Nano phase change thermal storage material with high decomposition temperature and melting point of 150-220℃
By using a high-decomposition temperature nanophase change heat storage material composed of 99 wt% low melting point mixed with molten salt and SiO2 nanoparticles, the problem of insufficient thermal properties of existing molten salt is solved, and a lower melting point and higher decomposition temperature is achieved, which reduces the The energy consumption and cost of solar thermal power generation systems improve the safety and stability of the system and heat transfer capabilities.
Patent Information
- Application Number
- CN202211547454.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-05
- Publication Date
- 2025-01-17
- Estimated Expiration
- 2042-12-05
AI Technical Summary
The existing mixed molten salt with melting points between 150-220°C has poor decomposition temperature, melting latent heat and other thermal properties, which cannot meet the needs of solar thermal power generation and industrial waste heat recovery, resulting in increased energy consumption and high system costs.
A high-decomposition temperature nanophase change heat storage material consisting of 99 wt% low melting point mixed molten salt and 1 wt% SiO2 nanoparticles, with a melting point between 150-220°C, and the low melting point mixed molten salt has a mass ratio of 60:40:(5 -20) consists of sodium nitrate, potassium nitrate and calcium nitrate, and the SiO2 nanoparticles have a particle size of 20nm.
A lower melting point and a higher decomposition temperature are achieved, which significantly reduces the cost of the heat transfer and heat storage system, improves the specific heat and thermal conductivity, and enhances the safety and stability of the system and heat transfer and heat storage capacity.
Smart Images
Figure CN115851237B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of mixed molten salt energy storage materials, in particular to a high decomposition temperature nano phase change heat storage material with a melting point of 150-220°C. Background Art
[0002] Using suitable molten salt as a heat transfer and heat storage medium can effectively improve the performance of solar thermal power generation systems. It can be used as a heat storage material or directly as a heat transfer fluid, simplifying the heat exchange process and realizing the integration of heat transfer and heat storage. Therefore, molten salt technology has become an important research direction for exploring ways to improve the efficiency of solar thermal power generation and reduce the cost of power generation.
[0003] Phase change heat storage materials, as a carrier for storing energy, play an important role in recycling industrial waste heat, solar thermal power generation and solar energy "peak shifting and valley filling" heat storage systems. Currently, the commonly used molten salts in business are Solar Salt (melting point is 220℃) and Hetic molten salt (melting point is 142℃).
[0004] However, there is a shortage of mixed molten salts with a melting point of 150-220°C on the market. A higher melting point will lead to increased energy consumption, while the existing mixed molten salts with a melting point of 150-220°C have poor decomposition temperature, latent heat of melting and other thermal properties and cannot meet usage requirements. Summary of the invention
[0005] The object of the present invention is to provide a nano phase change thermal storage material with a high decomposition temperature and a melting point of 150-220°C. The nano phase change thermal storage material has a low melting point and a melting point of 150-220°C, which makes up for the shortage of molten salt phase change thermal storage materials in this temperature range, can effectively reduce energy consumption, and has good decomposition temperature, melting latent heat and other thermal properties. The average specific heat of the nano phase change thermal storage material is 1.723, 1.910, 2.122, and 2.213 J / (g·k), respectively, which effectively reduces the cost of the heat transfer and thermal storage system, simplifies the initial operation procedure of the system, and increases the safety and stability of the entire system.
[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:
[0007] The high decomposition temperature nano phase change thermal storage material with a melting point of 150-220°C is composed of 99wt% of a low melting point mixed molten salt and 1wt% of SiO2 nanoparticles, wherein the low melting point mixed molten salt is composed of sodium nitrate, potassium nitrate and calcium nitrate in a mass ratio of 60:40:(5-20).
[0008] Furthermore, the particle size of the SiO2 nanoparticles is 20 nm.
[0009] Furthermore, it can be used for solar thermal power generation and factory waste heat recovery.
[0010] Compared with the prior art, the beneficial effects of the present invention are:
[0011] 1. The mixed nano molten salt prepared by the technical solution of the present invention has a low melting point (melting point range: 150-220°C) and a high decomposition temperature (decomposition temperature range: 675-693°C). Its application in solar thermal power generation systems will greatly reduce the cost of heat transfer and heat storage systems, simplify the initial operation procedures of the system, and increase the safety and stability of the entire system.
[0012] 2. The mixed nano molten salt prepared by the technical solution of the present invention has significantly improved specific heat and thermal conductivity, with an average specific heat of (1.732-2.213) J / (g·K), good heat transfer and heat storage capacity, and can be widely used in technical fields such as solar thermal power generation and factory waste heat recovery. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Attached Figure 1 This is the temperature-increasing DSC curve of Example 1 of the present invention.
[0014] Attached Figure 2 This is the temperature-increasing DSC curve of Example 2 of the present invention.
[0015] Attached Figure 3 This is the temperature-increasing DSC curve of Example 3 of the present invention.
[0016] Attached Figure 4 This is the temperature-increasing DSC curve of Example 4 of the present invention.
[0017] Attached Figure 5 This is the TG curve of Example 1 of the present invention.
[0018] Attached Figure 6 This is the TG curve of Example 2 of the present invention.
[0019] Attached Figure 7 This is the TG curve of Example 3 of the present invention.
[0020] Attached Figure 8 This is the TG curve of Example 4 of the present invention.
[0021] Attached Fig. 9 It is the specific heat curve of the nano phase change thermal storage material of the present invention. DETAILED DESCRIPTION
[0022] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the application equally.
[0023] Example 1: A high decomposition temperature nano phase change thermal storage material with a melting point of 150-220°C, used for solar thermal power generation and factory waste heat recovery, is composed of 99wt% low melting point mixed molten salt and 1wt% SiO2 nanoparticles, wherein the low melting point mixed molten salt is composed of sodium nitrate, potassium nitrate and calcium nitrate in a mass ratio of 60:40:5, and the particle size of the SiO2 nanoparticles is 20nm.
[0024] The preparation process is as follows: before the test, a mixed salt consisting of sodium nitrate, potassium nitrate and calcium nitrate in a mass ratio of 60:40:5 after drying is placed in a muffle furnace and heated until it is completely melted and mixed evenly. After the mixed molten salt is cooled, it is taken out and the molten salt is fully ground evenly using a mortar. Finally, the crushed molten salt is placed in a drying oven at a constant temperature for drying for subsequent use.
[0025] The mixed molten salt and SiO2 nanoparticles are mixed in a beaker, and deionized water is added to completely dissolve them; the mixed solution is placed in an ultrasonic cleaner, and after ultrasonic oscillation treatment for a certain period of time, a uniform dispersion system is obtained; the beaker containing the solution is placed on a heating plate, and evaporated at different temperatures to obtain dehydrated nanofluid samples, namely, the nano phase change thermal storage material of the present invention.
[0026] By the attached Figure 1 and attached Figure 5 It can be seen that the melting point of the mixed nano molten salt in this embodiment is 202.33°C and the decomposition temperature is 674.85°C.
[0027] Example 2: The preparation method in Example 1 is adopted, except that the mass ratio of sodium nitrate, potassium nitrate and calcium nitrate in this example is 60:40:10.
[0028] By the attached Figure 2 and attached Figure 6 It can be seen that the melting point of the mixed nano molten salt in this embodiment is 190.85°C and the decomposition temperature is 679.91°C.
[0029] Example 3: The preparation method in Example 1 is adopted, except that the mass ratio of sodium nitrate, potassium nitrate and calcium nitrate in this example is 60:40:15.
[0030] By the attached Figure 3 and attached Figure 7 It can be seen that the melting point of the mixed nano molten salt in this embodiment is 168.24°C and the decomposition temperature is 685.37°C.
[0031] Example 4: The preparation method in Example 1 is adopted, except that the mass ratio of sodium nitrate, potassium nitrate and calcium nitrate in this example is 60:40:20.
[0032] By the attached Figure 4 and attached Figure 8 It can be seen that the melting point of the mixed nano molten salt in this embodiment is 178.13°C and the decomposition temperature is 692.67°C.
[0033] Based on the above four embodiments, the decomposition temperature of the mixed nano molten salt prepared by the technical solution of the present invention is significantly improved (the decomposition temperature is between 675-693°C), which is about 125°C higher than Solar Salt and about 240°C higher than HITEC. Its application in solar thermal power generation systems will effectively reduce the cost of heat transfer and heat storage systems, simplify the initial operation procedures of the system, and increase the safety and stability of the entire system. And the average specific heat of the mixed nano molten salt of the present invention is (1.732-2.213) J / (g·K).
Claims
1. High decomposition temperature nano phase change thermal storage material with a melting point of 150-220°C, characterized by: The invention is composed of 99 wt% of low-melting-point mixed molten salt and 1 wt% of SiO2 nanoparticles, wherein the low-melting-point mixed molten salt is composed of sodium nitrate, potassium nitrate and calcium nitrate in a mass ratio of 60:40:(5-20).
2. According to claim 1, the high decomposition temperature nano phase change thermal storage material with a melting point of 150-220°C is characterized in that: The particle size of the SiO2 nanoparticles is 20 nm.
3. The high decomposition temperature nano phase change thermal storage material with a melting point of 150-220° C. according to claim 1, characterized in that: Used for solar thermal power generation and factory waste heat recovery.