Preparation and application of pressing and clamping refrigeration material
By using press-lock refrigeration materials prepared by methyl palmitate and methyl stearate, the inefficiency and environmental pollution of traditional refrigeration technology are solved, and the effect of efficient refrigeration at near room temperature and low pressure is achieved.
Patent Information
- Application Number
- CN202410112098.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-26
- Publication Date
- 2025-07-29
AI Technical Summary
The prior art is difficult to achieve efficient pressure-clog refrigeration under near room temperature and low pressure conditions. Traditional gas compression refrigeration has low efficiency and high energy consumption, and hydrofluorocarbon refrigerant is harmful to the ozone layer.
Methyl palmitate and/or methyl stearate are used as pressure-clamp refrigeration materials and prepared by mechanical mixing at constant temperature to form a mechanical mixture of methyl palmitate/methyl stearate (BFAME), which exhibits high isothermal entropy and adiabatic temperature change under pressure less than 100 MPa.
It realizes efficient refrigeration under near room temperature and low pressure conditions, with a wide phase transition temperature range and a high pressure clamping effect, reducing refrigeration energy consumption and reducing environmental pollution.
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Figure CN120383916A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of barocaloric refrigeration, and specifically to the preparation and application of a barocaloric refrigeration material. Background Art
[0002] Refrigeration technology is closely related to today's human society and is widely used in fields such as aerospace and air-conditioning refrigeration. According to statistics, 20-25% of the global electricity is used in refrigeration technology. Most of the current refrigeration technologies are mainly based on traditional gas compression refrigeration, which brings great convenience but also has the disadvantages of low efficiency and high energy consumption. It is worth noting that the emissions of gas compression refrigeration using hydrofluorocarbons as refrigerants are thousands of times more harmful to the ozone layer than CO2, which will exacerbate the greenhouse effect.
[0003] Therefore, in order to achieve the goal of "carbon neutrality", the use of low-emission technologies to replace traditional gas compression refrigeration technology has attracted more and more attention.
[0004] Refrigeration technology based on thermal effects is an environmentally friendly technology and one of the promising alternatives to traditional refrigeration. Thermal effects are usually generated by applying external fields such as magnetic fields, electric fields, and pressure fields. Specific materials undergo phase transitions under the drive of external fields, generating entropy change and temperature change to achieve the refrigeration effect. According to different external fields, thermal effects can be divided into magneto-(caloric) effect, electrocaloric (caloric) effect, elastocaloric (caloric) effect, and barocaloric (caloric) effect. Among them, the barocaloric effect is a thermal effect of phase change, temperature change, and entropy change caused by pressure. When a substance changes its state (solid, liquid, and gas) under the action of external conditions, it will undergo a significant configurational change, resulting in a drastic entropy change. Isothermal entropy change and adiabatic temperature change are important indicators for evaluating the refrigeration performance of solid-state phase change materials.
[0005] Different from other thermal effects, solid-liquid transformation materials exhibit obvious volume changes due to density changes, making them respond better to external pressure and can be used for the barocaloric effect. The barocaloric effect does not have system selectivity, so it can be observed in many materials, such as organic-inorganic hybrid materials, plastic crystals, ferroelastic materials, etc. In the field of barocaloric refrigeration, with the discovery of the giant barocaloric effect in plastic crystals, the rapid development of barocaloric materials has been launched. Its entropy change has also increased from dozens of traditional materials to over a hundred J / kg·K. At the same time, even though great progress has been made in current research and the driving pressure has dropped below 100 MPa, the most difficult challenge to overcome in actual production applications is that barocaloric materials are required to have high entropy change or adiabatic temperature change at room temperature or near room temperature under low driving pressure. However, the isothermal entropy change of most current solid-state phase change materials is difficult to exceed 100 J / kg -1 K -1 , and its adiabatic temperature change is also difficult to exceed 20 K. Summary of the Invention
[0006] In order to solve the problems of the existing technology, the object of the present invention is to overcome the deficiencies of the existing technology, and to provide a pressure-caloric refrigeration material and its formulation, preparation method and application, so as to realize refrigeration applications under near-room temperature and low-pressure conditions.
[0007] One object of the present invention is to provide a formulation of a pressure-caloric refrigeration material, which is composed of methyl palmitate and / or methyl stearate.
[0008] For the formulation of the pressure-caloric refrigeration material, the preferred ratio is:
[0009] Methyl palmitate: 84.2 wt.%;
[0010] Methyl stearate: 15.8 wt.%.
[0011] The preferred purity of the two components in the formulation of the pressure-caloric refrigeration material is 99.0%.
[0012] Another object of the present invention is to provide a preparation method of a pressure-caloric refrigeration material, which is prepared by using the above-mentioned formulation of the pressure-caloric refrigeration material, and has any one of the following technical features:
[0013] A. When the formulation of the pressure-caloric refrigeration material is a single component, the single component is the pressure-caloric refrigeration material;
[0014] B. When the formulation of the pressure-caloric refrigeration material is two components, preferably, the two components are mechanically mixed in a constant-temperature environment to obtain the pressure-caloric refrigeration material.
[0015] In the preparation method of the pressure-caloric refrigeration material, when the two components are mixed, the preferred parameters are: constant temperature of 60 °C and mechanical stirring for 30 min.
[0016] A third object of the present invention is to provide a pressure-caloric refrigeration material, which is prepared by the above-mentioned preparation method of the pressure-caloric refrigeration material.
[0017] Preferably, the pressure-caloric refrigeration material has a refrigeration capacity under near-room temperature and a pressure condition of ≤100 MPa.
[0018] Preferably, when the hydrostatic pressure of the pressure-caloric refrigeration material is ≤100 MPa, it has at least one of the following technical features:
[0019] A. The phase change temperature range is between 292 and 326 K;
[0020] B. The thermal hysteresis is between 6 and 10 K;
[0021] C. The pressure-caloric effect is between 500 and 740 J kg-1 K -1 Isothermal entropy change of
[0022] D. The phase transition temperature pressure sensitivity coefficient is between 0.10 and 0.15 K / MPa -1 Between.
[0023] Fourth, the object of the present invention is to provide the above-mentioned magnetocaloric refrigeration material for use in a magnetocaloric refrigerator, which has refrigeration capacity at near room temperature and ≤100 MPa.
[0024] Preferably, the magnetocaloric refrigeration material is a single-component methyl palmitate or methyl stearate, or a mechanical mixture of two components, methyl palmitate and methyl stearate.
[0025] Compared with the prior art, the beneficial effects of the present invention are:
[0026] The formula of a magnetocaloric refrigeration material provided by the present invention is composed of one or two raw materials. The formula is simple, the mixing compatibility between the raw materials is good, and it is easy to disperse evenly.
[0027] The preparation method of a magnetocaloric refrigeration material provided by the present invention has simple process steps, has no special requirements for equipment, and has strong operability.
[0028] A magnetocaloric refrigeration material provided by the present invention has a phase transition temperature close to room temperature and has a wide phase transition temperature range (292 - 326 K) at
[0029] ≤100 MPa pressure, and has a large magnetocaloric effect (500 - 740 J / kg -1 K -1 ) under a small driving pressure (≤100 MPa), and has good dT t / dP sensitivity.
[0030] The application of the magnetocaloric refrigeration material provided by the present invention, a single-component methyl palmitate or methyl stearate, or a mechanical mixture of methyl palmitate and methyl stearate in a certain proportion, is suitable for refrigeration applications under near room temperature and low pressure conditions. Compared with traditional solid-solid phase change materials, only a lower pressure is required to generate a higher isothermal entropy change and adiabatic temperature change in the solid-liquid phase change material. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 For the dQ / dT curves of MP( Figure 1 (A)), MS( Figure 1 (B)) and BFAME( Figure 1 )(C) at atmospheric pressure in the present invention;
[0032] Figure 2 For MP in the present inventionFigure 2 (A)), MS( Figure 2 (B)), and BFAME( Figure 2 (C)) dQ / dT curves at different pressures of P = 0.1, 20, 40, 60, 80 MPa;
[0033] Figure 3 For MP in the present invention, at P = 0.1, 20, 40, 60, 80, and 100 MPa, respectively, during cooling ( Figure 3 (A)) and heating ( Figure 3 (B)), the entropy change ΔS of solid-liquid transformation L-S ;
[0034] Figure 4 For MS in the present invention, at P = 0.1, 20, 40, 60, 80, and 100 MPa, respectively, during cooling ( Figure 4 (A)) and heating ( Figure 4 (B)), the entropy change ΔS of solid-liquid transformation L-S ;
[0035] Figure 5 For BFAME in the present invention, at P = 0.1, 20, 40, 60, 80, and 100 MPa, respectively, during cooling ( Figure 5 (A)) and heating ( Figure 5 (B)), the entropy change ΔS of solid-liquid transformation L-S ;
[0036] Figure 6 For MP( Figure 6 (A)), MS( Figure 6 (B)), and BFAME( Figure 6 (C)), the isothermal entropy change from P = 0.1 MPa to 20, 40, 60, 80, and 100 MPa
[0037] Figure 7 For the solid-liquid transformation temperature-pressure diagram and the phase transition temperature-pressure sensitivity coefficient of BFAME in the present invention. Detailed implementation manners
[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.
[0039] For easy understanding, first, the abbreviations or names mentioned in the following text are explained:
[0040] MP: Methyl palmitate, the solid sample was purchased from Aladdin with a purity of 99.0%;
[0041] MS: Methyl stearate, the solid sample was purchased from Aladdin with a purity of 99.0%;
[0042] The pressure values all refer to the hydrostatic pressure.
[0043] Example 1
[0044] 100% MP.
[0045] Example 2
[0046] 100% MS.
[0047] Example 3
[0048] In this example, the raw materials were 84.2 wt.% MP and 15.8 wt.% MS;
[0049] MP and MS were added to a container and mechanically stirred for 30 min under a water bath condition of 60 °C to obtain a binary fatty acid methyl ester material, labeled as BFAME.
[0050] Performance testing and characterization:
[0051] I. Thermodynamic testing under atmospheric pressure:
[0052] Using a DSC (μDSC7, Setaram) produced by Setaram, the atmospheric pressure heat flow curves of the materials obtained in the three examples were respectively tested. The test pressure was 0.1 MPa and the test rate was 2 K·min -1 , nitrogen gas was introduced into the two sample cells using a pressurizing device. At this time, the atmospheric pressure state (0.1 MPa) was maintained, and it was heated from 271 K to 333 K at a heating rate of 2 K / min, and then cooled to 271 K. The heat flow data of the samples were recorded, as Figure 1 shown. All three materials had clear initial transition temperatures. The latent heat of heating and the latent heat of cooling were calculated by integrating the DSC curves. The results are shown in Table 1. It shows that for the BFAME material, it had a phase transition temperature close to room temperature (292 K) during the phase transition process
[0053] Table 1 Phase transition temperatures, latent heat of heating and latent heat of cooling of MP, MS and BFAME materials
[0054]
[0055] II. Pressure - heat effect testing
[0056] Using a DSC (μDSC7, Setaram) produced by Setaram, the atmospheric pressure heat flow curves of the materials obtained in the three examples were respectively tested. The test pressure range was from 0.1 MPa to 100 MPa, and a pressure point was taken at intervals of 20 MPa. The test rate was 2 K·min -1 。The samples of the examples were respectively placed into an airtight high-pressure sample cell. One end of a K-type thermocouple was sealed with the sample of the example in a capsule, and the other end was sealed with a reference compound in another capsule. Then they were all placed into a DTA cell made of Teflon, and Daphne 7373 was used as the pressure medium. The Teflon cell was inserted into a Be-Cu-based pressure cylinder, and hydrostatic pressure was applied through a hydraulic press. An annular heating sheet was pasted on the outer surface of the cylinder for temperature control of the liquid nitrogen dewar. The sample was encapsulated in a high-pressure container, and the required pressure was generated by high-pressure nitrogen controlled by a high-pressure gas panel. Using the high-pressure gas control panel, pure nitrogen was introduced to keep the gas pressure constant at a predetermined pressure value (such as 0.1 MPa, 20 MPa, 40 MPa, 60 MPa, 80 MPa, and 100 MPa), and then it was heated from 271 K to 333 K at a heating rate of 2 K / min, and then cooled (cooling rate was 2 K / min) to 271 K and the heat flow data of the sample was recorded. The above measurement process was repeated, replacing the predetermined pressure value, and the heat flow data at different pressures was recorded.
[0057] As Figure 2 shown, they are the DSC curves of the three materials at different pressures. It can be seen that according to the measurement of dQ / dT at different pressures, the transition temperatures of the three materials basically increase with the increase of pressure, that is, pressure can drive the phase transition temperature to move towards the high-temperature region. Compared with atmospheric pressure, a pressure of 100 MPa will cause the phase transition temperature of MP( Figure 2 (A)) during the heating process to move by about 13 K, and the phase transition temperature during the cooling process to move by about 10 K (the pressure sensitivity coefficient of the phase transition temperature is 0.13 K MPa during the heating process -1 , and 0.10 K MPa during the cooling process -1 ); a pressure of 100 MPa will cause the phase transition temperature of MS( Figure 2 (B)) during the heating process to move by about 14 K, and the phase transition temperature during the cooling process to move by about 12 K (the pressure sensitivity coefficient of the phase transition temperature is 0.14 K MPa during the heating process -1 , and 0.12 K MPa during the cooling process -1 ); a pressure of 80 MPa will cause the phase transition temperature of BFAME( Figure 2 (C)) during the heating process to move by about 10 K, and the phase transition temperature during the cooling process to move by about 8 K (the pressure sensitivity coefficient of the phase transition temperature is 0.15 K MPa during the heating process -1 , and 0.11 K MPa during the cooling process-1 )。It shows that the BFAME material has a small thermal hysteresis (6 - 10 K).
[0058] Combined Figure 1 with Figure 2 it can be seen that the sample materials of the three examples have a wide phase transition temperature range (292 - 326 K) at ≤ 100 MPa.
[0059] III. Related parameters of solid - liquid transition
[0060] The heat - flow data obtained from the above tests was converted into entropy - change data. The subtraction of the two lines gives the entropy change when the pressure increases from 0.1 MPa to 20 MPa, 40 MPa, 60 MPa, 80 MPa, and 100 MPa.
[0061] Figure 3 Let ΔS be the entropy change of solid - liquid transition of MP during cooling and heating at P = 0.1, 20, 40, 60, 80, and 100 MPa respectively L-S . For the cooling process ( Figure 3 (A)), the maximum value of ΔS of MP L-S increases with the increase of the applied pressure, and the maximum value is 736 J Kg -1 K -1 at 100 MPa; for the heating process ( Figure 3 (B)), the maximum value of ΔS of MP L-S increases with the increase of the applied pressure, and the maximum value is 726 J Kg -1 K -1 .
[0062] Figure 4 Let ΔS be the entropy change of solid - liquid transition of MS during cooling and heating at P = 0.1, 20, 40, 60, 80, and 100 MPa respectively L-S . For the cooling process ( Figure 4 (A)), the maximum value of ΔS of MS L-S increases with the increase of the applied pressure, and the maximum value is 708 J Kg -1 K -1 at 100 MPa; for the heating process ( Figure 4 (B)), the maximum value of MS increases with the increase of the applied pressure, and the maximum value is 714 J Kg -1 K -1 .
[0063] Figure 5 Let ΔS be the entropy change of solid - liquid transition of BFAME during cooling and heating at P = 0.1, 20, 40, 60, and 80 MPa respectively L-S . For the cooling process (Figure 5 (A)), the maximum value of the entropy change of BFAME increases with the increase of the applied pressure, and a maximum value of 670 J kg is obtained at 80 MPa -1 K -1 ; for the heating process ( Figure 5 (B)), the maximum value of the entropy change of BFAME The temperature caused by the simple solid-liquid phase change shows no obvious change trend with the increase of pressure, and a huge pyroelectric entropy change of 632 J kg can be achieved at a small pressure (0.1 MPa) -1 K -1 .
[0064] Figure 6 For the isothermal entropy change of the three materials from P = 0.1 MPa to 20, 40, 60, 80 and 100 MPa MP( Figure 6 (A)) At 80 MPa, during the loading pressure process the maximum value is about 707 J kg at around 311 K -1 K -1 , and about 694 J kg at around 300 K during the unloading pressure process -1 K -1 ; MS( Figure 6 (B)) At 60 MPa, during the loading pressure process the maximum value is about 680 J kg at around 308 K -1 K -1 , and about 658 J kg at around 317 K during the unloading pressure process -1 K- 1 ; BFAME( Figure 6 (C)) At 80 MPa, during the loading pressure process the maximum value is about 591 J kg at around 295 K -1 K -1 , and about 509 J kg at around 305 K during the unloading pressure process -1 K- 1 , which is comparable to 520 J kg of commercial R134a -1 K -1 . It shows that BFAME has a high isothermal entropy change (about 600 J kg -1 K -1 ) at small pressures (≤100 MPa).
[0065] Combined Figures 3 to 6 it can be seen that all three materials, MP, MS and BFAME, have the magnetocaloric effect and have a large magnetocaloric effect (500 - 740 J kg -1K -1 )。
[0066] Figure 7 are the solid-liquid transition temperature-pressure diagram and the phase transition temperature-pressure sensitivity coefficient of BFAME. The phase transition temperature-pressure sensitivity coefficients dT t / dP of BFAME during heating and cooling processes are 0.15 K / MPa -1 and 0.11 K / MPa -1 respectively. This shows that BFAME has good dT t / dP sensitivity (0.10 - 0.15 K / MPa -1 ).
[0067] In summary, both single-component MP or MS and two-component BFAME have the electrocaloric effect and are suitable for refrigeration applications under near-room temperature and low-pressure conditions. However, considering the comprehensive performance, BFAME has more excellent performance and a better application prospect for electrocaloric refrigerators.
[0068] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A formula for a pressure card refrigeration material, characterized in that, It consists of methyl palmitate and / or methyl stearate.
2. The formulation of the press-fit refrigeration material according to claim 1, characterized in that, The component ratio is as follows: Methyl palmitate: 84.2 wt.%; Methyl stearate: 15.8 wt.%.
3. The formulation of the pressure card refrigeration material according to claim 1, wherein, The purity of each component is 99.0%.
4. A preparation method of a pressure card refrigeration material, characterized in that, Prepared using the formulation of the magnetocaloric refrigeration material according to any one of claims 1 to 3, having any one of the following technical features: A. When the formulation of the magnetocaloric refrigeration material is a single component, the single component is the magnetocaloric refrigeration material; B. When the formulation of the magnetocaloric refrigeration material is two components, the magnetocaloric refrigeration material is obtained by mechanically mixing the two components in a constant temperature environment.
5. In the method for preparing the pressure card refrigeration material according to claim 4, it is characterized in that, The parameters for mixing the two components are: constant temperature of 60 °C and mechanical stirring for 30 min.
6. A pressing card refrigeration material, characterized in that, Prepared by the preparation method of the magnetocaloric refrigeration material according to any one of claims 4 to 5.
7. The pressure card refrigeration material according to claim 6, wherein It has a refrigeration capacity at near room temperature and under a pressure of ≤100 MPa.
8. The pressure card refrigeration material according to claim 6, characterized in that, When the hydrostatic pressure is ≤100 MPa, it has at least one of the following technical features: A. The phase transition temperature range is between 292 and 326 K; B. The thermal hysteresis is between 6 and 10 K; C. having an isothermal entropy change with a pressure clamping effect between 500 and 740 J kg -1 K -1 ; D. The phase change temperature-pressure sensitivity coefficient is between 0.10 and 0.15 K / MPa -1 in between.
9. The pressure card refrigeration material according to any one of claims 6 to 8, characterized in that, It has a refrigeration capacity at near room temperature and under ≤100 MPa, and is applied to a magnetocaloric refrigerator.
10. The pressure card refrigeration material according to claim 9, characterized in that, It is a single component of methyl palmitate or methyl stearate, or a mechanical mixture of two components of methyl palmitate and methyl stearate.