CN114736658A

CN114736658A - Organic-inorganic eutectic mixture phase-change heat storage material based on sodium acetate trihydrate and preparation method thereof

Info

Publication number: CN114736658A
Application number: CN202210497330.0A
Authority: CN
Inventors: 孙婉纯; 梁国浩; 何海敏; 冯凤兰; 高志明; 曾梦琪; 钟岳津; 张乾莹
Original assignee: Shunde Polytechnic
Current assignee: Shunde Polytechnic
Priority date: 2022-05-09
Filing date: 2022-05-09
Publication date: 2022-07-12

Abstract

The invention discloses an organic-inorganic eutectic mixture phase-change heat storage material based on sodium acetate trihydrate and a preparation method thereof. The phase change heat storage material is prepared from the following components in percentage by mass: 80-95% of sodium acetate trihydrate, 1-10% of polyethylene glycol (molecular weight 200, 600, 1000, 1500, 2000, 4000, 6000), 3-5% of nucleating agent (disodium hydrogen phosphate dodecahydrate and sodium pyrophosphate decahydrate) and 2-3% of thickening agent (carboxymethylcellulose and oxhide gelatin). The invention uses the high molecular organic polymer polyethylene glycol to inhibit the phase separation of inorganic hydrated salt sodium acetate trihydrate, an organic-inorganic eutectic phase-change material system is constructed, the obtained phase-change heat storage material can be filled in closed containers with various shapes to be used as energy storage modules in heat storage systems, including industrial waste heat recovery systems, water heater heat storage systems and floor radiation heating systems, and the preparation method is simple and convenient to use.

Description

Organic-inorganic eutectic mixture phase-change heat storage material based on sodium acetate trihydrate and preparation method thereof

Technical Field

The invention relates to the technical field of preparation and application of organic-inorganic eutectic phase-change materials, in particular to an organic-inorganic eutectic mixture phase-change heat storage material based on sodium acetate trihydrate and a preparation method thereof.

Background

In data statistics of 'special reports of China in the world energy prospect in 2017', the proportion of industrial energy consumption and building energy consumption in China is 50% and 23% respectively. The proportion of space heating and domestic hot water in the building energy consumption is close to 40%, the part of energy consumption corresponds to the medium-low temperature heat supply demand, and the low-temperature heat which is up to 33% of the industrial energy consumption is directly discharged as waste heat. Therefore, the development of the high-performance phase-change energy storage material is applied to a medium-low temperature waste heat recovery and heat storage system, and has important significance in improving the overall utilization efficiency of energy, saving building energy consumption and reducing carbon emission.

A phase change material is a material that can absorb or release a large amount of heat during its melting-solidification phase change and maintain the temperature of the system near its phase change temperature, and thus can be used to absorb, store and transfer heat. The phase-change temperature range of the phase-change material required by the medium-low temperature heat storage system is 55-70 ℃, and the phase-change material currently widely researched comprises organic phase-change material paraffin and inorganic phase-change material sodium acetate trihydrate. Compared with paraffin, the hydrated inorganic salt has the advantages of low price and high heat conductivity coefficient, but the supercooling degree and the serious phase separation of the hydrated inorganic salt which is as high as 30 ℃ still need to be solved.

Most of the existing researches can improve the problems of sodium acetate trihydrate supercooling and phase separation to a certain extent by adding a proper amount of nucleating agent and thickening agent, but the stability of the sodium acetate trihydrate still needs to be improved after multiple cycles. Therefore, a phase change heat storage material which is suitable in phase change temperature (55-65 ℃), high in phase change latent heat, small in supercooling degree, free of phase separation and excellent in cycle stability needs to be prepared, an energy storage material is provided for a medium-low temperature waste heat recovery and heat storage system, and the application effect of the energy storage system is improved.

The organic phase change material has the obvious advantages of small supercooling degree and no phase separation, and the research of the invention combines the organic phase change material and the inorganic hydrated salt to prepare an organic-inorganic eutectic phase change system, so that the eutectic has the advantages of the organic phase change material and the inorganic hydrated salt, thereby solving the inherent defects of the inorganic hydrated salt.

Disclosure of Invention

The invention aims to overcome the problems of large supercooling degree, serious phase separation, poor circulation stability and the like of single hydrated inorganic salt phase-change material sodium acetate trihydrate, and provides an organic-inorganic eutectic mixture phase-change heat storage material based on sodium acetate trihydrate and a preparation method thereof, wherein the organic-inorganic eutectic mixture phase-change heat storage material has high phase-change latent heat, small supercooling degree, no phase separation and excellent circulation stability, and therefore the defects of the prior art are overcome.

The technical scheme for solving the technical problem is as follows:

firstly, uniformly mixing 80-95% of sodium acetate trihydrate, 1-10% of polyethylene glycol and 3-5% of nucleating agent by mass, heating the mixture at 70 ℃, and intermittently heating and stirring the mixture until the material is completely melted to obtain a molten mixture;

adding the thickener with the mass fraction of 2-3% into the molten mixture in the step (1) under the condition of continuous magnetic stirring, and uniformly stirring.

In the material components, the polyethylene glycol has the function of utilizing good water solubility of the polyethylene glycol and hydrated salt sodium acetate trihydrate to form a eutectic system, and the existence of an organic phase is utilized to improve the phase uniformity of the molten sodium acetate trihydrate, so that the phase separation of the sodium acetate trihydrate is inhibited.

The phase-change temperature of the organic-inorganic eutectic mixture phase-change heat storage material based on sodium acetate trihydrate changes along with the difference of the molecular weight and the addition amount of polyethylene glycol, so that the phase-change temperature can be adjusted within the range of 55-65 ℃.

The invention has the beneficial effects that:

1. the organic high molecular polymer is used for improving the phase uniformity of the single hydrated salt after melting and eliminating phase separation.

2. The phase change temperature of the phase change material is adjustable, and the adjustment range is 55-65 ℃; the phase change latent heat is 200-300kJ/kg, the supercooling degree is less than 2 ℃, the phase separation phenomenon does not occur after 600 times of circulation, the circulation stability is good, the thermal performance is excellent, and the heat storage system can be applied to various medium and low temperature waste heat recovery and heat storage systems.

3. The preparation method is simple, the components except the thickening agent are added at one time, and the thickening agent is added after mixing and eutectic melting.

Drawings

FIG. 1 is an image of an organic-inorganic eutectic mixture phase change thermal storage material of sodium acetate trihydrate-polyethylene glycol 200 according to the present invention;

FIG. 2 is a DSC curve of an organic-inorganic eutectic mixture phase-change heat storage material of sodium acetate trihydrate-polyethylene glycol 200;

FIG. 3 is an image of an organic-inorganic eutectic mixture phase change thermal storage material of sodium acetate trihydrate-polyethylene glycol 600;

FIG. 4 is a DSC curve of an organic-inorganic eutectic mixture phase-change heat storage material of sodium acetate trihydrate-polyethylene glycol 600;

FIG. 5 is an image of an organic-inorganic eutectic mixture phase-change thermal storage material of sodium acetate trihydrate-polyethylene glycol 6000;

FIG. 6 is a DSC curve of the organic-inorganic eutectic mixture phase-change heat storage material of sodium acetate trihydrate-polyethylene glycol 6000;

FIG. 7 is a schematic diagram of a heat storage module of a waste heat recovery system based on an organic-inorganic eutectic mixture phase-change heat storage material of sodium acetate trihydrate-polyethylene glycol 6000.

Detailed Description

The technical solution of the present invention is further specifically described below by using specific embodiments and with reference to the accompanying drawings. In the present invention, all the equipment and materials are commercially available or commonly used in the art, and the methods in the following examples are conventional in the art unless otherwise specified.

In order that those skilled in the art will better understand the disclosure, the following detailed description will be given with reference to the accompanying drawings. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

Example 1

Preparing sodium acetate trihydrate-polyethylene glycol 200 series phase change heat storage materials according to the following mass fraction ratio: 94% of sodium acetate trihydrate-2% of polyethylene glycol 200, 92% of sodium acetate trihydrate-4% of polyethylene glycol 200, 90% of sodium acetate trihydrate-6% of polyethylene glycol 200, 88% of sodium acetate trihydrate-8% of polyethylene glycol 200 and 86% of sodium acetate trihydrate-10% of polyethylene glycol 200, and 2% of disodium hydrogen phosphate dodecahydrate and 2% of carboxymethyl cellulose are added into the samples with different proportions. The prepared sodium acetate trihydrate-polyethylene glycol 200 series phase-change material is shown in figure 1, the DSC measurement result is shown in figure 2, and corresponding thermophysical property parameters are listed in table 1.

TABLE 1

Example 2

Preparing sodium acetate trihydrate-polyethylene glycol 600 series phase change heat storage materials according to the following mass fraction ratio: 94% of sodium acetate trihydrate-2% of polyethylene glycol 600, 92% of sodium acetate trihydrate-4% of polyethylene glycol 600, 90% of sodium acetate trihydrate-6% of polyethylene glycol 600, 88% of sodium acetate trihydrate-8% of polyethylene glycol 600, and 86% of sodium acetate trihydrate-10% of polyethylene glycol 600, and 2% of disodium hydrogen phosphate dodecahydrate and 2% of carboxymethyl cellulose are added into the samples with different proportions.

The prepared sodium acetate trihydrate-polyethylene glycol 600 series phase-change material is shown in figure 3, the DSC measurement result is shown in figure 4, and corresponding thermophysical property parameters are listed in table 2.

TABLE 2

Embodiment 3

The sodium acetate trihydrate-polyethylene glycol 6000 series phase change heat storage material is prepared according to the following mass fraction: 94% of sodium acetate trihydrate-2% of polyethylene glycol 6000, 92% of sodium acetate trihydrate-4% of polyethylene glycol 6000, 90% of sodium acetate trihydrate-6% of polyethylene glycol 6000, 88% of sodium acetate trihydrate-8% of polyethylene glycol 6000 and 86% of sodium acetate trihydrate-10% of polyethylene glycol 6000, and 2% of disodium hydrogen phosphate dodecahydrate and 2% of carboxymethyl cellulose are added into the samples with different proportions.

The prepared sodium acetate trihydrate-polyethylene glycol 6000 series phase-change material is shown in figure 5, the DSC measurement result is shown in figure 6, and corresponding thermophysical property parameters are listed in table 3.

TABLE 3

Example 4

In the embodiment, the phase-change material of sodium acetate trihydrate-polyethylene glycol 6000 (No. 2 in the embodiment 2) is used as the heat storage module of the waste heat recovery system, the phase-change temperature is 57.9 ℃, the phase-change enthalpy value is 268.1J/g, and the heat conductivity coefficient is 0.65W/(m.K).

Filling the phase-change material into a cavity 1 of the heat storage device as shown in fig. 7, welding the sealed cavity after filling, and filling the materials with the following weight: 30 kg.

In the heat storage mode, heating fluid enters through the coil pipe 2, the fluid is tap water, the inlet temperature is 75 ℃, and the flow rate is 400L/h. In the heat release mode, heat release fluid enters through the coil pipe 2, the fluid is tap water, the inlet temperature is 20 ℃, and the flow rate is 200L/h.

The operation mode is as follows: after industrial waste heat is recovered by taking tap water as a fluid, the heat source fluid flows through the coil 2 to heat the phase-change material, the phase-change material absorbs heat to melt, phase change is carried out, heat is stored, and waste heat recovery is realized.

When heat is needed, cold water flows through the coil pipe 2, the phase-change material releases heat and solidifies, the cold water absorbs the heat released by the phase-change material, and the temperature rises, so that hot water is prepared.

While 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 alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents, and all changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. An organic-inorganic eutectic mixture phase-change heat storage material based on sodium acetate trihydrate is characterized by comprising polyethylene glycol and sodium acetate trihydrate, wherein the phase-change temperature of the mixture phase-change heat storage material is in the range of 55-65 ℃, the phase-change latent heat is 200-300kJ/kg, the supercooling degree is less than 2 ℃, and no phase separation phenomenon exists after 600 times of circulation; the weight percentages of the components are as follows: 80-95% of sodium acetate trihydrate, 1-10% of polyethylene glycol, 3-5% of nucleating agent and 2-3% of thickening agent.

2. The sodium acetate trihydrate based organic-inorganic eutectic mixture phase change thermal storage material of claim 1, wherein the polyethylene glycol comprises one or more polyethylene glycols having molecular weights of 200, 600, 1000, 1500, 2000, 4000, 6000, respectively; the nucleating agent is disodium hydrogen phosphate dodecahydrate or sodium pyrophosphate decahydrate; the thickening agent is carboxymethyl cellulose or oxhide gelatin.

3. The method for preparing the sodium acetate trihydrate based organic-inorganic eutectic mixture phase change thermal storage material according to claim 1, which is characterized by comprising the following steps,

1) uniformly mixing 80-95% of sodium acetate trihydrate, 1-10% of polyethylene glycol and 3-5% of nucleating agent by mass percent, heating the mixture at 70 ℃, and intermittently heating and stirring the mixture until the material is completely melted to obtain a molten mixture;

2) adding the thickener with the mass fraction of 2-3% into the molten mixture in the step (1) under the condition of continuous magnetic stirring, and uniformly stirring.

4. The method for preparing the sodium acetate trihydrate based phase-change heat storage material as claimed in claim 3, wherein the step 1) of intermittent heating is that after heating for 20 minutes, the mixture is placed under 70 ℃ water bath heating condition for magnetic stirring for 5 minutes, and the stirring speed is 300-500 rpm.

5. The method for preparing the sodium acetate trihydrate based phase-change heat storage material as claimed in claim 3, wherein the continuous magnetic stirring speed in the step 2) is 300-500rpm, and the water bath heating condition at 70 ℃ is maintained.