Heat pump including heat recovery device and heat exchanger and method of carrying out the same

Abstract

Heat pump including heat recovery device and heat exchanger and method for implementing the same The present invention relates to a heat regenerator comprising a plurality of elastomeric material tubes (1), at least one actuator (23, 33), and a first box (2) and a second box (3), each having a bottom (20, 30) with a plurality of holes, the respective bottoms facing each other. Each hole in the first box (2) is in fluid communication with a hole in the second box (3) by a tube, and at least one of the first box or the second box is translatable by the actuator so that the elastomeric material tubes are successively subjected to extended and relaxed conditions. At least one of the first or second boxes has means (35, 53) for drawing suction into the box and then discharging fluid flowing through the tubes from the box. The invention also relates to a heat pump including such a heat regenerator and a method for its implementation.

Description

[Technical field]

[0001] The present invention relates to the field of heat pumps, and more particularly to heat regenerators and methods for their implementation. [Background technology]

[0002] In a new and viable cooling mechanism, caloric materials undergo a change in internal entropy upon application of either an electromagnetic field or mechanical stress / pressure. The development of better performing materials entails the need for a suitable heat engine design as well as proof of concept through experiments. From a systems perspective, some difficulties have been overcome by experiments with magnetocaloric and elastocaloric metallic compounds or electrocaloric ceramics. This has been paralleled by the discovery of materials that exhibit particularly high magnetic / electronic or elastocaloric performance such as magnetocaloric Heusler alloys, ferroelectric multilayer ceramics or barocaloric elastomer materials. Summary of the Invention [Problem to be solved by the invention]

[0003] One of the motivations for this work is to achieve low global warming potential for calorific-based devices and cooling solutions. This challenges the current trade-offs between refrigerant gas performance, toxicity, and environmental concerns. Among all calorific materials, elastomeric materials as high-performance materials have the lowest CO2 emissions during their production compared to metallic compounds. 2 It will be more effective in terms of lower emissions. In addition, the availability of the material is also an important factor. It should be a material that is either abundant or derived from renewable resources (i.e. some elastomeric materials).

[0004] With regard to elastomeric materials, some achievements have been presented, such as the use of membrane stretching and especially torsional deformation to produce large elastocaloric effects. Although quite likely, the possibility of scaling up these devices remains an open question, for example, considering not only the volume of the material but also its displacement during actuation. Uniaxially stretched soft elastomeric materials have been shown to exhibit significant elastocaloric effects (ΔT>10°C), but require large deformations that make them impractical for cooling via elastocaloric effects. Actuation from an initial stretched state results in lower but still large effects (ΔT~3-4°C) and an excellent fatigue life (stable up to >100k cycles) similar to Ni-Ti materials in compression. It is also noted that the recycling of elastomeric materials can be reused by blending used materials or used as filling materials for other applications.

[0005] When a calorific material is driven cyclically, it produces a time variation of temperature. The system needs to convert it into a spatial gradient, i.e. to transfer heat from the cold area to the hot area. One solution consists of physically moving the calorific material in contact with the heat source or heat sink (single-stage systems). Alternatively, heat recovery systems have attracted much attention, since they not only solve the time-space conversion problem, but also allow a higher temperature span of the system than an adiabatic change of the material. It consists of moving a heat transport fluid in contact with the calorific material in a cyclic motion to transport heat from a cold reservoir to the moving material and from the moving material to the hot reservoir. For elastomeric materials, the large deformations required (>500%) are problematic in implementing either single-stage or heat recovery systems.

[0006] It is therefore necessary to address the large deformation limitations of elastomeric materials. [Means for solving the problem]

[0007] This is achieved by designing an efficient heat recovery system with multiple tubular elastomer materials stretched periodically along their axis with a heat transfer fluid flowing inside the tubes. This design also solves the fixation problem of multiple tubular elastomer materials to withstand the axial stress caused by the tube stretching (>MPa).

[0008] More precisely, the invention concerns a heat regenerator comprising a plurality of N tubular elastomeric materials, at least one actuator, and first and second boxes, each having a bottom with a plurality of N channels, the respective bottoms facing each other and each channel of the first box being in fluid communication with a channel of the second box by means of one tubular elastomeric material, each end of the tubular elastomeric materials being fixed in a liquid-tight manner in its respective channel and at least one of the first box or the second box being translationally movable by at least one actuator, so that the plurality of tubular elastomeric materials are successively subjected to elongation and release conditions and to means for drawing into and then expelling from said box the fluid flowing through the elastomeric material tubes.

[0009] Optional, additional or alternative features of the invention are set out below.

[0010] In a preferred mode of operation, at least one of the first box or the second box may have a plunger mechanism therein for drawing heat transfer fluid into and then expelling the fluid flowing through the tubular elastomeric material from said box.

[0011] In a preferred mode of operation, the first box is disposed above the second box, the first and second boxes being mounted along substantially perpendicular axes, and only the second box having the reciprocating means.

[0012] Advantageously, the plurality of tubular elastomeric materials can include more than N=15 elastomeric materials, thereby including N flow paths for each box bottom. The cooling capacity can be increased to reach a target value and is proportional to the number of tubes N.

[0013] Preferably, the outer diameter of the tubular elastomeric material may be in the range of 2 mm to 5 mm in an unstretched state.

[0014] Preferably, the inside diameter of the tubular elastomeric material may range from 1 mm to 3 mm in an unstretched state.

[0015] Preferably, the elastomeric material may be a weakly crosslinked elastomer, including natural or synthetic rubber.

[0016] Elastomeric materials are defined for purposes of this invention as polymers that are viscoelastic (i.e., both viscous and elastic), have weak intermolecular forces, generally a low Young's modulus, and a high strain at break compared to other materials. Such materials have rubber-like properties.

[0017] The monomers that link to form polymers are each usually compounds of several of the elements carbon, hydrogen, oxygen and silicon. Elastomers are amorphous polymers that remain above their glass transition temperature, and thus allow considerable molecular reorganization without breaking covalent bonds. Thus, at ambient temperatures, such rubbers are relatively flexible (E≒3 MPa) and deformable.

[0018] Thermoplastic elastomers are materials that combine many of the attributes and characteristics of both vulcanized thermoset rubbers and thermoplastic materials. Thus, they exhibit elastomeric behavior while being processed as thermoplastic polymers. Most thermoplastic elastomers are copolymers with rigid and flexible segments in their backbone. The synthesis of these elastomers by either chain growth or step growth polymerization results in a wide range of thermoplastic elastomers.

[0019] Rubber-like solids that have elastic properties are called elastomers. The polymer chains in these materials are arranged by relatively weak intermolecular bonds, which allows the polymer to elongate in response to macroscopic stress.

[0020] Elastomers are usually thermosetting (requiring vulcanization), but may also be thermoplastic (see Thermoplastic elastomers). The long polymer chains crosslink during curing, i.e., vulcanization. The molecular structure of an elastomer can be imagined as a "spaghetti and meatball" structure, with the meatballs representing the crosslinks. The phenomenon of elasticity comes from the ability of the long chains to reconfigure themselves to distribute the applied stress. Covalent crosslinks are required for the elastomer to return to its original structure when the stress is removed. As a result of this extreme variability, elastomers can reversibly stretch by as much as 5-700%, depending on the particular material. In the absence of crosslinks, or in the presence of short, reconfigured chains, an applied stress will result in a permanent deformation.

[0021] Advantageously, the length of the tubular elastomeric material may be in the range of 20mm to 50mm in the unstretched state.

[0022] According to another preferred mode of operation, the bottoms of the first and second boxes consist of a plate, for example of acrylonitrile butadiene styrene, and each end of the tubular elastomeric material is fixed in a liquid-tight manner to the respective flow channels, which are preferably cone-shaped, by hollow cones, preferably made of polymer.

[0023] Advantageously, the outer surface of each bottom may be coated with a layer of a leak-proof material, preferably of epoxy resin, preferably about 10 mm thick.

[0024] Additionally, the first and second boxes may each be enclosed within an insulated container.

[0025] According to a particular implementation, the first and / or second box comprises a first and a second outlet so as to intentionally connect the insides of said boxes with a fluid loop.

[0026] The present invention is otherwise directed to a heat pump comprising a first and a second heat exchanger, a first and a second pump, and a first and a second flow path passing through said heat exchangers and said pumps respectively and comprising a first and a second fluid junction, said heat pump including a heat regenerator according to the invention, the first and second boxes respectively comprising a first and a second output, said heat regenerator being in fluid communication with a fluid loop by means of said first and second outlets respectively connected to said first and second fluid junctions.

[0027] A fluid loop can be used to control the temperature of the first and second boxes to that of the heat source and heat sink, respectively. The heat sink can be a room at ambient temperature, while the heat source can be a closed volume, and is therefore cooled by the system.

[0028] Optional, additional or alternative features of the invention are set out below.

[0029] Preferably, the fluid circulating in the loop is a liquid selected from the list defined by water, oil, a mixture of water and glycol, charged water.

[0030] The present invention also relates to a method for implementing the heat regenerator of the above invention, comprising the steps of: cooling a low-temperature fluid contained in a second box of the heat regenerator and heating a high-temperature fluid contained in a first box of the heat regenerator, A first step is performed during which a fluid contained in a first box is transferred to a second box by flowing into a tubular elastomeric material that is under a plurality of release conditions; A second step is performed during which the plurality of tubular elastomeric materials are stretched; A third step is subsequently performed during which the fluid contained in the second box is transferred to the first box by passing through a plurality of tubular elastomeric materials. Thereafter, a fourth step is performed during which the plurality of tubular elastomeric materials are released from elongation.

[0031] According to a preferred mode of operation, the stretch-release conditions of the plurality of tubular elastomeric materials correspond to stretches in the range of 300% to 400% of their initial lengths, and the stretch conditions of the plurality of tubular elastomeric materials correspond to strains in the range of 500% to 600% of their initial lengths, respectively.

[0032] Further advantages and features of the present invention will become apparent after reading the detailed description of the non-limiting modes of operation and embodiments, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0033] [Figure 1] FIG. 1 is a schematic diagram of a heat pump including a heat regenerator according to a particular mode of operation of the present invention; [Diagram 2] FIG. 2 is a perspective view of details of a heat regenerator according to a particular mode of operation of the present invention; [Diagram 3] FIG. 3 is a cross-sectional view of a detail of a heat regenerator according to the above-mentioned specific operating mode of the present invention; [Figure 4] FIG. 4 is a schematic diagram of the operating principle of a heat regenerator according to a particular mode of operation of the present invention; [Diagram 5] FIG. 5 shows (a) schematic of heat and energy balance, (b) waveform of tubular elastomeric material length (elongation) and flow velocity for 80 mm displacement, (c) waveform of tubular elastomeric material length (elongation) and flow velocity for 240 mm displacement, (d) resultant temperatures Tupper in the upper box, Tlower achieved as a result of fluid displacement for various applied powers in the lower box, (e) resultant temperatures Tupper in the upper box and Tlower in the lower box for 240 mm fluid displacement and various applied powers in the lower box. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] For clarity and conciseness, reference numbers in the figures correspond to like elements.

[0035] Because the embodiments described below are non-limiting, alternative embodiments of the invention may be considered to include only a selection of the described features, specifically separated from other described features (even if this selection is separated within a sentence that includes those other features), where the selection of features is sufficient to provide technical advantage or distinguish the invention from the prior art.

[0036] This selection includes at least one feature, preferably functional without any structural details, or functional with only a portion of a structural detail, if only this portion provides a technical advantage or is sufficient to distinguish the invention from the prior art.

[0037] Furthermore, the various features, aspects, alternatives and embodiments of the invention can be associated with one another according to various combinations, unless they are mutually incompatible or exclusive.

[0038] According to the embodiment of FIG. 1, the heat recovery device comprises a plurality of N tubular elastomeric materials 1, two actuators 23, 33, a first box 2 and a second box 3, each having a bottom 20, 30 with a plurality of N flow paths 201, 301.

[0039] The bottoms of the first box 2 and the second box 3 face each other, and each flow passage 201 of the first box 2 is fluidly connected to a flow passage 301 of the second box 3 by one tubular elastomer material 1.

[0040] Each end of the tubular elastomeric material is sealingly secured within a respective passage 201, 301, as depicted in FIGS.

[0041] Elastomeric materials are defined for purposes of this invention as polymers that are viscoelastic (i.e., both viscous and elastic), have weak intermolecular forces, generally a low Young's modulus, and a high strain at break compared to other materials. Such materials have rubber-like properties.

[0042] Each of the monomers that link to form a polymer is usually a compound of some of the elements carbon, hydrogen, oxygen, and silicon. Elastomers are amorphous polymers that remain above their glass transition temperature, and thus allow considerable molecular reorganization without the breaking of covalent bonds. Thus, at ambient temperatures, such rubbers are relatively flexible (E≒3 MPa) and deformable.

[0043] Rubber-like solids that have elastic properties are called elastomers. The polymer chains are held together in these materials by relatively weak intermolecular bonds, which allow the polymers to elongate in response to macroscopic stress.

[0044] Elastomers are usually thermosetting (requiring vulcanization), but may also be thermoplastic (see Thermoplastic Elastomers). The long polymer chains crosslink during curing, i.e., vulcanization. The molecular structure of an elastomer can be imagined as a "spaghetti and meatball" structure, with the meatballs referring to the crosslinks. Elasticity comes from the ability of the long chains to reconfigure themselves to distribute the applied stress. The covalent crosslinks ensure that the elastomer returns to its original configuration when the stress is removed. As a result of this extreme flexibility, elastomers can be reversibly stretched by 5 to 700%, depending on the particular material. In the absence of crosslinks, or in the presence of short, improperly reconfigured chains, the applied stress results in permanent deformation.

[0045] Thermoplastic elastomers are materials that combine many of the attributes and characteristics of both vulcanized thermoset rubbers and thermoplastic materials. Thus, they exhibit elastomeric behavior while being processed as thermoplastic polymers. Most thermoplastic elastomers are copolymers with rigid and flexible segments in their backbone. The synthesis of these elastomers by either chain growth or step growth polymerization results in a wide range of thermoplastic elastomers.

[0046] According to the embodiment of FIG. 1, the first and second boxes are translatable by actuators 23, 33, respectively, such that the multiple tubular elastomeric materials 1 are successively subjected to elongation and relaxation conditions under a load provided by the actuator 23.

[0047] According to the embodiment of FIG. 1, the first box is placed above the second box, so that the first box 2 and the second box 3 are aligned along a substantially vertical axis, and only the second box, located below the first box, comprises piston means 35 and actuator 36 for drawing in and then expelling from said box the fluid flowing through the tubular elastomeric material.

[0048] Due to the principle of gravity, the fluid contained in the first box 2 flows through a tube into the second box 3 and can be made to flow back into the first box under the action of a piston means 35 operated by an actuator 36.

[0049] According to another embodiment not shown in the drawings, a pump 53 is used to draw suction into the second box 3 and then expel the fluid flowing through the tubular elastomeric material from said box.

[0050] According to another embodiment not shown in the drawings, the first box 2 and the second box 3 are aligned along a substantially horizontal axis and the first plunger means and the second plunger means are associated with each box by means of a dedicated actuator.

[0051] To obtain an efficient coefficient of performance (COP), as established by the test results below, the multiple tubular elastomeric materials 1 preferably include more than N=15 tubular elastomeric materials, thereby including N flow paths 201, 301 for each bottom 20, 30.

[0052] Similarly, the outside diameter of the tubular elastomeric material, in its unexpanded state, is advantageously in the range of 2 mm to 5 mm.

[0053] Similarly, the inside diameter of the tubular elastomeric material, in its unexpanded state, is advantageously in the range of 1 mm to 3 mm.

[0054] Similarly, the length of the tubular elastomeric material is advantageously in the range 20mm to 50mm in the unstretched state.

[0055] According to the particular embodiment shown in Figures 2 and 3, the respective bottoms 20, 30 of the first box 2 and the second box 3 are preferably made of a plate of acrylonitrile butadiene styrene.

[0056] The fixation of each end of the tubular elastomeric material is achieved by the complementarity of shapes between the channels 201, 301 and the conical hollow fixtures 202, 302 inserted into the tubular elastomeric material 1. Each channel 201, 301 is preferably conical in shape to enhance sealing. This assembly by complementarity of shapes allows the end of the tube to be fixed to the bottom by minimizing constraints on the tube and maximizing the sealing area defined by the outer surface of the tube and the thickness of the channel.

[0057] To improve the sealing of the box, the outer surface of each bottom 20, 30 is surface treated with a layer of sealing material 203, 303, preferably of epoxy resin, preferably about 10 mm thick.

[0058] This layer 203, 303 makes it possible to maintain the part of the tube emerging from the flow channel and to avoid stress concentrations in this area.

[0059] This layer protects the tube from splitting and allows for over 10,000 stretching cycles.

[0060] To avoid heat loss between the interior of the boxes and the surroundings, the first and second boxes are enclosed in insulating chambers 24, 34 respectively.

[0061] In order to carry out heat recovery within the heat pump, the first box 2 and the second box 3 are provided with a first output 21, 31 and a second output 22, 32 intended to connect the inside of said boxes with the fluid loops 4, 5.

[0062] 1 means at least a heat exchanger 44, 54, a pump 43, 53 (e.g. as a diaphragm pump), and a fluid loop 4, 5 passing through said heat exchanger and said pump respectively. Each fluid loop 4, 5 comprises a first fluid junction 41, 51 and a second fluid junction 42, 52 in fluid communication with a first output 21, 31 and a second output 22, 32 of a heat regenerator respectively.

[0063] According to the embodiment shown in FIG. 1, the heat pump comprises first and second fluid loops 4, 5 passing through heat exchangers 44, 54 and pumps 43, 53 respectively.

[0064] The fluid loops 4, 5 each comprise a first fluid junction 41, 51 and a second fluid junction 42, 52 and are in fluid communication with the heat regenerator by means of a first output 21, 31 and a second output 22, 32 connected to the first fluid junction 41, 51 and the second fluid junction 42, 52, respectively. The fluid loops 4 and 5 are used to control the temperature of the first box 2 and the second box 3 to the temperature of the heat source and the heat sink, respectively. The heat sink may be at ambient temperature, while the heat source is a closed volume and is therefore cooled by the system.

[0065] It is envisaged that the heat pump will operate with a liquid selected from the list defined by water, oil, a mixture of water and glycol, and water fill.

[0066] The elastomeric material may be a weakly crosslinked elastomer, natural or synthetic rubber.

[0067] Turning now to the method of implementing the heat regenerator according to the present invention, the method for transferring heat from Box 3 to Box 2 includes the following steps as shown in FIG.

[0068] Fluid contained within box 2 is directed towards box 3 by flowing into the plurality of tubular elastomeric materials 1. A first step I is performed in which a plurality of tubular elastomeric materials 1 are placed under a release condition. A second step II is performed in which a plurality of tubular elastomeric materials 1 are stretched. A third step III is performed in which the fluid contained in the box 3 is directed towards the first box 2 by flowing into the plurality of stretched tubular elastomeric materials 1 . A fourth step IV is performed during which the plurality of tubular elastomeric materials 1 are released.

[0069] To improve the coefficient of performance (COP), the release conditions of the multiple tubular elastomeric materials 1 correspond to elongations in the range of 300% to 400% of the initial length, and the elongation conditions of the multiple tubular elastomeric materials 1 correspond to strains in the range of 500% to 600% of the initial length.

[0070] The above features have been established by several tests and experiments developed below and are based on the temperature one heat regenerator according to the present invention. For the prototype fabrication, a commercial grade natural rubber tubing (Omega Engineering, Norwalk, CT, USA), reference OMEGAFLEX Natural Latex TYGR-18116~100, was selected.

[0071] [Table 1] Table 1: Prototype dimensions, material properties, and heat pump performance.

[0072] First, a 1.5 m long rubber tube was stretched initially to an elongation of 6 (i.e., 9 m) and kept stretched for a few minutes. After releasing the stretch, the rubber tube was cut into short lengths of 50 mm tubes. Each tube was attached to an ABS plate 20, 30 with a flow passage 201, 301. The ends of the tube were then fixed on each plate as described above by inserting an elastomeric conical tube 202, 302 so that the rubber tube was pressed between the ABS plate 20, 30 and the conical tube 202, 302. The tube was stretched to an elongation of 4. Epoxy resin 203, 303 was poured onto the ABS plate 20, 30 at both ends to fix the external position of the rubber tube 1.

[0073] The rubber tube was stretched to an elongation of 6 and a second layer of epoxy was poured on both ends so that the total thickness of the epoxy resin reached about 1 cm. The tube diameter from the epoxy border was already at its final diameter, ensuring homogeneity of the elastic-thermal effect along the length of the tube. The device consisted of N=55 natural rubber tubes. The dimensions of the heat regenerator and the properties of the natural rubber are shown in Table 1. The fixing plates on both ends were then attached to boxes 2, 3.

[0074] The device was first tested without convective heat transfer. For characterization of this elastocaloric effect, the surface temperature of the rubber tube was measured with an infrared camera (Optris Xi400, Berlin, Germany). Under 4-6 cycles of extension, the temperature change in adiabatic conditions was measured to be about 3.8 K. The inner diameter of the tube upon extension was determined by the change in the heat regenerator fluid volume during extension, and the rubber volume was assumed to be independent of the extension.

[0075] The extension of the 55 rubber tubes 1 was performed by a linear actuator 23 (MISUMI RSDG306, Tokyo, Japan), and the fluid motion was given by an actuator 36 (MISUMI RSD112, Tokyo, Japan) pushing a piston pump acting as a plunger means 35. In this experiment, the box 3 was held in a fixed position and only the box 2 was translated. Therefore, the actuator 33 was not used. Two laser displacement sensors (Panasonic displacement sensors HG-C1400 and HG-C1100-P, Kadoma, Japan) were added to measure the displacement of the two actuators 23, 36. The boxes 2, 3 were added to the ends of the heat regenerator. Their volume was 6.4 mL each. The bottom box 3 was insulated and a thermal resistance of R = 96 mΩ was added as a heat source for testing purposes only. The fluid loop 5 was not added to the experimental setup, which was only aimed at the characterization of the heat pump prototype. A cone-shaped diffuser (not shown) was added inside the boxes 2, 3. The upper box 2 was left open to ensure that the pressure remained constant and that the fluid flowed downwards by gravity when the plunger means 35 moved downwards thanks to the actuator 36. Pure water was chosen as the fluid. The fluid in the upper box 2 was circulated through a fluid loop 4 in order to keep the internal temperature of the upper box 2 as close as possible to room temperature. A force sensor (Vishay Tedea Huntleigh load cell #615, Malvern, PA, USA) was attached to the bottom of the whole system. It was used to measure the mechanical work of the actuator 23 in stretching the rubber tube 1.

[0076] For testing of the elastocaloric cooling device, the temperature was measured at several locations using two thermocouples: inside the upper box 2 and inside the lower box 3 .

[0077] Figure 1 served as the basis for the experimental setup, with typical waveforms used to characterize the cooling device in Figure 5.

[0078] The characterization of the cooling prototype included the measurement of the temperature span, which was obtained directly by thermocouple measurements. The cooling capacity was measured by the heating performance of a resistor placed in box 3 under adiabatic conditions. During the characterization, a constant voltage was applied to the heating resistor. The generated power was the cooling power Q c (in watts). Because of heat losses in the system, the thermal recovery device actually moves more heat than is generated by the resistor, so its measurement is an underestimate of the true cooling power of the device. Therefore, in the worst case, it is estimated by the measured voltage across the resistor.

[0079]

number

[0080] where V and R are the measured voltage and resistance, respectively. The mechanical work of rubber tube 1 was determined by averaging the mechanical output over one cycle:

[0081]

number

[0082] where f, F(t) and v(t) are the actuator operating frequency, the measured force and velocity, respectively.

[0083] The coefficient of performance (COP) of refrigeration was determined by:

[0084]

number

[0085] FIG. 5(a) shows a schematic diagram of the energy balance between the heat and energy entering and leaving the heat regenerator. W ´ m is the average mechanical output of the actuator that extends the tube. Q ´H is the amount of heat dissipated by the high-temperature heat exchanger, and Q ´ L Q is the amount of heat transferred from the ambient room to the cold tube due to heat losses around the rubber tube. ´ C is the amount of heat generated by the heating resistor in the lower box.

[0086] The device was tested at a frequency of 0.1 Hz with a displacement of fluid in a 240 mm tube on the one hand (waveform shown in Figure 5(b)) and a displacement of fluid in an 80 mm tube on the other hand (waveform shown in Figure 5(c)).

[0087] For a fluid displacement of 240 mm, a maximum temperature span of 4.7 K was obtained, i.e. the temperature of the lower box 3 dropped by 4.7 K below room temperature. Next, heating amounts of 0.6 W, 1.1 W and 1.7 W were tested; Fig. 5(d) shows in the text the time signals of the temperatures of the upper and lower boxes 2, 3 together with the heating amount in the lower box 3, which leads to a decrease in the temperature span down to 1.3 K.

[0088] For a fluid displacement of 80 mm, a maximum temperature span of 8.2 K was obtained, i.e. the temperature of the lower box 3 dropped by 8.2 K below room temperature. Heating amounts of 0.6 W and 1.0 W were then tested; leading to a cancellation of the temperature span. Figure 5(e) shows the time signal of the temperatures of the upper and lower boxes 2, 3 together with the heating amount in the lower box 3 given in the text.

[0089] The experimental measurement values ​​are shown in Table 1.

[0090] FIG. 5(f) shows the heat pump characteristics, i.e. cooling capacity vs. temperature span, for both displacements of the fluid in the tubes, and FIG. 5(g) shows the coefficient of performance vs. temperature span for both displacement settings of the fluid in the tubes.

[0091] The maximum cooling capacity per unit mass of the natural rubber tube is 220W / kg. -1 and the temperature range of the system reaches up to 8.2 K. The selection of fluid displacement may be modified to adjust the target power and temperature span.

[0092] Based on the above principles, it is worth noting that other heat regenerator geometries can be developed to further improve the cooling capacity (by increasing the number of tubes) or temperature span (by changing the diameter and length of the elastomeric material tubes).

[0093] In summary, the heat regenerator according to the invention allows cooling by elastic calorific power as an alternative to conventional vapor compression systems, insofar as the Total Equivalent Warming Impact (TEWI) index can be reduced by 50% to 80% compared to vapor compression systems (Aprea, International Journal of Heat and Technology, 2018).

[0094] The heat regenerator according to the invention furthermore allows for an increased compactness of the device and exhibits a high COP (>3).

[0095] Among elastocaloric cooling systems, elastocaloric polymers such as rubber are renewable, low-cost, and CO2-free for elastomer material production. 2 The effect of is low (10 to 100 times lower than that of titanium alloys).

Claims

1. The system comprises a plurality of N elastomeric material tubes (1), at least one actuator (23, 33), a first box (2) and a second box (3), Each box has a bottom (20, 30) with a number N of channels (201, 301), The bottoms of the boxes face each other, and each flow passage (201) of the first box (2) is in fluid communication with a flow passage (301) of the second box (3) by an elastomeric material tube (1); Each end of the elastomeric material tube is fixed in a liquid-tight manner within a respective flow path (201, 301); at least one of the first or second boxes is translatable by at least one actuator (23, 33), such that the plurality of elastomeric material tubes (1) are successively subjected to stretched and relaxed conditions; and means (35, 36; 53) draw fluid flowing within the elastomeric material tubes into and then expel it from said box.

2. At least one of the first box or the second box has a plunger mechanism (35) therein that is actuated by an actuator (36); 2. The heat regenerator of claim 1, wherein a plunger mechanism (35) draws fluid flowing in an elastomeric material tube into the box and then expels it from the box.

3. 10. The heat regenerator according to any of the preceding claims, characterized in that the plurality of elastomeric material tubes (1) comprises more than N=15 elastomeric material tubes, thereby comprising N channels (201, 301) in each bottom (20, 30).

4. A heat regenerator according to any of the preceding claims, characterized in that the thickness of the elastomeric material tube in the unstretched state is in the range of 2 mm to 5 mm.

5. A heat regenerator according to any of the preceding claims, characterized in that the inner diameter of the elastomeric material tube in the unstretched state is in the range of 1 mm to 3 mm.

6. A heat regenerator according to any of the preceding claims, characterized in that the length of the elastomeric material tube in the unstretched state is in the range of 20mm to 50mm.

7. The bottoms (20, 30) of the first box (2) and the second box (3) are made of a plate; Each end of the elastomeric material tube is sealed in its respective flow passage (201, 301) in a liquid-tight manner; 10. A heat regenerator according to any of the preceding claims, characterized in that each flow passage (201, 301) is conically shaped, preferably by a hollow cone (202, 302).

8. 10. A heat regenerator according to the preceding claims, characterized in that the outer surface of each bottom part (20, 30) is coated with a layer of sealing material, preferably of epoxy resin (203, 303), preferably with a thickness of about 10 mm.

9. 10. A heat regenerator according to any of the preceding claims, characterized in that the first box (2) and the second box (3) are respectively enclosed in a thermal insulation layer (24, 34).

10. 10. A heat regenerator according to any of the preceding claims, characterized in that at least one of the first box (2) and the second box (3) comprises a first output (21, 31) and a second output (22, 32) intended to be connected to a flow path (4, 5) inside said box.

11. 10. A heat regenerator according to any of the preceding claims, characterized in that the elastomeric material is selected from weakly crosslinked elastomers, including natural and artificial rubbers.

12. A heat pump comprising first and second heat exchangers (44, 54), first and second pumps (43, 53), and first and second flow paths (4, 5) in fluid communication with the heat exchangers and the pumps, respectively, and each flow path having a first fluid junction (41, 51) and a second fluid junction (42, 52), The heat recovery device according to claim 10, the heat regenerator is in fluid communication with the flow paths (4, 5) by a first output (21, 31) and a second output (22, 32) connected to the first fluid junction (41, 51) and the second fluid junction (42, 52), respectively.

13. A heat pump according to the preceding claim, characterized in that the fluid circulating in the flow paths is a liquid selected from the list defined by: water, oil, a mixture of water and glycol, charged water.

14. A method for implementing a heat recovery system according to any one of claims 1 to 11, comprising the steps of: A method for cooling a fluid contained in a second box (3) of a heat regenerator and for heating a fluid contained in a first box (2) of a heat regenerator, characterized in that: A first step I is carried out while the plurality of elastomeric material tubes (1) are in a release condition and a fluid contained in the first box (2) is directed towards the second box (3) by flowing into the plurality of elastomeric material tubes (1), A second step II is carried out while the plurality of elastomeric material tubes (1) are stretched, A third step III is carried out while the fluid contained in the second box (3) is directed to the first box (2) by flowing into a number of elastomeric material stretch tubes (1), A fourth step IV of the method of implementing the heat regenerator is performed during which the plurality of elastomeric material tubes (1) are released.

15. 15. The method of claim 14, wherein the release condition of the plurality of elastomeric material tubes (1) corresponds to an elongation in the range of 300% to 400% of the initial length, and the elongation condition of the plurality of elastomeric material tubes (1) corresponds to a strain in the range of 500% to 600% of the initial length.

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