Application of material with abnormal piezocaloric effect in solid-state refrigeration and/or heat storage

A solid-state refrigeration and thermal effect technology, which is applied to machines using waste heat, heat storage equipment, indirect heat exchangers, etc., can solve problems such as energy loss, achieve heat transfer, improve energy utilization efficiency, and have great application prospects.

Active Publication Date: 2021-03-16
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

So much waste heat cannot be collected and causes great energy loss. Therefore, finding an effective energy storage material to collect waste heat is a very important way to improve energy efficiency

Method used

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  • Application of material with abnormal piezocaloric effect in solid-state refrigeration and/or heat storage
  • Application of material with abnormal piezocaloric effect in solid-state refrigeration and/or heat storage
  • Application of material with abnormal piezocaloric effect in solid-state refrigeration and/or heat storage

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] Negative thermal expansion material NH 4 Anomalous barocaloric effect of SCN

[0031] NH 4 SCN has two phase transitions at 360K and 390K respectively. Among them, a structural phase transition from ordered to disordered structural units occurs at 360K, and its crystal structure is shown in the attached figure 1 As shown, from 300K low-temperature monoclinic phase to 375K medium-temperature orthorhombic phase, where NH 4 + The phase is ordered at low temperature, while the phase is orientationally disordered at medium temperature. This phase change process is negative thermal expansion, that is, during the temperature-rising phase change process, the volume after the phase change is smaller than the volume before the phase change. attached figure 2 is NH 4 The variation of the volume of the SCN unit cell with temperature, the volume of the unit cell decreases sharply at 360K, and its negative thermal expansion rate is calculated as (V 2 -V 1 ) / V 1 = -4.9%. N...

Embodiment 2

[0033] Applications of materials with anomalous barothermic effect in solid-state refrigeration and / or heat storage

[0034] attached Figure 5 is based on the attached image 3 NH calculated from heat flow data at different pressures 4 Diagram of SCN autoclaving effect. P 0 is the atmospheric pressure, and P corresponds to 20MPa, 40MPa, 60MPa, 80MPa and 100MPa respectively. to NH 4 When pressure is applied to the SCN, the material undergoes an order-to-disorder endothermic phase transition. As the pressure increases, the entropy change of the barothermal effect increases. It reaches a saturated maximum value of 128.7J kg when the driving pressure is only 80MPa -1 K -1 . The depressurization process corresponds to the exothermic phase transition from disorder to order. Combining existing anomalous barocaloric materials with NH 4 SCN for comparison, the results are shown in the appendix Figure 6 . It can be seen that NH 4 The pressure-driven isothermal entropy cha...

Embodiment 3

[0036] Applications of materials with anomalous barothermic effect in solid-state refrigeration and / or heat storage

[0037] attached Figure 10 NH 4 SCN measured pressure and heat flow data. Fill the sample cell with nitrogen so that the initial pressure of the sample cell is 8.2MPa. Then pressurize it to 90MPa at a temperature of 349K to undergo an endothermic phase transition, and the enthalpy of this process becomes 43.01kJ kg -1 . When the pressure is stabilized at 90MPa, the temperature of the material is lowered to 313K. After the pressure is unloaded, an exothermic phase transition occurs, and the phase transition enthalpy becomes -45.2kJ kg -1 . In the cooling process, the heat flow curve in the figure is a straight line, which proves that there is no obvious heat loss at a constant pressure of 90MPa, so the heat transfer can be realized by controlling the pressure. attached Figure 11 Application scenario 2 for materials with anomalous barothermal effect in so...

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Abstract

The invention innovatively applies an abnormal piezocaloric effect material with negative thermal expansion properties in solid state refrigeration and/or heat storage application. An in-situ high-pressure differential scanning calorimeter test is carried out on a preferred material NH4SCN to verify that the abnormal piezocaloric effect material generates heat absorption phase change when pressureis applied and generates heat release phase change when the pressure is unloaded, the pressure can effectively control the heat absorption and release process of the phase change, heat can be effectively stored, and an experimental theoretical basis is provided for practical application of the abnormal piezocaloric effect material.

Description

technical field [0001] The invention belongs to the application field of refrigeration and heat storage, and in particular relates to the application of a material with anomalous pressure heat effect in solid-state refrigeration and / or heat storage. Background technique [0002] Traditional gas compression refrigeration technology is widely used in modern refrigeration equipment. Freon, as an early refrigerant, caused a serious hole in the ozone layer, while the current refrigerants, perfluorocarbons and hydrofluorocarbons, aggravate the greenhouse effect. Therefore, it is particularly important to seek alternative environmentally friendly refrigeration methods. The new solid-state refrigeration technology has attracted much attention as a potential development object. The refrigeration process has no greenhouse gas emissions and provides an effective way to solve the environmental damage caused by traditional refrigeration methods. The principle of solid-state refrigeratio...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F25B27/02F28D20/02
CPCF25B27/02F28D20/02Y02A30/274
Inventor 李昺张志东张哲
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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