Solid-solid phase change material, solid-solid phase change heat storage system and application of solid-solid phase change material and solid-solid phase change heat storage system in phase change energy storage device

Abstract

The invention discloses a solid-solid phase change material, a solid-solid phase change heat storage system and application thereof in a phase change energy storage device, the solid-solid phase change material contains choline groups, negative ions are one of Br <->, Cl <->, F <->, I <->, BrO3 <->, BrO <->, HCO3 <->, OH <->, ClO3 <->, ClO4 <->, ClO <->, IO3 <->, NO3 <->, NO2 <->, H2PO4 <->, HSO4 <->, HSO3 <->, AlSiO4 <->, C2H3O <->, HCO2 <->, HC2O4 <->, HS <->, NH2 <->, OCN <->, SCN <- The solid-solid phase change heat storage system comprises the solid-solid phase change material, heat-conducting epoxy resin and graphite. The phase change energy storage device is filled with a solid-solid phase change heat storage system, and the risk of phase change material leakage in the using process is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of heat storage and heat exchange, and in particular to a solid-solid phase change material, a solid-solid phase change heat storage system and applications thereof in a phase change energy storage device. Background Art

[0002] Phase change materials have great applications in valley power utilization and thermal energy storage. Phase change energy storage devices add phase change materials to the device, absorbing and releasing heat through the phase change of the phase change material. Due to its constant storage / release temperature, high energy storage density, and stable cycle performance, it has become a hot research direction in the field of energy storage.

[0003] In a phase-change energy storage water heater, the phase-change material is filled in the inner tank, and the state of the phase-change material changes to store and release heat energy; when the temperature is lower than the set temperature, the heating device starts to heat up, and the phase-change material starts to store heat; when low-temperature water flows into the water heater, the phase-change material starts to release heat, and the water is heated. For the phase-change material used in the water heater, it is required to have a large heat storage density, fast heat conduction, stable cycle performance, and a suitable phase change temperature; for the heat exchange device storing the phase-change material in the water heater, it is required to have good corrosion resistance, good sealing, and good thermal conductivity.

[0004] At present, solid-liquid phase change materials are often used as raw materials for heat storage in phase change energy storage water heaters. However, due to their phase change characteristics, they change from solid to liquid after the phase change, which poses a risk of leakage and increases safety hazards.

[0005] Solid-solid phase change materials have great practical value in thermal energy storage applications because they avoid the leakage problems common in solid-liquid phase change materials. This feature allows them to be mixed and assembled with other materials under simple packaging conditions without the need for additional strict sealing. The volume change of solid-solid phase change materials before and after the phase change is small, which prevents the expansion and contraction of the volume of solid-solid phase change materials during cyclic use from causing reciprocating fatigue damage to the storage container and improves durability. This is very important for devices that need to be used for a long time.

[0006] Using quaternary ammonium salt solid-solid phase change materials with suitable phase change temperature instead of solid-liquid phase change materials for heat storage and release can reduce the risk of leakage of energy storage materials before and after phase change. However, due to the problems of poor thermal conductivity, slight corrosiveness at high temperature, small amount of gas generated in the initial use and difficulty in dense filling of quaternary ammonium salt solid-solid phase change materials, it is necessary to optimize the existing heat exchange device in terms of preparation material, structure, etc., and change the filling method of the heat exchange device filler composition to enhance the convenience and practicality of the application of solid-solid phase change materials in water heaters. Summary of the invention

[0007] The purpose of the present invention is to provide a solid-solid phase change material to address the problems existing in the prior art, such as poor thermal conductivity, slight corrosiveness at high temperatures, generation of a small amount of gas in the initial stage of use and difficulty in dense filling.

[0008] Another object of the present invention is to provide a solid-solid phase change heat storage system based on the solid-solid phase change material.

[0009] Another object of the present invention is to provide an application of the solid-solid phase change material or the solid-solid phase change heat storage system in a phase change energy storage device.

[0010] Another object of the present invention is to provide a phase change energy storage device based on the solid-solid phase change material or solid-solid phase change heat storage system.

[0011] The technical solution adopted to achieve the purpose of the present invention is:

[0012] A solid-solid phase change material, the molecular formula is:

[0013]

[0014] Where X - Br - , Cl - 、F - ,I - BrO 3 - BrO - , HCO 3 - OH - , ClO 3 - , ClO 4 - , ClO - ,IO 3 - 、NO 3 - 、NO 2 - , H 2 PO 4 - , HSO 4 - , HSO 3 - 、AlSiO 4 - , C 2 H 3 O 2 - , HCO 2 - HC 2 O4 - , HS - NH 2 - 、OCN - 、SCN - , CN - 、MnO 4 - One of them.

[0015] Another aspect of the present invention also includes the use of the solid-solid phase change material in a phase change energy storage device.

[0016] Another aspect of the present invention also includes a solid-solid phase change heat storage system, including the solid-solid phase change material, thermal conductive epoxy resin and graphite.

[0017] In the above technical solution, in the solid-solid phase change heat storage system, the mass fraction of the solid-solid phase change material is 50 to 80 mass parts, the mass fraction of the thermal conductive epoxy resin is 10 to 40 mass parts, and the mass fraction of graphite is 10 to 40 mass parts.

[0018] In the above technical solution, the thermally conductive epoxy resin includes thermally conductive epoxy resin A and thermally conductive epoxy resin B, and the solid-solid phase change material is prepared by the following steps:

[0019] Step 1, adding thermal conductive epoxy resin A to the solid-solid phase change material, stirring and mixing evenly, and adding graphite to mix evenly to obtain a mixture;

[0020] Step 2, adding thermal conductive epoxy resin B to the mixture obtained in step 1, and continuously stirring to mix evenly to obtain a solid-solid phase change heat storage system.

[0021] Another aspect of the present invention also includes the use of the solid-solid phase change heat storage system in a phase change energy storage device.

[0022] Another aspect of the present invention further includes a phase change energy storage device, in which a heat exchange unit is provided, and the heat storage medium filled in the heat exchange unit includes the solid-solid phase change material or the solid-solid phase change heat storage system.

[0023] In the above technical solution, an anti-corrosion layer is applied at a position in the heat exchange unit that contacts the solid-solid phase change material or the solid-solid phase change heat storage system, and the anti-corrosion layer is a polytetrafluoroethylene coating.

[0024] In the above technical solution, the filling amount of the heat storage medium in the heat exchange unit is not less than 95% of the total volume and not more than 98% of the total volume.

[0025] In the above technical solution, a one-way gas valve is provided on the heat exchange unit to discharge the gas generated by the solid-solid phase change material or the solid-solid phase change heat storage system when heated.

[0026] In the above technical solution, the phase change energy storage device is a solid-solid phase change energy storage water heater, the heat exchange unit is a heat exchange tube, the heat exchange tube includes an outer tube and an inner tube nested inside the outer tube, the inner tube is for water circulation, the two ends of the inner tube are respectively connected to a water inlet pipe and a water outlet pipe, a closed space is formed between the outer tube and the inner tube and filled with the solid-solid phase change heat storage system, and a heating element is provided on the outside of the outer tube.

[0027] In the above technical solution, heat-conducting fins distributed in an annular shape are fixed between the inner tube and the outer tube, and the heat-conducting fins are stainless steel plates with a polytetrafluoroethylene coating.

[0028] In the above technical solution, the heating element is a heating wire, the heating wire is wound around the outside of the outer tube, and the heating wire is electrically connected to the heating device.

[0029] In the above technical solution, a temperature sensor is provided on the heat exchange tube, and the temperature sensor is electrically connected to the heating device.

[0030] In another aspect of the present invention, the working method of the phase change energy storage device comprises the following steps:

[0031] Step 1, heat storage stage: after the power is turned on, the temperature sensor detects a temperature signal and sends it to the heating device. When the temperature of the heat exchange tube is lower than the first set temperature, the first set temperature is lower than the phase change exothermic termination temperature of the solid-solid phase change material, the heating device starts to heat the heat exchange tube, the heat is absorbed by the heat exchange tube, and the solid-solid phase change material starts to store heat. When the heat exchange tube is heated to the second set temperature, the second set temperature is higher than the phase change endothermic termination temperature of the solid-solid phase change material, the phase change temperature sensor detects a temperature signal and sends it to the heating device, and the heating device stops heating.

[0032] Step 2, heat release stage: after the water flows into the inner tube, the solid-solid phase change material in the heat exchange tube begins to release heat, and the heat is absorbed by the water flow, completing the water flow heating process;

[0033] Step 3: After multiple uses, open the one-way air valve to discharge the gas.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention improves the solid-solid phase change material, the solid-solid phase change heat storage system, and the heat exchange device, thereby improving the safety and working efficiency of the phase change energy storage water heater, which is specifically manifested in the following aspects:

[0036] (1) Using solid-solid phase change materials or solid-solid phase change heat storage systems to replace traditional energy storage media reduces the risk of phase change material leakage during use.

[0037] (2) The solid-solid phase change material is further wrapped with a thermally conductive resin to eliminate the risk of leakage of the phase change material during use. Even if the phase change material storage pipeline is damaged, the wrapped resin can still ensure that the phase change material does not leak in the short term; at the same time, the hygroscopicity problem of the solid-solid phase change material is solved.

[0038] (3) The parts of the device that come into contact with the phase change material are coated with polytetrafluoroethylene, which solves the problem of slight corrosion of the phase change material at high temperatures without substantially affecting thermal conductivity.

[0039] (4) The solid-solid phase change material is compounded with a thermally conductive resin to prepare a phase change filling material with fluidity, which not only facilitates the filling of the phase change material in a curved and narrow pipe and improves the compactness of the filling, but also improves the sealing of the phase change material after the resin is cured.

[0040] (5) The solid-solid phase change heat storage system combines thermal conductivity and graphite, solving the problem of poor thermal conductivity of solid-solid phase change materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Shown is the DSC graph of choline chloride.

[0042] Figure 2 The following are the pictures of choline chloride before and after heating: a, room temperature; b, after heating at 200°C.

[0043] Figure 3 This is a schematic diagram of the internal device of a solid-solid phase change water heater, wherein 1 is a water inlet pipe, 2 is a water outlet pipe, 3 is a heat exchange tube, 4 is a temperature sensor, 5 is a heating device, 51 is a heating wire, and 6 is a one-way gas valve.

[0044] Figure 4 31 is an outer tube, 32 is a heat transfer fin, and 33 is an inner tube.

[0045] Figure 5 Shown is the DSC graph of choline bromide.

[0046] Figure 6 Shown are the actual pictures of choline bromide before and after heating: a, room temperature; b, after heating at 200°C.

[0047] Figure 7 Shown is the DSC graph of choline iodide.

[0048] Figure 8 Shown are the actual pictures of choline iodide before and after heating: a, room temperature; b, after heating at 200°C. DETAILED DESCRIPTION

[0049] The present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] Example 1

[0051] A solid-solid phase change material (choline chloride) having the molecular formula:

[0052] Where X - Cl - .

[0053] like Figure 1 As shown, the endothermic starting temperature of the choline chloride phase change is 78.09°C, the end temperature is 90.74°C, the phase change enthalpy is 109.32 J / g, the exothermic starting temperature of the phase change is 55.09°C, the end temperature is 50.27°C, and the phase change enthalpy is 105.37 J / g.

[0054] like Figure 2 As shown, a is the state at room temperature; b is after heating at 200℃. Figure 2 It can be seen that the solid state does not change before and after the phase change.

[0055] Example 2

[0056] A solid-solid phase change heat storage system comprises, by weight, 80 parts by weight of choline chloride described in Example 1, 10 parts by weight of thermally conductive epoxy resin, and 10 parts by weight of graphite particles. The thermally conductive epoxy resin ensures the thermal conductivity of the device and the filling density of the solid-solid phase change material, and the graphite particles can enhance the thermal conductivity of the phase change material and ensure uniform thermal conductivity.

[0057] The preparation method of the solid-solid phase change heat storage system is as follows:

[0058] Step 1: add 9.14 parts by mass of thermally conductive epoxy resin A to 80 parts by mass of choline chloride, stir and mix evenly, and add 10 parts by mass of graphite particles and mix evenly to obtain a mixture.

[0059] Step 2, adding 0.86 parts by mass of thermally conductive epoxy resin B to the mixture obtained in step 1, mixing evenly, and continuously stirring until the viscosity of the mixture increases, to obtain a solid-solid phase change heat storage system.

[0060] Example 3

[0061] like Figure 3-Figure 4As shown, a solid-solid phase change energy storage water heater, the heat exchange tube 3 includes an outer tube 31 and an inner tube 33 nested inside the outer tube 31, the inner tube 33 is for water circulation, and the two ends of the inner tube 33 are respectively connected to the water inlet pipe 1 and the water outlet pipe 2, the solid-solid phase change heat storage system described in Example 2 is filled between the outer tube 31 and the inner tube 33, and is left to stand at 70°C for 2 hours to solidify, and then is strongly sealed under vacuum conditions to ensure the drying of choline chloride.

[0062] A heating wire 51 is wound around the outside of the outer tube, and the heating wire 51 is electrically connected to the heating device 5. The heat exchange tube 3 is equipped with a heat-conducting fin 32 made of stainless steel with a polytetrafluoroethylene coating to enhance the thermal conductivity of the solid-solid phase change heat storage system. A one-way gas valve 6 is installed on the heat exchange tube 3 to facilitate the discharge of gas. A temperature sensor 4 is installed on the heat exchange tube 3, and the temperature sensor 4 is connected to the heating device 5.

[0063] The application scenario of the solid-solid phase change energy storage water heater is industrial plant heating, the room temperature is required to be no less than 10°C, and the outlet temperature is no less than 20°C. The method for using the water heater includes the following steps:

[0064] Step 1, heat storage stage: after the power is turned on, when the temperature of the heat exchange tube 3 is lower than the first set temperature of 25°C (from the perspective of hot water for household washing, the first set temperature can be set to 40°C), the temperature sensor detects the temperature signal and sends it to the heating device 5. The heating device 5 starts to heat the heat exchange tube 3, and the heat is absorbed by the heat exchange tube 3. When the heat is absorbed to a certain value, the heat exchange tube 3 starts to heat up. After the temperature reaches the second set temperature of 95°C, the temperature sensor detects the temperature signal and sends it to the heating device 5, and the heating device 5 stops heating.

[0065] Step 2, heat release stage: after the water flows into the inner tube 33, the phase change material in the heat exchange tube 3 starts to release heat, and the heat is absorbed by the water flow, completing the water flow heating process.

[0066] Step 3, after multiple uses, open the one-way air valve 6 to discharge the gas therein.

[0067] Example 4

[0068] A solid-solid phase change material (choline bromide) has the molecular formula:

[0069] Where X - Br - .

[0070] like Figure 5As shown, the phase transition endothermic starting temperature of choline bromide is 85.12°C, the end temperature is 100.59°C, the phase transition enthalpy is 83.12 J / g, the phase transition exothermic starting temperature is 67.09°C, the end temperature is 63.85°C, and the phase transition enthalpy is 105.37 J / g. It can be seen that choline bromide can achieve phase transition heat storage and release.

[0071] like Figure 6 As shown, a is the heating of choline bromide, and b is the actual picture of choline bromide after heating, proving that the solid state does not change before and after the phase change.

[0072] Example 5

[0073] A solid-solid phase change heat storage system comprises, by weight, 50 parts by weight of choline bromide as described in Example 4, 20 parts by weight of thermally conductive epoxy resin, and 30 parts by weight of graphite particles. The thermally conductive epoxy resin ensures the thermal conductivity of the device and the filling density of the solid-solid phase change material, and the graphite particles can enhance the thermal conductivity of the phase change material and ensure uniform thermal conductivity.

[0074] The preparation method of the solid-solid phase change heat storage system is as follows:

[0075] Step 1: add 19.14 parts by mass of thermally conductive epoxy resin A to 50 parts by mass of choline bromide, stir and mix evenly, and add 30 parts by mass of graphite particles and mix evenly to obtain a mixture.

[0076] Step 2, adding 0.86 parts by mass of thermally conductive epoxy resin B to the mixture obtained in step 1, mixing evenly, and continuously stirring until the viscosity of the mixture increases, to obtain a solid-solid phase change heat storage system.

[0077] Example 6

[0078] The structure of the solid-solid phase change energy storage water heater of this embodiment is the same as that of embodiment 3, except that it is filled with the solid-solid phase change heat storage system described in embodiment 5. The application scenario of the water heater is domestic hot water, the heat exchange tube temperature is required to be no less than 40°C, and the heat exchanger water outlet temperature is no less than 35°C. In the working method, the first set temperature is 40°C and the second set temperature is 105°C.

[0079] Example 7

[0080] A solid-solid phase change material (choline iodide) has the molecular formula:

[0081] Where X - For I - .

[0082] like Figure 7As shown, choline iodide has two endothermic peaks and exothermic peaks. The endothermic starting temperature of the endothermic phase change of endothermic peak 1 is 87.77°C and the end temperature is 99.04°C. The endothermic starting temperature of the endothermic phase change of endothermic peak 2 is 154.02°C and the end temperature is 163.28°C. The exothermic starting temperature of exothermic peak 1 is 73.98°C and the end temperature is 70.44°C. The exothermic starting temperature of exothermic peak 2 is 152.75°C and the end temperature is 142.36°C. The experiment shows that the above three substances are solid before and after the phase change.

[0083] like Figure 8 As shown, a is the heating of choline iodide, and b is the actual picture of choline iodide after heating at 200°C, proving that the solid state does not change before and after the phase change.

[0084] Example 8

[0085] A solid-solid phase change heat storage system comprises, by weight, 25 parts by weight of choline chloride, 25 parts by weight of choline iodide, 40 parts by weight of thermally conductive epoxy resin and 10 parts by weight of graphite particles.

[0086] The preparation method of the solid-solid phase change heat storage system is as follows:

[0087] Step 1: add 39.14 parts by mass of thermally conductive epoxy resin A to 25 parts by mass of choline chloride and 25 parts by mass of choline iodide, stir and mix evenly, and add 10 parts by mass of graphite particles and mix evenly to obtain a mixture.

[0088] Step 2, adding 0.86 parts by mass of thermally conductive epoxy resin B to the mixture obtained in step 1, mixing evenly, and continuously stirring until the viscosity of the mixture increases, to obtain a solid-solid phase change heat storage system.

[0089] Example 9

[0090] The structure of the solid-solid phase change energy storage water heater of this embodiment is the same as that of embodiment 3, except that it is filled with the solid-solid phase change heat storage system described in embodiment 8. The application scenario of the water heater is industrial constant temperature drying. During normal operation, the temperature of the heat exchange tube is not less than 60°C, and the outlet temperature of the heat exchanger water is between 40°C±5°C. In the working method, the first set temperature is 60°C and the second set temperature is 120°C.

[0091] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A solid-solid phase change material, characterized in that: The molecular formula is: Where X - Br - , Cl - 、F - ,I - BrO3 - BrO - 、HCO3 - OH - 、ClO3 - 、ClO4 - , ClO - IO3 - 、NO3 - 、NO2 - 、H2PO4 - 、HSO4 - 、HSO3 - 、AlSiO4 - 、C2H3O2 - 、HCO2 - 、HC2O4 - , HS - NH2 - 、OCN - 、SCN - , CN - 、MnO4 - One of them.

2. Use of the solid-solid phase change material as claimed in claim 1 in a phase change energy storage device.

3. A solid-solid phase change heat storage system, characterized in that: It comprises the solid-solid phase change material as claimed in claim 1, a thermally conductive epoxy resin and graphite.

4. The solid-solid phase change heat storage system according to claim 3, characterized in that: The mass fraction of the solid-solid phase change material is 50 to 80 mass parts, the mass fraction of the thermal conductive epoxy resin is 10 to 40 mass parts, and the mass fraction of graphite is 10 to 40 mass parts.

5. The solid-solid phase change heat storage system according to claim 3, characterized in that: The thermally conductive epoxy resin includes thermally conductive epoxy resin A and thermally conductive epoxy resin B. The solid-solid phase change heat storage system is prepared by the following steps: Step 1, adding thermal conductive epoxy resin A to the solid-solid phase change material, stirring and mixing evenly, and adding graphite to mix evenly to obtain a mixture; Step 2, adding thermal conductive epoxy resin B to the mixture obtained in step 1, and continuously stirring to mix evenly to obtain a solid-solid phase change heat storage system.

6. Application of the solid-solid phase change heat storage system as claimed in claim 3 in a phase change energy storage device.

7. A phase change energy storage device, characterized in that: A heat exchange unit is provided in the phase change energy storage device, and the heat storage medium filled in the heat exchange unit includes the solid-solid phase change material according to claim 1 or the solid-solid phase change heat storage system according to claim 3.

8. The phase change energy storage device according to claim 7, characterized in that: An anti-corrosion layer is applied at a position in the heat exchange unit that contacts the solid-solid phase change material or the solid-solid phase change heat storage system. The filling amount of the heat storage medium in the heat exchange unit is not less than 95% and not more than 98% of the total volume. A one-way gas valve is provided on the heat exchange unit to discharge the gas generated by the heat inside the energy storage device.

9. The phase change energy storage device according to claim 8, characterized in that: The phase change energy storage device is a solid-solid phase change energy storage water heater, the heat exchange unit is a heat exchange tube, the heat exchange tube includes an outer tube and an inner tube nested inside the outer tube, the inner tube is for water circulation, the two ends of the inner tube are respectively connected to an inlet pipe and an outlet pipe, a closed space is formed between the outer tube and the inner tube and filled with the solid-solid phase change heat storage system, a heating element is provided on the outside of the outer tube, an insulating coating layer is provided outside the heating element, heat-conducting fins distributed in an annular shape are fixed between the inner tube and the outer tube, the heat-conducting fins are stainless steel plates with a polytetrafluoroethylene coating, the heating element is a heating wire, the heating wire is wound around the outside of the outer tube, the heating wire is electrically connected to the heating device, a temperature sensor is provided on the heat exchange tube, and the temperature sensor is electrically connected to the heating device.

10. The working method of the phase change energy storage device according to claim 9, characterized in that: The following steps are involved: Step 1, heat storage stage: after the power is turned on, the temperature sensor detects a temperature signal and sends it to the heating device. When the temperature of the heat exchange tube is lower than the first set temperature, the first set temperature is lower than the phase change exothermic termination temperature of the solid-solid phase change material, the heating device starts to heat the heat exchange tube, the heat is absorbed by the heat exchange tube, and the solid-solid phase change material starts to store heat. When the heat exchange tube is heated to the second set temperature, the second set temperature is higher than the phase change endothermic termination temperature of the solid-solid phase change material, the phase change temperature sensor detects a temperature signal and sends it to the heating device, and the heating device stops heating. Step 2, heat release stage: after the water flows into the inner tube, the solid-solid phase change material in the heat exchange tube begins to release heat, and the heat is absorbed by the water flow, completing the water flow heating process; Step 3: After multiple uses, open the one-way air valve to discharge the gas.

Images