BE1028218B1 - Energy cell, device and method for converting heat into hydraulic energy - Google Patents

Abstract

An energy cell (1) for conversion of heat into hydraulic energy, provided with a pressure vessel (2), the pressure vessel (2) comprising two chambers separated from each other by an impermeable and elastic membrane (5) and a first chamber (6) respectively filled with a phase change material (23), and a second chamber (7) filled with a hydraulic fluid (24), the energy cell (1) being provided with a tube heat exchanger (16) for alternately heating and cooling the phase change material (23) to cause the phase change material (23) to pass alternately from the solidified to the molten phase and vice versa, such that a volume of the first chamber (6) alternately increases and decreases, wherein a wall of the pressure vessel (2) is provided with a passage ( 26) configured to allow a flow of hydraulic fluid (24) out and/or into the second chamber (7), respectively, upon an increase in volume and/or decrease in volume of the first chamber (6), the tube being and heat exchanger (16) comprises a number of straight tubes (17), characterized in that the tubes (17) have an outer diameter of maximum 3.0 millimeters.

Description

: 1 Energy cell, device and method for converting heat into hydraulic energy, | The present invention relates to an energy cell, a device and a method for Conversion of heat in | hydraulic energy.

More specifically, the invention relates to a power cell, apparatus and method utilizing the properties of a phase transition material whose volume changes by definition with each phase change from solidified to molten phase and vice versa, and wherein volume changes of the phase transition material are observed. used as a motor for generating hydraulic energy, such energy cell is known for example from US 2011/0024075 in which an energy cell is described in the form of a cylinder and a piston movable in the cylinder which closes in the cylinder a chamber filled with a such phase transition material which upon transition from a solidified to a melted form expands by heating and thereby displaces the piston in the cylinder, which displacement can be used to exert a mechanical force. cylinder one can alternate just phase ov starting material to melt and solidify and thereby alternately expand and contract in volume, resulting in an inward and outward movement of the

: BE2020/5258 piston, which movement can be reversed in a movement | for driving a motor or other device.

: Another example of an energy cell is known from {5 WO 2015/1845165. The energy cell in WO 2015/184516 is provided 9 with a pressure vessel with two chambers which are separated 9 from each other by an elastic membrane. A first chamber is filled with a phase transition material. The power cell is provided with a gypsy heat exchanger for alternating heating and cooling of the phase change material, wherein the first chamber alternately expands and decreases in volume, respectively, such that the membrane contracts and relaxes. A second chamber is filled with a hydraulic fluid. A wall of the pressure vessel is provided with a passageway configured to permit a flow of hydraulic fluid out and/or into the second chamber, respectively, upon volume increases and/or decreases in volume of the first chamber.

29 The energy cell described in WO 2015/184516 AZ contains the first room with the fass transfer material! around the tubes of the tube heat exchanger, The tubes of the tube heat exchanger are configured to be connected to a hot medium supply with a temperature 45 higher than a melting temperature of the phase change material and to a cold medium supply with a temperature lower than the melting temperature of the phase transition material.

comparison energy cell is more efficient than the version in the form of a suiger cylinder, as the cp and

9 Relaxation of the diaphragm no = friction losses occur. | To ensure a sufficiently large and uniform heat transfer between | 5 to effectuate a heat-exchanging medium as opposed to the tubes of the pipe heat exchanger and the phase change material in the Barley chamber of the energy cell, the tubes are preferentially provided on their outer wall with tens of | 9 10 fins extend radially outwardly relative to this outer wall. Due to the presence of these fins, the tube heat exchanger can be kept compact in structure.

A disadvantage! However, the advantage of the cemented fins is that they divide the first xamer into compartments, and thus can also provide axial pressure gradients between these compartments if a temperature change and consequently a change in volume of the phase change material in several of the compartments is not completely uniform, the second possibility In order to obtain a sufficiently large heat transfer between the medium in the tubes of the tube heat exchanger and the phase change material in the first chamber, a so-called 'multi-pass' tube heat exchanger is used in which a flow of heat exchanging medium in the tubes of the tube heat exchanger is applied several times. successively passes through the first chamber containing the phase transition material, where the

Flow of heat exchanging medium after each pass along the | first chamber is turned half a turn. : As a result, the heat exchanging medium travels a longer distance | 5 in the tubes of the tube heat exchanger than in a single | pass' tube heat exchanger in which the heat exchanging | medium is only passed through a tube of the 9-tube heat exchanger once, so that a total | heat exchange between this heat exchanging medium and the | 19 phase transition material in the first chamber in a multi-pass tube heat exchanger is larger.

However, due to this longer path in the tubes of a mniti-pass D tube heat exchanger, the pressure drop in this flow is greater after the flow of heat exchanging medium through the entire tube heat exchanger.

This is on the one hand due to friction with the inner walls of the tubes, and on the other hand also mainly due to friction when the flow of heat exchanging medium is reversed after each passage of the heat exchanging medium through the first chamber. Although the heat exchange medium in the tubes and the phase change material in the first chamber is larger, but not necessarily more uniform than in a single-pass tube heat exchanger, the objective of the present invention is to solve one or more of the aforementioned and/or other drawbacks. offer,

{ In particular, the present invention has as objective | to provide an energy cell, device and method for converting 9 heat into hydraulic energy wherein heat | is converted into hydraulic energy in an energetically 20 9 5 efficient manner, ie with the greatest possible 9 : possible heat transfer and as little possible pressure and | friction losses,

To this end, the invention relates to an energy cell for converting heat into hydraulic energy, which energy cell is provided with a pressure vessel, the pressure vessel comprising two chambers which are separated from each other by an impermeable and elastic membrane,

respectively a first chamber filled with a lase transition material whose density changes with each phase transition from a solidified to a molten phase and vice versa, and a second chamber filled with a hydraulic fluid when the energy cell is used, the energy cell being provided with heating and cooling means for alternately heating and cooling the phase change material to pass the phase change material alternately from the solidified to the molten phase and vice versa, such that a volume of the second chamber alternately increases and decreases, wherein a wall of the pressure vessel is provided with at least one passage configured LE To allow a flow of hydraulic fluid respectively out and/or into the second chamber in the event of an increase in volume and/or volume reduction of the first chamber,

| 5 wherein the means for alternating heating and cooling of the phase change material is a tube heat exchanger | include, | where the tube heat exchanger has a number of straight lines or | 5 nagenceg straight tubes, which pass through the first | chamber filled with the fass transition material, 9 characterized in that the tubes of the tube heat exchanger | have an outer diameter of no more than 3.0 millimeters.

The advantages of such an energy cell according to the invention are numerous. Firstly, the small outer diameter of the straight or substantially straight tubes of the tube heat exchanger ensures that these tubes can be arranged in a large number within a limited space at a small mutual distance from each other. In other words, the tubes in the energy cell according to the invention can be shot in a higher density than with previously known energy cells. In this way, the tubes form a large external heat-exchanging surface on their outer wall and a large internal heat-exchanging surface within the limited space. on their pin wall.

As a result, the use of fin structures on the tubes of the tube heat exchanger in the first chamber can be limited or even completely eliminated in an energy cell with dimensions that do not have to be excessively larger than those of already known energy cells.

9 occurring axial pressure differences in an energy cell containing this | fin structures on the tubes of the tube heat exchanger are | includes, reduced, or even avoided altogether | # 5 Furthermore, due to the absence of bends, the straight or almost straight pipes provide only a limited pressure drop in the energy cell. In addition, for generating hydraulic energy with the energy cell according to the invention, only elastic deformations of the membrane OD occur, whereby less friction losses would then arise in an energy cell that would contain a piston cylinder instead of a diaphragm for generating the hydraulic energy. : preferably at most 2.5 millimeters, more preferably at most 2.0 millimeters, more preferably at most 1.5 millimeters, even more preferably at most 1.0 millimeters.

In a preferred embodiment of the energy cell according to the invention, the tubes of the tube heat exchanger are free of external fins. as already mentioned above, any axial compressive forces occurring in the energy cell can be reduced in this way

: BE2020/5258 9 8 | or even be avoided altogether, and also not on this | acting on external fins, # in a further preferred embodiment of the energy cell according to the invention, the wall of the pressure vessel # is formed as a first tube about a longitudinal axis, | wherein openings on the longitudinal axis on either side of the pressure vessel are hermetically sealed by means of Lwee lidseis held at a distance from each other in the pressure vessel.

As a result, the energy cell is formed as a non-complicated structure, which simplifies assembly of the energy cell and maintenance, repair and/or replacement of parts in the energy cell.

In this embodiment, preferably at least one of the two covers is removable, preferably both covers are removable, and one or more seals are provided between each removable cover and the pressure vessel.

This makes assembly and maintenance, repair and/or replacement of the components of the energy cell even easier,

Furthermore, preferably in this embodiment of each of the tubes, a first end is sealed sealingly in a first lid of the two lids, and a second end is sealed opposite this first end in a second lid of the two lids opposite the first lid.

| BE2020/5258

Furthermore, in this embodiment, the membrane is also Dij { preferably designed as a second tube discoaxial within | the wall of the pressure vessel is arranged in such a way that the first | chamber is surrounded by the membrane and the second chamber | 5 extends around the membrane between the wall of hat | pressure vessel and the diaphragm. : More preferably, the diaphragm with its free edges # is sealingly enclosed in the two covers or between the covers and the wall of the pressure vessel, This allows seals between the tubes and/or the membrane to be located in the covers and not in the the wall of the pressure vessel. As a result, the wall of the pressure vessel does not have to be adapted to accommodate this type of seal.

Consequently, a standard tubular structure can be used as the wall of the pressure vessel, thereby preserving the full mechanical strength of the wall of the pressure vessel,

This also further simplifies the assembly and maintenance of the energy cell. Furthermore, due to the fact that the hydraulic fluid in the second chamber of the energy cell is on the outside of the tubular diaphragm, for the same volume displacement of the hydraulic fluid, a smaller expansion of the diaphragm diameter would be required if the Lweede chamber with the hydraulic fluid were on the inside of the diaphragm.

This

| leads to less tension in the membrane and lowers | consequently the risk of membrane rupture. In another preferred embodiment of the energy cell according to the invention, the phase transition material has a melting temperature between 25°C and | 90°C, preferably between 25°C and 60°C, the advantage here is that in this way heat can be recovered from a residual heat source at a low temperature, for example a stream of compressed gas at 60°C that has been heated by heat of compression in a compressor installation.

In this embodiment, the phase transition material is preferably selected from the group consisting of - gene wax; - a skin acid or a mixture of fatty acids, preferably palmitic acid or lauric acid; - a glyceride or a mixture of glycerides: or - a mixture thereof.

By 'wax' in this context is meant a mixture of organic compounds consisting mainly of alkyl chains of 12 or more carbon atoms that is malleable at an ambient temperature, but typically harder and more brittle than fats, and found a melting temperature or range of melting temperatures typically above 35° %C melts to a low-viscosity liquid with a dynamic viscosity typically less than 1000 mPa.s.

| Alternatively, the phase change material is preferably sen # paraffin, preferably cen alkane with an even number | carbon atoms or a mixture of alkanes with an even number of 9 carbon atoms, and even more preferentially octadecane.

# 5 | By "paraffin" in this context is meant a mixture of alkane chains with 15 or more carbon chains. Wax, a fatty acid, a glyceride, paraffin or a mixture thereof is a suitable phase change material for an intended application which, depending on the type of wax, fatty acid, glyceride or paraffin used, has a low melting temperature, for example around 45°C, and whose volume increases significantly when transitioning from the solidified to the molten phase and regains its original volume upon solidification. Moreover, by appropriate selection of these types of materials, based on the number of carbon atoms in the molecules in the material, the melting temperature or the The interval of the melting temperatures can be adapted to the intended application. It is hereby not excluded that a different type of material or mixture of materials is used as the phase transition material, which also has such a low melting temperature, that the volume increases considerably during the transition from the gestoid to the molten phase , and that upon solidification its original volume takes back,

[ BE2020/5258 iz An alkane with an even number of carbon atoms or a mixture of alkanes with an even number of carbon atoms Levert sen | maximum absolute ratio of the volume change of | the phase change material at a phase transition with respect to | 5 of Latent heat stored or released by the phase transition material 9 at a phase transition, which absolute | ratio in what follows further denoted ral be as | emissivity of the phase change material.

The advantages of 18 Octadecane are that it has a relatively high expansion capacity, is compatible with all kinds of metals and has a relatively low melting temperature of 27°C compared to most waxes. Due to the relatively low melting temperature, cotadecane is extremely suitable for heat recovery from a residual heat stream cp a relatively low temperature, due to the relatively large temperature difference between the residual heat flow and the phase transition material at the phase transition of the phase transition material, which temperature difference serves as the driving force for the heat transfer between the residual heat flow and the phase transition material.

Due to the relatively high expansion potential, ootadecane is extremely suitable for a velatively large conversion of heat from the residual heat flow into hydraulic energy. In another preferred embodiment of the energy cell according to the invention, the tubes of the tube heat exchanger are made of stainless steel, preferably AISI 304 stainless steel, or copper,

| An advantage of these types of materials is their excellent | thermal conductivity, which favors the heat transfer # between a heat exchange medium and the phase transition material. Furthermore, this | 5 kind of materials with good mechanical strength and rigidity, | allowing the tubes of the tube heat exchanger to withstand high pressures. Furthermore, this type of materials is characterized by their good machinability, which enables smooth production of large numbers of tubes with standard production techniques. In a further preferred embodiment of the energy cell according to the invention, the membrane is made of an elastic material. elastic material an elastomer or a composite material or a rubber, preferably a nitrile rubber.

The advantage of a membrane made of an elastic material is that the membrane yields easily and uniformly with the volume change of the phase change material in the first chamber, so that the membrane is not so prone to cracking, in another preferred embodiment the tubes of the tube heat exchanger are grouped in one or more modular units, wherein in each modular unit the tubes are arranged around a reference axis of this modular unit.

| + This facilitates production of parts and assembly: when building the energy cell, and also facilitates | dismantling due to maintenance, repair and/or replacement of | components of the energy cell, preferably in each modular unit the tubes 9 are arranged parallel about the reference axis.

This facilitates dense stacking of the tubes, which is necessary for uniform heat transfer between a heat exchanging medium and the phase change material.

Alternatively, in each modular unit, the tubes are arranged obliquely towards each other about the reference axis. As a result, the distance between adjacent tubes in a modular unit can be chosen to be smaller at an outlet of the energy cell than at an inlet of the energy cell.

Since the temperature of this hot heat exchanging medium, and consequently the temperature difference between the heat exchanging medium and the phase transition material in the first chamber, is higher at the inlet than at the outlet of the energy cell, since 28 the temperature difference between the heat exchanging medium and the phase transition material in the first chamber is 28 of the phase transition material, more uniformly distributed over an entire length of the energy cell. More preferably, in each modular unit, in a plane perpendicular to the reference axis, the centers of the tubes are arranged in a regular pattern.

With 'regular pattern' in this context is meant a pattern { in a two-dimensional plane that according to two | xrusting dimensions in this two-dimensional plane consists of | sen self-repeating simple figure, such as | 5, for example, a triangle or rectangle. | This provides additional improvements with regard to the | uniform heat transfer between a heat exchanging medium # and the phase transition material.

Preferably, the regular pattern is a hexagonsal pattern. Even more preferably, in each modular unit, in a plane perpendicular to the reference axis, the centers of neighboring tubes are at a fixed distance from each other. Until the uniform heat transfer between a heat exchanging medium and the phase transfer material. Even more preferably, the tubes of the tube heat exchanger are grouped as a plurality of modular units with parallel oriented reference axes, and ds in a plane perpendicular to these reference axes a second distance between the tubes of one of the multiple modular units and the tubes of neighboring ones. of the plurality of modular units greater than the aforementioned first distance.

: 16 This makes it possible to switch between the modular | zenheid reservoirs with increasingly melted | phase transition material less subject to the | heat transfer loops the heat exchanging medium and the | 5 phase transition material, These reservoirs of constantly molten 9 phase transition material can contain melting and # expanding phase transition material in the modular units | In this way, radial force action # of this expanding phase transition material on the tubes in the modular units is alleviated, thereby reducing or even avoiding dislocation of these tubes during expansion of the fasscoganos material. In a further preferred embodiment of the energy cell according to the invention, the tubes of the tube heat exchanger have a wall thickness of at least 0.075 millimetres, preferably at least 0.080 millimetres, more preferably at least 0.090, even more preferably at least 0.100 millimetres. wall thickness is that the tubes can withstand a high pressure, typically a pressure of 250 bar or more.

24 in another preferred embodiment of the power generator according to the invention, the tubes of the tube heat exchanger are configured to be connected to a supply and outlet of a warm medium, which warm medium is capable of melting the Fasco transition material; and/orË

9 - a supply and discharge of a cold medium, which cold medium | capable of solidifying the phase change material. { This has the advantage that use can be made of 9 5 heat that can be recovered from waste streams that # often in the form of hot water or the like as a by-product | produced from an industrial process, and which is usually lost as unusable heat, since a temperature of these waste streams is often insufficient to recover energy from them in a cost-effective way with existing energy recovery systems, in this preferred embodiment the warm medium is preferably a gas stream compressed by a compressor installation.

In this case, the heat of compression, through which the compressed gas stream in the compressor installation has been heated, can be recovered by means of the energy cell according to the invention. these two collectors are provided with two connections, respectively a first connection for connection to a warm circuit with the hot medium and a second connection for connection to a cold circuit with the cold medium,

{ 18 These collectors ensure a uniform supply and discharge 9 of hot and/or cold medium over the various pipes, | just not a uniform heating and/or cooling of the | More preferably, the two connections of each of the two colisctors are provided with a non-return valve 9 configured to supply the tube heat exchanger alternately with hot and cold medium.

The check valve ensures that either warm medium or cold medium flows into the tubes of the tube heat exchanger. By avoiding that the tubes of the tube heat exchanger would receive an addition of hot and cold medium at the same time, a uniform temperature and consequently uniform density of the phase change material in the first chamber is guaranteed, thereby avoiding large pressure gradients in the first chamber. also relates to a device for converting heat into hydraulic energy, characterized in that the device comprises one or more energy cells according to any one of the preceding claims, wherein each tube heat exchanger of the one or more energy cells is connected via a valve system to a supply of a cold medium, the supply temperature of which is lower than a melting temperature of the phase change material and to a supply of a warm medium, the supply temperature of which is greater than the melting temperature of the phase change material, where the

: valve system configured in such a way that the | salt medium and the warm medium each for a given | adjustable duration through the tube heat exchanger. | 5 9 When this device comprises several energy cells, it is | advantage of such a device that the supply of salt medium and warm medium does not have to be switched on and off alternately, but instead can be fed alternately to different energy cells, so that the supply of cold and warm medium can continue to flow, without the consecutive phase transitions necessary for the operation of the individual energy cells stop. In a preferred embodiment of the device according to the invention, the second chamber of the one or more energy cells is connected to a hydraulic circuit for driving a hydraulic consumer.

Preferably, the hydraulic consumer is a hydraulic motor for driving an electric generator. Useful electrical energy can hereby be generated with the device, for instance for driving parts of the device itself or of other nearby devices in an industrial installation, in a further preferred embodiment of the device according to the invention the device comprises an even number of energy cells, and is the valve system such?

| 20 configured that during operation of the device | first half of the number of energy cells and supply | of warm medium and another second half of the number 9 energy cells has gene supply of cold medium, | As a result, the supply of cold and warm medium can continue to flow continuously at the same flow rate. In addition, there are always cells which send hydraulic fluid to the consumer and the latter can always be driven in the same direction with greater regularity. In a further preferred embodiment of the device according to the invention, the valve system is controllably connected to a controller, which is with an inlet means for setting the predetermined adjustable duration and further comprising a method for alternating passing of the cold medium and the hot medium through the tube heat exchanger, each for the aforementioned predetermined adjustable duration.

By means of such a controller, the regulation and operation of the valve system takes place automatically with only the minimum necessary supervision of a human operator.

Furthermore, the invention also relates to a method for converting heat into hydraulic energy,

21 9 characterized in that use is made of an energy cell according to one of the above-described embodiments 9, : 5 It goes without saying that such a method has the same | offers advantages as the advantages of the above described | embodiments of an energy cell according to the invention, # in a preferred embodiment of the method | 10 according to the invention use is made of sen | device according to one of the above-described embodiments, comprising one or more energy cells according to one of the above-described embodiments, wherein via the valve system alternating cold medium and warm medium are each passed through the bubbler heat exchanger of the one or more energy cells for a determined adjustable duration.

Preferably, the device comprises an even number of energy cells, and during operation of the device a first half of the number of energy cells each have a supply of warm medium and another two-half of the number of energy cells have a supply of cold medium.

More preferably, simultaneously and at contemporaneous periods, a first half of the energy cells has a warm medium supply and the other second half of the energy cells has a cold medium supply, the supply of the first half of the energy cells and the supply of the other second half of the energy cells are simultaneously switched from warm to cold medium | and vice-versa. | this makes the regulation of the valve system very simple ; 5 and can only be performed at a minimum number of times, | Alternatively, more preferably the energy cells, | during a period of twice the predetermined adjustable duration, the energy cells are successively switched at an equal interval from a supply of warm medium to a supply of cold medium, the intermediate period having a duration equal to the period divided by the number of energy cells.

As a result, any transitory phenomena that occur during the switchover of the energy cells from a supply of warm medium to cold medium and flow, are distributed evenly and therefore uniformly spread over the precede period. As a result, a uniform quantity of hydraulic fluid is always sent to the consumer and this consumer is always uniformly driven in the same direction. embodiments of an energy cell according to the invention are described, with reference to the accompanying drawings, in which: figure 1 shows schematically and in perspective an energy cell according to the invention cut in half;

; 23 figure 2 shows a cross section of the energy cell of | figure 1, but with partial omission: figure 3 shows very schematically a device according to the invention which is provided with an energy cell 9 according to the invention with a phase change material in the solidified state; Figure 4 shows the device of Figure 3 but with the phase transition material in molten state; Figure 5 shows a cross-section of an alternative embodiment of an energy cell according to the invention.

The energy cell 1 shown in figure 1 is in this case composed of a tubular pressure vessel 2 with at both ends 21 and 22 a removable cover 3, which in this case is held in the pressure vessel 2 by a locking ring 4 in the form of a thin.

The pressure vessel Z is made to withstand very high pressures, for example pressures up to 25,600 kPa (250 bar}, depending on the desired pressures in a particular application. The space delimited by the pressure vessel 2 and by the 23 covers 3 is divided by means of a tubular membrane 5 into two chambers, respectively a first chamber & which is surrounded by the membrane 5 itself and a second chamber 7 which extends around the membrane 5 between the pressure vessel 2 and the membrane 5, as best can be seen in figure 2,

The membrane 5 is made of an impermeable elastic | material such as rubber, for example nitrile rubber, or a | elastomer or a composite material or the like, an is | at each end with a free edge B sealingly encased in 9 a respective cover 23. the 19 embodiment of figure 2, executed in two parts with a cerste desi JA which is held by the aforementioned locking ring 4 in the pressure vessel 2 and a second part 3B which is fastened in or against the first part 3A while clamping an aforesaid vand 8 with thickening 3 of the membrane 5 in a chamber 10 enclosed between the two parts 3A and 3B, the second part 35 of each cover 3 is clamped, the first part JA by means of bolts 11 or the like, Between the cover 3 and the pressure vessel Z and the retaining ring 4, seals 12 and 13 are provided.

On the outer side facing the second chamber 7, the membrane 5 can be provided with one or more ribs 14, in this case peripheral ribs 14, with a certain thickness, which can serve locally as spacers between the membrane a and the pressure vessel 2 and which are also serve as reinforcing ribs 14 of the diaphragm 5. In the example shown, the ribs 14 and diaphragm 5 are made in one piece 33 in the same material, although this is not an absolute necessity,

In the same way, the pressure vessel 2 on the to the membrane | 3 oriented inner side are provided with ribs 15 with a | a certain thickness, wherein these ribs 15 are preferably also designed as circumferential ribs 15 and preferably 9 are provided opposite corresponding ribs 14 of the membrane 5. The energy cell is further provided with a tube heat exchanger 16 in the form of a bundle of tubes 17 extending axially through the first chamber 6. The radial dimensions such as the outer and inner diameter of the tubes 17 are shown larger than in reality for a clear representation,

The tubes 17 with their ends 18 can be fitted in passages 12 in the respective covers 3 by means of a sealing O-ring. However, it is also possible that the ends 18 of the tubes 17 are welded into the passages 19 in the respective covers 3 The space around the tubes 17 in the first chamber 6 is filled with a phase transition material 23 which, when the energy cell 1 is not in use, is in a solidified state and which in this state occupies a volume just sufficient to fill the first chamber 6 to be filled when the energy cell 1 is empty and not in use or is slightly larger than this empty volume of the first chamber 6, so that the membrane 5 in this condition is not or only slightly stretched in radial direction.

The housings 17 form a connection between both ends 21 and 22 of the pressure vessel 2, which ends 21 and 22 can function as an inlet and/or an outlet for a cold or warm medium that can be passed through it for heating up. or cooling the phase transition material 23 to allow this 9 phase transition material 23 to melt or 9 to solidify, 9 When the energy cell 1 is in use, the second chamber 7 9 10 is filled with a hydraulic fluid 24 from a hydraulic circuit 31 which communicates hydraulically with the Lweede chamber 7 via two connecting nipples 75, each screwed into a passage 26 of the pressure vessel 2, and provided with a cap 27 that prevents the diaphragm 5 from radially entering the connecting nipple 25 or passage 26 could be pushed out of the pressure vessel 2 .

The membrane 5 serves as an impermeable barrier between the phase transition material 23 in the first chamber and the hydraulic fluid 24 in the second chamber 7. The use of an energy cell 1 according to the invention is very simple and is explained below with reference to Figure 3 wherein the energy cell 1 is shown as forming part of a device 28 according to the invention for recovering heat from an inlet A of a warm medium having a temperature higher than the melting temperature of the phase transition material 23. This inlet A of a warm medium vis is a valve system 29 connected to end 21 of the energy cell 1, while the

| other end 22 of the energy cell 1 is connected to a | outlet B for the warm medium after it has passed through the | The tube heat exchanger 16 of the energy cell 1 is controlled. In an analogous way, the energy cell 1 with the aforementioned 9 x valve system 23 is connected to a supply © for a cold medium and a discharge D for this same medium after passage | through the tube heat exchanger 16.

19 The cold medium supplied has a temperature lower than that of the melting temperature of the phase change material 23.

The valve system 25 is such that the cold medium and the hot medium can be alternately controlled through the tube heat exchanger 14 for a certain adjustable period of time. The tipping system 29 is controllably connected to a controller 20. the certain adjustable duration. Furthermore, this controller 20 is provided with an algorithm for leading the cold medium and the warm medium alternately, each during the aforementioned predetermined adjustable duration, through the tube heat exchanger 16. The energy cell 1 is also connected via the connecting nipples 25 and another valve system 30. on a hydraulic circuit 31 for driving a hydraulic consumer 32 which is here, by way of example,

| represented as a hydraulic motor 33 for driving an electric generator 34, the valve system 30 is provided that the liquid in | 5 bets hydraulic circuit 31 always in the same direction | circulates. The device 28 operates as follows.

Starting from a situation as shown in Figure 3, in which the phase transition material 23 is in a solidified state, the valve system 29 is controlled during a first period of, for example, fifteen seconds in such a way that during this period warm medium is transferred from the supply À through the tube heat exchanger 16 to the outlet B is controlled while the in and outlets C and D of the cold medium are closed. The heat from the hot medium heats up the {ase transition material 23 and causes it to melt, whereby the volume of the asse transition material 23 increases and passes through the diaphragm 5 is pushed radially outwards, causing the volume of the second chamber 7 to become smaller and the hydraulic fluid 24 from this second chamber 7 being forced into the hydraulic circuit 31 at a pressure which depends on a hydraulic resistance of this hydraulic circuit 31, and in particular of a tax requested by the consumer 32.

During a subsequent period, as shown in figure 4, the cold medium is replaced by the warm medium

| BE2020/5258 25 sent through the tube heat exchanger 16 by sen # appropriate actuation of the valve system 29, 9 This causes the molten phase change material 23 9 5 to re-solidify and decrease in volume, causing the | hydraulic fluid can flow back from the hydraulic circuit 31 to the energy cell 1.

In this way, the energy cell 1 functions, as it were, like a spinning heart to alternately supply the consumer 32 with hydraulic oil. In practice, a device 28 with an even number of energy cells 1 will always be switched on in the hydraulic circuit 31, whereby the valve system 29 will ensure that, during operation of the device 28, a first half of the number of energy cells 1 each time has a supply of warm medium and a second half of the number of energy cells 1 has a supply of cold medium,

Figure 5 shows a variant of an energy cell 1 in which part of the valve system 29 is integrated in a collector 35 with a double connection piece at each of the ends 21 and 22 of the energy cell 1 in the form of a non-return valve 36 in each of two connections 37 and 38 provided in each collector 35 for connection to a hot and a cold circuit.

Although in the example shown the pressure vessel 2 and the 38 membrane 5 are designed as coaxial cylinders, other shapes are not excluded which ensure that the

| membrane 5 is elastically stretched at an expansion of | the phase transition material 23, : Instead of using a phase transition material 23 that expands : 5 upon melting, it is possible to use a | to use phase change material that shrinks on melting.

The present invention is by no means limited to the embodiments described by way of example and shown in the figures, but an energy cell according to the invention can be realized in various dimensions and shapes without departing from the scope of the invention as defined in the claims,

Claims (1)

î 31 Conclusions | 1.- An energy cell for conversion of heat into hydraulic : 3 energy, which energy cell {1} is provided with a pressure vessel (23, # wherein the pressure vessel (21 comprises step chambers which are separated from each other by an impermeable and elastic membrane, ° 19 respectively a first chamber (6) filled with a phase-change material (23} whose density changes with each phase transition from a solidified to a molten phase and vice versa, and a second chamber {7} which, when using the energy cell (1 ) is filled with a hydraulic fluid (24), the energy cell {1} being provided with means for alternately heating and cooling the phase transition material (23) to change the {ase transition material {23} alternately from the solidified to the melted phase and vice versa such that a volume of the first kChamber {6} increases and decreases alternately, wherein a wall of the pressure vessel {2} is provided with at least one passage {26} configured to in the event of a volume increase and/or volume reduction of the first chamber {6}, flow of hydraulic fluid (24) can be admitted from and/or into the second chamber (7), respectively, wherein the means for alternately heating and cooling the Fnse transition material {23} Ben tube heat exchanger (16) include, | 32 wherein the tube heat exchanger {16} comprises a number of straight or nearly straight tubes {17}, which pass through the first | chamber {6} filled with the phase overcange material (231 ga), characterized in that the tubes {17} of the tube heat exchanger (16) have an outer diameter of a maximum of 3.0 millimetres.# 2. The energy cell according to claim 1, thereby characterized in that the tubes (17) of the tube heat exchanger (16) have an outer diameter of maximally 2.5 millimeters, preferably maximally 2.0 millimeters, more preferably maximally 1.5 millimeters, even more preferably maximally 1.0 millimeters, The energy cell according to claim 1 or 2, characterized in that the tubes (17) of the tube heat exchanger {16} are free of external fins The energy cell according to any one of the preceding claims 1 to 3, characterized in that the wall of the pressure vessel (2) is designed as a first tube around a longitudinal axis, openings on the longitudinal axis on either side of the pressure vessel (2) being hermetically closed by means of two covers (3) which are spaced apart in the pressure vessel (2) are held, The energy cell according to claim 4, characterized in that at least one of the two covers {3} is removable, preferably both covers (31) are removable, and in that one or more seals {12} are provided between each removable cover { 3} and the pressure vessel {2}. î BE2020/5258 | 33 | S.- The energy cell according to claim 4 or 5, thereby | characterized that from each of the tubes (17) a first vitsinde | (18) sealing in the first lid (3) of the two lids | 5 {3) seated, and a second end (18) opposite this 9 first end {18} sealing in a second cover {3} of 9 the two covers (3} opposite to the first cover (3) seated # seated, 7 /.- The energy cell according to one of the preceding claims à to 5, characterized in that the membrane {51 is designed as a second tube arranged coaxially within the wall of the pressure vessel (2), such that the first xamer (6) is surrounded by the membrane (5) and the second chamber {7} extends around the membrane {5} between the wall of the pressure vessel {2} and the membrane (53. The energy cell according to claim 7, characterized in that the membrane {5} is sealed with its free edges (8) in the two covers {3} or between the covers {3) and the wall of the pressure vessel {2}, The energy cell according to any one of the preceding claims 1 to 8, characterized in that the phase change material {23} has a melting temperature between 25°C and 90°C, preferably between 25°C and 60°C, The energy cell according to claim 9, characterized in that the phase change material (23) is selected from the group consisting of - a wax; { - Ben velic acid or a mixture of acids, preferably paimitic acid or Lauric acid: 9 - a glyceride or a mixture of glycerides;: or | - a mixture of these. | 5 The energy cell according to claim 9, characterized in that the phase change material (23) is a paraffin, with 9 preferred alkanes with an even number of carbon atoms or 9 with a mixture of alkenes with an even number of carbon atoms. 9 10 il. The energy cell according to claim 11, characterized in that the phase transition material (23) is octadecane. The energy cell according to one of the preceding claims 1 to 12, characterized in that the tubes {17} of the tube heat exchanger {16} are made of stainless steel, preferably AISI 304 stainless steel, or copper, 40 14, The energy cell according to any one of the preceding claims L to 13, characterized in that the membrane {5} is made of an elastic material. The energy cell according to claim 14, characterized in that the elastic material is an elastomer or a composite material or a rubber, in the case of VOCKSULr a nitrile rubber. 16.- The energy cell according to claims 1 to 15, characterized in that the tubes (17) of the tube heat exchanger (16) are grouped in one or more modular units, | where in each modular unit the tubes (17) around a | referenticas of this modular unit are set up, | 17. The energy cell according to claim 16, characterized in that | 5 that in each modular unit the tubes (17) are parallel around | the reference axis are arranged, 9 18. The energy cell according to claim 16, characterized in that in each modular unit the tubes {175 inclined to | 10 are arranged adjacent to each other about the reference axis. The energy cell according to claim 17 or 18, characterized in that in each modular unit, in a plane perpendicular to the reference axis, centers of the tubes {17} are arranged according to a regular pattern, preferably a hexagonal pattern, 20,- The energy cell according to claim 19, characterized in that in each modular unit, in a plane Icod right to the reference axis, the centers of adjacent tubes {17} are located at a fixed first distance from each other, The energy cell according to claim 20, characterized in that the tubes {17} of the tube heat exchanger (16) 423 are grouped as several modular units with reference axes oriented in parallel, and in a plane Perpendicular to the reference axes a second distance between the tubes (17) of one of the plurality of modular units and the tubes (17) of an adjacent one of the plurality of modular units is greater than the foremost first distance, | 22. The energy cell according to any one of the preceding claims | L to 21, characterized in that the tubes {17} of the | tube heat exchanger (16) and have a wall thickness of at least 9 9.075 millimetres, preferably at least 0.080 millimetres, 95 more preferably at least 0.090, even more preferably | at least 0.100 millimeters. The energy cell according to any one of the preceding claims L to 22, characterized in that the tubes {17} of the coil heat exchanger {161 are configured to be supplied and discharged by a warm medium, which warm medium is capable of is to melt the phase change material (23), and/or - a supply and discharge of a cold medium, which cold medium is capable of solidifying the phase change material {23}. <4." The energy cell according to claim 23, characterized in that the warm medium is a gas stream that has been compressed by a compressor installation. The energy cell according to claim 23 or 24, characterized in that the energy cell {1} is provided with two collectors {35} between which the tubes (17) of the tube heat exchanger (16) extend, each of these two collectors (35) is provided with two connections (37, 38), respectively a first connection (37) for connection to a hot circuit with the hot medium and a second connection (35) for connection to a cold circuit with the cold medium, : 26.7 The energy cell according to claim 25, characterized in that the two connections (37, 38) of each of the two: collectors (35) are provided with a check valve (363 9 5 configured to aerate the tube heat exchanger (16) 9 ). provided with hot and cold medium, dt, A device for converting heat into hydraulic energy, characterized in that the device 18 (28) comprises one or more energy cells (1) according to one of the preceding claims 1 to 26, each tube heat exchanger { 15} of the one or more energy cells (1} is connected via a valve system (29) to a supply of a cold medium whose supply temperature is lower than a melting temperature of the phase transition material (23) and to a supply of a warm medium of which the supply temperature is greater than the separation temperature of the = phase transition material {23}, whereby the valve system (29) is configured in such a way that the cold medium and the warm medium alternately medium are passed through the Thousand Heat Exchanger (16) each for a certain adjustable duration, The device according to claim 27, characterized in that the second chamber (7) of the one or more energy cells {1} is connected to a hydraulic circuit (313 for driving a hydraulic consumer (321, 23). The device according to claim 28, characterized in that the hydraulic consumer (32) has a hydraulic motor | {33) for driving an electric generator (34) is 9. 39. The device according to one of the preceding claims # 5 27 to 28, characterized in that the device (26) has a | comprises an even number of energy cells {13, and that the valve system {29} is configured such that, during operation of the device {23}, one half of the number of energy cells (1) is supplied with warm medium and another second half of the number energy cell (1) has a cold medium cofeed. The device according to any one of the preceding claims 27 to 30, characterized in that the valve system (293 is controllably connected to a controller (20) provided with an adjustment means for setting the determined adjustable duration, and which furthermore provides is an algorithm for alternating passing the cold medium and the hot medium through the tube heat exchanger (16), each for the aforementioned predetermined adjustable time. Process for converting heat into hydraulic energy, characterized in that an energy cell {1} according to one of the preceding claims 1 to 25 is used. 33. Method according to claim 32, characterized in that use is made of a device (28) according to one of the preceding claims 27 to 31, wherein cold medium and warm medium alternate via the valve system (29). | 39 are passed through the 9 tube heat exchanger {16} of the one or more energy cells (1) each for the determined adjustable duration. 34 - Method according to claim 33, characterized in that # the device {28} comprises an even number of energy cells {1}, 9 and that during operation of the device (28) one [first half of the number of energy cells {1 } has a supply 9 of warm medium and another second half of the number of 19 energy cells {1} has a supply of cold medium, A method according to claim 34, characterized in that simultaneously and with parallel periods a first half of the energy cells (1) has a warm medium supply and another second half of the energy cells {1} has a cold medium supply, the supply of the first half of the energy cells {1} and the supply of the other second half of the energy cells (13 is simultaneously switched from hot to cold medium and vice versa, respectively, A method according to claim 34, characterized in that during a period of twice the predetermined adjustable duration, the energy cells {1} are successively switched at an equal interval from a supply of warm medium to a supply of cold medium, the Intermediate period being a period of time. equal to the period divided by the number of energy cells (13.