FR2831949A1 - Phase change material fluid temperature regulator has casing containing material with internal plates for increased heat exchange - Google Patents

Abstract

The phase change material (PCM) fluid temperature regulator has a casing (2) to contain the material and placed in contact with the fluid. The regulator has a chamber (4) external to the casing. The casing has internal plates made of conductive metal in contact with the fluid and the phase change material for heat exchange. The chamber and fins provide for eventual phase change of the material. Claims include a fluid temperature regulation method using the regulator

Description

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DEVICE. METHOD AND INSTALLATION FOR REGULATING THE
TEMPERATURE OF A FLUID.

 The present invention relates to a device for regulating the temperature of a fluid of the type operating with a phase change material contained inside an envelope.

 In the context of the present invention, the expression regulation of the temperature of a fluid implies both the possibility of cooling the fluid and that of heating it. For the sake of simplification, only the case of cooling will be addressed in the present application, but it is obvious that a person skilled in the art is able to choose the different fluids and materials and their respective temperature according to the task to be performed, c that is to say cooling or heating of the fluid to be treated.

 There are two types of static device which use, to cool a fluid, the energy stored by a phase change material during its phase change from liquid to solid.

 The first type of device comprises a plurality of tubes in which circulate a coolant and a tank containing a phase change material, generally water. In a first step which constitutes the charging phase of the device, the circulating refrigerant allows the formation of more or less irregular sleeves of ice on the surface of the tubes. In the second step which constitutes the use or discharge phase of the device, the water in the tank in contact with the ice sleeves and therefore cooled is used either directly or through a heat exchanger for cooling the process.

 The second type of device from which the device of the invention is derived, comprises closed envelopes (generally tubes) which contain the phase change material. In the loading phase, the phase change of the material is caused by thermal transfer through the casing by circulating outside the tubes a fluid whose temperature is lower than the phase change temperature of the

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 material. During the discharge phase, the fluid to be cooled or an intermediate fluid is circulated outside the envelope.

 This type of device can only be used discontinuously, that is to say in battery, certain devices being in the charging phase while others are in the use phase.

 In addition, although it is easy to determine the total amount of stored frigories, it is difficult to control over time, the amount of heat that can be removed. The thermal transfer being a function not only of the temperature difference existing between the phase change material and the fluid to be cooled but also of the diameter of the tube containing the phase change material, it was thought to equip the device with tubes of diameters different. However, this solution considerably increases the manufacturing cost of the device.

 The document GB 2 327 751 describes a device for cooling a fluid which comprises an envelope containing a phase change material traversed by a tube in which a fluid circulates. This device operates according to charge-use cycles as mentioned above; the only difference is that the fluid to be treated or used to charge the device circulates in the aforementioned internal tube.

 A first object of the present invention is to provide a new device for regulating the temperature of a fluid of the type comprising a phase change material contained in an envelope brought into contact with this fluid.

 A second object of the present invention is to propose a new method for regulating the temperature of a fluid.

 This first object is achieved by means of a device for regulating the temperature of a fluid of the type comprising a phase change material contained in at least one envelope brought into contact with the fluid and which typically according to the invention comprises , in addition, at least one enclosure external to the envelope, which envelope comprises internal means for bringing the material contained in the envelope into contact with a fluid, the enclosure and / or the internal contacting means being

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 adapted to the circulation of a fluid so as to allow the possible phase change of the phase change material contained in the envelope.

 Due to the presence of the internal contacting means and of the enclosure, it is possible on the one hand to easily implement the charging step of the device of the invention either by circulation of a refrigerant fluid in the internal contacting means, the fluid whose temperature is to be regulated being in the enclosure or circulating in it, either by circulation of a refrigerant fluid in the enclosure, the fluid to be treated being or circulating in internal means of contact. It is therefore no longer necessary, as was the case for the devices of the prior art, to selectively supply either the enclosure or the internal means of contacting, the fluid whose temperature is to be regulated in order to performs the charging step.

 On the other hand, the device of the invention also allows continuous charging, due to the simultaneous presence of the refrigerant and the fluid whose temperature is to be regulated. It is therefore thus possible to regulate continuously over time, as required, the quantity of the two phases present in the envelope, which is equivalent to regulating the quantity of refrigerants available at any time.

 According to an alternative embodiment, the internal contacting means comprise an internal tube or conduit.

 The fluid whose temperature is to be regulated can circulate either in the enclosure or in the internal contacting means, the refrigerant being preferably in circulation in order to ensure the phase change of the material contained in the envelope. As previously explained, the fluid whose temperature is to be regulated and the refrigerant fluid can also both be in circulation.

 According to a first particular variant embodiment, the enclosure is a grille surrounding said envelope which makes it possible to limit the space occupied by the device of the invention and to form assemblable modules as will be described more fully below.

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According to a second alternative embodiment, the enclosure is of the tank type.
According to the invention, the type of phase change material is not limited. It can be a liquid-solid phase change material.

 According to one embodiment, the device of the invention further comprises means for forced circulation of a fluid in said enclosure and / or in said internal tube of said envelope.

 According to a particular embodiment, the device of the invention further comprises means for measuring the amount of at least one of the phases present in the envelope.

 According to a variant, the envelope containing, in addition to the phase change material, a determined volume of gas, the means for measuring the quantity of at least one of the phases comprise means for measuring the variation of the pressure of this gas in the envelope.

 According to another variant, the means for measuring the quantity of at least one of the phases contained in the envelope comprise means for measuring the change in volume of the phase change material.

 According to a particular embodiment, the device further comprises means for increasing the heat exchange surface between the internal tube and the phase change material.

 The device of the invention may also include means for increasing the heat exchange surface between the envelope containing said phase change material and the fluid contained in the enclosure.

 The second object of the invention is obtained by means of a process for regulating the temperature of a first fluid brought into contact with at least one envelope containing a phase change material. Characteristically, according to the method of the invention, the relative proportion of the two phases of the phase change material present in the envelope is dynamically regulated by simultaneous contact of the envelope with a second fluid, the second fluid circulating inside said envelope when said first fluid circulates inside the latter and vice versa.

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 According to a particular variant implementation of the method of the invention, the phase change material passing from the liquid state to the solid state, the quantity of the solid phase is measured by measuring the change in volume of said material in view of the above regulation.

 The implementation of the detection of the quantity of phase is not limited according to the invention. Thus, it is possible, in the case of a phase change material passing from the liquid state to the solid state, the envelope containing a determined volume of gas, to measure the quantity of the solid phase by measuring the variation of the pressure of this gas.

 The present invention also relates to an installation for regulating the temperature of a fluid to be treated, comprising: - an evaporator of a refrigeration unit in which a first fluid circulates; and - a heat exchanger connected to the refrigeration unit and which allows the heat exchange between said first fluid and a fluid to be treated.

Typically according to the invention, this installation comprises the device of the aforementioned invention, arranged between the refrigeration unit and the heat exchanger so as to allow the circulation of at least a fraction of the first fluid inside the duct. inside the enclosure and / or inside the enclosure
The installation can also include means allowing the selective circulation of at least a fraction of the first fluid in the device of the invention or in the refrigeration unit.

 The present invention, its characteristics and the various advantages which it provides will appear better on reading the description which follows and refers to the appended drawings representing two particular embodiments, presented by way of nonlimiting examples and in which: - FIG. 1 represents a view in longitudinal section of a first embodiment of the device of the invention; - Figure 2 shows a perspective view of a second embodiment of the invention;

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 - Figure 3 shows a cross-sectional view of an envelope fitted to the second embodiment of the invention, shown in Figure 2; and - Figure 4 shows an example of installation implementing) the device of the invention.

 Referring to Figure 1, the device of the invention 1 comprises, seen in longitudinal section, envelopes 2 which contain a phase change material denoted PCM.

 In the particular embodiment shown, the envelopes 2 have a substantially cylindrical shape. The above-mentioned envelopes 2 are contained in a tank 4 into which a fluid A is introduced. The envelopes 2 are arranged so as to optimize their contact surface with the fluid A.

In the present case, the envelopes 2 are arranged in a triangular or square pitch.

 Each envelope 2 is traversed by an internal tube 6 allowing the circulation of a fluid B within it. In the embodiment shown, a single tube 6 passes successively through each of the envelopes 2. The tube 6 is arranged so as to substantially coincide with the longitudinal axis of each of the envelopes 2. This particular arrangement is not characteristic of the invention. A person skilled in the art is able to best dispose the tube 6 as a function of the shape of the envelope 2 in order to optimize the heat transfers between the fluid B and the PCM phase change material. Likewise, the device of the invention may comprise a plurality of tubes 6, each passing through only one envelope 2.

 In FIG. 1, the fluid A is circulated from top to bottom relative to the bottom 4a of the tank 4. The direction of circulation of the fluid A and of the fluid B are not limiting of the invention. It is even possible to envisage regulating the temperature of a static fluid simply contained in the tank 4.

 In the particular embodiment shown in Figure 1, the envelopes 2 have on their inner surface longitudinal fins 2a which extend radially at the areas where the tube 6 passes through the

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 envelopes 2. These fins make it possible to increase the exchange surface between the PCM phase change material and the fluid A, which improves the efficiency of the heat transfer between the fluid A and the PCM material.

 A particular operation (use for cooling the fluid A by means of a phase change material passing from the solid state to the liquid state) of the first embodiment of the device of the invention will now be described.

 It is assumed that at the initial instant all the PCM material is in its solid form. The fluid A is introduced into the tank 4. The heat transfer existing between the PCM contained in the envelopes 2 and the fluid A to be treated causes on the one hand the lowering of the temperature of the fluid A and on the other hand, the passage from the solid state to the liquid state of a fraction of the PCM material. The fluid A is circulated through the tank 4 via circulation means which can be, for example, a pump 3. The fluid A therefore enters the tank 4 by an inlet 4b and leaves it via the outlet 4c located in the bottom 4a of the tank 4. The flow speed and therefore the residence time of the fluid A in the tank 4 being fixed by the aforementioned circulation means 3, both the temperature of the fluid A at the outlet is controlled of the tank 4 and the quantity of solid phase of the PCM material contained in the envelopes 2. The control of the temperature at the outlet of the fluid A is implemented by means of temperature measurement 5.

 The detection of the quantity of solid phase of the PCM material contained in the envelopes 2 is implemented by means of measuring the quantity of at least one phase 8, an exemplary embodiment of which will be explained in greater detail with reference to FIG. 3 .

 When the quantity of solid phase contained in the envelopes 2 becomes insufficient to ensure a sufficient drop in the temperature of the fluid A or the energy requirement of the process cycle, a fluid 9 is put into circulation in the tube 6, for example by a pump 9 B which is in this case a refrigerant. The circulation of the fluid B causes, by thermal transfer, the phase change of the liquefied portion of the PCM material contained in the envelope 2. The second fluid B must of course

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 be at a temperature below the phase change temperature of the PCM material. Those skilled in the art are able to size the various elements of the device so as to optimize the heat transfers between the various fluids and materials.

 With reference to FIGS. 2 and 3, a second embodiment of the device of the present invention will now be described. The elements in common with the first embodiment described above are referenced identically. In this second embodiment, the tank 4 is replaced by a series of tubes 10 which are interconnected. As in the embodiment described above, the envelopes 2 are cylindrical and arranged in layers of adjacent envelopes. Each envelope 2 is surrounded by a tube 10 which is coaxial with it. On the same layer, the four tubes 10 are supplied, in the particular example shown, in parallel, by means of a collector 10a, the tubes 6 being also supplied in parallel by means of a collector 7. In the particular example shown, each tube 10 and each tube 6 is also connected respectively to tube 10 and tube 6 of the adjacent layer which is superimposed on it.

 The assembly formed by the envelopes 2 and the tubes 10 is placed on a frame 9. Each assembly formed by an envelope 2 and a tube 10 is equipped with a support 9a which makes it possible to place it stably on the chassis 9. The entire device of the invention can be insulated.

 The external face of the tubes 6 can, as shown in FIG. 3, be provided with fins 6a arranged in a spiral so as to increase the heat exchange surface between the PCM material and the fluid B circulating in the tubes 6. The fins 6a and 2a mentioned above can be wires or strips of various shape and thickness fixed to the elements concerned by crimping or any other known method (soldering, soldering, tinning, galvanizing etc.) or extruded in the mass.

 With reference to FIG. 3, an exemplary embodiment of means 8 for measuring the quantity of solid phase of the PCM material contained in the envelope will now be described.

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 In this particular embodiment, each envelope 2 contains, in addition to the PCM material, a determined volume of gas G. When the tube is in a given position, the volume of gas forms a gas pocket. Means 8a for measuring the variation in the pressure of this gas G contained in the aforementioned bag make it possible to determine the quantity of solid phase contained in the envelope 2. In fact, when the PCM material passes from the liquid state (indicated by PCMI) in the solid state (referenced by PCMs), there follows an increase in the volume of the PCM material which results in an increase in the pressure of the gas G.

 It is also possible, according to an embodiment not shown, to provide an expansion vessel connected to one or all of the envelopes 2.

In this case, the envelopes 2 contain the PCM plus a neutral liquid which remains liquid at the minimum operating temperature; the increase in the volume of the PCM during the phase change is then determined by measuring the level of the neutral liquid contained in an expansion vessel.

 A particular mode of operation of the second embodiment of the device of the invention will now be described. This particular mode corresponds to the cooling of the fluid B which circulates in the tubes 6.

 The fluid B circulating in the tubes 6 (via a pump not shown) transmits calories to the PCM material contained in each of the envelopes 2. This results in a change of state of a fraction of the PCM material which passes from the solid state in the liquid state. The change in liquid solid state occurs from tube 6 to envelope 2. Simultaneously, the fluid A circulating in the interval between tube 10 and envelope 2 (via a pump not shown) and whose temperature is lower. at the phase change temperature of the PCM material makes it possible to dynamically compensate for this supply of energy by cooling the PCM material so as to cause it to solidify. In this case, the heat transfer takes place from the outside of the envelope 2 to the tube 6, through the layer of solid PCM material which, in general, has better thermal conductivity than the PCM material in liquid form. There is therefore, as in the operation of the first embodiment, solid phase formation

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 while using the device. The device of the invention can therefore operate continuously unlike the devices of the prior art which operate according to a charge-discharge cycle. It can also operate according to charge-discharge cycles if, for example, the refrigerant A comes from another process and is not continuously available or when the fluid B is not to be treated continuously.

 The presence of the means for measuring the outlet temperature 5 of the fluid B and / or the means for measuring the amount of at least one phase present in the envelopes makes it possible to automatically regulate the circulation of the fluid A as a function a given setpoint which will be compared to the effective temperature of the fluid B at the outlet of the device. The temperature measurement means 5 at the output of the device measure the temperature of the fluid B and compare it with a set temperature. At the same time, the means 8 for measuring the quantity of at least one phase in the envelope 2 evaluate the quantity, for example of the solid phase of the PCM material present in each of the envelopes 2 and therefore the quantity of available frigories . The inlet valve (not shown) 3b of the fluid A is slaved to the means 5 for measuring the temperature at the outlet of the fluid B and to the means 8 for measuring the quantity of solid phase of PCM. It follows that the circulation of fluid A is regulated as a function of the two preceding parameters so as to obtain a fluid outlet temperature B in accordance with the set point. The same reasoning can be applied to the temperature level of fluid A to regulate the outlet temperature of fluid B.

 By way of indication only, the diameter of the tubes 6 can vary from 8 to 50 mm, the diameter of the tubes 10 can vary from 25 to 200 mm and the diameter of the cylindrical casings 2 can vary from 20 to 180 mm.

exemple présenter une température de changement d'état comprise entre - 400C et +60 C. The PCM materials used can be of all types. They can by

example present a state change temperature between - 400C and +60 C.

Similarly, it is possible according to the invention to adapt the fluids A and the PCM material so as to allow the temperature rise of the fluid B.

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 With reference to FIG. 4, an example of installation comprising the device of the invention will now be described.

 This installation includes an evaporator E, a PE heat exchanger which can be, for example, a plate exchanger, a three-way valve V, the device of invention 1 and a control system M (for example an automaton) with its sensors. The evaporator E, which cools the refrigerant A, is connected in a loop to the device of the invention 1 (at the level of the gap between the tubes 10 and the envelopes 2 for example) and to the PE exchanger; the device of the invention 1 (at the level of the tubes 6) and the PE exchanger are connected in series with reference to the fluid B to be cooled. The valve V makes it possible to send a fraction of the fluid flow rate coming from the evaporator E to the device of the invention or to the PE exchanger. A pump P ensures the circulation of the fluid A in the installation. A pump, not shown, circulates the fluid B to be cooled. Furthermore, at least a fraction of the flow rate of fluid leaving the evaporator can be diverted towards the device of the invention 1 at the level of the tubes 10 so as to cause the solidification of the PCM material contained in the device 1 of the invention . The control system collects the following information: the temperature of the fluid B cooled at the outlet of the device of the invention via means for measuring the temperature 5, the quantity of ice therefore energy in stock via means of measurement 8 of the quantity of solid phase and the final temperature of the fluid B via means 5 ′ for measuring the temperature. It also controls the 3-way valve V, the power supplied by the chiller, the temperature of the fluid A delivered by the chiller, and the flow (all or nothing) of the fluid A from the pump P.

 A mode of operation of this installation will now be described.

 In energy charge mode, all the fluid A, cooled by the evaporator, is transported by the pump P into the device of the invention 1 where it causes the solidification of the PCM. In use, the possible operations are as follows:

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- The evaporator is stopped or switched off, the pump P which conveys the fluid A is stopped and the fluid B cools in the device 1 causing the PCM to liquefy
In order to save the energy stock, the evaporator and the pump P are put into operation; all the flow rate of the fluid A circulates between the evaporator E and the device 1. The control system M determines the power to be supplied to reach the desired outlet temperature of the fluid B; this operation allows dynamic storage of the amount of energy in the device 1.

 If the device 1 does not manage to cool the fluid B sufficiently, the control system M then causes the valve V to open and a portion of the flow of the fluid A to be sent to the plate exchanger PE; the fluid 8 already cooled in 1 is cooled again more finely in PE.

The presence of the device of the invention makes it possible on the one hand to increase the refrigerating capacity of the installation and on the other hand to operate the evaporator continuously, the demand for refrigerants not generally being constant during time, the device of the invention overcomes the sudden demand which reduces wear from operation in discontinuous mode.

 It is also possible to envisage evaporating all or part of the refrigerant directly in the device of the invention 1 in place of the fluid circuit A.

Claims (1)

CLAIMS 1. Device (1) for regulating the temperature of a fluid of the type comprising a phase change material (PCM) contained in at least one envelope (2) brought into contact with said fluid, characterized in that it comprises, furthermore, at least one enclosure (4; 10) external to said envelope (2) and in that said envelope (2) comprises internal means (6) for bringing a fluid into contact with the material (PCM) contained in said envelope (6), said enclosure ( 4; 10) and / or said internal contacting means (6) being adapted to the circulation of a fluid (A; B) so as to allow the possible phase change of said phase change material (PCM). 2. Device according to claim 1, characterized in that said internal means for bringing a fluid into contact comprise an internal conduit (6) to said envelope (2). 3. Device according to claim 1 or 2, characterized in that said enclosure is a grille (10) surrounding said envelope (2). 4. Device according to any one of claims 1 to 3, characterized in that said enclosure is a tank (4). 5. Device according to any one of claims 1 to 4, characterized in that said phase change material is a liquid-solid phase change material. 6. Device according to any one of claims 1 to 5, characterized in that it further comprises means of forced circulation (3) of a fluid in said enclosure (4; 10) and / or in said internal contacting means (6) of said envelope (2). 7. Device according to any one of claims 1 to 6, characterized in that it further comprises measurement means (8) <Desc / Clms Page number 14>  the amount of at least one of the phases present in said envelope (2). 8. Device according to claim 7, characterized in that said means for measuring (8) of the amount of at least one of the phases contained in said envelope comprises means for measuring the change in volume of the material (PCM) contained in said envelope (2). 9. Device according to claim 8, characterized in that said envelope (2) containing, in addition to the phase change material (PCM), a determined volume of gas (G), said means for measuring the quantity (8) of at least one of the phases comprises means for measuring (8a) the variation in the pressure of said gas in said envelope (2). 10. Device according to any one of claims 2 to 9, characterized in that it further comprises means for increasing (6a) the heat exchange surface between said internal tube (6) and said change material phase (PCM). 11. Device according to any one of claims 2 to 10, characterized in that it comprises means for increasing (2b) the heat exchange surface between said envelope (2) containing said phase change material ( PCM) and said fluid contained in said enclosure (4; 10). 12. Method for regulating the temperature of a first fluid brought into contact with at least one envelope containing a phase change material, characterized in that the relative proportion of the two phases of said change material is dynamically regulated phase present in said envelope by simultaneous contacting of said envelope with a second fluid, the second fluid circulating inside said envelope when said first fluid circulates outside of the latter and vice versa. 13. Method according to claim 12, characterized in that the phase change material passing from the liquid state to the solid state, <Desc / CRUD Page number 15>  measures the quantity of the solid phase by measuring the change in volume of said material for the purpose of said regulation. 14. The method of claim 12 or 13, characterized in that the phase change material passing from the liquid state to the solid state and said envelope containing a determined volume of gas, the quantity of the solid phase is measured by measuring the variation of the pressure of said gas. 15. installation for regulating the temperature of a fluid to be treated comprising: - a refrigeration unit (E) in which a first fluid circulates (A); and - a heat exchanger (PE) connected to said refrigeration unit (E) and which allows heat exchange between said first fluid (A) and said fluid to be treated (C); - Said installation being characterized in that it comprises the device (1) according to any one of Claims 1 to 11 disposed between said refrigeration unit (E) and said heat exchanger (PE) so as to allow the circulation of at least a fraction of said first fluid (A) inside the internal contacting means (6) of said envelope and / or in said enclosure (4; 10). 16. nstat! ation seton ta claim 15, characterized in that it comprises means (V1; V2) allowing the selective circulation of at least a fraction of said first fluid (A) in said device according to any one of claims 1 to 11 or in said refrigeration unit (E).