Atmospheric water extraction device based on hygrochromic drive and working method

Abstract

The present invention provides an atmospheric water extraction device and operating method based on hygrochromic drive. The device is composed of a hygrochromic material, a graphene coating, a radiative cooling coating, and a water collection chamber. The present invention utilizes the changes in the spectral properties of the hygrochromic material during the water adsorption-desorption process to effectively reflect or fully transmit sunlight to control the temperature of the hygrochromic material, thereby realizing an atmospheric water extraction process that is completely driven spontaneously by humidity and temperature. Graphene is used as the bottom coating of the hygrochromic material, and its excellent photothermal capacity is utilized to promote the desorption process of water in the hygrochromic material. A radiative cooling coating is used to cool the top surface of the water collection chamber to promote the condensation and collection process of water vapor. The present invention does not require sunshade equipment, manual intervention, or additional power input, and can spontaneously control the adsorption and desorption processes in atmospheric water collection. It has great application prospects in water collection in arid areas.

Description

Technical Field

[0001] The present invention relates to the technical field of atmospheric water extraction, and in particular to an atmospheric water extraction device based on hygrochromic drive and a working method. Background Art

[0002] Global water scarcity, driven by population growth and climate change, has become a vital challenge. Due to a combination of factors, including uneven geographical distribution, overexploitation, pollution, and technological limitations, the world faces water scarcity, necessitating the urgent need for innovative water extraction methods.

[0003] The atmosphere contains abundant water resources, equivalent to six times the total freshwater content of all rivers and lakes on Earth. This water can be easily replenished through evaporation and atmospheric circulation. Atmospheric water extraction technology has become popular in recent years as an effective method for extracting moisture from the air, with significant application value, especially in arid regions.

[0004] Most existing atmospheric water extraction devices rely on hygroscopic materials, which require heating or other external energy input to desorb water after absorbing water. In order to make full use of solar energy as a natural heat source, it is usually necessary to add photothermal materials to the hygroscopic materials to increase their solar absorption rate and promote desorption efficiency. However, the adsorption stage requires a low-temperature environment and can often only be carried out at night, resulting in low daily water extraction efficiency. In order to achieve multiple adsorption-desorption cycles in a day and improve water extraction efficiency, additional shading equipment must be added to the adsorption stage to control the temperature, and manual intervention or automated control equipment is often required to switch the adsorption and desorption states, which increases the complexity, manpower and cost of the device. Summary of the Invention

[0005] In view of the limitations of existing atmospheric water extraction technology, such as low daily water extraction efficiency, complex equipment, and high manpower and equipment costs, an atmospheric water extraction device and working method based on hygrochromic drive is proposed.

[0006] On the one hand, the present application provides an atmospheric water extraction device based on hygrochromic drive, the purpose of which is: the device utilizes the changes in the spectral properties of hygrochromic materials during the water adsorption-desorption process to achieve an atmospheric water extraction process that is completely driven spontaneously by humidity and temperature, without the need for shading equipment, manual intervention and additional power input.

[0007] The technical solution of the present invention is: a hygrochromic-driven atmospheric water intake device, comprising a hygrochromic material, a graphene coating, a radiative cooling coating, and a water collection chamber, wherein the hygrochromic material is located at the center of the atmospheric water intake device, the graphene coating is located at the bottom of the hygrochromic material, the center of the bottom of the water collection chamber surrounds the hygrochromic material and the graphene coating, and the radiative cooling coating is located on the outer surface of the top of the water collection chamber;

[0008] The water collection chamber is connected to all components of the atmospheric water intake device and is used to collect and store condensed water droplets;

[0009] A portion of the upper surface of the hygrochromic material is exposed to the external environment and in direct contact with the atmosphere, while a portion is enclosed in a water collection chamber to facilitate the collection of moisture. The reflection and transmission of sunlight are controlled by changes in the spectral properties of the hygrochromic material, spontaneously promoting the conversion of the adsorption and desorption processes of the hygrochromic material.

[0010] The graphene coating is located at the bottom layer of the hygrochromic material and is used to absorb solar energy and quickly heat the upper hygrochromic material to achieve the desorption process of water in the hygrochromic material;

[0011] The radiation cooling coating is located on the outer surface of the top of the water collection chamber, and uses its high solar reflectivity and emissivity to reduce the temperature of the top of the water collection chamber in direct contact with the coating, thereby promoting the condensation of water vapor on the top.

[0012] Furthermore, there is a groove at the center of the bottom of the water collection chamber for placing the hydrochromic material containing the graphene coating.

[0013] Furthermore, the top of the water collection chamber is sloped, with an inclination of 30° to the horizontal direction, and serves as a condensation surface when collecting water.

[0014] Furthermore, the left and right sides of the water collection chamber are divided into two chambers for jointly condensing and subsequently collecting water; a water valve is provided at the bottom of the right chamber to control the outflow of water to avoid saturation of the water collection chamber.

[0015] Furthermore, the hygrochromic material is a hygroscopic salt-aerogel composite porous material, and the hygroscopic salt needs to be embedded in the pore structure of the silica aerogel with a porosity of 0.8-0.9.

[0016] Furthermore, the optical refractive index of the hygroscopic salt solution in the hygrochromic material in the adsorption equilibrium state matches the optical refractive index of the silicon dioxide material n=1.457.

[0017] Furthermore, the overall thickness of the hygrochromic material is designed to be within a range of 50±20 microns.

[0018] Furthermore, the graphene coating has a thickness of 15 nanometers, a solar light absorptivity of the coating greater than 0.9, and a thermal conductivity of 1200-1500 W / (m·K).

[0019] Furthermore, the radiation cooling coating is a white paint cold coating with a thickness of 150 microns, a solar reflectivity of the coating of 0.8-0.95, and an infrared emissivity of 0.9-0.95.

[0020] Another aspect of the present application provides a method for operating an atmospheric water intake device based on hygrochromic drive, the atmospheric water intake device based on hygrochromic drive comprising the following steps:

[0021] Step 1: Nighttime water adsorption: The hygroscopic salt in the dry hygrochromic material adsorbs water from the atmosphere. After the salt solution reaches equilibrium, the refractive index difference between the porous silica matrix, the air pores, and the salt solution decreases, and the spectral properties of the entire hygrochromic material change from high solar reflectivity to high solar transmittance.

[0022] Step 2: Daytime solar energy drives water desorption: During the day, solar energy passes through the hygrochromic material and reaches the graphene coating at the bottom. The graphene coating absorbs heat and rapidly conducts it throughout the hygrochromic material. As the temperature rises, water vapor in the pores of the hygrochromic material gradually desorbs and escapes, rising to the top surface of the radiative cooling coating within the water collection chamber and condensing. The condensed water then gathers and flows down along the slope and sidewalls, reaching the bottom of the water collection chamber.

[0023] Step three, daytime hygrochromic-driven secondary adsorption process: During the desorption process of step two, as the water content in the pores of the hygrochromic material gradually decreases, the refractive index of the hygroscopic salt increases and the volume of the air pores increases, the refractive index difference between the porous silica matrix, air pores and the hygroscopic salt gradually increases, and the spectral properties of the entire hygrochromic material gradually change from high solar transmittance to high solar reflectivity; the solar heat reaching the hygrochromic material is reflected back, the bottom graphene coating no longer absorbs heat, and the overall temperature of the hygrochromic material gradually decreases; due to the decrease in temperature and water content, the vapor pressure in the pores is lower than the vapor pressure of the external environment, and the hygroscopic salt adsorbs water in the atmosphere again, and a secondary adsorption process is carried out; then the cycle is repeated, and the solar-driven water desorption process is carried out again under the transformation of the spectral properties.

[0024] Beneficial effects of the present invention:

[0025] By utilizing the changes in the spectral properties of hygrochromic materials, automatic switching of the adsorption and desorption processes in atmospheric water intake is achieved. There is no need to add additional sunshade equipment during the water adsorption stage, which reduces manual intervention and additional power input of control equipment, ensures the number of water intake cycles in a day, and improves the efficiency and stability of the water intake device. It is especially suitable for arid areas and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the atmospheric water extraction device based on hygrochromic drive of the present invention;

[0027] Figure 2 Schematic diagram of the color change principle of the hygrochromic material used in the atmospheric water intake device based on hygrochromic drive of the present invention;

[0028] Figure 3 This is a graph showing the changes in optical properties during the adsorption-desorption stages of the lithium chloride-silicon dioxide aerogel porous composite material used in the atmospheric water extraction device driven by hygrochromism in the present invention.

[0029] In the picture:

[0030] 1. Hygrochromic material, 2. Graphene coating, 3. Radiative cooling coating, 4. Water collection chamber. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0032] Example 1, with reference to Figure 1 , which is the first embodiment of the present invention, provides an atmospheric water intake device based on hygrochromic drive, which consists of a hygrochromic material layer 1, a graphene coating 2, a radiation cooling coating 3 and a water collection chamber 4. The hygrochromic material 1 is located at the center of the atmospheric water intake device, the graphene coating 2 is located at the bottom of the hygrochromic material 1, the center of the bottom of the water collection chamber 4 surrounds the hygrochromic material 1 and the graphene coating 2, and the radiation cooling coating 3 is located on the outer surface of the top of the water collection chamber 4.

[0033] The water collection chamber 4 is connected to all components of the atmospheric water intake device and is used to collect and store condensed water droplets. There is a groove in the center of the bottom of the water collection chamber for placing the hygrochromic material 1 containing the graphene coating 2; the top is sloped with an inclination of 30° to the horizontal direction, which is used as the condensation surface for water collection; the left and right sides are divided into two chambers for the condensation and subsequent collection of water; a water valve is provided at the bottom of the right chamber to control the outflow of water to avoid saturation of the water collection chamber.

[0034] The hygrochromic material 1 is prepared by a sol-gel method using a mixture of hygroscopic salt and silica aerogel in a specific ratio. The aerogel has a porosity of 0.8-0.9 and a thickness of 50±20 microns. A portion of the upper surface of the hygrochromic material 1 is exposed to the atmosphere, while a portion is enclosed in a water collection chamber 4 to facilitate moisture collection. By varying the spectral properties of the hygrochromic material 1, the reflection and transmission of sunlight are controlled, spontaneously promoting the transition between adsorption and desorption processes within the hygrochromic material 1.

[0035] The graphene coating 2 is deposited using chemical vapor deposition and then transferred to the bottom layer of the hygrochromic material 1. The graphene coating 2, with a thickness of 15 nanometers, absorbs solar energy and rapidly heats the hygrochromic material 1 above it, desorbing water from the hygrochromic material 1.

[0036] The radiation cooling coating 3 is evenly coated on the outer surface of the top of the water collection chamber 4 by spraying. The thickness of the coating is controlled at 150 microns, and the solar reflectivity and infrared emissivity are controlled between 0.8-0.95 and 0.9-0.95 respectively, so as to reduce the temperature of the top of the water collection chamber 4 in direct contact with the coating and promote the condensation of water vapor at the top.

[0037] Example 2, reference Figure 1-Figure 3 , which is a second embodiment of the present invention, provides a working method of an atmospheric water intake device based on hygrochromic drive, using the atmospheric water intake device based on hygrochromic drive, comprising the following steps:

[0038] Step 1: Nighttime water adsorption process:

[0039] When the ambient humidity is high at night, the lithium chloride salt in the dry hygrochromic material 1 absorbs moisture in the atmosphere; Figure 2 As shown in the figure (right), when the salt solution reaches equilibrium, the refractive index difference between the porous silica matrix, air pores and the salt solution is significantly reduced, forming an optical matching state; this change causes a significant change in the optical properties of the hygrochromic material 1, as shown in the figure (right). Figure 3 As shown in FIG, the solar reflectance of the wet-induced chromic material 1 is reduced from the initial 0.80 to 0.25 (at a thickness of 50 μm), while the solar transmittance is significantly improved; this high transmittance state lays the foundation for the efficient use of solar energy during the day.

[0040] Step 2: Daytime solar energy drives water desorption process:

[0041] During the day, sunlight passes through the hygrochromic material 1 in a high-transmittance state and reaches the graphene coating 2 at the bottom; Figure 3 As shown, the transmittance of the hygrochromic material 1 with a thickness of 50-100 microns can reach above 0.6 after adsorption; the graphene coating 2, with its excellent heat absorption and thermal conductivity, quickly and evenly conducts solar heat energy to the entire hygrochromic material 1; as the temperature rises, the water vapor in the pores of the hygrochromic material 1 gradually desorbs and escapes, rising to the top surface containing the radiation cooling coating 3 in the water collection chamber 4 and condensing; the condensed water quickly condenses under the low temperature of the radiation cooling coating 3, and gathers and flows down along the slope and side walls, and finally reaches the bottom of the water collection chamber 4 for collection; this process makes full use of the optical property transformation characteristics of the hygrochromic material 1, and realizes the efficient capture and utilization of solar energy.

[0042] Step 3: Daytime hygrochromism drives secondary adsorption process:

[0043] During the desorption process of step 2, as the water content in the pores of the hygrochromic material 1 gradually decreases, the refractive index of the hygroscopic salt increases and the volume of the air pores increases, and the refractive index difference between the porous silica matrix, the air pores and the hygroscopic salt increases again, presenting a high scattering state, such as Figure 2 As shown (left), n represents the refractive index; this change causes the optical properties of the wet-induced chromic material 1 to undergo a reversible change, such as Figure 3 As shown, the solar reflectivity of the hygrochromic material 1 gradually returns to its initial high reflectivity state, reaching above 0.7; at this time, most of the sunlight is reflected, the bottom graphene coating 2 no longer absorbs a large amount of heat, and the overall temperature of the hygrochromic material 1 gradually decreases; due to the decrease in temperature and water content, the vapor pressure in the pores is lower than that of the external environment, and the hygroscopic salts again adsorb moisture in the atmosphere to achieve secondary adsorption; then the cycle repeats, and the solar-driven water desorption process is carried out again under the transformation of spectral properties; this intelligent adjustment mechanism can realize a continuous adsorption-desorption cycle, thereby improving the water extraction efficiency of the device.

[0044] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An atmospheric water extraction device based on hygrochromic drive, characterized by: The device consists of a hygrochromic material (1), a graphene coating (2), a radiation cooling coating (3), and a water collection chamber (4), wherein the hygrochromic material (1) is located at the center of the atmospheric water intake device, the graphene coating (2) is located at the bottom of the hygrochromic material (1), the center of the bottom of the water collection chamber (4) surrounds the hygrochromic material (1) and the graphene coating (2), and the radiation cooling coating (3) is located on the outer surface of the top of the water collection chamber (4); The water collection chamber (4) is connected to all components of the atmospheric water extraction device and is used to collect and store condensed water droplets; A portion of the upper surface of the hygrochromic material (1) is exposed to the external environment and in direct contact with the atmosphere, while a portion is enclosed in a water collection chamber (4) to facilitate the collection of moisture. The reflection and transmission of sunlight are controlled by changes in the spectral properties of the hygrochromic material (1), thereby spontaneously promoting the conversion of the adsorption and desorption processes of the hygrochromic material (1); The graphene coating (2) is located at the bottom layer of the hygrochromic material (1) and is used to absorb solar energy and quickly heat the upper hygrochromic material (1), thereby achieving a desorption process of water in the hygrochromic material (1); The radiation cooling coating (3) is located on the outer surface of the top of the water collection chamber (4), and utilizes its high solar reflectivity and emissivity to reduce the temperature of the top of the water collection chamber (4) in direct contact with the coating, thereby promoting the condensation of water vapor on the top.

2. The atmospheric water intake device based on hygrochromic drive according to claim 1, characterized in that: The water collecting chamber (4) has a groove at the center of the bottom thereof for placing the hydrochromic material (1) containing the graphene coating (2).

3. The atmospheric water intake device based on hygrochromic drive according to claim 1, characterized in that: The top of the water collection chamber (4) is sloped, with an inclination of 30° to the horizontal direction, and serves as a condensation surface for water collection.

4. The atmospheric water intake device based on hygrochromic drive according to claim 1, characterized in that: The water collection chamber (4) is divided into two chambers on the left and right sides for condensing and subsequently collecting water; a water valve is provided at the bottom of the right chamber for controlling the outflow of water.

5. The atmospheric water intake device based on hygrochromic drive according to claim 1, characterized in that: The hygrochromic material (1) is a hygroscopic salt-aerogel composite porous material, and the hygroscopic salt needs to be embedded in the pore structure of the silica aerogel with a porosity of 0.8-0.

9.

6. The atmospheric water intake device based on hygrochromic drive according to claim 1, characterized in that: The optical refractive index of the hygroscopic salt solution in the hygrochromic material (1) in the adsorption equilibrium state matches the optical refractive index of the silicon dioxide material n=1.

457.

7. The atmospheric water intake device based on hygrochromic drive according to claim 1, characterized in that: The overall thickness of the wet-induced color-changing material (1) is designed to be within a range of 50±20 micrometers.

8. The atmospheric water intake device based on hygrochromic drive according to claim 1, characterized in that: The graphene coating (2) has a thickness of 15 nanometers, a solar light absorptivity of >0.9, and a thermal conductivity of 1200-1500 W / (m·K).

9. The atmospheric water intake device based on hygrochromic drive according to claim 1, characterized in that: The radiation cooling coating (3) is a white paint cold coating with a thickness of 150 microns. The solar reflectivity of the coating is 0.8-0.95, and the infrared emissivity is 0.9-0.

95.

10. The method for operating the atmospheric water intake device based on hygrochromic drive according to any one of claims 1 to 9, wherein the atmospheric water intake device based on hygrochromic drive is used, characterized in that: The following steps are involved: Step 1, nighttime water adsorption process: the hygroscopic salt in the dry hygrochromic material (1) adsorbs water in the atmosphere. After the salt solution reaches equilibrium, the refractive index difference between the porous silica matrix, air pores and the salt solution decreases, and the spectral properties of the entire hygrochromic material (1) change from high solar reflectivity to high solar transmittance. Step 2: Daytime solar energy drives water desorption process: During the day, solar energy passes through the hygrochromic material (1) and reaches the graphene coating (2) at the bottom. After the graphene coating (2) absorbs heat, it quickly conducts the heat to the entire hygrochromic material (1). After the temperature rises, the water vapor in the pores of the hygrochromic material (1) gradually desorbs and escapes, rising to the top surface containing the radiation cooling coating (3) in the water collection chamber (4) and condensing. The condensed water gathers and flows down along the slope and side walls and reaches the bottom of the water collection chamber (4). Step 3, daytime hygrochromic driven secondary adsorption process: During the desorption process of step 2, as the water content in the pores of the hygrochromic material (1) gradually decreases, the refractive index of the hygroscopic salt increases and the volume of the air pores increases, the refractive index difference between the porous silica matrix, the air pores and the hygroscopic salt gradually increases, and the spectral properties of the entire hygrochromic material (1) gradually change from high solar transmittance to high solar reflectivity; the solar heat reaching the hygrochromic material (1) is reflected back, the bottom graphene coating (2) no longer absorbs heat, and the overall temperature of the hygrochromic material (1) gradually decreases; due to the decrease in temperature and water content, the vapor pressure in the pores is lower than the vapor pressure of the external environment, and the hygroscopic salt adsorbs water in the atmosphere again, and a secondary adsorption process is carried out; then the cycle repeats, and the solar-driven water desorption process is carried out again under the change of spectral properties.

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