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:
In
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
According to a first variant embodiment illustrated in
According to a second variant embodiment illustrated in
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
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
Referring also to
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
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 p, 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
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 φ 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 p 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 φ 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-à-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 p 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.
The results for a pipe 2 with a distance D of 1 mm are set out in
In
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
According to another approach of the present invention illustrated in
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.
Number | Date | Country | Kind |
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12/00473 | Feb 2012 | FR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/IB2013/000736 | 2/14/2013 | WO | 00 |