Dual temperature-adaptive building cooling and energy conservation device based on passive radiative cooling

Abstract

Disclosed in the present invention is a dual temperature-adaptive building cooling and energy conservation device based on passive radiative cooling, consisting of straight pipes (2) located outdoors and each coated with an adaptive passive radiative cooling coating (1), top coiled pipes (5) located indoors for heat exchange, a top liquid storage tank (14), a bottom liquid storage tank (10), solenoid valves and temperature sensors connected to a central controller (21), and a connected piping system. The device of the present invention can effectively cool the interior of a building by using the passive radiative cooling technology; a working fluid is directly introduced into the top of the interior for heat exchange; and in addition, the working state can be automatically adjusted on the basis of the self-modulation effect of the adaptive passive radiative cooling coatings (1) and the difference between an indoor / outdoor temperature and a set temperature, to avoid overcooling of the building, thereby achieving energy conservation in the building throughout all seasons of the year. The cooling and energy conservation device of the present invention is particularly suitable for buildings or devices with high internal heat generation, such as server rooms, boiler rooms, steelmaking workshops, and transformer boxes.

Description

A dual-temperature adaptive building cooling and energy-saving device based on passive radiative cooling Technical Field

[0001] This invention relates to the field of building energy conservation, specifically to a dual temperature adaptive building cooling and energy-saving device based on passive radiative cooling. Background Technology

[0002] Currently, most building cooling relies on air conditioning equipment. The growing demand for thermal comfort drives energy consumption for cooling and massive carbon emissions, exacerbating global warming. Buildings such as computer rooms and cold storage facilities require long-term use of refrigeration equipment, consuming significant amounts of energy. The development of energy-saving building cooling devices aligns with the trend of achieving carbon emission reduction.

[0003] Passive radiative cooling is a newly emerging green, zero-energy cooling technology. It achieves self-cooling through the combined effects of the following mechanisms: high reflectivity across the entire spectrum of sunlight; and high infrared emissivity within the atmospheric window band. Applying passive radiative cooling technology to building cooling is a significant and emerging application. Summary of the Invention

[0004] This invention aims to propose a dual-temperature adaptive building cooling and energy-saving device based on passive radiative cooling, suitable for various types of buildings, to achieve low-energy indoor cooling. Passive radiative cooling technology is an important energy-saving and environmentally friendly method for building cooling. Furthermore, the adjustable passive radiative cooling technology allows for the on / off switching of the cooling function, making it suitable for a wider range of applications.

[0005] The technical solution adopted in this invention is as follows: A dual-temperature adaptive building cooling and energy-saving device based on passive radiative cooling, comprising an outdoor straight pipe coated with an adaptive passive radiative cooling coating, an indoor top coil for heat exchange, a top liquid storage tank, a bottom liquid storage tank, a solenoid valve and temperature sensor connected to a central controller, and a connected piping system. Multiple segments of straight pipes are regularly and densely arranged on the building's outdoor roof and the sun-facing walls of each floor, and each segment of the straight pipe is interconnected. An outdoor temperature sensor is installed on each straight pipe. The upper end of the straight pipe is connected to the inlet and outlet of the indoor top coil via two T-joints. A straight pipe solenoid valve is installed between the two T-joints. The T-joints are polymer plastic fittings with low thermal conductivity. An indoor temperature sensor and a coil solenoid valve are installed on the indoor top coil. The bottom of the vertically placed outdoor straight pipe is connected to a manifold, which is connected to one port of the liquid pump in the bottom liquid storage tank. The other port of the liquid pump is connected to a return pipe, which is equipped with a return pipe solenoid valve. The other end of the return pipe is connected to a liquid storage tank on the top of the building, which is equipped with a level gauge. Simultaneously, each outlet of the top liquid storage tank is equipped with a replenishment solenoid valve connected to the outdoor top straight pipe. The level gauge on the top liquid storage tank monitors the liquid level inside. The outer surfaces of the multiple straight pipes on the top and each layer of the sun-facing wall, as well as the surface of the top liquid storage tank, are coated with an adaptive passive radiation cooling coating. The formulation, coating area and thickness of the adaptive passive radiation cooling coating, and the number of cooling straight pipes can be configured according to regional and climatic characteristics.

[0006] In some implementations, turbulence-enhancing elements can be installed inside the pipes to strengthen heat transfer, and protective devices can be installed on the outside of the outdoor straight pipes to extend the service life of the adaptive passive radiation cooling coating.

[0007] In some embodiments, the adaptive passive radiation cooling coating includes a thermochromic radiation cooling coating material. It is mainly composed of a polymer substrate (TPU, PVDF, PMMA, etc.), inorganic particles (ZrO2, SiO2, BaSO4, etc.), and phase change metal materials (VO2), possessing multi-level micro / nano structures such as pores, particles, and fibers. When the ambient temperature is high, the adaptive passive radiation cooling coating exhibits high solar reflectivity and high emissivity in the mid-infrared band; when the ambient temperature is low, the adaptive passive radiation cooling coating exhibits low solar reflectivity and low emissivity in the mid-infrared band, reducing passive radiation cooling capacity and preventing excessive cooling of the building interior; the self-modulation function of the adaptive passive radiation cooling coating achieves the first layer of adaptive temperature regulation. Simultaneously, the aforementioned adaptive passive radiation cooling coating may possess superhydrophobic and self-cleaning properties, as well as resistance to photoaging.

[0008] In some embodiments, solenoid valves are installed on the outdoor pipeline and connected to the central controller. The indoor and outdoor temperature sensors are also connected to the central controller, which collects data from both sensors. The indoor temperature sensor collects the real-time indoor temperature, and the outdoor temperature sensor collects the temperature of the working fluid in the vertical pipe. By comparing the temperature data collected by the temperature sensors in the indoor and outdoor pipelines with the system's preset temperature, the opening and closing of solenoid valves at different locations in the pipelines can be controlled to manage the passive radiant cooling effect of the building. A second layer of adaptive temperature regulation is achieved through the central controller. When the indoor temperature sensor's temperature data is higher than the central controller's preset temperature, the coil solenoid valve, the return pipe solenoid valve, and the replenishment solenoid valve connected to the top liquid storage tank open, while the straight pipe solenoid valve between the tee joints in the outdoor pipeline closes. The working fluid circulates under the action of the adaptive passive radiant cooling coating to achieve building cooling. If the indoor temperature sensor's temperature data is lower than the outdoor temperature sensor's temperature data or the required indoor temperature, the indoor top coil solenoid valve closes, and the fluid in the pipe stops flowing. If this device is not needed for a long period of time, close the indoor top coil solenoid valve, close the liquid replenishment solenoid valve at the outlet of the liquid storage tank on the top of the building to stop replenishing the working fluid, and open the outdoor straight pipe solenoid valve to drain the working fluid into the bottom liquid storage tank. After draining the fluid in the pipe, prevent heat dissipation.

[0009] In some embodiments, the building rooftop liquid storage tank can be connected to the building's water supply pipeline, allowing direct replenishment when the working fluid is water; when the working fluid is refrigerant, nanofluid, etc., it can be directly added to the building rooftop liquid storage tank. When the working fluid in the straight pipe coated with the adaptive passive radiation cooling coating is insufficient, the liquid replenishment solenoid valve at the outlet of the building rooftop liquid storage tank opens to replenish the working fluid; in cold regions, to avoid situations where cooling is not needed for extended periods, the working fluid can be promptly discharged to prevent freezing and damage to the pipeline system, by opening all outdoor straight pipe solenoid valves to discharge the working fluid to the building bottom liquid storage tank, which is equipped with an insulation layer; when continuous operation of the working fluid is required in the straight pipe coated with the adaptive passive radiation cooling coating and the indoor rooftop coil, the coil solenoid valve, the return pipe solenoid valve, and the liquid replenishment solenoid valve are opened, while the straight pipe solenoid valve between the outdoor pipeline tee joints is closed, achieving fluid circulation during operation.

[0010] In some implementations, the working fluid includes, but is not limited to, water, refrigerant, nanofluids, and mixtures thereof, which can be added to the piping system as needed when replenishing the working fluid. The circulation of the working fluid can be achieved through, but is not limited to, thermal convection, gas-liquid flow, pumping, and directional water delivery structures using microchannels in the piping. During building cooling, the working fluid in the straight pipe flows naturally downwards under the action of the adaptive passive radiative cooling coating. The working fluid enters the indoor top coil through the tee interface, and after sufficient heat exchange with the indoor air, it flows into the lower-level piping of the building for further cooling under natural convection. This process is repeated until it enters the liquid storage tank at the bottom of the building. Under the action of pumping, the working fluid enters the top liquid storage tank through the return pipe. The liquid replenishment solenoid valve connected to the top liquid storage tank opens, and the working fluid enters the outdoor piping, completing the cooling cycle.

[0011] In some implementations, in order to ensure that the indoor top coil is filled with working fluid when it is in operation, and that the working fluid can not only achieve more cooling outdoors, but also fully exchange heat in the indoor top coil, the inner diameter of the outdoor straight pipe is 1.2 to 2.2 times the inner diameter of the indoor top coil.

[0012] In some implementations, the building cooling is carried out through a refrigeration cycle. To ensure continuous flow of the working fluid and sufficient heat exchange, the inner diameter of the outdoor straight pipe can be 18–40 mm.

[0013] In some implementations, to enhance heat exchange performance, the indoor ceiling coil can utilize high thermal conductivity metal pipes, such as aluminum or copper pipes, or polymer plastic pipes filled with high thermal conductivity materials. Considering both heat exchange effect and ambient temperature, the outdoor straight pipe can be made of metal pipes with different thermal conductivity or polymer plastic pipes filled with high thermal conductivity materials, depending on requirements. The wall thickness of both the indoor ceiling coil and the outdoor straight pipe can vary from 2 to 10 mm depending on the pipe diameter.

[0014] In some implementations, the indoor and outdoor temperature sensors required for each floor of the building can be installed individually or in multiple ways as needed. If each floor uses one indoor temperature sensor and one outdoor temperature sensor, they can be arranged symmetrically at the top of the coils or in the middle of multiple straight pipes on each floor to measure the temperature. If multiple sensors are set, they can be evenly distributed on multiple pipes to measure the average temperature, which is then input into the central controller.

[0015] In some embodiments, the straight pipe is fixed to the building wall by a water pipe clamp, and a retractable protective cover is installed on the outer surface of the straight pipe. The protective cover can be moved up and down by a ball screw slide rail driven by a motor under the control of the central controller to cover the outer surface of the straight pipe or retract and store at the bottom of the straight pipe, so as to protect the adaptive passive radiation cooling coating of the pipe wall in severe weather.

[0016] In some embodiments, a flow-disrupting element may be installed inside the straight pipe. The flow-disrupting element includes, but is not limited to, a combined rotor, a spiral ribbon, etc. The flow-disrupting element rotates spontaneously under force when the working fluid flows, making the heat transfer of the working fluid inside the rotatable pipe more uniform and preventing scale buildup inside the pipe, thereby enhancing the cooling effect and extending the service life.

[0017] In some implementations, the indoor top coil can be fitted with a finned structure to improve the heat exchange efficiency between the fluid inside the coil and the indoor air.

[0018] In some embodiments, the tee connector polymer plastic pipe fitting can be prepared by injection molding foaming or other methods, and has an extremely low thermal conductivity, avoiding direct heat exchange between indoor and outdoor air through the pipe wall and reducing parasitic heat in the system.

[0019] In some implementations, the device is preferably powered by solar panels, but it can also be connected to the building's power supply system.

[0020] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: the adaptive building energy-saving cooling device can effectively cool the interior of the building through passive radiation cooling technology. By introducing the working fluid into the top of the room for direct heat exchange, the heat exchange efficiency is higher. At the same time, it can adjust its working state according to the self-modulation effect of the adaptive passive radiation cooling coating and the difference between the indoor and outdoor temperatures and the set temperature, so as to avoid the building from getting too cold. Thus, it can save energy for the building all year round. It has the advantages of energy saving and environmental protection, simple operation and structure, and wide applicability, and has high application value. Attached Figure Description

[0021] Figure 1 is an axonometric view of the piping layout of a dual temperature adaptive building cooling and energy-saving device based on passive radiative cooling disclosed in one or more embodiments.

[0022] Figure 2 shows the microstructure of the adaptive passive radiation cooling coating at point A in Figure 1.

[0023] Figure 3 is a magnified view of the indoor and outdoor pipe connection at point B in Figure 1.

[0024] Figure 4 is a left view of the pipeline layout in Figure 1.

[0025] Figure 5 is a schematic diagram of the connection and fixing structure of the straight pipe and the protective cover in the deployed state of the dual temperature adaptive building cooling energy-saving device based on passive radiation cooling disclosed in one or more embodiments.

[0026] Figure 6 is a schematic diagram of the connection and fixing structure of the straight pipe and the shrinkage state protective cover of the dual temperature adaptive building cooling energy-saving device based on passive radiation cooling disclosed in one or more embodiments.

[0027] Figure 7 is a schematic diagram of the adaptive building energy-saving temperature control system of a dual temperature adaptive building cooling and energy-saving device based on passive radiative cooling disclosed in one or more embodiments.

[0028] Figure 8 is a schematic diagram of a flow-disrupting element installed inside a straight pipe of a dual temperature adaptive building cooling and energy-saving device based on passive radiative cooling disclosed in one or more embodiments.

[0029] In the attached figures, the reference numerals are as follows: 100-Dual temperature adaptive building cooling and energy-saving device based on passive radiation cooling; 1-Adaptive passive radiation cooling coating; 2-Straight pipe; 3-T-connector; 4-Outdoor temperature sensor; 5-Top coil; 6-Straight pipe solenoid valve; 7-Coil solenoid valve; 8-Indoor temperature sensor; 9-Manifold; 10-Bottom liquid storage tank; 11-Liquid pump; 12-Return pipe; 13-Return pipe solenoid valve; 14-Top liquid storage tank; 15-Level gauge; 16-Replenishment solenoid valve; 17-Water pipe clamp; 18-Motor; 19-Protective cover; 20-Ball screw slide rail; 21-Central controller; 22-Break current element. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] The purpose of this invention is to provide a dual temperature adaptive building cooling and energy-saving device based on passive radiation cooling, which is suitable for various types of buildings and achieves the goal of energy conservation and emission reduction by cooling the indoor environment of low-energy buildings.

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] As shown in Figures 1-4, this embodiment provides a dual-temperature adaptive building cooling and energy-saving device 100 based on passive radiative cooling. The device consists of straight pipes 2 coated with an adaptive passive radiative cooling coating 1 on the outside, top coils 5 for heat exchange indoors, a top liquid storage tank 14 for storing working fluid and located on the top of the building, a bottom liquid storage tank 10 located at the bottom of the building, multiple solenoid valves and multiple temperature sensors connected to a central controller 21, and a connected piping system. Simultaneously, flow-turbulence elements 22 can be installed inside the piping to enhance heat exchange, and protective devices can be installed on the outside of the outdoor piping to extend the service life of the adaptive passive radiative cooling coating 1. Specifically, multiple segments of straight pipes 2 coated with the adaptive passive radiative cooling coating 1 are regularly and densely arranged on the roof of the building and the sun-facing walls of each floor, and each segment of the straight pipe 2 is connected by a tee joint 3. Each floor of the building has a straight pipe 2 equipped with an outdoor temperature sensor 4. The upper end of the straight pipe 2 is connected to the inlet and outlet of the indoor ceiling coil 5 via two T-joints 3. A straight pipe solenoid valve 6 is installed between the two T-joints 3. The T-joints 3 are polymer plastic fittings with low thermal conductivity. A coil solenoid valve 7 and an indoor temperature sensor 8 are installed on the indoor ceiling coil 5. The bottom of the outdoor straight pipe 2 is connected to a manifold 9. The manifold 9 is connected to one connection port of the liquid pump 11 in the bottom liquid storage tank 10. The other connection port of the liquid pump 11 is connected to a return pipe 12. A return pipe solenoid valve 13 is installed on the return pipe 12. The other end of the return pipe 12 is connected to the building's ceiling liquid storage tank 14. A level gauge 15 is installed on the ceiling liquid storage tank 14, and each of its outlets is equipped with a replenishment solenoid valve 16 that connects to the outdoor ceiling straight pipe 2. The ceiling liquid storage tank 14 can also be connected to the building's water supply pipeline. The adaptive passive radiation cooling coating 1 has a temperature adaptive regulation function. The formulation, coating area and thickness of the adaptive passive radiation cooling coating 1, as well as the number of straight pipes 2, can be configured according to regional and climatic characteristics. Water pipe fixing clamps 17 are installed on the pipes on the building walls and indoor ceilings. A retractable protective cover 19 is installed on the outer surface of the straight pipe 2. The retractable protective cover 19 can move up and down along the ball screw slide rail 20 driven by the motor 18. Under the control of the central controller 21, it can cover the outer surface of the straight pipe 2 or shrink to store the bottom, as shown in Figures 5 and 6. A flow-turbulence element 22 can be installed inside the straight pipe 2, as shown in Figure 8. The flow-turbulence element 22 includes, but is not limited to, spiral ribbons, combined rotors, etc. The cooling device uses the temperature data collected by the central controller 21 to control the solenoid valves and liquid pumps 11 of each pipeline to provide instructions for automatic operation.

[0034] In some embodiments, the adaptive passive radiation cooling coating 1 includes a thermochromic radiation cooling coating material. It is mainly composed of a polymer substrate, inorganic particles, and phase change metal materials, and has a multi-level micro / nano structure including pores, particles, and fibers. When the ambient temperature is high, the adaptive passive radiation cooling coating has high solar reflectivity and high emissivity in the mid-infrared band; when the ambient temperature is low, the adaptive passive radiation cooling coating has low solar reflectivity and low emissivity in the mid-infrared band, reducing passive radiation cooling capacity and preventing excessive cooling of the building interior; the self-modulation function of the adaptive passive radiation cooling coating achieves the first layer of adaptive temperature regulation. Simultaneously, the aforementioned adaptive passive radiation cooling coating may possess superhydrophobic and self-cleaning properties, as well as resistance to photoaging. The polymer substrate materials include, but are not limited to, TPU (thermoplastic polyurethane), PVDF (polyvinylidene fluoride), and PMMA (polymethyl methacrylate); the inorganic particle materials include, but are not limited to, ZrO2 (zirconia), SiO2 (silicon dioxide), and BaSO4 (barium sulfate); and the phase change metal materials include, but are not limited to, VO2 (vanadium dioxide).

[0035] The specific implementation principle of this invention is shown in Figure 7: The system achieves temperature-adaptive building cooling under the dual action of the adaptive passive radiation cooling coating 1 and the central controller 21. In use, initially there is no working fluid inside the pipeline. Depending on the selection of the working fluid, when the working fluid is building water supply, the building water supply is directly delivered into the top liquid storage tank 14, and the replenishing solenoid valve 16 opens to replenish the working fluid; when the working fluid is refrigerant, nanofluid, etc., it can be added to the top liquid storage tank 14 as needed, and the replenishing solenoid valve 16 at the outlet of the top liquid storage tank 14 opens to replenish the working fluid.

[0036] When cooling a building, if the outdoor temperature is higher than the phase transition temperature of the thermochromic phase change metal material within the adaptive passive radiation cooling coating 1, and the coating has high solar reflectivity and high emissivity in the mid-infrared band, the coating activates passive radiation cooling. When the indoor temperature sensor 8's temperature data is higher than the preset temperature of this device, the working fluid in the straight pipe 2 cools down under the passive radiation cooling effect of the adaptive passive radiation cooling coating 1 and flows downwards naturally. At this time, the straight pipe solenoid valve 6 between the two T-junction joints 3 of the outdoor pipeline is closed, and the working fluid enters the indoor top coil 5 through the T-junction interface. After sufficient heat exchange with the indoor air, it flows into the lower straight pipe 2 of the building under natural convection for further cooling. This process is repeated until the fluid enters the bottom liquid storage tank 10 of the building. Under the pumping action of the liquid pump 11, the working fluid enters the top liquid storage tank 14 through the return pipe 12. At this time, the return pipe solenoid valve 13 is open, and the top liquid storage tank 14 is connected to the replenishment solenoid valve 16 of the outdoor pipeline. The working fluid enters the outdoor pipeline for further cooling, thus completing the cooling cycle. If the temperature data from the indoor temperature sensor 8 is lower than the temperature data from the outdoor temperature sensor 4 or the required indoor temperature setting, the coil solenoid valve 7 installed on the indoor top coil 5 will close, and the working fluid will no longer function. When the outdoor temperature is lower than the phase transition temperature of the phase change metal material inside the thermochromic adaptive passive radiation cooling coating 1, the solar reflectivity and mid-infrared emissivity of the adaptive passive radiation cooling coating 1 will decrease, and the passive radiation cooling function of the adaptive passive radiation cooling coating 1 will automatically shut off to prevent the building interior from becoming too cold.

[0037] When the refrigeration unit is not required to perform refrigeration for an extended period, the protective cover 19 unfolds under the control of the central controller 21 and covers the outer wall of the straight pipe 2, protecting the adaptive passive radiation refrigeration coating 1. When refrigeration is required, the protective cover 19 can be retracted towards the bottom of the straight pipe 2 by the ball screw slide rail driven by the motor 18 for storage, thereby exposing the adaptive passive radiation refrigeration coating 1.

[0038] In this building cooling cycle, to ensure continuous flow of the working fluid and sufficient heat exchange, the inner diameter of the outdoor straight pipe 2 is 1.5 times the inner diameter of the indoor top coil 5, and the inner diameter of the outdoor straight pipe 2 is 20mm. The indoor top coil 5 is made of copper with high thermal conductivity, while the outdoor straight pipe 2 is made of polyvinyl chloride filled with high thermal conductivity carbon nanoparticles. The wall thickness of both the outdoor straight pipe 2 and the indoor top coil 5 is 2mm. Each floor of the building uses one outdoor temperature sensor 4 and one indoor temperature sensor 8, which are respectively arranged in the middle of the straight pipe 2 and the middle of the top coil 5 on each floor to measure the temperature. The temperature data is input into the central controller 21.

[0039] The phase transition temperature of the phase change material in the adaptive passive radiation cooling coating 1 can be determined based on regional, climatic and other characteristics.

[0040] Generally speaking, the preset temperature of the controller of this device can be determined according to the local climate and the user's personal needs. When the temperature is higher than the preset temperature, the temperature adaptive building energy-saving cooling device can activate the cooling function to cool the building interior according to the difference between the set temperature and the indoor temperature, or enter the evacuation dormancy state when it is not needed.

[0041] This adaptive energy-saving indoor temperature control device can be used in cold storage, data centers, warehouses, residential buildings, and office buildings, and is particularly suitable for buildings or devices with high internal heat generation, such as computer rooms, boiler rooms, steelmaking workshops, and transformer boxes. Furthermore, the preset temperature and appropriate adaptive passive radiant cooling coating can be selected according to specific needs.

[0042] The adaptive building energy-saving cooling device provided by this invention can effectively cool the interior of a building through passive radiative cooling technology. By introducing the working fluid into the top of the room for direct heat exchange, the heat exchange efficiency is higher. At the same time, it can automatically adjust its working state according to the self-modulation effect of the adaptive passive radiative cooling coating and the difference between the indoor and outdoor temperatures and the preset temperature, so as to avoid the building from getting too cold. Thus, it can reduce the building's energy consumption all year round. It has the advantages of energy saving and environmental protection, simple operation, and wide applicability, and has high application value.

[0043] This invention has illustrated its principles and implementation methods through embodiments. The descriptions of these embodiments are merely illustrative of the method and its core ideas; furthermore, those skilled in the art will recognize that modifications may be made to the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as limiting the invention. All variations or substitutions based on this invention are included within the scope defined by the claims of this invention.

Claims

1. A dual-temperature adaptive building cooling and energy-saving device based on passive radiative cooling, characterized in that: The system consists of outdoor straight pipes coated with an adaptive passive radiative cooling coating, indoor top coils for heat exchange, a top liquid storage tank, a bottom liquid storage tank, solenoid valves and temperature sensors connected to a central controller, and a connected piping system. Multiple segments of straight pipes are regularly and densely arranged on the building's outdoor roof and the sun-facing walls of each floor, with each segment interconnected. Outdoor temperature sensors are installed on the straight pipes. The upper ends of the straight pipes are connected to the inlet and outlet of the top coils via two tee fittings. A solenoid valve is installed between the two tee fittings. The tee fittings are made of polymer plastic with low thermal conductivity. Indoor temperature sensors and coil solenoid valves are installed on the top coils. The bottom of the vertically placed outdoor straight pipe system is connected to a central controller. The manifold is connected to one port of the liquid pump in the bottom liquid storage tank, and the other port of the liquid pump is connected to the return pipe. A return pipe solenoid valve is installed on the return pipe, and the other end of the return pipe is connected to the top liquid storage tank. A level gauge is installed on the top liquid storage tank, and each outlet of the top liquid storage tank is equipped with a replenishment solenoid valve connected to the outdoor top straight pipe. The level gauge can monitor the liquid level in the top liquid storage tank. The outer sides of the multiple straight pipes on the top and each layer of the sun-facing wall, as well as the surface of the top liquid storage tank, are coated with an adaptive passive radiation cooling coating. The formulation, coating area and thickness of the adaptive passive radiation cooling coating, and the number of cooling straight pipes are configured according to the region and climate characteristics.

2. The dual-temperature adaptive building cooling and energy-saving device based on passive radiative cooling according to claim 1, characterized in that: Adding turbulence-inducing elements inside the pipeline enhances heat exchange, and adding protective devices to the outside of the outdoor straight pipe extends the service life of the adaptive passive radiation cooling coating.

3. The dual-temperature adaptive building cooling and energy-saving device based on passive radiative cooling according to claim 1, characterized in that: The adaptive passive radiation cooling coating includes a thermochromic radiation cooling coating material, which is mainly composed of a polymer substrate, inorganic particles and phase change metal materials, and has a multi-level micro-nano structure of pores, particles and fibers.

4. The dual-temperature adaptive building cooling and energy-saving device based on passive radiative cooling according to claim 3, characterized in that: The polymer substrate is made of TPU, PVDF, or PMMA, the inorganic particles are made of ZrO2, SiO2, or BaSO4, and the phase change metal is made of VO2.

5. The dual-temperature adaptive building cooling and energy-saving device based on passive radiative cooling according to claim 1, characterized in that: Each solenoid valve is installed on the outdoor pipeline and connected to the central controller; the indoor temperature sensor and the outdoor temperature sensor are connected to the central controller, and the central controller collects data from the indoor and outdoor temperature sensors. The indoor temperature sensor collects the real-time indoor temperature, and the outdoor temperature sensor collects the temperature of the working fluid in the vertical pipe. By comparing the temperature data collected by the temperature sensors in the indoor and outdoor pipelines with the system's preset temperature, the opening and closing of the solenoid valves at different positions in the pipeline can be controlled to manage the on / off state of the building's passive radiant cooling effect; the central controller enables a second level of adaptive temperature regulation.

6. The dual-temperature adaptive building cooling and energy-saving device based on passive radiative cooling according to claim 1, characterized in that: The top liquid storage tank is connected to the building's water supply pipeline, and can be directly replenished when the working fluid is water; Alternatively, when the working fluid is a refrigerant or nanofluid, it can be directly added to the top reservoir.

7. The dual-temperature adaptive building cooling and energy-saving device based on passive radiative cooling according to claim 1, characterized in that: The inner diameter of the outdoor straight pipe is 1.2 to 2.2 times the inner diameter of the indoor top coil; for building cooling through refrigeration circulation, to ensure continuous flow of the working fluid and sufficient heat exchange, the inner diameter of the outdoor straight pipe is 18 to 40 mm; the indoor top coil uses aluminum or copper pipes with high thermal conductivity, or polymer plastic pipes filled with high thermal conductivity materials; the outdoor straight pipe uses metal pipes with different thermal conductivity or polymer plastic pipes filled with high thermal conductivity materials; the wall thickness of the outdoor straight pipe and the indoor top coil is selected from 2 to 10 mm according to the pipe diameter.

8. The dual-temperature adaptive building cooling and energy-saving device based on passive radiative cooling according to claim 1, characterized in that: The straight pipe is fixed to the building wall by a water pipe fixing clamp. A retractable protective cover is installed on the outer surface of the straight pipe. Under the control of the central controller, the protective cover moves up and down by a ball screw slide rail driven by a motor to cover the outer surface of the straight pipe or retracts and stores at the bottom of the straight pipe, so as to protect the pipe wall's adaptive passive radiation cooling coating in severe weather.

9. The dual-temperature adaptive building cooling and energy-saving device based on passive radiative cooling according to claim 1, characterized in that: The device is powered by solar panels or connected to the building's power supply system.

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