Absorption-induced caloric effect and its uses.

Abstract

The present invention relates to the use of a fluid to drive a phase transition induced by absorption / desorption of the fluid into and out of a caloric material. A method is provided in which a sorptiocaloric material is contacted with a fluid such that the fluid is at least partially absorbed into the sorptiocaloric material, inducing a phase transition, allowing heat to flow to or from the sorptiocaloric material. The fluid is then released and desorbed out of the sorptiocaloric material, inducing a reverse phase transition and reverse heat flow. The sorptiocaloric phase transition allows for a very large latent heat under ambient conditions, making it potentially useful for conventional cooling and heating applications as well as heat storage.

Description

[Technical Field]

[0001] The present invention relates to methods of caloric cooling or heating, and in particular to such methods and materials that exhibit a caloric effect induced by the absorption and desorption of a fluid into the material. The invention also relates to cooling or heating devices and the use of such caloric materials for cooling or heating applications. Such uses may be in continuous heating and cooling cycles (e.g., in refrigeration) or in heat storage devices (e.g., transporting heat from a location where excess heat is produced, such as a power plant, to a location where heat is needed, such as an industrial plant).

[0002] The project leading to this application has been funded by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 680032). [Background technology]

[0003] The magnetocaloric, electrocaloric, and mechanocaloric effects are nominally reversible thermal changes that occur in magnetically, electrically, and mechanically responsive materials when subjected to changes in applied magnetic, electrical, and mechanical fields, respectively. Mechanocaloric effects can be subdivided into those driven by uniaxial stress (elastocaloric effect) and those driven by hydrostatic pressure (barocaloric effect). These effects, which are strongest near phase transitions, are similar to the pressure-induced thermal changes in fluids currently utilized in most heating and cooling systems. Importantly, these caloric effects offer the potential for increased energy efficiency and eliminate the need for ozone depletion or greenhouse gases.

[0004] Therefore, developing new heating or cooling technologies based on the caloric effect has the potential to alleviate problems related to energy usage and protect the environment. To exploit this potential, appropriate transitions (e.g., on the scale and conditions required) and materials are needed. For example, an alternative cooling or heating effect would ideally require a large (huge), fully reversible thermal change in response to an applied small, inexpensive field. Even more preferably, this change would occur near room temperature for reasons of ease of implementation and environmental impact.

[0005] Magnetic, electric, and elastocaloric materials have been widely investigated with the aim of providing environmentally friendly heating and cooling applications. In some cases, relatively large thermal changes have been observed. However, to date, magnetocaloric materials have typically required the use of large magnetic fields, which are expensive permanent magnets to generate. This is generally not only less easy to implement but also potentially requires more energy, making them less environmentally friendly. Similarly, electrocaloric and elastocaloric materials discovered to date typically require the use of large electric fields or large mechanical stresses, which often lead to electrical and mechanical damage and eventual failure. These issues may explain why heating and cooling technologies based on magnetocaloric, electrocaloric, and elastocaloric materials have yet to reach the marketplace despite decades of research.

[0006] More recently, pressure caloric materials have been disclosed, such as in WO2018 / 069506. Pressure caloric materials exhibit a caloric effect driven by large pressure changes acting on the material. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] WO2018 / 069506 Summary of the Invention [Problem to be solved by the invention]

[0008] There is a need to identify materials that exhibit large caloric effects, particularly materials that undergo reversible phase transitions near room temperature and in response to small, inexpensive stimuli.It is an object of the present invention to solve one or more of the problems discussed above. [Means for solving the problem]

[0009] The present invention relates to the use of fluids to drive a phase transition in a caloric material for cooling or heating. The phase transition is induced by the absorption / desorption of the fluid into / out of the caloric material. This type of caloric effect can be called the sorptiocaloric effect, and caloric materials that exhibit such an effect can be called sorptiocaloric materials.

[0010] In a first aspect, there is provided a method for thermal cooling or heating, comprising: (i) providing a sorptive caloric material; (ii) contacting the sorptiocaloric material with a fluid such that the fluid is at least partially absorbed into the sorptiocaloric material to induce a phase transition; (iii) allowing heat flow to or from the sorptiocaloric material; (iv) releasing the fluid so that the fluid is desorbed from the sorptive caloric material and induces a reverse phase transition; and (v) enabling heat flow to or from the sorptiocaloric material; A method is provided which includes:

[0011] In this method, the sorptive caloric material undergoes a fluid-driven phase transition based on a new caloric effect that is distinct from the previously described magnetocaloric, electrocaloric, elastocaloric, and barocaloric effects.

[0012] The phase transition of the sorbtiocaloric material in the present invention is a reversible transition between a first state in which no fluid is absorbed throughout the sorbtiocaloric material and a second state in which the fluid is absorbed throughout the sorbtiocaloric material. The phrase "absorbed throughout the sorbtiocaloric material" refers to the case in which the fluid is not only present on the surface of the sorbtiocaloric material, but also the case in which the fluid is absorbed throughout the three-dimensional structure of the sorbtiocaloric material, such as in the pores within the internal structure of the sorbtiocaloric material.

[0013] The fluid can form intermolecular interactions with the sorptiocaloric material. The phase transition is induced by the absorption / desorption of the fluid on the sorptiocaloric material ("sorptiocaloric"). The sorptiocaloric phase transition in the present invention can be a first-order phase transition.

[0014] Sorptive caloric phase transitions are capable of very large latent heat and volume changes, which have been proposed to be the result of structural or conformational phase transitions driven by fluid absorption.

[0015] In this way, the Sorptioncaloric processes, uses, and devices described herein can provide improved caloric efficiency compared to known systems. Further advantageously, the Sorptioncaloric phase transition can be achieved at low pressures and can occur at or near room temperature, making it particularly useful for heating or cooling applications and thermal energy storage.

[0016] Preferably, the phase transition in the sorptive caloric material is 10 kJ kg -1 More than, for example, 25kJ kg -1 More than, for example, 50kJ kg -1 More than, for example, 100kJ kg -1 More than, for example, 250kJ kg -1 More than, for example, 500kJ kg -1 The latent heat, |Q0|, is shown to be greater than or equal to

[0017] Preferably, the sorptive caloric material is 5J K -1 kg -1 For example, 10J K -1 kg -1 For example, 15J K -1 kg -1 For example, 20J K -1 kg -1 For example, 25J K -1 kg -1 For example, 50J K -1 kg -1 For example, 75J K -1 kg -1 For example, 100J K -1 kg -1 For example, 150J K -1 kg -1 For example, 200J K -1 kg -1 The entropy change at the phase transition is |ΔS0|.

[0018] The sorptiocaloric materials may have a phase transition at a temperature in the range of 10 K to 500 K, such as 50 K to 500 K, preferably 200 K to 450 K, such as 250 K to 350 K, for example 280 K to 340 K. These sorptiocaloric materials are particularly suitable for use under ambient conditions.

[0019] Preferably, the phase transition of the sorptive caloric material is a first order phase transition. The phase transition may be a first order structural phase transition, such as between symmetric groups.

[0020] The sorptive caloric material may be contacted with the fluid at a pressure of 500 MPa or less, such as 200 MPa or less, for example 100 MPa or less, such as 50 MPa or less, for example 25 MPa or less, for example 20 MPa or less, for example 10 MPa or less, for example 5 MPa or less, for example 1 MPa or less. The pressure may be relatively low, for example, compared to methods using mechanocaloric materials which may be driven by hydrostatic pressures of typically 100 MPa or more.

[0021] In a second aspect, Sorptiocaloric materials as cooling or heating agents; means for transferring heat to and from the sorptive caloric material; and means for reversibly contacting the sorption caloric material with a fluid such that the fluid is absorbed throughout the sorption caloric material to induce a phase transition; A cooling or heating device is provided, comprising:

[0022] The cooling or heating device may include means for applying hydrostatic pressure or means for transferring heat to the sorptive caloric material.

[0023] Preferred features of the first aspect apply equally to the second aspect.

[0024] In a third aspect, there is provided a use of a sorption caloric material as a cooling or heating material, comprising contacting the sorption caloric material with a fluid such that the fluid is absorbed throughout the sorption caloric material to induce a phase transition.

[0025] Preferred features of the first aspect apply equally to the third aspect.

[0026] The present invention will now be described with reference to the figures listed below. [Brief explanation of the drawings]

[0027] [Figure 1] Calorimetric analysis of MIL-53(Fe) at ambient pressure. Panel (a) shows dQ / |dT| in MIL-53(Fe) upon heating (red) and cooling (blue), and panel (b) shows the corresponding thermally driven entropy change around the dehydration / hydration transition in MIL53(Fe) for the low-temperature (hydrated) phase. [Figure 2]Calorimetric analysis of the dehydration / hydration-induced structural transition in MIL-53(Fe). Panel (a) shows the dQ / |dT| measurements at isobaric pressure. Panel (c) shows the transition temperatures of the transitions as a function of pressure p upon cooling and heating, with a linear fit to the entire data set. [Figure 3] Sorptive caloric effect in MIL-53(Fe) near its dehydration / hydration-induced transition. Panel (a) shows the isothermal ΔSit(T) driven by water absorption (pressurization 0 → p) or water desorption (depressurization p → 0). DETAILED DESCRIPTION OF THE INVENTION

[0028] In a general aspect, the present invention relates to the use of a fluid to drive a phase transition in a caloric material for cooling or heating, the phase transition being induced by absorption / desorption of the fluid.

[0029] Caloric effects driven by magnetically, electrically, or mechanically applied fields are known, but magnetocaloric, electrocaloric, and mechanocaloric materials suffer from drawbacks.

[0030] We have now established that phase transitions driven by fluid absorption and desorption in materials can result in large caloric effects, which can be used as an alternative to the previously described magnetocaloric, electrocaloric, and mechanocaloric effects.

[0031] Boldrin described a "breathing transition" observed in ZIF materials and described the use of zeolites as energy storage materials. Boldrin suggested that ZIF materials could be excellent barocaloric candidates. However, Boldrin reported that many materials in the ZIF subfamily have irreversible transitions. ZIF-4(Zn) is reported to have a reversible transition at a temperature of 140 K, making the particular transition disclosed by Boldrin unsuitable for typical cooling and heating applications near room temperature.

[0032] The present invention provides reversible transformations in sorptive caloric materials using the absorption / desorption of fluids, such as benign gases and liquids. These new sorptive caloric effects and materials represent a paradigm shift in thermal heating and cooling, with the ability to produce large thermal changes associated with environmentally friendly, efficient, and inexpensively driven room-temperature structural phase transitions, such as those in hybrid organic-inorganic materials.

[0033] Specifically, in a first aspect, there is provided a method for thermal cooling or heating, comprising: (i) providing a sorptive caloric material; (ii) contacting the sorptiocaloric material with a fluid such that the fluid is at least partially absorbed into the sorptiocaloric material to induce a phase transition; (iii) allowing heat flow to or from the sorptiocaloric material; (iv) releasing the fluid so that the fluid is desorbed from the sorptive caloric material and induces a reverse phase transition; and (v) enabling heat flow to or from the sorptiocaloric material; A method is provided which includes:

[0034] In some embodiments, the fluid is substantially entirely absorbed into the sorptive caloric material to induce a phase transition, while in other embodiments, the fluid is only partially absorbed into the sorptive caloric material, which is sufficient to induce a phase transition.

[0035] The reversible phase transition is induced by contacting the sorbtiocaloric material with a fluid such that the fluid is absorbed by the sorbtiocaloric material. The fluid may chemically interact with the sorbtiocaloric material. Preferably, the fluid forms one or more intermolecular bonds, such as one or more hydrogen bonds, with the sorbtiocaloric material.

[0036] The phase transition in the present invention differs from barocaloric transitions, which are induced by a change in pressure and may involve the use of a pressure-transmitting fluid. In the present method, the fluid interacts with and is absorbed into the sorptive caloric material, for example, forming intermolecular bonds, which facilitates the phase transition.

[0037] The sorptive caloric phase transitions of the present invention can exhibit large latent heats and volume changes. In this way, the present invention can provide improved caloric effects compared to known magnetocaloric, electrocaloric, or mechanocaloric materials, and can provide performance tailored to application needs. For example, the latent heat associated with the transitions (and processes, uses, and apparatus) described herein is typically 50 kJ kg-1 at very low pressures, around 10 bar. -1 By comparison, for mechanocaloric materials, the typical latent heat value is 10J kg -1 This is driven by a change in hydrostatic pressure of around 2,000 bar.

[0038] In this manner, the present invention provides a fluid-driven reversibly heating or cooling process with large thermal changes at room temperature and low pressure.

[0039] The use of the term "absorption" herein requires that the fluid be contained within (and throughout) the three-dimensional structure of the sorbtiocaloric material (i.e., consistent with the usual meaning of absorption). For example, a porous sorbtiocaloric material, such as an open-framework material, may contain pores within the material. Absorption of a fluid may involve the occupation of pores in the porous sorbtiocaloric material. Absorption may involve the formation or breaking of chemical bonds or van der Waals interactions between the fluid and the sorbtiocaloric material, such as the formation of host-guest interactions of the fluid within the pores of the porous sorbtiocaloric material.

[0040] As used herein, absorption includes and is permitted to include adsorption of fluid onto surfaces, including the exterior surface, of the sorptiocaloric material. That is, surface adsorption can occur in the process of the present invention, so long as the fluid is absorbed into the sorptiocaloric material.

[0041] Desorption of a fluid from a sorbtiocaloric material involves the release of fluid absorbed in the sorbtiocaloric material. Desorption may involve severing the host-guest interaction between the fluid and the sorbtiocaloric material. After desorption, the fluid may be present in the vicinity of the sorbtiocaloric material or may no longer be in contact with the sorbtiocaloric material.

[0042] In some embodiments, the phase change is a structural or conformational phase change, preferably a structural change. In some cases, the phase change may be a first order structural or conformational phase transition.

[0043] The fluid (used to drive the phase transition) can be an inert fluid. Preferably, the fluid is nitrogen gas, CO2, C 1~6 The fluid may be an alkane or water, and more preferably the fluid is water.

[0044] C 1~6 Alkanes are C 1~4It may be an alkane, for example methane or ethane, preferably methane.

[0045] Such fluids are typically cheap and abundant, making them particularly suitable for use in cooling and heating applications.

[0046] In some embodiments, the sorptive caloric material is MIL-53(Al). Preferably, the sorptive caloric material is not MIL-53(Al).

[0047] Sorption Caloric Materials The sorptive caloric materials used in the methods, uses and devices of the present invention are materials that exhibit a caloric effect in response to the absorption / desorption of fluid from the material.

[0048] Without wishing to be bound by theory, it is believed that the absorption and desorption of fluid from a sorption caloric material results in the formation and severing of bond interactions between the sorption caloric material and the fluid. This results in a change in the total energy of the system, leading to a phase transition accompanied by a caloric effect. The fluid can be absorbed as a guest into the host network of the sorption caloric material. The absorption and desorption of fluid can also result in a change in volume, but it is believed that the bond interactions are the driving mechanism for the phase transition and the caloric effect.

[0049] In the methods, uses, and devices described herein, the sorptive caloric material is contacted with a fluid, and the fluid is absorbed by the sorptive caloric material to induce a phase transition. Preferably, the phase transition has some first order character, and even more preferably, the phase transition is a first order phase transition.

[0050] Typically, the sorption caloric material is solid. Preferably, the sorption caloric material is porous. In some embodiments, the sorption caloric material comprises a crystalline structure, such as a porous crystalline structure. The sorption caloric material may comprise a nanoporous crystalline structure. In this manner, the sorption caloric material may form a host-guest interaction with the fluid to induce a phase transition in the sorption caloric material.

[0051] In some embodiments, the sorptive caloric material is an open structure material. Open structure materials have a porous crystalline structure and can undergo a transition between structural phases. Examples of open structure materials include metal organic frameworks and covalent organic frameworks. In this way, the sorptive caloric material can undergo a phase transition between a narrow pore structure and a large pore structure induced by the absorption or desorption of a fluid.

[0052] The sorptiocaloric material may include pores having a diameter of 0.1 nm or more, for example, 0.2 nm or more, for example, 0.5 nm or more, for example, 0.7 nm or more, for example, 0.9 nm or more, for example, 1.0 nm or more, for example, 1.5 nm or more, for example, 2 nm or more, for example, 2.5 nm or more, for example, 3.0 nm or more, for example, 3.5 nm or more, for example, 4 nm or more. The sorptiocaloric material may include pores having a diameter of 10 nm or less, for example, 7 nm or less, for example, 5 nm or less, for example, 4 nm or less, for example, 3.5 nm or less, for example, 3 nm or less, for example, 2.5 nm or less, for example, 2.0 nm or less, for example, 1.5 nm or less, for example, 1.0 nm or less, for example, 0.9 nm or less. The sorptiocaloric material may include pores having a diameter within the above upper and lower limits, for example, 0.1 nm to 10 nm, 0.1 nm to 5 nm, 0.5 to 1.5 nm, etc.

[0053] The pore size may be an average pore diameter, for example, a median or mean pore size.

[0054] Sorptiocaloric material is 0.1cm 3 g-1 More than, for example, 0.5 cm 3 g -1 or more, for example, 1 cm 3 g -1 or more, for example, 1.5 cm 3 g -1 More than, for example, 2 cm 3 g -1 The Sorption Caloric material may have a pore volume of 10 cm or more. 3 g -1 For example, 8cm 3 g -1 For example, 5cm 3 g -1 For example, 3cm 3 g -1 For example, 2.5cm 3 g -1 The sorptive caloric material may have a pore volume within the upper and lower limits as set forth above, e.g., 0.1 cm 3 g -1 ~10cm 3 g -1 , 1cm 3 g -1 ~5cm 3 g -1 etc., 1cm 3 g -1 ~3cm 3 g -1 etc.

[0055] Pore ​​size or pore volume may be measured by scanning electron microscopy, as described in Horcajada et al., or by quasi-elastic light scattering. Scanning electron microscopy may be performed at a voltage of 5 kV, a current of 10 μA, and a working distance of 810 mm, as described in Zhang et al.

[0056] Pore ​​size or pore volume may be measured using an adsorption analyzer such as a Micromeritics_ASAP 2020 adsorption analyzer or a Quantachrome Autosorb iQ series automated gas sorption analyzer. Shahrak et al. describe a typical experiment for analyzing pore volume by analysis of adsorption and desorption nitrogen isotherms at 77 K.

[0057] Suitable sorptive caloric materials include covalent organic frameworks (COFs), metal-organic frameworks (MOFs), hybrid perovskites, zeolites, and mixtures thereof. These materials are porous and capable of undergoing reversible structural transformations that can be triggered by (de)sorption of guest molecules.

[0058] Without wishing to be bound by theory, sorptive caloric materials, particularly porous crystalline materials (e.g., covalent organic frameworks, metal-organic frameworks, zeolites, and hybrid perovskites), have been proposed to have complex phase diagrams that include numerous crystalline structures. As a result, sorptive caloric materials have many useful properties, particularly efficient gas and liquid storage. It has been proposed that these materials can also exhibit large changes in lattice constants with first-order phase transitions that can be driven using the absorption of benign gases such as nitrogen and benign liquids such as water, thereby enabling giant sorptive caloric transitions in these materials.

[0059] Preferably, the sorptive caloric material is or comprises a metal organic framework. Examples of MOFs suitable for use as sorptive caloric materials include those in: MIL family, e.g., MIL-53, including MIL-53(Fe), MIL-53(Al), MIL-53(Cr), and MIL-53(Ga); MIL-47(V IV MIL-47, including MIL-100 and MIL-101; and The ZIF family, for example, ZIF-4 and ZIF-7.

[0060] Preferably, the sorptive caloric material is a MOF of the MIL family, such as MIL-53(Fe).

[0061] Fluids for use with MOFs are preferably selected from carbon dioxide, water, and methane.

[0062] In some preferred embodiments: The sorptive caloric material is MIL-53(Fe) and the fluid is selected from carbon dioxide, water, and methane; The sorptive caloric material is MIL-53(Cr) and the fluid is selected from carbon dioxide and methane; The sorptive caloric material is MIL-53(Al) and the fluid is selected from water, carbon dioxide, and methane, for example, the fluid is selected from water and methane; the sorptive caloric material is MIL-53(Ga) and the fluid is water; or The sorptive caloric material is MIL-101 or MIL-100, and the fluid is carbon dioxide.

[0063] The term metal-organic framework (“MOF”) refers to a class of compounds in which metal ions or clusters are coordinated with organic ligands to form one-, two-, or three-dimensional structures.

[0064] As used herein, the acronym "MIL" (MIL = Materials of Institut Lavoisier) refers to a group of MOFs that share the characteristic of trivalent metal cations at the nodes linked by carboxylate ligands. The materials were first produced at the Institut Lavoisier and are known to be relatively highly flexible.

[0065] "MIL-53" refers to a specific type of MIL MOF. The MIL-53 structure consists of an inorganic [M-OH] chain connected to four neighboring inorganic chains by terephthalate-based linker molecules. Each metal center is octahedrally coordinated by six oxygen atoms. Four of these oxygen atoms come from four different carboxylate groups, and the remaining two oxygen atoms belong to two different μ-OH moieties, which bridge the adjacent metal centers. The resulting framework contains one-dimensional, rhombohedral pores. The term "MIL-53(Fe)" refers, for example, to a MIL-53 MOF in which the metal is iron (Fe).

[0066] As used herein, the acronym "ZIF" (ZIF = zeolite-imidazolate structure) refers to a group of MOFs with tetrahedrally coordinated transition metal ions connected by imidazolate linkers. Examples include ZIF-4 and ZIF-7.

[0067] In a preferred embodiment, the sorptive caloric material is selected from MIL-53(Fe) and ZIF-4(Zn). More preferably, the sorptive caloric material is MIL-53(Fe).

[0068] The sorptive caloric material may be or include a covalent organic framework. Preferred examples include COF-1, COF-5, COF-6, COF-8, and COF-10. Preferably, the fluid for use with these sorptive caloric materials is carbon dioxide.

[0069] The term covalent organic framework ("COF") refers to a group of compounds with two- or three-dimensional structures formed through the reaction between organic precursors. COFs are crystalline, porous organic polymers with highly ordered structures. "COF-1," for example, refers to a specific type of COF. The COF-1 structure contains rigid, two-dimensional layers composed of benzene and BO rings, with weak van der Waals bonds between the layers. COF-5 has a 2D structure linked by boronic esters, formed from 2,3,6,7,10,11-hexahydroxytriphenylene and 1,4-phenylenebis(boronic acid) monomers. COF-6, COF-8, and COF-10 are formed by the co-condensation reaction between 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) and 1,3,5-benzenetriboronic acid (BTBA), 1,3,5-benzenetris(4-phenylboronic acid) (BTPA), and 4,4′-biphenyldiboronic acid (BPDA), respectively.

[0070] Preferably, the sorptive caloric material is selected from COFs and MOFs, more preferably the sorptive caloric material is selected from COFs and MOFs of the MIL family such as MIL-53, for example MIL-53(Fe).

[0071] The term zeolite refers to a group of porous aluminosilicate minerals with a tetrahedral three-dimensional crystal structure. An example is merlinoite.

[0072] In some embodiments, the sorptive caloric material comprises a hybrid material, such as an organic-inorganic hybrid material, such as a metal-organic framework. An organic-inorganic hybrid material refers to a material that comprises a metal ion or cluster and one or more organic ligands.

[0073] Sorption caloric materials for use in accordance with the present invention may exhibit a conventional caloric effect in response to contact with a fluid, or may exhibit a reverse caloric effect, the same preferences applying equally to the sorption caloric processes and materials described herein.

[0074] References to the properties of sorptive caloric materials are generally made in terms of those that exhibit a conventional caloric effect, however, these references may also be interpreted as references to materials that exhibit the opposite effect, as those skilled in the art will understand that the behavior of such materials is opposite to that of conventional materials.

[0075] Sorption caloric materials for use in the present invention may be materials that have a reversible phase transition at a temperature in the range of 10K to 500K, 50K to 500K, 100K to 450K, for example 200K to 450K, for example at ambient pressure, for example 101.3 kPa.

[0076] The phase transition can be a structural phase transition. Examples include a breathing transition, which involves displacement of structure atoms between narrow pore (np) and large pore (lp) morphologies, and a swelling transition, which usually results in gradual expansion of the structure while retaining the unit cell shape and space group. Preferably, the sorptive caloric material of the present invention comprises a porous crystalline structure having a phase transition between narrow pore (np) and large pore (lp) morphologies.

[0077] Typically, the phase transition in a sorptive caloric material is reversible. Irreversible phase changes cannot be used for cooling or heating cycles and are therefore unsuitable for cooling or heating applications.

[0078] Preferably, the phase transition is a first-order phase transition. Without wishing to be bound by theory, an ideal first-order phase transition is one in which, for two coexisting different phases that can be converted into one another by changes in pressure, temperature, absorption of guest molecules, solvation, or field variables such as magnetic or electric fields, the molar Gibbs energies or molar Helmholtz energies of the two phases (or the chemical potentials of all components in the two phases) are equal at the transition temperature, but their first derivatives with respect to temperature and pressure (e.g., specific enthalpy and specific volume of the transition) are discontinuous at the transition point.

[0079] For example, the sorptive caloric material may have a reversible phase transition at a temperature of 10 K or more, such as 50 K or more, for example 100 K or more, such as 150 K or more, for example 200 K or more, such as 210 K or more, for example 220 K or more, such as 230 K or more, for example 240 K or more, such as 245 K or more, for example 250 K or more, for example 260 K or more, such as 270 K or more, for example 280 K or more. The reversible phase transition may be at a temperature of 500 K or less, such as 450 K or less, for example 400 K or less, such as 390 K or less, for example 380 K or less, such as 370 K or less, for example 360 ​​K or less, such as 350 K or less, for example 340 K or less, for example 330 K or less, such as 320 K or less, for example 315 K or less, for example 310 K or less. The phase transition may be within a range having the above upper and lower limits, for example, 10K to 500K, for example, 50K to 500K, for example, 100 to 450K, for example, 200K to 450K, for example, 245 to 340K, for example, 245 to 315K, or 280 to 330K.

[0080] Preferably, the phase transition occurs at a temperature of 200K or higher, such as 250K or higher.

[0081] Most preferably, the phase transition occurs at a temperature close to or at room temperature. Thus, as mentioned above, the reversible phase transition may occur at a temperature in the range of 245 to 340 K, for example, 245 to 315 K or 280 to 330 K.

[0082] The phase transition of a material that exhibits a conventional caloric effect may be at a temperature below room temperature, for example, below 250 K. When the sorptive caloric material is contacted with a fluid, the transition temperature may shift to a temperature within the ambient range or above, for example, within the range of 250-340 K, e.g., 270-340 K, e.g., 280-330 K.

[0083] The phase transition of a material that exhibits an inverse caloric effect may be at a temperature above room temperature, for example above 350 K. When the sorptive caloric material is contacted with a fluid, the transition temperature may shift to a temperature within or below the ambient range, for example, within the range of 250-340 K, for example, 270-340 K, for example, 280-330 K.

[0084] The temperature indicated as the transition temperature may refer to the onset temperature of the transition, which may refer to the beginning of the transition in a cooling or heating cycle at a constant temperature ramp rate.

[0085] The sorptive caloric materials described herein include MIL-53(Fe), which has a reversible first-order structural phase transition from monoclinic to triclinic structure at around 320K.

[0086] The sorptiocaloric material may have multiple reversible phase transitions, and one or each phase transition may occur at a temperature within the limits set forth above. If the sorptiocaloric material has multiple reversible phase transitions, the method of the present invention may utilize one or more of these transitions, typically one of these transitions. The method of the present invention may utilize the transition closest to room temperature, for example, closest to 270, 280, or 300 K.

[0087] The existence of a phase transition in a sorptive caloric material can be confirmed from an analysis of the heat flow performance of the material over a temperature range including those temperatures mentioned above. For example, heat flow measurements can be performed by differential scanning calorimetry, e.g., at 10 K min -1 For example, Lloveras et al. describe a typical experiment for determining the transition temperature at atmospheric pressure (see "Methods" section "Calorimetry at Atmospheric Pressure" on page 5, along with Figure 1(b)).

[0088] The phase transition temperature may be expressed as the transition temperature observed upon heating, upon cooling, or as the average of the heating and cooling transitions.

[0089] A sorptive caloric material may exhibit an endothermic transition upon heating through the transition point (so the latent heat Q0 is > 0). Therefore, the sorptive caloric material will then exhibit an exothermic transition upon cooling through the transition point (so Q o is <0).

[0090] The entropy change at the transition, |ΔS0|, is at least 5 J K -1 kg -1 , for example 10J K -1 kg -1 For example, 12J K -1 kg -1 For example, 15J K -1 kg -1 or more, for example, at least 20 J K -1 kg -1 For example, 25J K -1 kg -1 For example, 50J K -1 kg -1 For example, 75J K -1 kg -1 or more, for example, 100J K -1 kg -1 For example, 150J K -1 kg -1 For example, 200J K -1 kg -1 This is the magnitude of the change, which can be positive or negative, as appropriate, during heating and cooling through the transition.

[0091] The entropy change may refer to the entropy change of the entire transition. Alternatively, if the transition includes a first-order transition, possibly along with other order transitions, the entropy change may refer to only the entropy change of that first-order transition. If there is a first-order transition that is part of an entire transition, the entropy change of that first-order transition may be at least 30%, at least 40%, or at least 50% of the entropy change of the entire transition.

[0092] The entropy change may be expressed as the entropy change observed upon heating, upon cooling, or as an average of the heating and cooling transitions.

[0093] The entropy change at the transition may be determined by differential scanning calorimetry, as described herein.

[0094] Phase transitions can be accompanied by a change in the unit cell volume of a material; for example, the unit cell volume can increase upon heating through a phase transition, a change observed in conventional caloric materials. Conversely, a decrease in unit cell volume can be observed in solvatiocaloric materials.

[0095] The volume change at transition is 1.0 mm 3 g -1 Above, for example, 5.0 mm 3 g -1 or more, for example, 10 mm 3 g -1 or more, for example, 15 mm 3 g -1 or more, for example, 20 mm 3 g -1 or more, for example, 25 mm 3 g -1 or more, for example, mm 3 g -1 or more, for example, 40 mm 3 g -1 or more, for example, 50 mm 3 g -1 The volume change at the transition may be a change of 0.1% or more, such as 0.2% or more, for example 0.5% or more, such as 1% or more, for example 2% or more, such as 5% or more, for example 8% or more, such as 10% or more.

[0096] The numbers given above relate to the magnitude of the change, which may be positive or negative, as appropriate, during heating and cooling through a transition. For example, a volume change may refer to an increase in volume (positive) as may be observed upon heating through a phase transition.

[0097] The volume change may refer to the volume change of the entire transition. Alternatively, if the transition includes a first-order transition, possibly along with other ordered transitions, the volume change may refer to only the volume change of that first-order transition. If there is a first-order transition that is part of an entire transition, the volume change of that first-order transition may be at least 30%, at least 40%, or at least 50% of the volume change of the entire transition.

[0098] The change in volume at a transition may be determined from X-ray diffraction analysis of the sorptive caloric material during a temperature sweep across the phase transition (where the transition typically occurs over a range of temperatures). For example, Lloveras et al. describe a typical experiment for determining the volume change at atmospheric pressure (see "X-Ray Diffraction" in the "Methods" section on page 5 along with Figure 1(d)). The change in volume at a transition may be determined from volumetric thermal expansion measurements or from volumetric isothermal compressibility measurements at various temperatures.

[0099] The phase transition in the sorptive caloric material is 10 kJ kg -1 More than, for example, 25kJ kg -1 More than, for example, 50kJ kg -1 More than, for example, 100kJ kg -1 More than, for example, 250kJ kg -1 More than, for example, 500kJ kg -1 The value of the latent heat may be determined from a differential scanning calorimetry analysis of the material.

[0100] Without wishing to be bound by theory, it is believed that the latent heat Q and ΔS from the structural phase transitions described herein that result in the solvatiocaloric effect in an absorber-absorbed system are not solely due to the volume change of the absorber structure, but also involve the interaction of the absorber and absorbed components, including bond formation and bond breaking, and the subsequent effects on the total bond energy in the entire thermodynamic system, including effects on bond rotation and bond vibration.

[0101] fluid Fluids for use in the sorptive caloric methods, devices, or uses of the present invention may be liquids or gases.

[0102] The fluid may be a guest molecule for absorption into the sorption caloric material. The fluid may be in liquid or gaseous state when contacted with the sorption caloric material.

[0103] The fluid may be a benign fluid. A benign fluid may be a chemically inert fluid. Examples of suitable fluids include water, carbon dioxide, nitrogen, hydrogen, and C 1~6 Alkanes are mentioned.

[0104] Preferably, the fluid is water. In these embodiments, the sorptiocaloric material may undergo a phase transition through hydration and / or dehydration, for example, driven by the absorption and / or desorption of water molecules in the pores of the sorptiocaloric material. Water may be contacted with the sorptiocaloric material as a liquid or as a gas.

[0105] In a preferred embodiment, the fluid is water and the sorptive caloric material is a hybrid organic-inorganic material, preferably a metal organic framework, more preferably MIL-53, most preferably MIL-53(Fe).

[0106] The contacting of the fluid with the sorption caloric material may be carried out in the presence of a secondary fluid, which may be a gas such as nitrogen or carbon dioxide, which may be used to apply pressure to the fluid to promote absorption into the sorption caloric material.

[0107] The fluid may be used to induce a phase transition and as a heat exchange fluid. For example, the device of the present invention may be adapted so that heat can be extracted from the fluid after desorption by causing the fluid to flow through a heat exchanger. Similarly, the method of the present invention may include the additional step of extracting heat from the fluid after desorption by causing the fluid to flow through a heat exchanger. In such a case, the fluid is preferably water. In this way, the method, use, and device of the present invention are more efficient.

[0108] The fluid may be used to induce a phase transition and as a heat storage fluid. For example, the device of the present invention may be adapted to allow heat storage and / or heat transfer in a fluid after desorption. In such a case, the fluid is preferably carbon dioxide. In this way, the method, use and device of the present invention are more efficient.

[0109] In some embodiments, the method of the present invention may be a method of thermal energy storage and optionally transport, in which case the combination of the absorbed fluid and sorptive caloric material after step (ii) may be used for thermal energy storage.

[0110] Methods and Uses The present invention provides a cooling method that uses the fluid-driven caloric effect of the sorption caloric materials described herein. Thus, the sorption caloric materials find use as refrigerants, for example in refrigeration systems. The sorption caloric materials may also be referred to as refrigerants.

[0111] The method of the present invention utilizes the change in thermal behavior of a sorptive caloric material in response to contact with a fluid. Absorption / desorption of the fluid into the sorptive caloric material induces a phase transition. The caloric effect can be advantageously used within a heat pump cycle or a refrigeration cycle to provide heating or cooling, respectively.

[0112] The method of the present invention allows the use of sorptive caloric materials that exhibit not only the conventional caloric effect but also the inverse caloric effect.

[0113] The method of calorific cooling or heating is (i) providing a sorptive caloric material; (ii) contacting the sorptiocaloric material with a fluid such that the fluid is at least partially absorbed into the sorptiocaloric material to induce a phase transition; (iii) enabling heat flow to or from the sorptiocaloric material; may include:

[0114] Contacting the sorptive caloric material with a fluid induces a phase transition, such as a structural phase transition accompanied by a change in volume.

[0115] The fluid is 10 cm 3 g -1 or more, for example, 50cm 3 g -1 , for example 100cm 3 g -1 For example, 150cm 3 g -1 or more, for example, 200 cm 3 g -1 For example, 220cm 3 g -1 For example, 250cm 3 g -1 For example, 260cm 3 g -1 The fluid can be absorbed in amounts greater than 800 cm 3 g -1 For example, 600cm 3 g -1 For example, 500cm 3 g -1 For example, 400cm 3 g -1 For example, 300cm 3 g -1 The fluid can be absorbed in the following amounts: 3 g -1 , 50~500cm 3 g -1can be absorbed in amounts equal to

[0116] The amount of absorbed fluid may be measured by methods using an absorption device such as a Micromeritics_ASAP 2020 absorption device or a Quantachrome Autosorb iQ Series Automatic Gas Sorption Analyzer. Measurements may be performed at pressures up to 0.107 MPa and temperatures such as 77 K, 273 K, 298 K, or 323 K. For example, Shahrak et al. described a typical experiment for measuring the absorption of a fluid such as carbon dioxide at pressures up to 800 mmHg (0.107 MPa), with the initial degassing process performed at 150°C for 12 hours under a vacuum pressure of 0.0001 mmHg (0.013 Pa). Zhang et al. described a typical experiment for nitrogen sorption isotherms measured at 77 K. Llewellyn et al. described a typical experiment for measuring the adsorption of carbon dioxide or methane, which was performed at 303 K and a final temperature of 423 K after degassing under vacuum.

[0117] The amounts of absorbed fluid described herein may be gas volumes at STP (standard temperature and pressure; 273 K and 105 Pa).

[0118] The method of the present invention can be carried out at a temperature of 10 K to 500 K, for example, 50 K to 500 K, for example, 200 K to 450 K, for example, 200 K to 400 K, for example, 350 K to 400 K, for example, 270 K to 340 K, for example, 275 K to 340 K, for example, 280 K to 310 K, for example, 280 K to 305 K. Preferably, the method is carried out at around room temperature, for example, around 298 K or around 300 K.

[0119] The method of the present invention may include, in step (ii), applying a pressurized force to bring the sorption caloric material into contact with a fluid, for example, to absorb guest molecules of the fluid into the sorption caloric material.

[0120] In some embodiments, a pressure of 500 MPa or less, for example, 200 MPa or less, for example, 100 MPa or less, for example, 50 MPa or less, for example, 25 MPa or less, for example, 20 MPa or less, for example, 10 MPa or less, for example, 8 MPa or less, for example, 5 MPa or less, for example, 1 MPa or less, is applied. A pressure of 0.01 MPa or more, for example, 0.05 MPa or more, for example, 0.1 MPa or more, for example, 0.5 MPa or more, for example, 1 MPa or more, for example, 5 MPa or more may be applied. The applied pressure may be within the range having the above upper and lower limits, for example, 0.01 MPa to 500 MPa, 0.5 MPa to 100 MPa, etc., 5 MPa to 50 MPa, etc.

[0121] Preferably, a pressure of 10 MPa or less, for example, between 1 and 10 MPa, is applied.

[0122] The applied pressure may be hydrostatic pressure.

[0123] The application of hydrostatic pressure may be achieved by applying water to a fluid absorbed by the sorptive caloric material, in which case the fluid itself may be water.

[0124] The application of hydrostatic pressure may be achieved by applying pressure to a sorption caloric material contained within a pressure transmission medium. Pressure transmission media are known in the art and include liquid and solid materials. The pressure transmission medium may be the same as the fluid absorbed by the sorption caloric material, or the pressure transmission medium may be different from the fluid absorbed by the sorption caloric material.

[0125] An example of a pressure transmitting liquid is an alkoxysilane material such as DW-Therm available from Huber Kaltemaschinenbau GmbH. An example of a pressure transmitting solid is alumina powder.

[0126] The pressure may be applied near a transition temperature of the sorptive caloric material, for example, the pressure may be applied at a temperature within 50 K, such as within 20 K, for example within 15 K, for example within 10 K, for example within 5 K, for example within 2 K, for example within 1 K, for example within 0.5 K of the transition temperature.

[0127] In some embodiments, the fluid absorbed into the sorbtiocaloric material is water. In these embodiments, hydrostatic pressure may be applied to contact the water with the sorbtiocaloric material so that the water molecules are absorbed into the sorbtiocaloric material. The fluid may be contacted with the sorbtiocaloric material in the presence of a secondary fluid, which may be to promote absorption. The fluid may be contacted with the sorbtiocaloric material in a nitrogen atmosphere. The nitrogen atmosphere may be pressurized / depressurized to promote the absorption / desorption process.

[0128] The method comprises the following steps: (iv) releasing the fluid so that the fluid is desorbed out of the sorptive caloric material and induces a reverse structural phase transition; and (v) enabling heat flow to or from the sorptiocaloric material; It may further include:

[0129] The method can thus form a complete heating and cooling cycle.

[0130] Steps (iv) and (v) may be performed immediately after steps (i) to (iii). Steps (iv) and (v) may also be performed at a later time, for example, after the sorptive caloric material has been transported, allowing the process of the present invention to be used for heat transfer between different locations.

[0131] Steps (i) to (v) are preferably carried out in order.

[0132] In the method of the present invention, the sorption caloric material may be used with a heat transfer fluid, and heat can be transferred to or from the heat transfer fluid. The heat transfer fluid is typically a liquid. The heat transfer fluid can transfer heat to the sorption caloric material, thereby causing relative cooling of the heat transfer fluid. The cooled heat transfer fluid can then be removed from the sorption caloric material and delivered to a location where cooling is desired.

[0133] The heat transfer fluid can receive heat transfer from the sorption caloric material, thereby causing a relative cooling of the sorption caloric material. The heated heat transfer fluid can then be removed from the sorption caloric material and delivered to a location for cooling, such as a radiator or another such heat exchanger, for example for cooling to room temperature.

[0134] The heat transfer fluid may be different from the fluid absorbed by the sorptive caloric material, or these fluids may be the same. Preferably, the fluid contacted with the sorptive caloric material in step (ii) may itself be used as the heat transfer fluid. In these embodiments, the fluid is preferably water or carbon dioxide.

[0135] The heat transfer fluid does not necessarily have to be in direct contact with the sorptive caloric material; heat transfer can occur via a heat exchanger. The heat exchanger can use a thermal switch, such as a thermoelectric thermal switch, an electromechanical thermal switch, a solid-state thermal diode, or a heat pipe. The use of these types of miniature switches can improve the design of cooling devices and enhance their energy efficiency.

[0136] In the method of the present invention, the sorptiocaloric material and fluid may be used to store heat generated by the sorptiocaloric effect. For example, the fluid may store heat energy that can be absorbed in the sorptiocaloric material (step (ii)) and released at a selected time and place in step (iv).

[0137] In some embodiments, the method includes storing heat in a heat storage fluid between steps (iii) and (iv).

[0138] The heat storage fluid may be different from the fluid absorbed in the sorption caloric material, or these fluids may be the same. Preferably, the fluid contacted with the sorption caloric material in step (ii) may itself be used as the heat storage fluid. Because heat is released from the fluid, for example, upon release of pressure, these fluids can be used in pressure-controlled storage devices that do not exhibit energy loss. This is particularly useful for transporting heat over long distances. In these embodiments, the fluid is preferably carbon dioxide.

[0139] The sorptive caloric material may also be used in conjunction with a heat reservoir to modify or increase the temperature range of operation. The sorptive caloric material may itself be used as a heat reservoir.

[0140] The caloric effect observed in sorptive caloric materials can be realized at relatively low pressures, which can be lower than typical pressure caloric effects.

[0141] The methods of the invention may be for use in one or more of the following: Cooling food or beverages; Refrigeration of pharmaceutical products; Cooling of biological samples such as tissue; Cooling of electronic devices, such as devices for analytical measurements; and Cooling of air, such as the air in a building or vehicle.

[0142] Also provided herein is the use of a sorption caloric material as a cooling or heating material, comprising contacting the sorption caloric material with a fluid such that the fluid is absorbed throughout the sorption caloric material to induce a phase transition. Contacting the sorption caloric material with the fluid induces a phase transition, for example a reversible phase transition, for example a reversible first-order phase transition, of the sorption caloric material. The preferences and features described for the method of the present invention equally apply to the use of the sorption caloric material as a cooling or heating material.

[0143] Cooling or heating equipment The present invention provides a cooling or heating device containing a sorption caloric material as described herein, the cooling or heating device being adapted to provide caloric cooling or heating using the sorption caloric material.

[0144] The cooling or heating device includes a sorption caloric material and a means for reversibly contacting the sorption caloric material with a fluid such that the fluid is absorbed by the sorption caloric material and induces a phase transition. Typically, the cooling or heating device further includes a means for transferring heat to or from the sorption caloric material. This means may be a heat transfer fluid, which may be the fluid absorbed by the sorption caloric material, or may be a separate heat transfer fluid.

[0145] The sorptiocaloric material may undergo a phase transition induced by absorption or desorption of guest molecules. The absorption or desorption may be under applied pressure. Thus, the cooling or heating device may further comprise means for applying pressure, such as hydrostatic pressure, to the sorptiocaloric material.

[0146] The chiller may be used to cool food and beverages, and thus may be a component of a refrigerator or freezer. The chiller may find general application in cooling air, and thus may be a component of an air conditioning unit.

[0147] In another aspect of the invention, there is more generally provided a heat engine for transferring heat between environments, the heat engine comprising a sorptive caloric material as described herein.

[0148] While the primary use of refrigerants is in refrigerators and air conditioning units, the underlying principles of the mechanism for cooling an environment can also be used to heat an indoor environment, for example, in an air-source heat pump. In this case, a cold sorptiocaloric material in a first phase can be warmed by the outdoor ambient environment (including indirectly via a heat transfer fluid). The warmed sorptiocaloric material can then be transported to a second phase (including indirectly via a heat transfer fluid) with heat transfer from the ambient environment to the sorptiocaloric material. The sorptiocaloric material can then be returned to the indoor environment, where it can return to the first phase with heat transfer from the sorptiocaloric material to the indoor environment. There may be intermediate stages between the first and second phases.

[0149] Other embodiments All compatible combinations of the above embodiments are expressly disclosed herein as if each and every combination were individually and expressly recited. Various further aspects and embodiments of the present invention will be apparent to those skilled in the art in view of the present disclosure.

[0150] "And / or," as used herein, is considered a specific disclosure of each of the two specified features or components, with or without the other. For example, "A and / or B" is considered a specific disclosure of (i) A, (ii) B, and (iii) each of A and B, as if each were individually set forth herein.

[0151] Unless the context dictates otherwise, the above feature descriptions and definitions are not limited to any particular aspect or embodiment of the invention, but apply equally to all aspects and embodiments described.

[0152] Certain aspects and embodiments of the present invention will now be described, by way of example, and with reference to the figures mentioned above. [Example]

[0153] Several exemplary systems were prepared and tested.

[0154] material The materials used in this example were prepared according to the following procedure.

[0155] Synthesis of MIL-53(Fe) In a small glass beaker, 0.541 g of iron(III) chloride hexahydrate (FeCl3·6H2O) and 0.334 g of terephthalic acid were added to 10 mL of DMF (1:1:65 molar ratio) and stirred until the solids dissolved. The solution was then transferred to a 23 mL Parr Acid Digestion Bomb and placed in a Heraeus oven at 423 K for 72 h, then cooled to room temperature. An orange powder was then collected by vacuum filtration, washed three times with approximately 3 mL of DMF, and placed in a vacuum oven at 423 K overnight to yield desolvated MIL-53(Fe).

[0156] Synthesis of ZIF-4 In a glass bottle, 1.202 g of zinc(II) nitrate hexahydrate and 0.909 g of imidazole were added to 90 mL of DMF and stirred until the solids dissolved (molar ratio 4:13:860, as performed by Wharmby et al.). The bottle was placed in a Heraeus oven at 373 K for 72 h, then removed and cooled to room temperature. Vacuum filtration was used to obtain a white ZIF-4 powder, which was subsequently washed three times with 3 mL of DMF and dried in air for 24 h. More sample was obtained by pouring the filtrate back into the glass bottle and returning it to the oven two more times, each time following the vacuum filtration process. ZIF-4(DS) was obtained by placing the pristine ZIF-4-as sample in a vacuum oven at 423 K for 5 h.

[0157] Synthesis of ZIF-7 1.602 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and 0.471 g of benzimidazole were dissolved in 150 mL of DMF (molar ratio 4:5:2000, as described by Wu et al. [Ref. 79]) under magnetic stirring. The solution was then transferred to two sealed 100 mL Teflon autoclaves and heated at 403 K for 48 h. Vacuum filtration was used to obtain pale white ZIF-7 crystals, which were subsequently washed three times with 3 mL of DMF, air-dried, and then placed in a capped glass vial.

[0158] Synthesis of MIL-53(Al) 1.309 g of aluminum(III) nitrate nonahydrate (Al(NO3)3·9H2O) and 0.287 g of terephthalic acid were added to 8.7 ml of deionized water (molar ratio 2:1:160, as reported by Loiseau et al.) and stirred until the solids dissolved. The solution was then transferred to a 23 ml Parr Acid Digestion Bomb and heated at 493 K for 72 h, then cooled to room temperature. The white powder was vacuum filtered, washed three times with deionized water, and placed in an oven at 573 K for 2 h to ensure that excess terephthalic acid molecules were expelled from the pores. X-ray diffraction of the sample was performed after 16 h.

[0159] method In this example, the following method was used.

[0160] Differential scanning calorimetry (DSC) DSC measurements were performed on all samples using a TA Instruments Q2000 ambient-pressure DSC with a linear temperature gradient heat flux DSC method over an operating temperature range of 123–673 K. A liquid nitrogen cooling system was used to cool the sample chamber below room temperature. Samples of MOFs weighing 5–20 mg or polymer hydrogels weighing 25–32 mg were placed in aluminum crucibles and sealed to prevent solvent or water loss during the run. They were then inserted into a DSC autosampler along with a sealed, empty aluminum crucible as a reference. The autosampler transported them into the thermally isolated sample chamber for measurement.

[0161] Heat flow measurements were used to calculate the entropy change rather than heat capacity measurements because using conventional measurements would require much more detailed analysis by performing multiple runs on calibration samples of known heat capacity, such as indium or sapphire, before and after each sample run to obtain an accurate heat capacity value for each sample.

[0162] Sorptive caloric effect in MIL-53(Fe) In this example, we investigate MIL-53(Fe) to evaluate the zero-field thermally driven entropy change of this material, which is a good indicator of how well they can perform as solvatiocaloric materials. MOFs are synthesized using solvothermal or hydrothermal techniques, which require metal salts and organic ligand sources dissolved in solvents or water, respectively.

[0163] Metal-organic frameworks are materials consisting of hybrid structures constructed using metal ions or clusters and organic ligands. The combination of these two heterogeneous components offers a wide range of structural design opportunities, with the advantage of corresponding dimensionality and large tunability of topology, which are key to the fluid sorption properties of these material systems. This structural diversity allows for tuning of properties such as density, porosity, electrical properties, and magnetic properties. In particular, some of these hybrid materials can achieve large porosity and have very large values ​​of surface area-to-mass ratio (approximately 6,000 m). 2 / g). As a result, several metal-organic frameworks have been reported to be highly efficient gas absorbents, for example, for harmless nitrogen gas, CO2, or water, either by adsorption of molecules on the surface or by absorption within the bulk of the material. These adsorption or absorption processes are collectively labeled sorption processes and involve the formation or scission of chemical bonds or van der Waals interactions.

[0164] These sorption capabilities are one aspect of the dynamic properties of metal-organic frameworks under external stimuli. In addition to their flexibility under temperature and pressure changes, these porous materials undergo reversible structural transitions triggered by the sorption of guest molecules. These include a breathing transition, which involves the displacement of framework atoms between narrow-pore (np) and large-pore (lp) morphologies induced by sorption and thermomechanical stimuli, and a swelling transition, which results in the gradual expansion of the framework upon absorption, usually while retaining the unit cell shape and space group. Accordingly, such transitions are accompanied by volume changes in the metal-organic framework, which arise from the formation of intermolecular bonds between the absorbent and framework molecules at the pore walls, usually hydrogen bonds (H-bonds) that lead to physisorption.

[0165] Certain metal-organic frameworks are grouped into families based on common features such as structural similarity and are known to exhibit characteristic structural flexibility. The thermal properties of selected MOFs are shown in Table 1.

[0166] The MIL family (MIL = Materials of Institut Lavoisier) consists of trivalent metal cations in nodes connected by carboxylate ligands, generating porous structures that exhibit typical flexibility. In particular, the MIL-53 group, consisting of nodes octahedrally coordinated by terephthalate (1,4 benzenedicarboxylate), is well known to exhibit a flexible breathing mode, while the MIL-88 group, consisting of a trimer of nodes connected by ligands forming a trigonal bipyramidal cage, exhibits swelling (Mellot-Draznieks et al.).

[0167] Zeolite-imidazolate frameworks (ZIFs) are another family of metal-organic frameworks known to possess dynamic structures. ZIFs, which are isostructural to zeolites, consist of transition metal ions tetrahedrally coordinated to imidazolate ligands, where the metal-imidazolate metal angle is 145°, similar to the Si O Si angle in zeolites. In addition to exhibiting breathing transitions (Henke et al., Gandara-Loe et al.), many ZIFs are known to undergo reconfiguration and dislocation phase transitions due to linker rotations induced by changes in temperature, pressure, and sorption (Ryder et al.), which can lead to large volume and entropy changes (Wharmby et al.).

[0168] [Table 1]

[0169] Initially, upon heating to T≈313 K, the low-temperature hydrated MIL-53(Fe)-lt structure [monoclinic (C2 / c)] dehydrates and transforms into the intermediate triclinic (P1) anhydrous phase, MIL-53(Fe)-int, undergoing a volume loss of approximately 94 Å (9.6%). Further heating to T≈423 K produces the stable anhydrous high-temperature MIL-53(Fe)-ht structure, followed by a small 0.8% increase in unit cell volume. However, because the intermediate phase is still fully dehydrated, we use the lower T and the relatively large volume change from the lt←→int transition to explore the caloric effects around this sorption-driven phase transition in MIL-53(Fe).

[0170] A particularly interesting transition in MIL-53(Fe) is the dehydration / hydration-induced structural transition, which occurs at approximately 320 K. This transition was first investigated by ambient pressure calorimetric measurements using a TA Q2000 with hydrated MIL-53(Fe)-1 powder sealed in a sealed sample holder, yielding |dT / dt| = 2 K min. -1 During this time, heat flow peaks from the first-order transition were clearly observed during heating and cooling (Fig. 1).

[0171] The peak in Figure 1 shows very low hysteresis (about 1.5 K), and the dehydration / hydration process in MIL-53(Fe) induces a transition spanning about 30 K at T about 308 K, with |ΔS0| about 14.4 JK. -1 kg -1 This indicates that

[0172] The Clausius-Clapeyron relationship for volume and pressure is not applicable to this example because the phase transition accompanying the volume change in the MIL-53(Fe) structure is not directly induced by the change in pressure, but rather by the sorption and desorption of guest molecules (i.e., water) in the thermodynamic system.

[0173] Since the high-temperature phase of MIL-53(Fe) has a smaller volume (ΔV / V = -9.6% upon heating), the dehydrated phase should stabilize under higher applied p, resulting in an inverse caloric effect. However, the results clearly show a conventional caloric effect, since dT / dp > 0. The hydrated phase stabilizes at higher p, despite its larger volume than the dehydrated phase. This suggests that the free energy of the hydrated system decreases with increasing pressure, possibly due to enthalpy stabilization, a phenomenon commonly observed in MOFs, demonstrating that the transition is driven by the absorption and desorption of water molecules.

[0174] Furthermore, hydration induces a maximum increase in the unit cell volume, ΔV / V, of 10.6% in the MIL-53(Fe) structure. This ΔV / V value, along with the bulk density, ρ, of the dehydrated phase, is approximately 1.06 g cm. -3 and initial thermal drive associated with dehydration-hydration transition |ΔS0| approx. 14.4 JK -1 kg -1 Using the Clausius-Clapeyron relation to estimate dT0 / dp, |dT0 / dp| is approximately 694K kbar. -1 is calculated, which is unrealistically high and inconsistent with experimental data (see Figure 2(b)).

[0175] Thus, the latent heat Q and ΔS from this phase transition, which produces the sorptive caloric effect in this absorber-absorbate system, are not solely due to the volume change of the absorber structure, but rather to the interaction between the absorber and absorbate, including bond formation and bond breaking, and the subsequent effects on the total bond energy in the entire thermodynamic system (including effects on bond rotation and bond vibration). It is not an interaction between a small volume phase and a large volume phase, but rather an interaction between the absorbed and desorbed states. Note that N2 is required here to support this effect, since an experimental system using only water is under construction. Without the guest molecule (water), no such transition occurs, and therefore no caloric effect occurs with pressure changes. A water-free reference sample does not exhibit the transition.

[0176] Figure 3 shows the sorptive caloric effect exhibited by this material, which is highly reversible due to the small hysteresis of the dehydration / hydration transition.

[0177] References A number of publications have been cited above in order to more fully describe and disclose the present invention and the state of the art to which it pertains. Full citations for these references are set forth below. Each of these references is incorporated herein in its entirety. Boldrin, Appl. Phys. Lett. 119, 2021 Gandara-Loe et al., J. Mater. Chem. A 7(24), 2019 Horcajada et al., Nat. Mater. 9(2), 2010 Henke et al., Chem. Sci. 9(6), 2018 Llewellyn et al., Langmuir 24(14), 2008 Lloveras et al. Nature Commun. 2015, 6, Article no. 8801 Mellot-Draznieks et al., J. Am. Chem. Soc. 127(46), 2005 Ryder et al., Phys. Rev. Lett. 113(21), 2014 Shahrak et al., Chin. J. Chem. Eng. 25(5), 2017 Wharmby et al., Angew. Chem. Int. Ed. 54(22), 2015 Zhang et al., Sci. Rep. 4, 2014

Claims

1. A method of thermal cooling or heating, comprising: (i) providing a sorptive caloric material; (ii) contacting the sorptive caloric material with a fluid such that the fluid is at least partially absorbed into the sorptive caloric material to induce a phase transition; (iii) allowing heat flow to or from the sorption caloric material; (iv) releasing the fluid so that the fluid is desorbed from the sorptive caloric material and a reverse phase transition is induced; and (v) enabling heat flow to or from the sorption caloric material. A method comprising:

2. Sorptiocaloric materials as cooling or heating agents; means for transferring heat to and from said sorption caloric material; and means for reversibly contacting said sorption caloric material with said fluid so that said fluid is absorbed into said sorption caloric material; A cooling or heating device comprising:

3. 1. Use of a sorptiocaloric material as a cooling or heating material, comprising contacting said sorptiocaloric material with a fluid such that the fluid is absorbed throughout said sorptiocaloric material to induce a phase transition.

4. 4. The method, device or use of any one of claims 1 to 3, wherein the sorptiocaloric material is porous.

5. 5. The method, device or use of claim 4, wherein the sorptive caloric material comprises pores having a diameter in the range of 0.1 to 5 nm.

6. 5. The method, device or use of claim 4, wherein the sorptive caloric material comprises pores having a diameter in the range of 0.5 to 1.5 nm.

7. The sorptive caloric material is 0.1 cm 3 g -1 ~10cm 3 g -1 , e.g., 1 cm 3 g -1 ~5cm 3 g -1 , or 1 cm 3 g -1 ~3cm 3 g -1 7. The method, apparatus or use according to any one of claims 4 to 6, wherein the pore volume is

8. 8. The method, device or use according to any one of claims 1 to 7, wherein the sorptive caloric material is a crystalline structure, such as a porous crystalline structure.

9. 9. The method, apparatus or use of claim 8, wherein the crystalline structure is an open structure material.

10. The sorptive caloric material is selected from metal organic frameworks and covalent organic frameworks, preferably The sorptive caloric material is selected from covalent organic frameworks and metal organic frameworks of the MIL family, such as MIL-53, e.g., MIL-53(Fe), 10. The method, device or use according to any one of claims 1 to 9.

11. 11. The method, apparatus or use of claim 10, wherein the sorptive caloric material comprises a metal organic framework.

12. The metal organic framework is a metal organic framework of the MIL family or ZIF family, for example, MIL-53, including MIL-53(Fe), MIL-53(Al), MIL-53(Cr), and MIL-53(Ga), or MIL-47(V). IV 12. The method, device or use of claim 11, wherein the sorptive caloric material is MIL-47; MIL-100 and MIL-101; or ZIF-4 and ZIF-7, and preferably the sorptive caloric material is a metal organic framework of the MIL family, such as MIL-53(Fe).

13. 13. The method, apparatus or use of claim 11 or 12, wherein the fluid is selected from carbon dioxide, water and methane.

14. 11. The method, apparatus or use of claim 10, wherein the sorptive caloric material comprises a covalent organic framework.

15. 15. The method, apparatus or use of claim 14, wherein the covalent organic framework is selected from COF-1, COF-5, COF-6, COF-8, and COF-10.

16. 16. The method, apparatus or use of claim 14 or 15, wherein the fluid is carbon dioxide.

17. 17. The method, apparatus or use of any one of claims 1 to 16, wherein the fluid is a benign fluid, optionally selected from nitrogen, carbon dioxide and water.

18. 17. The method, apparatus or use of any one of claims 1 to 16, wherein the fluid comprises water.

19. 19. The method, apparatus or use of any one of claims 1 to 18, wherein the fluid further provides heat transfer to and from the sorption caloric material.

20. The phase transition in the sorptive caloric material is 10 kJ kg -1 More than, for example, 25kJ kg -1 More than, for example, 50kJ kg -1 More than, for example, 100kJ kg -1 More than, for example, 250kJ kg -1 More than, for example, 500kJ kg -1 The latent heat, which is greater than or equal to |Q 0 20. The method, device or use according to any one of claims 1 to 19, wherein |

21. The sorptive caloric material is 5J K -1 kg -1 For example, 10J K -1 kg -1 For example, 15J K -1 kg -1 The entropy change at the phase transition, |ΔS 0 21. The method, device or use of any one of claims 1 to 20, comprising |

22. 22. The method, apparatus or use of any one of claims 1 to 21, wherein the sorptive caloric material has a phase transition at a temperature in the range of 200 to 450K, such as 250 to 350K, such as 280 to 340K.

23. 23. The method, device or use of any one of claims 1 to 22, wherein the phase transition of the sorptive caloric material is a first order phase transition.

24. 24. The method, device or use of any one of claims 1 to 23, wherein the phase transition of the sorptive caloric material is a first order structural phase transition, such as between symmetric groups.

25. 25. The method or use of any one of claims 1 and 3 to 24, wherein the sorptiocaloric material is contacted with the fluid at a pressure of at most 500 MPa, such as at most 200 MPa, for example at most 100 MPa, such as at most 50 MPa, for example at most 25 MPa, such as at most 20 MPa, for example at most 10 MPa, such as at most 5 MPa.

26. The fluid is 10 cm 3 g -1 or more, for example, 50cm 3 g -1 or more, for example, 50 to 500 cm 3 g -1 26. The method, device or use of any one of claims 1 to 25, wherein the amount of

27. 27. The method or use of any one of claims 1 and 3 to 26, wherein the sorptive caloric material having absorbed fluid therein is used for heat storage.

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