor or the like. The heat exchanger 1 of the present invention offers the possibility of avoiding exacerbating surface dimensions and reducing the overall footprint of the heat exchanger 1. This is because a heat exchanger 1 of the present invention is advantageously compact, its dimensions being reduced over all by virtue of a better transfer of the heat flow cp through the first wall 4 because of the deformability of the second wall 7. The result of this is that, according to a particular embodiment of the present invention, such a heat exchanger 1 is able to discharge a sizable heat flow φ coming from the external medium 6. The latter is consequently able to contain a large number of electronic components that will advantageously be cooled rapidly and effectively, from a discharge of the heat that the latter produce by means of the fluid 3. Such a discharge in addition being effected through a first wall 4 that is of reduced size.

The result of this also is an improved modularity of the heat exchanger 1 of the present invention in that the transfer of the heat flow cp effected by such a heat exchanger 1 is independent of the fluid flow rate 3 so that, in the case where the fluid flow rate 3 is imposed for a particular application, a quantity of heat of relatively any size is able to be discharged by the heat exchanger 1 of the present invention. These arrangements , make it possible to avoid the use of a powerful and bulky pump that normally forms part of a heat exchange loop of the prior art.

These arrangements are such that a heat exchange loop 10 of the present invention is as simple as possible Such a heat exchange loop 10 comprises for example all in all the heat exchanger 1 and a thermal exchanger 11 that operates vis-a-vis the fluid 3 the heat exchange that is the reverse of that carried out in the heat exchanger 1. The thermal exchanger 11 optionally has the same features as those described for the heat exchanger 1. In other words, in the case where the transfer of the heat flow φ carried out in the heat exchanger 1 is a heat transfer in . which the external medium 6 yields heat to the fluid 3, then the heat transfer in the thermal exchanger 11 is a heat transfer in which the fluid 3 yields heat to an external environment 12. Conversely, in the case where the transfer of the heat flow φ carried out in the heat exchanger 1 is a heat transfer in which the external medium 6 captures heat from the fluid 3, then the heat transfer in the thermal exchanger 11 is a heat transfer in which the fluid 3 captures heat from the external environment 12. Each of the heat transfers previously mentioned are carried out using a circulation of the fluid 3 in the heat exchange loop 10 in a circulation direction 13 solely from the use of said deformation means 8 of the heat exchanger 1 of the present invention. In other words, the heat exchange loop 10 of the present invention contains no pump, or other mechanical means of circulating the fluid 3 in the heat exchange loop 10, such a function being provided by the heat exchanger 1, which advantageously integrates the function of pumping the fluid 3. According to another approach of the present invention, the heat exchanger 1 makes it possible to reduce a power of an accessory pump installed on the heat exchange loop 10.

The flow of fluid 3 in the heat exchange loop 10 is caused by the deformation wave 9 that drives the fluid 3 by means of the viscous and pressure forces. An immediate consequence of the integration of the pumping function in the heat exchanger 11 is an increased compactness of the heat exchange loop 10. The absence of a pump on the heat exchange loop 10 in addition avoids all the malfunctionings and maintenance operations inherent in a heat exchange loop of the prior art comprising such a pump . Figure 11 shows a gain G on the heat transfer coefficient as a function of a relative amplitude A/D for various deformation wave frequencies 9 lying between 1 Hz and 50 Hz, and for a distance D equal to 1 mm and a wave number equal to ten. It will be observed that the gain G on the heat transfer coefficient is a simultaneous function of the relative amplitude A/D and of the frequency f of the deformation wave 9. Thus gains ranging up to 600% on the intensity of the heat transfers can be achieved for the greatest values of the relative amplitude A/D and for frequencies of a few tens of hertz. The fact that the greatest gains are obtained for high relative amplitudes of the deformation means that this method is particularly well suited to systems consisting of channels with a small distance D. This is because, in this case, a small amplitude A leads to a high relative amplitude A/D.

Figure 12 shows a mass flow H as a function of the relative amplitude A/D, for different deformation wave frequencies 9 lying between 1 Hz and 50 Hz. Apart from the fact that the integration of the pump in the heat exchanger 1 improves the compactness of the heat exchange loop 10, it will be observed that, for experimental conditions identical to those previously described, the mass flow H varies from 1 kg/m². s to 260 kg/m².s, the best pumping performances being obtained for the greatest relative amplitudes A/D, which makes the heat exchange loop 10 of the present invention particularly relevant for pipes 2 with, a small distance D.

The results for a pipe 2 with a distance D of 1 mm are set out in figure 13 in the form of a graph in which all the points lying in the hatched area Z of figure 13 are accessible. Thus, if for example a method requires a heat transfer coefficient four times greater than that of a heat exchanger of the prior art, that is to say a gain G of 300%, all the mass flows H lying between 0 kg/m². S and 230 kg/m².s can be used without modifying the intensity of the heat flow φ. In the hatched area Z, the heat transfer coefficients are thus decoupled from the value of the mass flow H of the fluid 3. This property is particularly interesting in terms of control of the thermal processes. A knowledge of the relationship between the exchange coefficient (and respectively the mass flow H) and the amplitude A and the frequency of the deformation wave 9 makes it possible to easily use a control of the deformation according to requirements, by simple measurement of the temperature of the first wall 4 or of the temperature of the fluid 3 discharged from the heat exchanger 1.

In figures 14 and 15, these results are achieved using deformation means 8 that comprise at least one actuator 14 that may be either electromagnetic, pneumatic, hydraulic, piezoelectric or the like. Among the piezoelectric actuators 14 that are relevant for implementing the present invention, actuators with direct longitudinal deformation without amplification can be cited, such as solid and multilayer ceramics, external lever-effect actuators, such as "Moonie" actuators or of the lever type, or "Bender" actuators with internal lever effect, such as pre-stressed "Bender" actuators or bimorphic actuators.

For a miniaturised heat exchanger 1, actuators 14 with motive action distributed along the second wall 7 are favoured. For a heat exchanger 1 of larger size, a plurality of actuators 14 distributed along the second wall 7 are used, such actuators 14 being of the localised motive action type and being equipped with independent parameterisable control means for producing a variety of deformation waves 9. By way of non-limitative example, a heat exchanger 1 of the present invention exploits an actuation principle based on the use of multilayer piezoelectric ceramics. Because of the required travels, which are variable and around 1 mm, it is necessary to use means of amplifying the movement obtained by the actuators 14, such means being for example of the cantilever and/or flexion beam type. In this case, the high forces generated by the actuators 14 are used to set in movement the lever that amplifies the movement. Several levers are able to put in series. Preferably, levers with a flexible structure are chosen to avoid friction and plays. According to various variant embodiments, the actuators 14 are thrust actuators or thrust and traction actuators.

Moreover, such a pipe 2 and/or heat exchanger 1 equipped with such deformation means 8 is improved with regard to its resistance to fouling because of the presence of the deformation means 8, which interfere with, or even prevent, deposition of . a compound from the fluid 3 on an internal face of the pipe 2.

In figure 16, and according to a third embodiment of the present invention, a direction of flow SI of the fluid 3 in the pipe 2 is orthogonal to a direction of entry S2 of the fluid 3 in the pipe 2. More particularly, the direction of flow SI is radial with respect to the direction of entry S2. According to the variants shown in the previous figures, said direction of entry S2 and said direction of flow are parallel to each other while, according to the variant shown in figure 16, these directions form an non-zero angle a, typically around 90°, and secondarily this angle a is able to be relatively any angle being in particular greater than 0°. In this case, the deformation wave undergoes planar and radial propagation .

According to another approach of the present invention illustrated in figures 17 and 18, the deformation means 8 constitute means of reversing the direction of circulation 13 of the fluid 3 in the pipe 2 and consequently in the heat exchange loop 10. Through a judicious use of means 15 of controlling the deformation means 8, the fluid 3 is able to be directed in a circulation direction 13 or in an opposite circulation direction 13 in the pipe 2 and in the heat exchange loop 10. The control means 15 are able to deliver an appropriate control law for shaping the second wall 7 as judiciously as possible in order to control the flow of fluid 3 and/or the transfer of heat φ.

Finally, the deformation means 8 advantageously constitute means of homogenisation of a temperature of the exchange surface 5 and/or of a circulation of the fluid 3.

Claims

1. Pipe (2) forming part of a heat exchanger (1), the pipe (2) being delimited by at least a first separation wall (4) for a fluid (3) circulating inside the pipe (2) and an external medium (6), a heat flow (φ) transfer occurring between said fluid (3) and said external medium

(6) through said first wall (4), characterised in that said pipe (2) is also delimited by a second wall (7) not participating in the heat flow (φ) transfer between said fluid (3) and said external medium (6), said second wall (7) being equipped with means (8) of deforming the wall

(7) .

2. Pipe (2) according to claim 1, characterised in that the first wall (4) is not equipped with means (8) of deforming the wall (4).

3. Pipe (2) according to claim 1, characterised in that the first wall (4) is also equipped with means (8) of deforming the wall (4).

4. Pipe (2) according to any one of the preceding claims, characterised in that the deformation means (8) constitute a means of causing fluid (3) to circulate inside the pipe (2) .

5. Pipe (2) according to any one of the preceding claims, characterised in that the deformation means (8) constitute a means of controlling the circulation of the fluid (3) inside the pipe (2) .

6. Pipe (2) according to any one of the preceding claims, characterised in that the deformation means (8) constitute a means of intensification of the heat flow transfer (cp) .

7. Pipe (2) according to any one of the preceding claims, characterised in that the deformation means (8) constitute a means of controlling the heat flow transfer (φ) -

8. Pipe (2) according to any one of the preceding claims, characterised in that the deformation means (8) constitute a means of decoupling a control of the fluid flow (3) and the heat flow transfer (cp) .

9. Pipe (2) according to any one of the preceding claims, characterised in that the deformation means (8) constitute a means of reversing a direction of flow (13) of the fluid (3) inside the pipe (2) .

10. Pipe (2) according to any one of the preceding claims, characterised in that the deformation means (8) constitute a means of disturbing limit layers (CI, C2) of the fluid (3) inside the pipe (2) .

11. Pipe (2) according to any one of the preceding claims, characterised in that the deformation means (8) comprise at least one actuator (14) that may be electromagnetic, pneumatic, hydraulic or piezoelectric.

12. Pipe (2) according to claim 11,. characterised in that the actuator (14) is able to apply a deformation wave (9) to the wall (4, 7), the deformation wave (9) being progressive or standing in nature.

13. Heat exchanger (1) comprising at least one pipe (2) according to any one of the preceding claims.

14. Heat exchanger (1) according to claim 13, characterised in that the heat exchanger (1) comprises a plurality of pipes (2) that are disposed parallel to one another in a general extension plane (P) of the heat exchanger ( 1 ) .

15. Heat exchange loop (10) in which a fluid (3) circulates, the heat exchange loop (10) comprising a means of moving the fluid (3), characterised in that the means of moving the fluid (3) comprises a heat exchanger (1) according to either one of claims 13 or 14.