Leak-proof phase change energy storage wood with a chitosan-based protective layer and its preparation method

Abstract

This invention relates to a leak-proof phase change energy storage wood with a chitosan-based protective layer and its preparation method, belonging to the field of wood surface functionalization modification technology. To prepare leak-proof phase change energy storage wood, the invention includes: preparing and modifying delignified wood; preparing a phase change energy storage liquid; immersing the delignified wood in the phase change energy storage liquid, subjecting it to vacuum heating for a certain time, followed by atmospheric pressure heating for a certain time, repeating this process 3-5 times, then removing and drying it to obtain the phase change energy storage wood; preparing a mixed solution of chitosan and acetic acid; treating the phase change energy storage wood in a sodium hydroxide solution for a certain time to obtain a negatively charged phase change energy storage wood surface; then vacuum impregnating it in the mixed solution of chitosan and acetic acid for a certain time, removing and drying it, and then impregnating it in a hexagonal boron nitride nanosheet dispersion for a certain time, removing and drying it to obtain leak-proof phase change energy storage wood with a chitosan-based protective layer. This invention provides a leak-proof effect for the phase change liquid.

Description

Technical Field

[0001] This invention belongs to the field of wood surface functionalization modification technology, specifically relating to a leak-proof phase change energy storage wood with a chitosan-based protective layer and its preparation method. Background Technology

[0002] With the increasing severity of energy crises and environmental pollution, phase change energy storage materials (PCEs), due to their ability to store thermal energy through phase changes, are widely used in thermal energy storage, playing a crucial role in building temperature control, electronic component temperature control, and textile temperature regulation. PCEs, especially organic solid-liquid PCEs, are widely applied due to their advantages such as high latent heat of phase change, good thermal reliability and stability, no supercooling or phase separation, non-toxicity, and non-corrosiveness. However, a major problem in practical applications is liquid leakage during the phase change process. Wood possesses a unique anisotropic porous structure, excellent mechanical strength, biodegradability, low cost, wide availability, and environmental friendliness. Combining wood with PCEs can utilize the capillary action of wood's hierarchical porous structure to address the leakage problem during the phase change process. Unfortunately, even after multiple cycles of use, partial leakage still occurs in PCE wood. Therefore, technological innovation is needed to further improve the leak-proof properties of PCE wood. Summary of the Invention

[0003] The problem to be solved by this invention is to prepare leak-proof phase change energy storage wood, and to propose a leak-proof phase change energy storage wood with a chitosan-based protective layer and its preparation method.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for preparing leak-proof phase change energy storage wood with a chitosan-based protective layer includes the following steps:

[0006] S1. Preparation and modification of delignified wood: fast-growing timber was treated with delignification using a mixed solution of NaClO2 and glacial acetic acid. The treated fast-growing timber was then soaked and washed in distilled water until the pH of the distilled water was neutral. After removal, it was freeze-dried to obtain delignified wood for later use.

[0007] S2. Preparation of phase change energy storage fluid: Weigh a certain amount of palmitic acid, stearic acid and boron nitride according to the weight proportions. Dissolve palmitic acid and stearic acid at a certain temperature, then add boron nitride and sonicate for a certain time under ice-water bath conditions to obtain phase change energy storage fluid for later use.

[0008] S3. Preparation of phase change energy storage wood: The delignified wood obtained in step S1 is immersed in the phase change energy storage liquid prepared in step S2. The mixture is heated under vacuum for a certain period of time and then heated under normal pressure for a certain period of time. The above conditions are repeated 3-5 times. The wood is then removed and dried to obtain phase change energy storage wood for later use.

[0009] S4. Prepare a mixed solution of chitosan and acetic acid for later use;

[0010] S5. Preparation of leak-proof phase change energy storage wood with chitosan-based protective layer: After the phase change energy storage wood obtained in step S3 is placed in sodium hydroxide solution for a certain period of time, phase change energy storage wood with negative charge on the surface is obtained.

[0011] Then, it is placed in a mixed solution of chitosan and acetic acid obtained in step S4 and vacuum impregnated for a certain time. After being taken out and dried, it is then placed in a hexagonal boron nitride nanosheet dispersion and impregnated for a certain time. After being taken out and dried, a leak-proof phase change energy storage wood with a chitosan-based protective layer is obtained.

[0012] Furthermore, the delignification treatment in step S1 is carried out by heating in a water bath at 75-80°C with 2g of fast-growing timber chips, 0.75-0.1g of NaClO2, 0.5-1mL of glacial acetic acid and 65-100mL of deionized water, and adding 0.75g of NaClO2 and 0.5mL of glacial acetic acid every 1 hour, for a total of 3-5 times.

[0013] After the reaction is complete, soak and wash the product in distilled water, changing the distilled water every half hour until the pH of the distilled water is neutral.

[0014] The conditions for freeze drying are a vacuum degree of less than 10 Pa and a temperature of less than -50°C.

[0015] Furthermore, in step S2, the palmitic acid comprises 63-70 parts by weight, the stearic acid comprises 37-45 parts by weight, and the boron nitride comprises 1-1.5 parts by weight. The palmitic acid and stearic acid are stirred at 80-85°C for 0.5-1h, and then boron nitride is added. The mixture is then sonicated in an ice-water bath for 10-12h at an ultrasonic frequency of 75-100Hz.

[0016] Furthermore, in step S3, the vacuum heating conditions are: 60-65℃ under vacuum for 30 minutes; and 30 minutes under normal pressure. The drying conditions are: drying at room temperature for 5-10 minutes.

[0017] Furthermore, the method for preparing the mixed solution of chitosan and acetic acid in step S4 is to add 1-2g of chitosan to 100g of 1wt% acetic acid aqueous solution, stir evenly, and then obtain the mixed solution of chitosan and acetic acid.

[0018] Furthermore, in step S5, the sodium hydroxide solution is prepared by adding 2g of NaOH to 5-10mL of water and then adding 10-15mL of ethanol; the phase change energy storage wood obtained in step S3 is placed in the sodium hydroxide solution and treated at 75-80℃ for 10-15min.

[0019] Furthermore, in step S5, after vacuum impregnation in a mixed solution of chitosan and acetic acid for 20-30 minutes, the mixture is removed and transferred to an oven at 30-40°C for drying for 20-30 minutes.

[0020] Furthermore, in step S5, the concentration of the hexagonal boron nitride nanosheet dispersion is 0.2-0.5 wt%. After immersing in the hexagonal boron nitride nanosheet dispersion for 20-30 min, it is transferred to an oven at 30-40℃ and dried for 5-10 min to obtain leak-proof phase change energy storage wood with a chitosan-based protective layer.

[0021] A method for preparing leak-proof phase change energy storage wood with a chitosan-based protective layer. The leak-proof phase change energy storage wood with a chitosan-based protective layer has a multi-layer structure.

[0022] The beneficial effects of this invention are:

[0023] This invention discloses a method for preparing leak-proof phase change energy storage wood with a chitosan-based protective layer. The method involves impregnating delignified wood with a phase change solution composed of palmitic acid, stearic acid, and boron nitride. Subsequently, sodium hydroxide treatment converts the fatty acids to sodium fatty acids, resulting in negatively charged wood. Finally, an electrostatic self-assembly technique is used to coat the impregnated wood with a positively charged chitosan layer, yielding leak-proof phase change energy storage wood. The introduction of the chitosan coating layer, supplementing the capillary action of the wood's graded porous structure, fixes the phase change energy storage solution within the wood frame, further enhancing the leak-proof properties of the wood. The leak-proof phase change energy storage wood obtained by this invention does not exhibit any leakage of the phase change solution after being placed on a 75°C hot table for 10 hours. Furthermore, the leak-proof phase change energy storage wood did not leak after 200 heating and cooling cycles at 75°C. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for preparing a leak-proof phase change energy storage wood with a chitosan-based protective layer, as described in this invention.

[0025] Figure 2 SEM images of a leak-proof phase change energy storage wood with a chitosan-based protective layer prepared according to the present invention and elemental content distribution diagrams corresponding to each layer are shown. In this paper, a is an SEM image of the leak-proof phase change energy storage wood with a chitosan-based protective layer and b is an elemental content distribution diagram corresponding to each layer.

[0026] Figure 3 Comparative photographs of the phase change energy storage wood prepared in this invention and the leak-proof phase change energy storage wood with a chitosan-based protective layer under different temperature conditions, wherein a is the phase change energy storage wood and b is the leak-proof phase change energy storage wood with a chitosan-based protective layer. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described specific embodiments are merely a part of the embodiments of the invention, and not all of them. The components of the specific embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations, and the invention may also have other embodiments.

[0028] Therefore, the following detailed description of specific embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected specific embodiments of the invention. All other specific embodiments obtained by those skilled in the art based on these specific embodiments without inventive effort are within the scope of protection of this invention.

[0029] To further understand the invention's content, features, and effects, the following specific embodiments are provided, along with accompanying drawings. Figure 1 -Appendix Figure 3 Detailed explanation is as follows:

[0030] Example 1:

[0031] A method for preparing leak-proof phase change energy storage wood with a chitosan-based protective layer includes the following steps:

[0032] S1. Preparation and modification of delignified wood: fast-growing timber was treated with delignification using a mixed solution of NaClO2 and glacial acetic acid. The treated fast-growing timber was then soaked and washed in distilled water until the pH of the distilled water was neutral. After removal, it was freeze-dried to obtain delignified wood for later use.

[0033] Furthermore, the delignification treatment in step S1 is carried out by heating in a water bath at 75°C with 2g of fast-growing timber chips, 0.75g of NaClO2, 0.5mL of glacial acetic acid and 65mL of deionized water, and adding 0.75g of NaClO2 and 0.5mL of glacial acetic acid every 1 hour, for a total of 3 times.

[0034] After the reaction is complete, soak and wash the product in distilled water, changing the distilled water every half hour until the pH of the distilled water is neutral.

[0035] The conditions for freeze drying are a vacuum degree of less than 10 Pa and a temperature of less than -50°C.

[0036] S2. Preparation of phase change energy storage fluid: Weigh a certain amount of palmitic acid, stearic acid and boron nitride according to the weight proportions. Dissolve palmitic acid and stearic acid at a certain temperature, then add boron nitride and sonicate for a certain time under ice-water bath conditions to obtain phase change energy storage fluid for later use.

[0037] Furthermore, in step S2, palmitic acid comprises 63 parts by weight, stearic acid comprises 37 parts by weight, and boron nitride comprises 1 part by weight. The palmitic acid and stearic acid are stirred at 80°C for 0.5 h, and then boron nitride is added. The mixture is then sonicated in an ice-water bath for 12 h at a frequency of 75 Hz.

[0038] S3. Preparation of phase change energy storage wood: The delignified wood obtained in step S1 is immersed in the phase change energy storage liquid prepared in step S2. The mixture is heated under vacuum for a certain period of time and then heated under normal pressure for a certain period of time. The above conditions are repeated 3 times. The wood is then taken out and dried to obtain phase change energy storage wood for later use.

[0039] Furthermore, in step S3, the vacuum heating conditions are: 60°C under vacuum for 30 minutes; atmospheric pressure for 30 minutes; and drying conditions are: drying at room temperature for 5 minutes.

[0040] S4. Prepare a mixed solution of chitosan and acetic acid for later use;

[0041] Furthermore, the method for preparing the mixed solution of chitosan and acetic acid in step S4 is to add 1g of chitosan to 100g of 1wt% acetic acid aqueous solution, stir evenly, and then obtain the mixed solution of chitosan and acetic acid.

[0042] S5. Preparation of leak-proof phase change energy storage wood with chitosan-based protective layer: After the phase change energy storage wood obtained in step S3 is placed in sodium hydroxide solution for a certain period of time, phase change energy storage wood with negative charge on the surface is obtained.

[0043] Then, it is placed in a mixed solution of chitosan and acetic acid obtained in step S4 and vacuum impregnated for a certain time. After being taken out and dried, it is then placed in a hexagonal boron nitride nanosheet dispersion and impregnated for a certain time. After being taken out and dried, a leak-proof phase change energy storage wood with a chitosan-based protective layer is obtained.

[0044] Furthermore, in step S5, the sodium hydroxide solution is prepared by adding 2g NaOH to 5mL of water and then adding 10mL of ethanol; the phase change energy storage wood obtained in step S3 is placed in the sodium hydroxide solution and treated at 75℃ for 10min.

[0045] Furthermore, in step S5, after vacuum impregnation in a mixed solution of chitosan and acetic acid for 20 minutes, the sample is removed and transferred to a 30°C oven for drying for 20 minutes.

[0046] Furthermore, in step S5, the concentration of the hexagonal boron nitride nanosheet dispersion is 0.2 wt%. After immersing in the hexagonal boron nitride nanosheet dispersion for 20 min, it is transferred to a 30°C oven and dried for 5 min to obtain leak-proof phase change energy storage wood with a chitosan-based protective layer.

[0047] Furthermore, the fast-growing material used in step S1 is balsa wood chips, and the thickness of the wood chips is 1-4 mm.

[0048] This embodiment describes a method for preparing leak-proof phase change energy storage wood with a chitosan-based protective layer. The resulting leak-proof phase change energy storage wood has a multi-layered structure, such as... Figure 2 As shown, from Figure 2 It can be seen that NaOH treatment can produce phase change storage wood with a negatively charged surface (9 μm thick), which provides the conditions for subsequently introducing a chitosan layer through layer-by-layer electrostatic self-assembly technology. Based on this, a chitosan layer (16 μm thick) was successfully coated on the surface of the phase change storage wood. Simultaneously, to avoid affecting the phase change characteristics of the phase change storage wood, a boron nitride layer with a thickness of approximately 0.2 μm was also coated on the outside of the chitosan layer. Combining Figures a and b, it can be seen that NaOH treatment can produce phase change storage wood with a negatively charged surface, which provides the conditions for subsequently introducing a chitosan layer through layer-by-layer electrostatic self-assembly technology. Based on this, a chitosan layer (16 μm thick) was successfully coated on the surface of the phase change storage wood. Simultaneously, to avoid affecting the phase change characteristics of the phase change storage wood, a boron nitride layer with a thickness of approximately 0.2 μm was also coated on the outside of the chitosan layer.

[0049] This embodiment describes a method for preparing leak-proof phase change energy storage wood with a chitosan-based protective layer. The chitosan coating layer, as a supplement to the capillary action of the wood's graded porous structure, fixes the phase change energy storage liquid within the wood frame, further enhancing the leak-proof properties of the phase change energy storage wood. Figure 3As shown in Figures a and b, comparing them reveals that neither type of phase change energy storage wood exhibits phase change fluid leakage at 25°C. However, after placing the phase change energy storage wood on a 75°C hot surface for 10 hours, significant phase change fluid leakage is observed. In contrast, the leak-proof phase change energy storage wood with a chitosan-based protective layer does not exhibit this leakage. Therefore, this embodiment effectively improves the leak-proof properties of phase change energy storage wood by constructing a chitosan-based protective layer. Furthermore, the obtained leak-proof phase change energy storage wood did not leak after 200 heating and cooling cycles at 75°C.

[0050] The method for preparing a leak-proof phase change energy storage wood with a chitosan-based protective layer described in this embodiment yields a leak-proof phase change energy storage wood with a chitosan-based protective layer. The performance comparison is shown in Table 1.

[0051] Table 1:

[0052]

[0053]

[0054] As can be seen from Table 1, the introduction of the chitosan protective layer does not have a significant impact on the melting temperature, melting phase change enthalpy, solidification temperature, and solidification phase change enthalpy of phase change energy storage wood. Therefore, the introduction of the chitosan protective layer can enhance the leakage prevention characteristics of the sample without weakening the energy storage characteristics of phase change energy storage wood.

[0055] Example 2:

[0056] A method for preparing leak-proof phase change energy storage wood with a chitosan-based protective layer includes the following steps:

[0057] S1. Preparation and modification of delignified wood: fast-growing timber was treated with delignification using a mixed solution of NaClO2 and glacial acetic acid. The treated fast-growing timber was then soaked and washed in distilled water until the pH of the distilled water was neutral. After removal, it was freeze-dried to obtain delignified wood for later use.

[0058] Furthermore, the delignification treatment in step S1 is carried out by heating in a water bath at 80°C with 2g of fast-growing timber chips, 0.1g of NaClO2, 1mL of glacial acetic acid and 100mL of deionized water, and adding 0.75g of NaClO2 and 0.5mL of glacial acetic acid every 1 hour, for a total of 5 times.

[0059] After the reaction is complete, soak and wash the product in distilled water, changing the distilled water every half hour until the pH of the distilled water is neutral.

[0060] The conditions for freeze drying are a vacuum degree of less than 10 Pa and a temperature of less than -50°C.

[0061] S2. Preparation of phase change energy storage fluid: Weigh a certain amount of palmitic acid, stearic acid and boron nitride according to the weight proportions. Dissolve palmitic acid and stearic acid at a certain temperature, then add boron nitride and sonicate for a certain time under ice-water bath conditions to obtain phase change energy storage fluid for later use.

[0062] Furthermore, in step S2, the palmitic acid is 70 parts by weight, the stearic acid is 45 parts by weight, and the boron nitride is 1.5 parts by weight. The palmitic acid and stearic acid are stirred at 85°C for 0.5 hours, and then boron nitride is added. The mixture is then sonicated in an ice-water bath for 12 hours at a frequency of 100 Hz.

[0063] S3. Preparation of phase change energy storage wood: The delignified wood obtained in step S1 is immersed in the phase change energy storage liquid prepared in step S2. The mixture is heated under vacuum for a certain period of time and then heated under normal pressure for a certain period of time. The above conditions are repeated 5 times. The wood is then removed and dried to obtain phase change energy storage wood for later use.

[0064] Furthermore, in step S3, the vacuum heating conditions are: 65°C under vacuum for 30 minutes; atmospheric pressure for 30 minutes; and drying conditions are: drying at room temperature for 10 minutes.

[0065] S4. Prepare a mixed solution of chitosan and acetic acid for later use;

[0066] Furthermore, the method for preparing the mixed solution of chitosan and acetic acid in step S4 is to add 2g of chitosan to 100g of 1wt% acetic acid aqueous solution, stir evenly, and then obtain the mixed solution of chitosan and acetic acid.

[0067] S5. Preparation of leak-proof phase change energy storage wood with chitosan-based protective layer: After the phase change energy storage wood obtained in step S3 is placed in sodium hydroxide solution for a certain period of time, phase change energy storage wood with negative charge on the surface is obtained.

[0068] Then, it is placed in a mixed solution of chitosan and acetic acid obtained in step S4 and vacuum impregnated for a certain time. After being taken out and dried, it is then placed in a hexagonal boron nitride nanosheet dispersion and impregnated for a certain time. After being taken out and dried, a leak-proof phase change energy storage wood with a chitosan-based protective layer is obtained.

[0069] Furthermore, in step S5, the sodium hydroxide solution is prepared by adding 2g NaOH to 10mL of water and then adding 15mL of ethanol; the phase change energy storage wood obtained in step S3 is placed in the sodium hydroxide solution and treated at 80℃ for 15min.

[0070] Furthermore, in step S5, after vacuum impregnation in a mixed solution of chitosan and acetic acid for 30 minutes, the sample is removed and transferred to an oven at 40°C for drying for 30 minutes.

[0071] Furthermore, in step S5, the concentration of the hexagonal boron nitride nanosheet dispersion is 0.5 wt%. After immersing in the hexagonal boron nitride nanosheet dispersion for 30 min, it is transferred to an oven at 30-40℃ and dried for 10 min to obtain leak-proof phase change energy storage wood with a chitosan-based protective layer.

[0072] The method for preparing a leak-proof phase change energy storage wood with a chitosan-based protective layer described in this embodiment produces a leak-proof phase change energy storage wood with a chitosan-based protective layer, wherein the leak-proof phase change energy storage wood with a chitosan-based protective layer has a multi-layer structure.

[0073] Example 3:

[0074] A method for preparing leak-proof phase change energy storage wood with a chitosan-based protective layer includes the following steps:

[0075] S1. Preparation and modification of delignified wood: fast-growing timber was treated with delignification using a mixed solution of NaClO2 and glacial acetic acid. The treated fast-growing timber was then soaked and washed in distilled water until the pH of the distilled water was neutral. After removal, it was freeze-dried to obtain delignified wood for later use.

[0076] Furthermore, the delignification treatment in step S1 is carried out by heating in a water bath at 75°C with 2g of fast-growing timber chips, 0.8g of NaClO2, 0.6mL of glacial acetic acid and 70mL of deionized water, and adding 0.75g of NaClO2 and 0.5mL of glacial acetic acid every 1 hour, for a total of 4 times.

[0077] After the reaction is complete, soak and wash the product in distilled water, changing the distilled water every half hour until the pH of the distilled water is neutral.

[0078] The conditions for freeze drying are a vacuum degree of less than 10 Pa and a temperature of less than -50°C.

[0079] S2. Preparation of phase change energy storage fluid: Weigh a certain amount of palmitic acid, stearic acid and boron nitride according to the weight proportions. Dissolve palmitic acid and stearic acid at a certain temperature, then add boron nitride and sonicate for a certain time under ice-water bath conditions to obtain phase change energy storage fluid for later use.

[0080] Furthermore, in step S2, palmitic acid is 65 parts by weight, stearic acid is 40 parts by weight, and boron nitride is 1 part by weight. The palmitic acid and stearic acid are stirred at 80°C for 0.5 h, and then boron nitride is added. The mixture is then sonicated in an ice-water bath for 12 h at a frequency of 80 Hz.

[0081] S3. Preparation of phase change energy storage wood: The delignified wood obtained in step S1 is immersed in the phase change energy storage liquid prepared in step S2. The mixture is heated under vacuum for a certain period of time and then heated under normal pressure for a certain period of time. The above conditions are repeated 4 times. The wood is then removed and dried to obtain phase change energy storage wood for later use.

[0082] Furthermore, in step S3, the vacuum heating conditions are: 60°C under vacuum for 30 minutes; atmospheric pressure for 30 minutes; and drying conditions are: drying at room temperature for 10 minutes.

[0083] S4. Prepare a mixed solution of chitosan and acetic acid for later use;

[0084] Furthermore, the method for preparing the mixed solution of chitosan and acetic acid in step S4 is to add 1.5g of chitosan to 100g of 1wt% acetic acid aqueous solution, stir evenly, and then obtain the mixed solution of chitosan and acetic acid.

[0085] S5. Preparation of leak-proof phase change energy storage wood with chitosan-based protective layer: After the phase change energy storage wood obtained in step S3 is placed in sodium hydroxide solution for a certain period of time, phase change energy storage wood with negative charge on the surface is obtained.

[0086] Then, it is placed in a mixed solution of chitosan and acetic acid obtained in step S4 and vacuum impregnated for a certain time. After being taken out and dried, it is then placed in a hexagonal boron nitride nanosheet dispersion and impregnated for a certain time. After being taken out and dried, a leak-proof phase change energy storage wood with a chitosan-based protective layer is obtained.

[0087] Furthermore, in step S5, the sodium hydroxide solution is prepared by adding 2g NaOH to 5mL of water and then adding 12mL of ethanol; the phase change energy storage wood obtained in step S3 is placed in the sodium hydroxide solution and treated at 75℃ for 10min.

[0088] Furthermore, in step S5, after vacuum impregnation in a mixed solution of chitosan and acetic acid for 20 minutes, the mixture is removed and transferred to an oven at 35°C for drying for 25 minutes.

[0089] Furthermore, in step S5, the concentration of the hexagonal boron nitride nanosheet dispersion is 0.3 wt%. After immersing in the hexagonal boron nitride nanosheet dispersion for 20 min, it is transferred to an oven at 35°C and dried for 5 min to obtain leak-proof phase change energy storage wood with a chitosan-based protective layer.

[0090] The method for preparing a leak-proof phase change energy storage wood with a chitosan-based protective layer described in this embodiment produces a leak-proof phase change energy storage wood with a chitosan-based protective layer, wherein the leak-proof phase change energy storage wood with a chitosan-based protective layer has a multi-layer structure.

[0091] Example 4:

[0092] A method for preparing leak-proof phase change energy storage wood with a chitosan-based protective layer includes the following steps:

[0093] S1. Preparation and modification of delignified wood: fast-growing timber was treated with delignification using a mixed solution of NaClO2 and glacial acetic acid. The treated fast-growing timber was then soaked and washed in distilled water until the pH of the distilled water was neutral. After removal, it was freeze-dried to obtain delignified wood for later use.

[0094] Furthermore, the delignification treatment in step S1 is carried out by heating in a water bath at 75°C with 2g of fast-growing timber chips, 0.9g of NaClO2, 0.9mL of glacial acetic acid and 80mL of deionized water, and adding 0.75g of NaClO2 and 0.5mL of glacial acetic acid every 1 hour, for a total of 5 times.

[0095] After the reaction is complete, soak and wash the product in distilled water, changing the distilled water every half hour until the pH of the distilled water is neutral.

[0096] The conditions for freeze drying are a vacuum degree of less than 10 Pa and a temperature of less than -50°C.

[0097] S2. Preparation of phase change energy storage fluid: Weigh a certain amount of palmitic acid, stearic acid and boron nitride according to the weight proportions. Dissolve palmitic acid and stearic acid at a certain temperature, then add boron nitride and sonicate for a certain time under ice-water bath conditions to obtain phase change energy storage fluid for later use.

[0098] Furthermore, in step S2, the palmitic acid is 63 parts by weight, the stearic acid is 37 parts by weight, and the boron nitride is 1 part by weight. The palmitic acid and stearic acid are stirred at 80°C for 0.5 h, and then boron nitride is added. The mixture is then sonicated in an ice-water bath for 10 h at a frequency of 75 Hz.

[0099] S3. Preparation of phase change energy storage wood: The delignified wood obtained in step S1 is immersed in the phase change energy storage liquid prepared in step S2. The mixture is heated under vacuum for a certain period of time and then heated under normal pressure for a certain period of time. The above conditions are repeated 3 times. The wood is then taken out and dried to obtain phase change energy storage wood for later use.

[0100] Furthermore, in step S3, the vacuum heating conditions are: 60°C under vacuum for 30 minutes; atmospheric pressure for 30 minutes; and drying conditions are: drying at room temperature for 10 minutes.

[0101] S4. Prepare a mixed solution of chitosan and acetic acid for later use;

[0102] Furthermore, the method for preparing the mixed solution of chitosan and acetic acid in step S4 is to add 1g of chitosan to 100g of 1wt% acetic acid aqueous solution, stir evenly, and then obtain the mixed solution of chitosan and acetic acid.

[0103] S5. Preparation of leak-proof phase change energy storage wood with chitosan-based protective layer: After the phase change energy storage wood obtained in step S3 is placed in sodium hydroxide solution for a certain period of time, phase change energy storage wood with negative charge on the surface is obtained.

[0104] Then, it is placed in a mixed solution of chitosan and acetic acid obtained in step S4 and vacuum impregnated for a certain time. After being taken out and dried, it is then placed in a hexagonal boron nitride nanosheet dispersion and impregnated for a certain time. After being taken out and dried, a leak-proof phase change energy storage wood with a chitosan-based protective layer is obtained.

[0105] Furthermore, in step S5, the sodium hydroxide solution is prepared by adding 2g NaOH to 5mL of water and then adding 10mL of ethanol; the phase change energy storage wood obtained in step S3 is placed in the sodium hydroxide solution and treated at 75℃ for 10min.

[0106] Furthermore, in step S5, after vacuum impregnation in a mixed solution of chitosan and acetic acid for 20-30 minutes, the sample is removed and transferred to a 30°C oven for drying for 20 minutes.

[0107] Furthermore, in step S5, the concentration of the hexagonal boron nitride nanosheet dispersion is 0.4 wt%. After immersing in the hexagonal boron nitride nanosheet dispersion for 20 min, it is transferred to a 30°C oven and dried for 5 min to obtain leak-proof phase change energy storage wood with a chitosan-based protective layer.

[0108] The method for preparing a leak-proof phase change energy storage wood with a chitosan-based protective layer described in this embodiment produces a leak-proof phase change energy storage wood with a chitosan-based protective layer, wherein the leak-proof phase change energy storage wood with a chitosan-based protective layer has a multi-layer structure.

[0109] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0110] Although this application has been described above with reference to specific embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of this application. In particular, as long as there is no structural conflict, the features in the specific embodiments disclosed in this application can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, this application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing a leak-proof phase change energy storage wood with a chitosan-based protective layer, characterized in that, Comprising the following steps: S1. Preparation of modified delignified wood: the fast-growing wood is treated with a mixed solution of NaClO2 and glacial acetic acid, and then placed in distilled water for washing until the pH of the distilled water is neutral. After being taken out, it is freeze-dried to obtain delignified wood, which is ready for use; S2. Preparation of phase change energy storage liquid: a certain amount of soft fat acid, stearic acid and boron nitride is weighed according to the weight fraction, and the soft fat acid and stearic acid are dissolved at a certain temperature. Then, the boron nitride is added and ultrasonicated in an ice water bath for a certain time to obtain the phase change energy storage liquid, which is ready for use; S3. Preparation of phase change energy storage wood, the delignified wood obtained in step S1 is immersed in the phase change energy storage liquid prepared in step S2. After being continuously treated under vacuum heating conditions for a certain time and then continuously treated under normal pressure conditions for a certain time, the above conditions are repeated for 3-5 times. Then, it is taken out and dried to obtain the phase change energy storage wood, which is ready for use; S4. Preparation of a mixed solution of chitosan and acetic acid, which is ready for use; S5. Preparation of leak-proof phase change energy storage wood with chitosan-based protective layer, the phase change energy storage wood obtained in step S3 is treated in a sodium hydroxide solution for a certain time to obtain phase change energy storage wood with negative charges on the surface; Then, it is vacuum-impregnated in the mixed solution of chitosan and acetic acid obtained in step S4 for a certain time. After being taken out and dried, it is immersed in a hexagonal boron nitride nanosheet dispersion liquid for a certain time. After being taken out and dried, the leak-proof phase change energy storage wood with chitosan-based protective layer is obtained.

2. The method for preparing the leakage-proof phase change energy storage wood with a chitosan-based protective layer according to claim 1, characterized in that, In step S1, the delignification treatment method is as follows: 2 g of fast-growing wood pieces, 0.75-0.1 g of NaClO2, 0.5-1 mL of glacial acetic acid, and 65-100 mL of deionized water are added in a water bath at 75-80ºC. Every 1 h, 0.75 g of NaClO2 and 0.5 mL of glacial acetic acid are added for 3-5 times; After the reaction is completed, it is immersed in distilled water for washing, and the distilled water is replaced every half hour until the pH of the distilled water is neutral; The freeze-drying conditions are as follows: the vacuum degree is less than 10 Pa, and the temperature is lower than -50º.

3. The method for preparing the leakage-proof phase change energy storage wood with the protective layer of chitosan according to claim 1 or 2, characterized in that, In step S2, the weight fraction of soft fat acid is 63-70 parts, the weight fraction of stearic acid is 37-45 parts, and the weight fraction of boron nitride is 1-1.5 parts. The soft fat acid and stearic acid are stirred at 80-85ºC for 0.5-1 h, and then the boron nitride is added. Ultrasonic treatment is performed in an ice water bath for 10-12 h, and the ultrasonic frequency is 75-100 Hz.

4. The method for preparing the leakage-proof phase change energy storage wood with the protective layer of chitosan according to claim 3, characterized in that, In step S3, the vacuum heating conditions are as follows: vacuum at 60-65ºC for 30 min; normal pressure conditions for 30 min; and drying conditions are as follows: drying at room temperature for 5-10 min.

5. The method for preparing the leakage-proof phase change energy storage wood with the protective layer of chitosan according to claim 4, characterized in that, In step S4, the preparation method of the mixed solution of chitosan and acetic acid is as follows: 1-2 g of chitosan is added to 100 g of 1 wt% acetic acid aqueous solution, and then stirred uniformly to obtain the mixed solution of chitosan and acetic acid.

6. The method for preparing the leakage-proof phase change energy storage wood with the protective layer of chitosan according to claim 5, characterized in that, The method for preparing the sodium hydroxide solution in step S5 is: 2 g of NaOH is added to 5-10 mL of water and then 10-15 mL of ethanol is added; the phase change energy storage wood obtained in step S3 is placed in the sodium hydroxide solution and treated at 75-80ºC for 10-15 min.

7. The method for preparing the leakage-proof phase change energy storage wood with the protective layer of chitosan according to claim 6, characterized in that, After vacuum impregnation in the mixed solution of chitosan and acetic acid for 20-30 min in step S5, the wood is taken out and transferred to a 30-40ºC oven for drying for 20-30 min.

8. The method for preparing the leakage-proof phase change energy storage wood with the protective layer of chitosan according to claim 7, characterized in that, The concentration of the hexagonal boron nitride nanosheet dispersion liquid in step S5 is 0.2-0.5 wt%, after impregnation in the hexagonal boron nitride nanosheet dispersion liquid for 20-30 min, the wood is transferred to a 30-40ºC oven for drying for 5-10 min, to obtain the leakage-proof phase change energy storage wood with a chitosan-based protective layer.

9. A leakage-proof phase change energy storage wood with a chitosan-based protective layer prepared according to the method of any one of claims 1-8, characterized in that, The leakage-proof phase change energy storage wood with a chitosan-based protective layer has a multi-layer structure.

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