Thermal storage unit and assembly method therefor, and heat pump system

Abstract

A thermal storage unit and an assembly method therefor, and an application. The thermal storage unit (100) comprises a metal thermal storage housing and a phase change layer. The phase change layer fills a thermal storage space inside the metal thermal storage housing. The phase change material of the phase change layer comprises the following components: a phase change base material: 85.0-95.0 wt.%; a nucleating agent: 1.0-3.0 wt.%; a thickener: 2.0-4.0 wt.%; and a corrosion inhibitor: 0.5-2.0 wt.%; wherein the phase change base material comprises one of a saturated fatty acid, an alcohol compound, or an inorganic phase change base material; and the corrosion inhibitor comprises at least one of a nitrogen-containing heterocyclic compound, an oxygen-containing heterocyclic compound, a molybdate, a chromate, and a tungstate.

Description

Heat storage unit, assembling method thereof and heat pump system

[0001] Related applications

[0002] The present application claims priority to the following Chinese patent application: Application No. 202411364709.X, filed on September 27, 2024, entitled "Heat storage unit, assembling method thereof and heat pump system"; the aforementioned patent is hereby incorporated by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of energy storage materials, in particular to a heat storage unit, an assembling method thereof and applications. BACKGROUND

[0004] With the deepening of industrialization, the energy gap is becoming more and more obvious. The shortage of primary energy has attracted people's high attention, and for this reason, people have come up with many solutions, and improving energy utilization and developing renewable energy have become important issues.

[0005] Phase change energy storage is a technology that uses phase change materials to store energy through phase change (solid-liquid, gas-liquid). In the process of heating, two processes of sensible heat storage and latent heat storage are involved, and in the process of latent heat storage, the temperature of the material is almost constant. Compared with water that only stores heat by sensible heat, phase change materials have higher heat storage capacity, so phase change materials have very high application advantages in heat pump systems, for example, in the temperature range of 10℃-65℃, the energy storage density of phase change materials can reach twice that of water, and the volume of phase change modules can be reduced to 50% of that of independent water tanks. In the heat pump system, the phase change material absorbs heat from the heat source during its energy storage process, and the phase change material transfers heat to low-temperature domestic water during its heat release process, realizing instant hot water, and the higher the phase change temperature of the phase change material, the higher the outlet water temperature.

[0006] In the process of heat storage and release, the phase change material needs to be in contact with the heat exchange structure. For a long time, the corrosion prevention of phase change materials has been less developed, and there is a lack of systematic solutions. Moreover, the heat exchange structure is usually made of metal, which is easy to be corroded, so the corrosion problem of phase change materials on metal heat exchange structures cannot be ignored. SUMMARY

[0007] The present application provides a heat storage unit, an assembling method thereof and applications, which can solve the problem that phase change materials easily cause corrosion of metal heat exchange structures.

[0008] In a first aspect, the present application provides a heat storage unit for a heat pump system, the heat storage unit comprising a metal heat storage shell and a phase change layer, the metal heat storage shell having a heat storage space inside, and the phase change layer being filled in the heat storage space.

[0009] The phase change layer includes a phase change material, and the phase change material includes the following components:

[0010] The phase change base material 85.0wt.%~95.0wt.%, nucleating agent 1.0wt.%~3.0wt.%, thickening agent 2.0wt.%~4.0wt.%, corrosion inhibitor 0.5wt.%~2.0wt.%;

[0011] The phase change base material includes one of saturated fatty acid, alcohol compound or inorganic phase change base material;

[0012] The nucleating agent is selected from at least one of phosphate, silicate, carbonate;

[0013] The corrosion inhibitor includes at least one of nitrogen-containing heterocyclic compound, oxygen-containing heterocyclic compound, molybdate, chromate and tungstate.

[0014] In some embodiments, the phase change material includes the following components based on the total weight of the phase change material:

[0015] The phase change base material 92wt.%~94wt.%, nucleating agent 2.0wt.%~3.0wt.%, thickening agent 3.0wt.%~4.0wt.%, corrosion inhibitor 0.5wt.%~1.5wt.%.

[0016] In some embodiments, the weight ratio of the phase change base material to the corrosion inhibitor ranges from 90.5 to 92.5.

[0017] In some embodiments, the saturated fatty acid of the phase change base material is selected from at least one of myristic acid, palmitic acid, fatty acid;

[0018] The alcohol compound of the phase change base material is selected from at least one of mannitol, polyethylene glycol, dodecanol;

[0019] The inorganic phase change base material of the phase change base material is selected from at least one of sodium sulfate decahydrate, calcium chloride hexahydrate, sodium acetate trihydrate, magnesium chloride hexahydrate, sodium carbonate decahydrate, sodium thiosulfate pentahydrate.

[0020] In some embodiments, the nitrogen-containing heterocyclic compound of the corrosion inhibitor is selected from at least one of carboxyethyl imidazoline and its derivatives, benzotriazole and its derivatives, imidazoline;

[0021] The oxygen-containing heterocyclic compound of the corrosion inhibitor is selected from at least one of chitosan-o-vanillin Schiff base, furfural-adenine Schiff base, furfural-melamine Schiff base;

[0022] The molybdate of the corrosion inhibitor is selected from at least one of sodium molybdate, strontium molybdate, nickel molybdate;

[0023] The chromate of the corrosion inhibitor is selected from at least one of sodium chromate, potassium chromate, magnesium chromate, and the like.

[0024] The tungstate of the corrosion inhibitor is selected from at least one of calcium tungstate, sodium tungstate, cobalt tungstate, ferrous tungstate, and the like.

[0025] In some embodiments, the thickening agent is selected from at least one of hydroxymethyl cellulose, soluble starch, gelatin, polyvinylpyrrolidone, sodium polyacrylate xanthan gum, and the like.

[0026] In some embodiments, the metal heat storage shell comprises a main shell and a heat exchange structure, the heat exchange structure comprises:

[0027] A plurality of heat-conducting fins are arranged in the internal space of the main shell, each of the heat-conducting fins has a heat-conducting hole;

[0028] A plurality of heat exchange tubes are arranged in the internal space of the main shell, and each of the heat exchange tubes passes through the heat-conducting holes of a plurality of the heat-conducting fins, the main shell and the heat exchange structure define the heat storage space;

[0029] The phase change layer is filled in the heat storage space and in contact with the outer surface of the heat exchange tube and the outer surface of the heat-conducting fin to exchange heat with the heat exchange medium in the heat exchange tube;

[0030] The material of at least one of the main shell, the heat-conducting fin and the heat exchange tube comprises copper.

[0031] In some embodiments, each of the heat-conducting fins extends in the vertical direction, and a heat-conducting space extending in the vertical direction is formed between two adjacent heat-conducting fins, the phase change material is filled in the heat-conducting space;

[0032] The main shell has a filling inlet, the filling inlet communicates with the internal space of the main shell, the phase change material enters the internal space of the main shell through the filling inlet, and the filling inlet is located above the heat exchange tube in the vertical direction.

[0033] In some embodiments, the heat exchange structure further comprises a plurality of inlet headers and a plurality of outlet headers;

[0034] Each of the inlet headers communicates with the inlets of a plurality of the heat exchange tubes;

[0035] Each of the outlet headers communicates with the outlets of a plurality of the heat exchange tubes;

[0036] In the vertical direction, the inlet headers and the outlet headers are both located above a plurality of the heat exchange tubes and are installed on the main shell.

[0037] In some embodiments, the heat exchange structure further comprises a plurality of inlet headers in one-to-one correspondence with the plurality of inlet manifolds, and a plurality of outlet headers in one-to-one correspondence with the plurality of outlet manifolds.

[0038] Each of the inlet manifolds is in communication with the inlets of the plurality of heat exchange tubes through the corresponding inlet headers.

[0039] Each of the outlet manifolds is in communication with the outlets of the plurality of heat exchange tubes through the corresponding outlet headers.

[0040] In the vertical direction, the inlet headers and the outlet headers are both above the plurality of heat exchange tubes.

[0041] In some embodiments, the heat exchange structure further comprises a plurality of adapter groups, each of which comprises an adapter main pipe and an adapter branch pipe, the adapter branch pipe having a plurality of adapter ends, and one end of the adapter main pipe being connected to one of the adapter ends of the adapter branch pipe.

[0042] The adapter groups comprise inlet adapter groups and outlet adapter groups.

[0043] The other end of the adapter main pipe of the inlet adapter groups is connected to the inlet headers, and the remaining adapter ends of the adapter branch pipes are connected to the inlets of the plurality of heat exchange tubes in one-to-one correspondence.

[0044] The other end of the adapter main pipe of the outlet adapter groups is connected to the outlet headers, and the remaining adapter ends of the adapter branch pipes are connected to the outlets of the plurality of heat exchange tubes in one-to-one correspondence.

[0045] In some embodiments, the plurality of heat exchange tubes comprise heat storage tubes and heat release tubes, the inlet section of the heat storage tube being in communication with the outlet end of a heat source, and the outlet section being in communication with the inlet end of the heat source, the inlet section of the heat release tube being in communication with a municipal water source, and the outlet section being in communication with a domestic water pipe.

[0046] The heat exchange structure satisfies one of the following conditions:

[0047] (1) The material of the heat exchange tubes is at least one of copper, copper alloy, and stainless steel.

[0048] (2) The material of the heat exchange tubes is copper, and the materials of the inlet manifolds, the outlet manifolds, the inlet headers, and the outlet headers are stainless steel.

[0049] (3) The materials of the heat storage tubes and the adapter groups connected to the heat storage tubes are aluminum, and the materials of the heat release tubes and the adapter groups connected to the heat release tubes are stainless steel.

[0050] In a second aspect, the application provides an assembling method of a heat storage unit, comprising: mixing components of a phase change material to obtain a final mixture, and filling the final mixture into a heat storage space of a metal heat storage shell, wherein the final mixture forms a phase change layer.

[0051] In some embodiments, the mixing of the components of the phase change material comprises the following steps:

[0052] mixing the phase change base material and the corrosion inhibitor, and heating to a preset temperature to perform an emulsification treatment, wherein the preset temperature is greater than the melting point of the phase change base material, and a molten mixture A is obtained;

[0053] mixing the molten mixture A and the nucleating agent to perform a first mixing treatment, and a mixture B is obtained;

[0054] mixing the mixture B and the thickening agent to perform a second mixing treatment, and a molten final mixture is obtained;

[0055] the filling of the final mixture into the heat storage space of the metal heat storage shell comprises: filling the molten final mixture into the heat storage space inside the metal heat storage shell, and the molten final mixture is cooled and solidified to form the phase change layer.

[0056] In some embodiments, the emulsification treatment at least comprises: the preset temperature is 70-80°C, the stirring speed is 2000-3000 r / min, and the time is 15-30 min;

[0057] the first mixing treatment at least comprises: the stirring speed is 80-120 r / min, and the time is 1-2 h;

[0058] the second mixing treatment at least comprises: the thickening agent is added to the mixture B in several times, the stirring speed is 20-40 r / min, the time is 2-3 h, and the weight of the thickening agent added each time is 20-25% of the total weight of the thickening agent.

[0059] In a third aspect, the application provides a heat pump system, comprising:

[0060] a heat source for providing heat; and

[0061] a heat storage unit as described above, wherein the phase change material of the heat storage unit is used to obtain the heat provided by the heat source to perform phase change energy storage.

[0062] Based on the heat storage unit, the assembling method and the application of the embodiment of the present application, by selecting the combination of the phase change base material and the corrosion inhibitor, the phase change base material can provide the solvent of the corrosion inhibitor, promote the dissociation of the corrosion inhibitor and form the negatively charged BTA - , MnO4 2- , CrO4 2- and other substances, at the same time, since the metal of the metal shell loses electrons when contacting with the phase change material, the positively charged metal ions are dissolved in the phase change material, the positively charged metal ions can combine with the negatively charged BTA - , MnO4 2- , CrO4 2- and other substances to form a dense long-chain complex, and form a protective film on the metal surface through physical adsorption, thereby inhibiting the further contact of other corrosion ions with the metal, so as to achieve the purpose of corrosion prevention. Among them, the phase change material belongs to alkaline, in the alkaline environment, the selected corrosion inhibitor of the present application can further promote the positive reaction of the corrosion inhibitor in the phase change material, so as to generate negatively charged substances and promote the formation of the complex on the wall surface of the metal heat storage shell. BRIEF DESCRIPTION OF DRAWINGS

[0063] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiment or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0064] Fig. 1 is a perspective structural schematic view of the heat storage unit of one embodiment of the present application;

[0065] Fig. 2 is a perspective structural schematic view of the heat exchange structure of one embodiment of the present application;

[0066] Fig. 3 is a perspective structural schematic view of the connection of the plurality of heat exchange pipes and the plurality of heat conduction fins of one embodiment of the present application;

[0067] Fig. 4 is a perspective structural schematic view of the plurality of groups of switching pipes of one embodiment of the present application;

[0068] Fig. 5 is a structural schematic view of the heat pump system of one embodiment of the present application;

[0069] Fig. 6 is a flow chart of the preparation method of the phase change material of one embodiment of the present application;

[0070] Fig. 7a is a surface topography view of the copper heat exchange pipe and the phase change material in embodiments 1-6 in thermal environment contact;

[0071] Fig. 7b is a surface topography view of the copper heat exchange pipe and the phase change material in comparative example 1-1 in thermal environment contact;

[0072] Figure 8 is a graph of corrosion depth of copper heat exchange tube in contact with phase change material in Examples 1-6 in a thermal environment;

[0073] Figure 9 is a graph of surface topography of 304 stainless steel in contact with phase change material in Examples 1-6 in a thermal environment;

[0074] Figure 10 is a graph of surface topography of aluminum plate in contact with phase change material in Comparative Example 1-1 in a thermal environment.

[0075] Reference signs: 10, heat pump system; 100, heat storage unit; 100a, phase change layer; 20, heat exchange structure; 200, heat exchange tube; 215, heat storage tube; 216, heat release tube; 212, heat conduction fin; 22, inlet header; 23, outlet header; 24, inlet manifold; 25, outlet manifold; 2101, adapter main pipe; 2102, adapter branch pipe; 300, heat source; 310, outlet end; 320, inlet end; 400, heating unit; 500, reversing valve; 510, first reversing valve; 520, second reversing valve; 610, municipal water source; 620, domestic water pipe. DETAILED DESCRIPTION

[0076] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as exactly that endpoint. Any values that fall within the range, including the upper or lower limit, are encompassed if the upper or lower values fall within the range. Whenever a numerical range is indicated, it is meant to include all values subsumed under the same degree of precision. Values that are less common are also intended to be implicitly defined. For example, a range from about 5% to about 95% is intended to include, 5%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, etc., up to and including 95%, 95.1%, 95.2%, 95.3%, 95.4%, 95.5%, etc., as well as 10% to 50%, 20% to 40%, 30% to 50%, etc.

[0077] It should be noted that in various aspects of the present application, the present application describes only once in one aspect for the same component in various aspects and does not repeat the description, and the person skilled in the art should not understand it as the limitation of the present application.

[0078] In the present application, unless otherwise specified, the room temperature or normal temperature means 25±2℃.

[0079] In the related art, inorganic hydrated salt is selected as a phase change material, and a metal heat exchange structure is often matched to meet the heat exchange requirement. For example, the metal heat exchange structure includes copper, aluminum, stainless steel, and the like. The inorganic hydrated salt can corrode the metal heat exchange structure. In addition, the amount of the inorganic hydrated salt is usually large, which can further aggravate the corrosion of the metal heat exchange structure, reduce the reliability of the product, and greatly shorten the service life of the product. Metal corrosion often occurs in the forms of electrochemical corrosion, galvanic corrosion, intergranular corrosion, pitting corrosion, and uniform corrosion. The inventors find that the corrosion problem in the whole life cycle can be covered by adding an inhibitor to the phase change material system and increasing the thickness of the metal heat exchange structure, and the corrosion of the metal heat exchange structure by the phase change material can be blocked by coating a corrosion-resistant coating or plating layer. However, the inhibitor needs to be added according to the type of metal, and increasing the thickness of the metal heat exchange structure increases the system cost. In addition, the coating or plating layer method generally has incomplete coating, defects caused by the process and many gaps in the metal heat exchange structure, and high cost. Based on this, the embodiments of the present application provide a heat storage unit that can improve the corrosion of the metal heat exchange structure by the phase change material.

[0080] As shown in FIG. 1, it is a perspective structural schematic diagram of a heat storage unit 100 according to an embodiment of the present application. The heat storage unit 100 provided by the embodiments of the present application is used in a heat pump system. The heat storage unit 100 includes a metal heat storage shell and a phase change layer. The metal heat storage shell has a heat storage space inside. The phase change layer is filled in the heat storage space. The phase change layer includes a phase change material. The phase change material is used to exchange heat with the material in the heat storage space to perform phase change energy storage.

[0081] The phase change material according to the embodiments of the present application includes the following components:

[0082] The phase change material includes 85.0 wt.% to 95.0 wt.% of a phase change base material, 1.0 wt.% to 3.0 wt.% of a nucleating agent, 2.0 wt.% to 4.0 wt.% of a thickening agent, and 0.5 wt.% to 2.0 wt.% of an inhibitor. The phase change base material includes at least one of a saturated aliphatic acid, an alcohol compound, and an inorganic phase change base material. The inhibitor includes at least one of a nitrogen-containing heterocyclic compound, an oxygen-containing heterocyclic compound, a molybdate, a chromate, and a tungstate.

[0083] In the present application, the phase change base material is the main component of the phase change material that undergoes phase change. The nucleating agent is used to provide nucleation sites for the phase change base material, so that the phase change material can repeatedly melt-crystallize and then perform phase change energy storage. The thickening agent is used to improve the overall viscosity of the phase change material. The thickening agent can capture water molecules to prevent them from escaping, so as to inhibit the phase separation of the phase change material and make the phase change material have good stability in the frequent phase change process.

[0084] The application selects one of a saturated fatty acid, an alcohol compound or an inorganic phase change base material, and at least one of a corrosion inhibitor including a nitrogen-containing heterocyclic compound, an oxygen-containing heterocyclic compound, a molybdate, a chromate and a tungstate, the phase change base material can provide a solvent for the corrosion inhibitor, promote the dissociation of the corrosion inhibitor and form a negatively charged BTA - , MnO4 2- , CrO4 2- and the like (such as BTA: BTA+OH - =BTA - +H2O), and at the same time, since the metal ions are dissolved in the phase change material, the metal of the metal heat storage shell loses electrons (such as oxygen absorption corrosion of iron: 2Fe+O2+2H2O==2Fe 2+ +4OH - ), to form positively charged metal ions, and the positively charged metal ions (for example, Cu 2+ , Fe 2+ , Al 3+ ) can combine with the negatively charged BTA - , MnO4 2- , CrO4 2- to form a dense long-chain complex, and form a protective film on the metal surface by physical adsorption, to inhibit further contact of other corrosion ions with the metal, thereby achieving the purpose of corrosion prevention. Among them, the phase change material belongs to alkaline, in an alkaline environment, it can further promote the positive reaction of the corrosion inhibitor selected by the application in the phase change material, thereby generating negatively charged substances, and promoting the formation of complex on the wall surface of the metal heat storage shell. In the embodiments of the application, by selecting the phase change base material, the nucleating agent and the thickening agent and the components of the corrosion inhibitor in a suitable range, and after mixing the components of the phase change base material, the nucleating agent and the thickening agent, the entire phase change material system can be alkaline, thereby further promoting the formation of complex on the wall surface of the metal heat storage shell and improving the corrosion prevention effect.

[0085] In the embodiments of the application, the components of the phase change material can be uniformly mixed, and the phase change material in a molten state can be filled in the heat storage space after being heated. After the molten phase change material solidifies, a phase change layer is formed. The corrosion inhibitor is uniformly dispersed in the phase change layer, and in the process of repeated melting-crystallization of the phase change material in the phase change layer, the corrosion inhibitor uniformly contacts the wall surface of the metal heat storage shell, and a protective film is generated on the wall surface of the metal heat storage shell. Taking a metal heat storage shell containing copper material and a corrosion inhibitor including benzotriazole (BTA) as an example, the corrosion prevention mechanism of the corrosion inhibitor is as follows:

[0086] When the phase change material is heated to a molten state, benzene propyl triazole (BTA) is solvated, reaction ① is a reversible reaction, when BTA is in an alkaline environment, the concentration of BTA ions will be increased to a greater extent; copper (metal) is oxidized to generate cuprous ions Cu + (metal ions); Cu + (metal ions) and BTA ions (corrosion inhibitor ions) form a dense long-chain complex, and are physically adsorbed on the metal surface to inhibit further contact of other corrosion ions with the metal, thereby achieving the purpose of corrosion protection.

[0087] When the weight percentage of the phase change base material is less than the lower limit 85.0wt.%, the content of the phase change base material decreases, resulting in a lower heat enthalpy value of the phase change material, and when the weight percentage of the phase change base material is higher than the upper limit 95.0wt.%, the content of other components of the phase change material decreases, resulting in problems such as a decrease in phase stability and an increase in supercooling degree of the phase change material. When the weight percentage of the corrosion inhibitor is less than the lower limit 0.5wt.%, the content of the corrosion inhibitor is too low, the coverage and thickness of the surface complex formed are poor, and the protection effect on the metal is poor, and when the weight percentage of the corrosion inhibitor is higher than the upper limit 1.5wt.%, the corrosion inhibitor is redundant, resulting in waste of cost and aggravation of environmental burden.

[0088] In some embodiments, the phase change base material is 92wt.%-94wt.%, the nucleating agent is 2.0wt.%-3.0wt.%, the thickening agent is 3.0wt.%-4.0wt.%, and the corrosion inhibitor is 0.5wt.%-1.5wt.%. Under this component, the components of the phase change material can be more stably dispersed, the phase change stability is better, the regulation of water temperature is more stable, the heating water energy efficiency of the heat pump system can be further improved, and the corrosion of the entire phase change material on the wall surface of the metal heat storage shell is smaller.

[0089] In some embodiments, the weight ratio of the phase change base material to the corrosion inhibitor is 90.5-92.5, and in this ratio range, the phase change base material and the corrosion inhibitor cooperate with each other to further improve the corrosion of the phase change material on the wall surface of the metal heat storage shell.

[0090] The melting point Tm of the phase change base material is the basis of the phase change temperature of the phase change material, and in the embodiments of the present application, the phase change temperature of the phase change material is approximately equal to the melting point Tm of the phase change base material.

[0091] In some embodiments, the saturated fatty acid of the phase change base material is selected from at least one of myristic acid, tetradecanoic acid, and palmitic acid, at this time, the melting point Tm of the saturated fatty acid ranges from 25°C to 60°C, and by selecting the above-mentioned saturated fatty acid, the molybdate, chromate and tungstate corrosion inhibitors can promote the formation of molybdate, chromate and tungstate in an acidic environment, can quickly passivate the corroded metal and form a dense oxide film on the surface to achieve the purpose of corrosion protection.

[0092] In some embodiments, the alcohol compound of the phase-change base material is selected from at least one of mannitol, polyethylene glycol, dodecanol, and the melting point Tm of the alcohol compound ranges from 20℃ to 65℃. By selecting the alcohol compound, the solubility of the nitrogen-containing heterocyclic compound, the oxygen-containing heterocyclic compound, and the polar corrosion inhibitor can be greatly improved, the solvation degree of the corrosion inhibitor is increased, and the dispersion uniformity of the corrosion inhibitor is better.

[0093] In some embodiments, the inorganic phase-change base material of the phase-change base material is selected from at least one of sodium sulfate decahydrate, calcium chloride hexahydrate, sodium acetate trihydrate, magnesium chloride hexahydrate, sodium carbonate decahydrate, and sodium thiosulfate pentahydrate, and the melting point Tm of the inorganic phase-change base material ranges from 30℃ to 60℃. By selecting the inorganic phase-change base material, the inorganic salt belongs to a strong base weak acid or a strong base strong acid salt (a weak base or neutral hydrated salt), and because the alkaline environment is full of OH - ions, the formation of anions can be effectively promoted, and a dense complex with metal cations can be quickly formed.

[0094] In some embodiments, the nitrogen-containing heterocyclic compound of the corrosion inhibitor is selected from at least one of carboxyethyl imidazoline and its derivatives, benzotriazole and its derivatives. The oxygen-containing heterocyclic compound of the corrosion inhibitor is selected from at least one of chitosan-o-vanillin Schiff base, furfural-adenine Schiff base, and furfural-melamine Schiff base. The molybdate of the corrosion inhibitor is selected from at least one of sodium molybdate, strontium molybdate, and nickel molybdate. The chromate of the corrosion inhibitor is selected from at least one of sodium chromate, potassium chromate, and magnesium chromate. The tungstate of the corrosion inhibitor is selected from at least one of calcium tungstate, sodium tungstate, and cobalt tungstate. By selecting the above corrosion inhibitor, the corrosion inhibitor can be combined with various metal ions to form a complex in an alkaline phase-change material system, so that the material of the metal heat storage shell can have more choices. The diversity of the corrosion inhibitor means that the mechanism of corrosion inhibition not only includes the formation of a complex, but also the combination of corrosion inhibitors can effectively passivate the metal to achieve the purpose of corrosion protection.

[0095] In some embodiments, the nucleating agent is selected from at least one of a phosphate, a silicate, and a carbonate. The phosphate of the nucleating agent is selected from at least one of sodium dihydrogen phosphate and disodium hydrogen phosphate dodecahydrate. The carbonate of the nucleating agent is selected from at least one of calcium carbonate and magnesium carbonate. The silicate of the nucleating agent is selected from at least one of sodium metasilicate pentahydrate and calcium silicate. By selecting the above nucleating agent, the phase-change base material can be provided with a crystallization site, so that the phase-change material can repeatedly melt-crystallize, and the phase-change stability is better.

[0096] When the nucleating agent is an insoluble particle, the particle size Dv 50 of the nucleating agent satisfies 200 μm≤Dv 50≤400 μm nucleating agent, in this particle size range, the nucleating agent can be uniformly dispersed in the phase change material, providing crystallization sites for the phase change material.

[0097] In some embodiments, the phase change substrate has relatively poor thermal conductivity, and the phase change material further comprises a thermal conductive filler having good thermal conductivity, which is used to improve the overall thermal conductivity of the phase change material, so as to improve the heat transfer efficiency of the phase change material. The weight percentage of the thermal conductive filler is 1.0wt.% to 7.0wt.% based on the total weight of the phase change material. The thermal conductive filler is selected from at least one of fumed silica, copper foam, expanded graphite, carbon nanotubes and molybdenum disulfide.

[0098] The metal heat storage shell comprises a main shell and a heat exchange structure 20, as shown in FIG. 2 and FIG. 3, the heat exchange structure 20 comprises a plurality of heat conduction fins 212, which are arranged in the internal space of the main shell. One part of the phase change material is filled in the gap between two adjacent heat conduction fins 212, and the other part is filled in the gap between the heat conduction fin 212 and the main shell. The distance between two adjacent heat conduction fins 212 is L1, and the distance between the heat conduction fin 212 and the inner wall surface of the main shell is L2, 1.3mm≤L1≤1.8mm, 3mm≤L2≤6mm. In this distance range, the components of the molten phase change material can smoothly enter the metal heat storage shell, and uniformly enter the gap between two adjacent heat conduction fins 212 and the gap between the heat conduction fin 212 and the main shell, preventing the generation of bubbles.

[0099] Optionally, each heat conduction fin 212 extends in the vertical direction, and two adjacent heat conduction fins 212 form a heat conduction space extending in the vertical direction, which is filled with phase change material. The main shell has a filling inlet which communicates with the internal space of the main shell. The phase change material enters the internal space of the main shell through the filling inlet. The filling inlet is located above the heat exchange pipe in the vertical direction, which facilitates the smooth filling of the phase change material in the heat conduction space between two adjacent heat conduction fins 212.

[0100] The heat exchange structure 20 further comprises a plurality of heat exchange pipes 200, and the heat conduction fin 212 has a heat conduction hole. Each heat exchange pipe 200 penetrates the heat conduction hole of a plurality of heat conduction fins 212, and the main shell and the heat exchange structure 20 define a heat storage space. The phase change material is filled in the heat storage space and covers the outer surface of the heat exchange pipe 200 and the heat conduction fin 212, so as to exchange heat with the heat exchange medium in the heat exchange pipe 200. The heat exchange pipe 200 is connected to the heat conduction fin 212 through the plurality of heat conduction fins 212, and the heat exchange pipe 200 can also exchange heat with the phase change material through the heat conduction fin 212, thereby increasing the heat exchange area and improving the heat exchange efficiency.

[0101] In some embodiments, the heat exchange structure 20 further comprises a plurality of inlet headers 22 and a plurality of outlet headers 23, each of the inlet headers 22 is in communication with the inlets of the plurality of heat exchange tubes 200, and the heat exchange medium in the plurality of heat exchange tubes 200 is input through the same inlet header 22, each of the outlet headers 23 is in communication with the outlets of the plurality of heat exchange tubes 200, and the heat exchange medium in the plurality of heat exchange tubes 200 is output through the same outlet header 23. In the vertical direction, the inlet headers 22 and the outlet headers 23 are located above the plurality of heat exchange tubes 200, and are installed on the main shell 10, so as to be in a suitable position, which helps to shorten the length of the pipeline and save space.

[0102] Optionally, the heat exchange structure 20 further comprises a plurality of inlet headers 22 and a plurality of outlet headers 23, each of the inlet headers 22 is in communication with the inlets of the plurality of heat exchange tubes 200, and the heat exchange medium in the plurality of heat exchange tubes 200 is input through the same inlet header 22, each of the outlet headers 23 is in communication with the outlets of the plurality of heat exchange tubes 200, and the heat exchange medium in the plurality of heat exchange tubes 200 is output through the same outlet header 23. In the vertical direction, the inlet headers 22 and the outlet headers 23 are located above the plurality of heat exchange tubes 200, and are installed on the main shell 10, so as to be in a suitable position, which helps to shorten the length of the pipeline and save space.

[0103] Optionally, as shown in FIG. 4, the heat exchange structure 20 further comprises a plurality of adapter pipe groups, each of the adapter pipe groups comprises an adapter main pipe 2101 and an adapter branch pipe 2102, the adapter branch pipe 2102 has a plurality of adapter ends, one end of the adapter main pipe 2101 is connected with one of the adapter ends of the adapter branch pipe 2102, and the adapter pipe groups comprise an inlet adapter pipe group 213 and an outlet adapter pipe group 214. The other end of the adapter main pipe 2101 of the inlet adapter pipe group 213 is connected with the inlet header 24, and the remaining adapter ends of the adapter branch pipe 2102 are connected with the inlets of the plurality of heat exchange tubes 200 one by one. The other end of the adapter main pipe 2101 of the outlet adapter pipe group 214 is connected with the outlet header 25, and the remaining adapter ends of the adapter branch pipe 2102 are connected with the outlets of the plurality of heat exchange tubes 200 one by one.

[0104] In some embodiments, the plurality of heat exchange pipes include the heat storage pipe 215 and the heat release pipe 216, the inlet section of the heat storage pipe 215 is in communication with the outlet end of the heat source, and the outlet section is in communication with the inlet end of the heat source, the inlet section of the heat release pipe 216 is in communication with the municipal water source, and the outlet section is in communication with the domestic water pipe, the heat exchange medium in the heat storage pipe 215 receives the heat of the heat source and transfers the heat to the phase change material for heat storage, and the phase change material transfers the heat to the water flow in the heat release pipe 216 to realize heat release. In order to reduce the loss of heat in the transmission process and improve the thermal efficiency of the heat exchange structure 20, the heat storage pipe 215 and the heat release pipe 216 are alternately arranged, and optionally, the number of the heat storage pipe 215 and the heat release pipe 216 is the same, and the plurality of heat storage pipes 215 and the plurality of heat release pipes 216 in the heat exchange structure 20 are periodically and periodically arranged along a predetermined direction. The predetermined direction can be vertical or horizontal. Periodic arrangement helps to realize uniform distribution and stable release of heat, and avoids the occurrence of local overheating or overcooling.

[0105] In some embodiments, the material of the heat exchange pipe 200 is at least one of copper, copper alloy, and stainless steel; or the material of the heat exchange pipe 200 is copper, and the materials of the inlet header pipe 22, the outlet header pipe 23, the inlet manifold 24, and the outlet manifold 25 are stainless steel; or the materials of the heat storage pipe 215 and the adapter pipe group connected to the heat storage pipe 215 are aluminum, and the materials of the heat release pipe 216 and the adapter pipe group connected to the heat release pipe 216 are stainless steel.

[0106] It can be understood that copper has excellent heat conduction performance, but copper also has the disadvantage of poor corrosion resistance. In the embodiments of the present application, the material of at least one of the main shell, the heat conduction fin 212, the heat exchange pipe 200, the inlet header pipe 22, the outlet header pipe 23, the inlet manifold 24, the outlet manifold 25, the adapter main pipe 2101 and the adapter branch pipe 2102 can include copper. By selecting the type and content of each component of the phase change material, even in the presence of copper material, the corrosion degree of the phase change material to the part in contact with the heat exchange structure 20 containing copper is smaller, and the phase change material is filled in the heat storage space, and the corrosion inhibitor is uniformly distributed in the entire system of the phase change material, which can also prevent the occurrence of corrosion dead angle.

[0107] As shown in FIG. 5, it is a structure schematic diagram of a heat pump system 10 according to an embodiment of the present application. The heat pump system 10 includes a heat source 300 for providing heat, and the heat source 300 is in communication with at least one heat exchange pipe 200 of the heat storage unit 100, so that the heat source 300 can provide heat to at least one heat exchange pipe 200, and then transmit to the inorganic hydration phase change material of the phase change layer for heat storage.

[0108] Exemplarily, in FIG. 5, the plurality of heat exchange pipes 200 of the energy storage unit 100 include a heat storage pipe 215 and a heat release pipe 216, the inlet section of the heat storage pipe 215 is in communication with the outlet end 310 of the heat source 300, and the outlet section is in communication with the inlet end 320 of the heat source 300, the inlet section of the heat release pipe 216 is in communication with the municipal water source 610, and the outlet section is in communication with the domestic water pipe 620, the energy storage unit 100 has a heat storage mode, a heat release mode and a mixed mode, specifically, in the heat storage mode, the high-temperature heat exchange medium of the heat source 300 enters the heat storage pipe 215 from the inlet section of the heat storage pipe 215, the phase change material 100a absorbs the heat of the high-temperature heat exchange medium in the heat storage pipe 215 and stores the heat, and the high-temperature heat exchange medium becomes low-temperature heat exchange medium and returns to the inlet end 320 of the heat source 300 from the outlet section of the heat storage pipe 215; in the heat release mode, the low-temperature water flow supplied by the municipal water source 610 enters the heat release pipe 216 from the inlet section of the heat release pipe 216, the phase change material 100a transfers heat to the low-temperature water flow in the heat release pipe 216, and the low-temperature water flow absorbs heat to become high-temperature water flow and flows out of the outlet section of the heat release pipe 216 for use by the user; in the mixed mode, the high-temperature heat exchange medium of the heat source 300 enters the heat storage pipe 215 from the inlet section of the heat storage pipe 215, at the same time, the low-temperature water flow supplied by the municipal water source 610 enters the heat release pipe 216 from the inlet section of the heat release pipe 216, the phase change material 100a absorbs the heat of the high-temperature heat exchange medium in the heat storage pipe 215 and simultaneously transfers heat to the low-temperature water flow in the heat release pipe 216, and the low-temperature water flow absorbs heat to become high-temperature water flow or medium-temperature water flow and flows out of the outlet section of the heat release pipe 216 for use by the user.

[0109] The heat pump system 10 further includes a heating unit 400, a reversing valve 500 and connecting pipes for communication between various structures, the reversing valve 500 includes a first reversing valve 510, the first end of the first reversing valve 510 is in communication with the outlet end 310 of the heat source 300, the second end is in communication with the heating unit 400, and the third end is in communication with the heat exchange pipe 200 of the energy storage unit 100, by switching the flow path of the first reversing valve 510, the outlet end 310 of the heat source 300 is in communication with at least one of the heating unit 400 and the energy storage unit 100, to correspondingly provide high-temperature heat exchange medium to the heating unit 400 and the energy storage unit 100. The number of heating units 400 can be multiple, and the reversing valve 500 can further include a second reversing valve 520, the second reversing valve 520 is arranged in the connecting pipe between the second end of the first reversing valve 510 and the plurality of heating units 400, by switching the flow path of the second reversing valve 520, the second end of the first reversing valve 510 is in communication with one or more of the plurality of heating units 400, and the heat source 300 is in communication with one or more of the plurality of heating units 400.

[0110] The present application also provides an assembly method of the energy storage unit, as shown in FIG. 6, the assembly method includes:

[0111] Step S1, mixing the components of the phase change material as above.

[0112] Step S2, filling the mixed components of the phase change material into the heat storage space inside the metal heat storage shell.

[0113] In FIG. 6, Step S1 of mixing the components of the phase change material includes the following steps:

[0114] Step S110, mixing the phase change base material with the corrosion inhibitor and heating to a preset temperature to perform emulsification treatment, the preset temperature being greater than the melting point of the phase change base material, to obtain a molten mixture A;

[0115] Step S120, mixing the molten mixture A with the nucleating agent to perform a first mixing treatment to obtain a mixture B;

[0116] Step S130, mixing the mixture B with the thickening agent to perform a second mixing treatment to obtain a final mixture.

[0117] Step S2 includes: filling the molten final mixture of Step S130 into the heat storage space inside the metal heat storage shell, and the molten final mixture is cooled and solidified to form a phase change layer.

[0118] In the embodiments of the present application, the components of the phase change material can be hot-melted and uniformly mixed, and then filled into the heat storage space inside the metal heat storage shell in a molten state. The components mixed together can also be uniformly dispersed. When the molten final mixture is filled into the heat storage space inside the metal heat storage shell, the molten final mixture can be in contact with the wall surface of the metal heat storage shell without distinction, so that the corrosion inhibitor can be in contact with the wall surface of the metal heat storage shell, thereby having good corrosion prevention effect. In addition, the phase change material has good stability during heat storage and heat release.

[0119] In some embodiments, the emulsification treatment of Step S110 includes: the preset temperature is 70-80°C, the stirring speed is 2000-3000 r / min, and the time is 15-30 min. The preset temperature is greater than the melting point Tm of the phase change base material, so that the phase change base material can be fully melted, and the stirring treatment can be combined to uniformly emulsify and mix the phase change base material and the corrosion inhibitor.

[0120] When the melting point Tm of the phase change base material satisfies the condition formula 20°C≤Tm≤40°C, the preset temperature in the emulsification treatment is 50-60°C, and the time is 1-2 h; when the melting point Tm of the phase change base material satisfies the condition formula 40°C

[0121] In some embodiments, the step S120 and the step S130 can both maintain the temperature at a preset temperature to maintain the molten state of the phase change substrate, and at this temperature, the nucleating agent in the step S120 can be uniformly dispersed, and the thickening agent in the step S130 can be more fully swollen, so that the obtained molten final mixture has a suitable viscosity, facilitating smooth filling into the heat storage space inside the metal heat storage shell.

[0122] In some embodiments, the first mixing process at least includes: stirring at a speed of 80 r / min to 120 r / min for 1 h to 2 h, and emulsifying and shearing the molten inorganic hydrated salt and the nucleating agent by the emulsifying equipment under the emulsifying process conditions, so that the nucleating agent is uniformly dispersed in the molten inorganic hydrated salt, so that the crystalline phase formed by the inorganic hydrated salt during crystallization has better integrity and uniformity.

[0123] In some embodiments, the second mixing process at least includes: adding the thickening agent to the mixture B in multiple times, stirring at a speed of 20 r / min to 40 r / min for 2 h to 3 h, and the weight of the thickening agent added each time is 20% to 25% of the total weight of the thickening agent. The method of adding the thickening agent in multiple small amounts facilitates the swelling and uniform dispersion of the thickening agent in the inorganic hydrated salt phase change material, so as to better improve the phase separation and prevent the thickening agent from clumping and causing uneven dispersion when added in large amounts.

[0124] In some embodiments, when the phase change material is combined with the heat-conducting filler, the heat-conducting filler can be added to the mixture B together with the thickening agent in the step S130 to perform the second mixing process, and obtain a final mixture including the heat-conducting filler.

[0125] In some embodiments, when the particles of the nucleating agent and the heat-conducting filler are large, the nucleating agent and the heat-conducting filler are respectively subjected to a crushing process, and then mixed with other components. The particle size Dv 50 of the crushed nucleating agent satisfies 200 μm≤Dv 50 ≤400 μm, and the particle size Dv 50 of the crushed heat-conducting filler satisfies 300 μm≤Dv 50 ≤900 μm, so that the nucleating agent can be uniformly dispersed in the premix liquid. The crushing process can use at least one of a ball mill and a high-speed crusher.

[0126] The preparation method of the phase change material is described below in combination with examples and comparative examples. Those skilled in the art will understand that the preparation method described in the present application is only an example, and any other suitable preparation method is within the scope of the present application. In the following examples, unless otherwise specified, the various raw materials used are commercially available.

[0127] In the embodiments and comparative examples of the present application, the performance test method of the phase change material is as follows:

[0128] (1) Phase change temperature and supercooling degree test method

[0129] The phase change temperature adopts the step cooling curve method: 100 g of the phase change material is placed in a high borosilicate glass bottle, a K-type thermocouple is inserted into the middle of the phase change material, and then the phase change material is heated to 20°C above the melting point of the phase change material and stabilized for 30 min. Then, it is placed in an environment of 30°C below the melting point for natural cooling, and the temperature information of the phase change material changing with time is collected to obtain the temperature-time curve and the corresponding theoretical phase change temperature (T theory ) and actual phase change temperature (T actual ).

[0130] The difference between the theoretical phase change temperature (T theory ) and the actual phase change temperature (T actual ) is the supercooling degree (T sc ).

[0131] (2) Heat enthalpy value attenuation rate test method after 2000 cycles

[0132] The initial unit mass heat enthalpy value of the phase change material is measured by a DSC device.

[0133] The phase change material is loaded into a cycle test device, and the melting-crystallization cycle is carried out according to the following steps:

[0134] (1) The initial temperature is 0°C, and it is stationary for 5 min;

[0135] (2) The temperature is raised at a rate of 5°C / min, and the temperature is stopped at 80°C, and it is stationary for 5 min;

[0136] (3) The temperature is lowered at a rate of 5°C / min, and the temperature is stopped at 0°C, and it is stationary for 1 min.

[0137] Among them, the above steps (1)-(3) are the first melting-crystallization cycle, and then the steps (2)-(3) are a melting-crystallization cycle. After the phase change material is subjected to the melting-crystallization cycle for 2000 times, the unit mass heat enthalpy value of the phase change material after 2000 cycles is measured by a DSC device.

[0138] The calculation formula of the unit mass heat enthalpy value attenuation rate is: H% = (1-△H n / △H0) x 100%;

[0139] Among them, △H n is the unit mass heat enthalpy value of the phase change material after n cycles, kJ / kg;

[0140] AH0 is the initial unit mass enthalpy of the phase change material, kJ / kg.

[0141] (3) Energy storage density test method

[0142] The solid-state (p s ) and liquid-state density (p l ) of the phase change material are measured by a density meter;

[0143] The solid-state specific heat capacity C ps and liquid-state specific heat capacity C pl of the phase change material are tested by a differential scanning calorimeter (DSC) using the MDSC method.

[0144] The initial unit mass enthalpy AH0 of the phase change material is measured by a differential scanning calorimeter (DSC).

[0145] The energy storage density AQ is calculated according to the following formula: AQ = p s × (T actual -10) × C ps + (p s + p l ) / 2 × AH0 + p l× (65-T actual ) × C pl .

[0146] (4) Anti-corrosion test method

[0147] The phase change materials are divided into organic phase change materials, inorganic phase change materials and eutectic phase change materials, and different material systems have different corrosion characteristics on metals. In order to ensure the authenticity of the test, the components in the system which are in direct or indirect contact with the phase change material are used to evaluate the service life, and two test methods are used to investigate the corrosion characteristics of the phase change material on the metal.

[0148] The components are filled in the phase change material and placed in an oven with a temperature higher than the phase change temperature of the phase change material by 15℃, and a thermal environmental corrosion experiment is carried out, with a time period of 209 days (5000h), and sampling detection is carried out every 42 days (1000h), the microstructure of the corroded sample is analyzed by scanning electron microscopy, the main components of the corrosion product are analyzed by element analysis and EDX, and the corrosion depth of the sample is observed by 3D microscope.

[0149] Example 1-1

[0150] The embodiment provides a preparation method of a phase change material prepared from a phase change material, which comprises the following steps:

[0151] (1) Emulsification treatment

[0152] 85.0 g of inorganic phase change base material sodium acetate trihydrate (CH3COONa·3H2O) and 1.0 g of corrosion inhibitor BTA were weighed, heated to a preheating temperature of 75 °C in an emulsifying device, and emulsified at a stirring speed of 2500 r / min for 20 min to obtain a molten mixture A.

[0153] The weight percentage of sodium acetate trihydrate was 85.0 wt.%, and the weight percentage of BTA was 1.0 wt.% based on the total weight of the phase change material.

[0154] (2) First mixing treatment

[0155] At 75 °C, 3.0 g of nucleating agent disodium phosphate dodecahydrate and 7.0 g of thermal conductive filler carbon nanotube were added to the molten mixture A, and the first mixing treatment was carried out in a stirring device at a stirring speed of 90 r / min for 1.5 h to obtain a mixture B.

[0156] Among them, the weight percentage of disodium phosphate dodecahydrate was 3.0 wt.%, and the weight percentage of carbon nanotube was 7.0 wt.% based on the total weight of the inorganic hydrated phase change material.

[0157] (3) Second mixing treatment

[0158] At 75 °C, the thickening agent sodium carboxymethyl cellulose was added to the final mixture in 5 times, and the second mixing treatment was carried out in a stirring device at a stirring speed of 30 r / min for 2 h, and the amount of each addition was 0.6 g to obtain a molten final mixture.

[0159] Among them, the weight percentage of sodium carboxymethyl cellulose was 4.0 wt.% based on the total weight of the inorganic hydrated phase change material.

[0160] (4) Cooling treatment

[0161] The molten final mixture was cooled to room temperature of 25 °C, and the final mixture was solidified to form a phase change material.

[0162] Among them, the phase change layer of the heat storage unit was solidified by cooling the molten final mixture to room temperature of 25 °C.

[0163] Examples 1-2 to 1-7, Examples 1-13 to 1-21, Comparative Examples 1-1 to 1-4, except that the content of the phase change base material, nucleating agent, corrosion inhibitor, thickening agent and thermal conductive filler was adjusted according to Table 1 in each processing step, the rest was the same as Example 1-1.

[0164] Example 1-8, except that the type of phase change base material was adjusted according to Table 1 in step (1), and the treatment temperature was adjusted to 50°C according to Table 1 in step (1)-step (2), and the rest was the same as Example 1-6.

[0165] Example 1-9, except that the type of phase change base material was adjusted according to Table 1 in step (1), and the treatment temperature was adjusted to 50°C according to Table 1 in step (1)-step (2), and the rest was the same as Example 1-6.

[0166] Example 1-10, except that the type of phase change base material was adjusted according to Table 1 in step (1), and the treatment temperature was adjusted to 70°C according to Table 1 in step (1)-step (2), and the rest was the same as Example 1-6.

[0167] Example 1-11, except that the type of phase change base material was adjusted according to Table 1 in step (1), and the treatment temperature was adjusted to 50°C according to Table 1 in step (1)-step (2), and the rest was the same as Example 1-6.

[0168] Example 1-12, except that the type of phase change base material was adjusted according to Table 1 in step (1), and the treatment temperature was adjusted to 70°C according to Table 1 in step (1)-step (2), and the rest was the same as Example 1-6.

[0169] The preparation parameters and performance parameters of Example 1-1 to Example 1-21, Comparative Example 1-1 to Comparative Example 1-4 are shown in Table 1.

[0170] As can be seen from Example 1-1 to Example 1-24, Comparative Example 1-1 to Comparative Example 1-4 in Table 1, when the phase change base material is selected from saturated fatty acids, alcohol compounds or inorganic phase change base materials, and combined with corrosion inhibitors for phase change materials, the phase change temperature, the enthalpy value after 2000 cycles, the enthalpy value attenuation rate after 2000 cycles, the supercooling degree and the energy storage density of the phase change material are all within a suitable range. The phase change material of the present application can be used in a heat pump system for cold storage and heat storage. When the weight percentage content of the phase change base material is less than 85wt.%, the enthalpy value energy storage density of the phase change material is poor. When the weight percentage content of the phase change base material is higher than 95wt.%, the content of the phase change base material is too high, which can easily lead to insufficient content of other components of the phase change material, and can easily cause phase separation. When the weight percentage content of the corrosion inhibitor is less than the lower limit of 0.5wt.%, the coverage and thickness of the surface complex formed by the corrosion inhibitor is insufficient, and the protection effect on the metal is poor. When the weight percentage content of the corrosion inhibitor is higher than the upper limit of 1.5wt.%, the corrosion inhibitor is redundant, which can cause waste of cost and can aggravate the environmental burden.

[0171] As shown in Fig. 7a, the morphology of the outer surface of the copper heat exchange tube at the butt joint after the copper heat exchange tube was contacted with the phase change material prepared in Example 1-6 and used as the phase change layer and subjected to corrosion experiment for 1000h in a 75℃ environment; as shown in Fig. 7b, the morphology of the outer surface of the copper heat exchange tube after the copper heat exchange tube was contacted with the phase change material prepared in Comparative Example 1-1 and used as the phase change layer and subjected to corrosion experiment for 1000h in a 75℃ environment. As can be seen from Fig. 7a, the morphology of the outer surface of the copper heat exchange tube at the butt joint is good, and there is no large area of corrosion region. As can be seen from Fig. 7b, the outer surface of the copper heat exchange tube at the butt joint has a large area of corrosion region, indicating that the phase change material of the present application has a small corrosion degree on the butt joint of the copper heat exchange tube and has a good corrosion prevention effect.

[0172] As shown in Fig. 8, the corrosion depth of the copper heat exchange tube after the copper heat exchange tube was contacted with the phase change material prepared in Example 1-6 and used as the phase change layer and subjected to corrosion experiment for 1000h in a 75℃ environment. As can be seen from Fig. 8, after the high-temperature corrosion experiment for 1000h, the corrosion depth of the copper tube is <20μm.

[0173] As shown in Fig. 9, the corrosion of the 304 stainless steel inner liner sheet metal after the 304 stainless steel was contacted with the phase change material prepared in Example 1-6 and used as the phase change layer and subjected to corrosion experiment for 1000h in a 75℃ environment. As can be seen from Fig. 9, the surface of the 304 stainless steel sheet is intact and no uniform corrosion phenomenon occurs.

[0174] As shown in Fig. 10, the corrosion of the aluminum sheet after the aluminum sheet was contacted with the phase change material prepared in Comparative Example 1-1 and used as the phase change layer and subjected to corrosion experiment for 1000h in a 75℃ environment. As can be seen from Fig. 10, the aluminum sheet surface forms a corrosion (green marked as the corrosion region of the aluminum sheet) region with an area of about 3 / 4 of the aluminum sheet area, and the corrosion degree is serious.

[0175] The above only describes the preferred embodiments of the present application and should not be used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A thermal storage unit, wherein, The heat storage unit, which is installed in a heat pump system, includes a metal heat storage shell and a phase change layer. The metal heat storage shell has a heat storage space inside, and the phase change layer fills the heat storage space. The phase change layer includes a phase change material, which comprises the following components: Phase change substrate 85.0 wt.%–95.0 wt.%, nucleating agent 1.0 wt.%–3.0 wt.%, thickener 2.0 wt.%–4.0 wt.%, corrosion inhibitor 0.5 wt.%–2.0 wt.%; The phase change substrate includes one of saturated fatty acids, alcohol compounds, or inorganic phase change substrates; The nucleating agent is selected from at least one of phosphates, silicates, and carbonates; The corrosion inhibitor includes at least one of nitrogen-containing heterocyclic compounds, oxygen-containing heterocyclic compounds, molybdates, chromates, and tungstates.

2. The thermal storage unit of claim 1, wherein, Based on the total weight of the phase change material, the phase change material comprises the following components: Phase change substrate 92wt.%–94wt.%, nucleating agent 2.0wt.%–3.0wt.%, thickener 3.0wt.%–4.0wt.%, corrosion inhibitor 0.5wt.%–1.5wt.%.

3. The thermal storage unit of any one of claims 1-2, wherein, The weight ratio of the phase change substrate to the corrosion inhibitor ranges from 90.5 to 92.

5.

4. The heat storage unit according to claim 1, wherein, The saturated fatty acid of the phase change substrate is selected from at least one of myristic acid, palmitic acid, and fatty acids; The alcohol compound of the phase change substrate is selected from at least one of mannitol, polyethylene glycol, and dodecanol; The inorganic phase change substrate of the phase change substrate is selected from at least one of sodium sulfate decahydrate, calcium chloride hexahydrate, sodium acetate trihydrate, magnesium chloride hexahydrate, sodium carbonate decahydrate, and sodium thiosulfate pentahydrate.

5. The heat storage unit according to claim 1, wherein, The nitrogen-containing heterocyclic compound of the corrosion inhibitor is selected from at least one of carboxyethyl imidazoline and its derivatives, benzotriazole and its derivatives, and imidazoline; The oxygen-containing heterocyclic compound of the corrosion inhibitor is selected from at least one of chitosan-o-vanillin Schiff base, furfural-adenine Schiff base, and furfural-melamine Schiff base. The molybdate of the corrosion inhibitor is selected from at least one of sodium molybdate, strontium molybdate, and nickel molybdate; The chromate in the corrosion inhibitor is selected from at least one of sodium chromate, potassium chromate, and magnesium chromate. The tungstate of the corrosion inhibitor is selected from at least one of calcium tungstate, sodium tungstate, cobalt tungstate, and ferrous tungstate.

6. The heat storage unit according to claim 1, wherein, The thickener is selected from at least one of hydroxymethyl cellulose, soluble starch, gelatin, polyvinylpyrrolidone, sodium xanthan gum polyacrylate.

7. The thermal storage unit of claim 1, wherein, The metal thermal storage shell includes a main shell and a heat exchange structure, the heat exchange structure including: Multiple heat-conducting fins are disposed in the internal space of the main housing, and each heat-conducting fin has a heat-conducting hole; Multiple heat exchange tubes are disposed in the internal space of the main shell, and each heat exchange tube is provided with multiple heat-conducting holes of the heat-conducting fins. The main shell and the heat exchange structure define the heat storage space. The phase change layer is filled in the heat storage space and is in contact with the outer surface of the heat exchange pipe and the outer surface of the heat conduction fin to exchange heat with the heat exchange medium in the heat exchange pipe; The material of at least one of the main housing, the heat conduction fin and the heat exchange pipe comprises copper.

8. The heat storage unit according to claim 7, wherein, Each of the heat conduction fins extends in the vertical direction, and adjacent two of the heat conduction fins form a heat conduction space extending in the vertical direction, and the heat conduction space is filled with the phase change material; The main housing has a filling inlet in communication with the internal space of the main housing, and the phase change material enters the internal space of the main housing through the filling inlet, and the filling inlet is located above the heat exchange pipe in the vertical direction.

9. The heat storage unit according to claim 7, wherein, The heat exchange structure further comprises a plurality of inlet headers and a plurality of outlet headers; Each of the inlet headers is in communication with the inlets of a plurality of the heat exchange pipes; Each of the outlet headers is in communication with the outlets of a plurality of the heat exchange pipes; In the vertical direction, the inlet headers and the outlet headers are both located above the plurality of heat exchange pipes and are installed on the main housing.

10. The heat storage unit according to claim 9, wherein, The heat exchange structure further comprises a plurality of inlet collectors in one-to-one correspondence with the plurality of inlet headers and a plurality of outlet collectors in one-to-one correspondence with the plurality of outlet headers; Each of the inlet headers is in communication with the inlets of a plurality of the heat exchange pipes through the corresponding inlet collector; Each of the outlet headers is in communication with the outlets of a plurality of the heat exchange pipes through the corresponding outlet collector; In the vertical direction, the inlet collectors and the outlet collectors are both located above the plurality of heat exchange pipes.

11. The heat storage unit according to claim 10, wherein, The heat exchange structure further comprises a plurality of groups of adapter pipe groups, each of the adapter pipe groups comprises an adapter main pipe and an adapter branch pipe, the adapter branch pipe has a plurality of adapter ends, and one end of the adapter main pipe is connected to one of the adapter ends of the adapter branch pipe; The adapter pipe groups comprise inlet adapter pipe groups and outlet adapter pipe groups; The other end of the adapter main pipe of the inlet adapter pipe groups is connected to the inlet collector, and the remaining adapter ends of the adapter branch pipe are connected to the inlets of a plurality of the heat exchange pipes in one-to-one correspondence; The other end of the adapter main pipe of the outlet adapter pipe groups is connected to the outlet collector, and the remaining adapter ends of the adapter branch pipe are connected to the outlets of a plurality of the heat exchange pipes in one-to-one correspondence.

12. The heat storage unit according to claim 11, wherein, The plurality of heat exchange pipes comprise heat storage pipes and heat release pipes, the inlet section of the heat storage pipe is in communication with the outlet end of the heat source, and the outlet section is in communication with the inlet end of the heat source, the inlet section of the heat release pipe is in communication with the municipal water source, and the outlet section is in communication with the domestic water pipe; The heat exchange structure satisfies one of the following conditions: (1) The material of the heat exchange pipe is at least one of copper, copper alloy and stainless steel; (2) The material of the heat exchange pipe is copper, and the materials of the inlet header, the outlet header, the inlet collector and the outlet collector are stainless steel; (3) the material of the heat storage tube and the adapter tube group connected to the heat storage tube is aluminum, and the material of the heat releasing tube and the adapter tube group connected to the heat releasing tube is stainless steel.

13. A method of assembling a thermal storage unit, wherein, Comprising: After mixing the components of the phase change material according to any one of claims 1-12, a final mixture is obtained, and the final mixture is filled into the heat storage space of the metal heat storage shell, and the final mixture forms the phase change layer.

14. The assembly method of claim 13, wherein, The mixing of the components of the phase change material comprises the following steps: The phase change base material is mixed with the corrosion inhibitor, and heated to a preset temperature for emulsification treatment, the preset temperature is greater than the melting point of the phase change base material, and a molten mixture A is obtained; The molten mixture A is mixed with the nucleating agent for first mixing treatment, and a mixture B is obtained; The mixture B is mixed with the thickening agent for second mixing treatment, and a molten final mixture is obtained; The filling of the final mixture into the heat storage space of the metal heat storage shell comprises: filling the molten final mixture into the heat storage space inside the metal heat storage shell, and the molten final mixture is cooled and solidified to form the phase change layer.

15. The assembly method of claim 14, wherein, The emulsification treatment at least comprises: the preset temperature is 70-80℃, the stirring speed is 2000-3000r / min, and the time is 15-30min; The first mixing treatment at least comprises: the stirring speed is 80-120r / min, and the time is 1-2h; The second mixing treatment at least comprises: the thickening agent is added to the mixture B in batches, the stirring speed is 20-40r / min, the time is 2-3h, and the weight of the thickening agent added each time is 20-25% of the total weight of the thickening agent.

16. A heat pump system wherein, Comprising: a heat source for providing heat; and The heat storage unit according to any one of claims 1-12, the phase change material of the heat storage unit is used to obtain the heat provided by the heat source for phase change energy storage.

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