Cool storage and supply system coupled with sky radiation and multi-stage evaporation refrigeration

Abstract

The invention discloses a cold storage and supply system coupled with sky radiation and multi-stage evaporation refrigeration, and belongs to the technical field of building energy conservation and renewable energy utilization. The system comprises a sky radiant panel, an air-water heat exchanger, an air circulation system, a water supply and return system and a multi-stage evaporative cooler. A water channel of the air-water heat exchanger is divided into an upper part and a lower part, the upper half part is embedded into the sky radiation plate for radiation heat exchange, and the lower half part is located in the air channel for heat exchange with air. And an indirect evaporative cooling section in the multi-stage evaporative cooler adopts a two-stage core cascade structure. Through the design, the cooling capacity and the energy efficiency ratio (EER) of the system under the dry and hot climate can be remarkably improved by combining the sky radiation cooling cold storage and the two-stage pre-cooling process, and meanwhile, the system can effectively cope with extreme high-temperature weather and keep good cooling capacity under the partial humid and hot climate condition.

Description

Technical Field

[0001] This invention relates to the field of building energy conservation and renewable energy application technology, specifically to a cold storage and cooling system that combines sky radiation cooling, water storage cooling, and multi-stage evaporative cooling. Background Technology

[0002] Traditional vapor compression air conditioning systems consume enormous amounts of energy, and most of the refrigerants used have a significant greenhouse effect. Therefore, developing passive cooling and natural cooling technologies that rely on little or no electricity to drive compressors has become a current research hotspot and important direction.

[0003] Sky radiation cooling technology utilizes a transparent window in the Earth's atmosphere within a specific infrared band. Through materials with high infrared emissivity, it directly radiates heat to outer space, where temperatures approach absolute zero, thereby lowering the radiator's own temperature below that of the surrounding air. This technology generates cooling without energy consumption, but its maximum cooling capacity occurs at night, creating a significant time mismatch with the peak cooling load of buildings during the day. Storing the radiative cooling generated at night for daytime use using water-based cooling technology is an effective way to resolve this supply-demand time mismatch.

[0004] Evaporative cooling technology utilizes the principle of heat absorption during water evaporation, offering high energy efficiency and serving as a highly effective passive cooling method. Indirect evaporative cooling technology separates the primary air to be cooled from the secondary air undergoing evaporation through a heat exchange core, avoiding the need for air supply and humidification and expanding its application scenarios. However, its performance is limited by the heat exchange temperature difference and efficiency between the primary and secondary air. In traditional single-stage indirect evaporative cooling systems, the secondary air is typically indoor exhaust air or outdoor air. When the wet-bulb temperature of this secondary air is high, its cooling capacity for the primary air decreases rapidly.

[0005] Therefore, in systems that couple sky radiation cooling, water storage cooling, and evaporative cooling, how to deeply explore and recover the potential cold energy within the evaporative cooling process, break through the performance limit of a single heat exchange, and thus significantly improve the overall cooling capacity, energy efficiency ratio, and operational stability of the system under extreme hot and dry climate conditions, is a key problem that has not yet been solved by existing technologies. Summary of the Invention

[0006] This invention aims to overcome the shortcomings of existing passive cooling technologies, such as performance limitations due to weather conditions, mismatch between cooling time and peak building load, sharp decline in cooling efficiency under high temperature and humidity climates, low coupling between different cold source technologies, and low system integration. The purpose of this invention is to provide a highly integrated, intelligently controlled passive cooling coupled with cold storage and cooling supply system. This system can: 1) efficiently collect and store radiant cold energy at night; 2) comprehensively utilize the stored cold energy during the day and perform multi-stage pre-cooling of outdoor air, greatly improving the inlet air conditions for evaporative cooling, thereby significantly expanding its effective cooling range and geographical applicability; 3) ensure stable and reliable cooling supply under all weather conditions and different meteorological conditions through optimized water circuit design and multi-mode intelligent switching, ultimately achieving near-zero energy consumption operation for building cooling.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention proposes a cold storage and cooling system that couples sky radiation and multi-stage evaporative cooling. The system is characterized by being a modular and intelligently controllable fluid and air handling integrated device, which mainly includes a sky radiation cooling module, an air-water heat exchange and air circulation module, a cold storage and fluid distribution module, a multi-stage evaporative cooling module with integrated cold energy recovery function, and a central intelligent control module.

[0009] The sky radiation cooling module includes at least one sky radiation panel. The sky radiation panel is preferably covered with a selective radiation coating with high infrared emissivity and low solar absorptivity, and is installed at an angle on the building roof or suitable facade to maximize its effective radiative heat exchange with the night sky.

[0010] The air-to-water heat exchange and air circulation module includes an integrated air-to-water heat exchanger and related air duct system. The air-to-water heat exchanger has a composite flow channel structure, comprising a continuous water channel and an independent air channel. The upper half of the water channel is tightly embedded within the sky radiant panel using a highly thermally conductive material, forming a radiant panel-water heat exchange surface; the lower half of the water channel is exposed in the air channel, forming an air-to-water heat exchange surface. The air circulation system includes an air inlet and outlet communicating with the air channel, a heat exchanger exhaust fan driving airflow, ducts and an indoor air supply fan for supplying air to the room, a return air inlet and duct for drawing air back from the room, and an exhaust fan and outlet for exhausting air to the outside. Controllable baffles are installed at key air duct nodes to switch airflow direction between different operating modes.

[0011] The core of the cold storage and fluid distribution module is a tiered cold water tank and an innovative dual-circuit system. The tiered cold water tank is a vertically placed, slender container. Its interior naturally forms stable temperature stratification based on water temperature differences, including an upper high-temperature water layer, a middle inclined temperature layer, and a lower low-temperature water layer. The supply and return water system includes a water replenishment solenoid valve, a proportional three-way valve, a first vacuum pump, a second vacuum pump, a first supply and return water main, and a second supply and return water main. The first supply and return water main connects the lower low-temperature water layer of the tiered cold water tank to the inlet of the lower half of the air-water heat exchanger's water channel. The first vacuum pump and the proportional three-way valve are installed on the pipeline. A first bypass pipeline with a gate valve is connected in parallel at both ends of the first vacuum pump. The second supply and return water main connects the upper high-temperature water layer of the tiered cold water tank to the inlet of the upper half of the air-water heat exchanger's water channel. The second vacuum pump is installed on the pipeline. A second bypass pipeline with a gate valve is connected in parallel at both ends of the second vacuum pump.

[0012] The multi-stage evaporative cooling module is a compact air handling unit, comprising an air filter, an indirect evaporative cooling section, and a direct evaporative cooling section. The indirect evaporative cooling section includes a first core and a second core arranged in series. A key improvement of this module is the inclusion of an airflow diversion and guidance device. In daytime operation mode, outdoor air flows as primary air through the primary air sides of both the first and second cores; indoor return air flows as secondary air through the secondary air side of the first core; and a portion of the air cooled after flowing through the primary air side of the first core is guided to the secondary air side of the second core, thus enabling the reuse of cooling capacity within the system. A spray system provides low-temperature spray water to both the indirect and direct sections, and a spray water collection chamber and return pipe are used to guide unevaporated water back to the chilled water tank.

[0013] The intelligent control system integrates multiple sensors and controllers to automatically select the operating mode and adjust the operating status of each fan, water pump, valve and baffle in real time according to environmental and system status parameters, especially to optimize the proportion of the cold energy recovery air volume.

[0014] Preferably, the airflow diversion and guiding device includes a first air valve disposed on the upstream air duct of the primary air side outlet of the first core, a diversion air duct connected to the secondary air side inlet of the second core, and a second air valve and a diversion fan disposed on the diversion air duct.

[0015] Preferably, the proportional three-way valve is an electric regulating valve used to dynamically adjust the cold water flow distribution ratio between the spray system and the cold water precooling section of the air-water heat exchanger.

[0016] Preferably, the system has a nighttime cold storage and cooling mode. In this mode, the second vacuum pump operates, water is taken out from the top of the water tank, cooled by the radiant plate, and then the air in the air channel is cooled. The cooled air can be directly sent into the room, and the generated low-temperature cold water is introduced into the bottom of the water tank for storage.

[0017] Preferably, the system operates in a combined cooling mode during the day. The first vacuum pump draws cold water from the bottom of the water tank, part of which is used for spraying and the other part is used for pre-cooling the air. After being pre-cooled in multiple stages, the air is successively sent into the room after passing through the first stage of indirect cooling, cold energy recovery and the second stage of deep indirect cooling, and direct evaporative cooling.

[0018] Compared with existing technologies, the system provided by this invention has the following significant advantages: Through the dual-core design of the multi-stage evaporative cooler, it breaks through the wet-bulb temperature limitation of traditional evaporative cooling, greatly improving cooling capacity and energy efficiency in hot and dry climates; through a unique dual-path water system, it achieves physical separation and optimization of the cold storage and release processes, reducing mixing losses; by adding a vacuum pump bypass pipeline, it improves the system's maintenance convenience and operational flexibility; through the deep coupling and intelligent switching of sky radiation cooling, water storage cooling, and multi-stage evaporative cooling, it achieves optimal synergy of natural cold sources in terms of time and quality, resulting in a highly adaptable and stable system that provides a highly efficient near-zero energy cooling solution for buildings. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the overall structure and principle of a cold storage and cooling system provided in an embodiment of the present invention.

[0020] Figure 2 This is a front view of the structure of the sky radiation plate and air-water heat exchanger in this invention.

[0021] Figure 3 In this invention, the sky radiant plate and the air-water heat exchanger are in Figure 2 Cross-sectional view of section aa in the middle.

[0022] Figure 4 In this invention, the sky radiant plate and the air-water heat exchanger are in Figure 2 Cross-sectional view of section bb in the middle.

[0023] Figure 5 This is a top view of the sky radiation plate and air-water heat exchanger in this invention.

[0024] Figure 6 This is a schematic diagram of the internal temperature stratification structure of the stratified cold water tank in this invention.

[0025] The components referred to by the labels in the diagram are as follows:

[0026] 1. Sky Radiant Panel

[0027] 2. Air-to-water heat exchanger; 21. Radiant plate-to-water heat exchange surface; 22. Water channel; 23. Air-to-water heat exchange surface; 24. Air channel.

[0028] 3. Air circulation system; 31. Heat exchanger air inlet; 32. Heat exchanger air outlet; 33. Heat exchanger exhaust fan; 34. Controllable baffle; 35. Indoor exhaust fan; 36. Indoor exhaust vent; 37. Indoor return air vent; 38. Outdoor exhaust fan; 39. Outdoor exhaust vent

[0029] 4. Water supply and return system; 41. Layered cold water tank; 411. Tank outer wall (including insulation layer); 412. Upper high-temperature water layer; 413. Middle heat exchange layer (temperature gradient layer); 414. Lower low-temperature water layer; 42. Water supply solenoid valve; 43. Proportional three-way valve; 44. First vacuum pump; 45. Second vacuum pump; 46. First water supply and return main pipe; 47. Second water supply and return main pipe; 48. First bypass pipe; 49. Second bypass pipe

[0030] 5. Multi-stage evaporative cooler; 51. Air filter; 52. Indirect evaporative cooling section core; 521. First core; 522. Second core; 53. Direct evaporative cooling section packing; 54. Spray nozzle; 55. Primary air baffle; 56. Spray water pipe; 57. Secondary air baffle; 58. Spray water collection chamber; 59. Spray water return pipe Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0032] It should be noted that in this embodiment, the orientation or positional relationship indicated by terms such as "upper," "lower," "front," and "rear" is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application. Furthermore, terms such as "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Please refer to the following first. Figure 2 , Figure 3 , Figure 4 and Figure 5 These four accompanying drawings together form the basis for understanding the core component of this invention—the integrated structure of the sky radiant panel and the air-water heat exchanger. Figure 2 The main view shows the overall shape and relative position of the sky radiant panel 1 and the air-to-water heat exchanger 2. The view is marked with the viewing direction lines for sections aa and bb (viewed from right to left). The inlet and outlet ends of the water channel 22, used to connect the supply and return water systems, are shown in this view. The independent air channel 24 and the structure of the heat exchanger outlet 32 ​​are also clearly shown. Understanding its key internal structures requires referring to the sectional views. Figure 3 It is along Figure 2 The cross-sectional view of section aa is located at the heat exchanger outlet 32 ​​and the side where the water channel connects to the external pipeline. Figure 4 It is along Figure 2 The cross-sectional view of section bb, located at the pipe connection bend of water channel 22, is key to understanding the functional division of the upper and lower parts of the water channel. Figure 3 and Figure 4 It is clearly shown that the upper part of the water channel 22 is completely embedded in the substrate of the sky radiant plate 1 by a highly thermally conductive material, and the two are tightly combined to form a highly efficient radiant plate-water heat exchange surface 21. The lower part of the water channel 22 is completely exposed in the air channel 24, forming an air-water heat exchange surface 23 for sensible heat exchange with the air. Figure 5 The top view further clarifies the spatial relationship between the sky radiant panel 1, the air-to-water heat exchanger 2 housing, and the internal piping layout. These four figures together reveal the innovative design of this invention, which deeply integrates the radiant cooling surface and the air-to-water heat exchange surface in terms of physical structure, laying the hardware foundation for subsequent efficient cold transfer and conversion.

[0035] Please see Figure 6 This diagram schematically illustrates the internal structure of the core of the water supply and return system 4—the stratified cold water tank 41. The diagram clearly shows the upper high-temperature water layer 412 at the top of the tank, the lower low-temperature water layer 414 at the bottom, and the middle heat exchange layer 413, where the temperature gradually changes between the two. The outer wall 411 of the tank is covered with a high-performance insulation layer to maintain this stable internal temperature stratification structure to the greatest extent possible. This structure is the physical prerequisite for efficiently storing and releasing cold energy of different grades, ensuring that the coldest and highest-grade cold water always accumulates at the bottom for use, while the warmer return water is located at the top.

[0036] Please see Figure 1This diagram serves as a schematic representation of the overall structure and principle of the invention, integrating all the aforementioned components into a complete system framework. It is not a simple display of component stacking, but rather a clear illustration of the pipe connections and airflow organization paths between the sky radiant panel 1, the air-to-water heat exchanger 2, the air circulation system 3, the water supply and return system 4, and the multi-stage evaporative cooler 5, and it also marks the connections between all key components and the controller. Figure 1 It is the overall blueprint for understanding how the flow of matter, energy, and information in the entire system works together, and all subsequent descriptions of operating modes are based on this diagram.

[0037] like Figures 1 to 6 As shown, the cold energy recovery system that couples sky radiation cooling and multi-stage evaporative cooling provided in this embodiment has the following specific structure, connection relationship and cooperative working mode:

[0038] The system's construction begins with the integrated construction of the sky radiant panel 1 and the air-to-water heat exchanger 2. For example... Figure 3 and Figure 4 As shown, the water channel 22 of the air-to-water heat exchanger 2 is designed as a continuous whole, but its upper and lower sections have different functions. The upper section of the pipe is completely embedded inside the sky radiant plate 1 through a high thermal conductivity bonding layer, forming a radiant plate-to-water heat exchange surface 21. The lower section of the pipe is regularly arranged in an independent air channel 24, and the surface of the pipe is usually provided with fins to increase the heat exchange area, forming an air-to-water heat exchange surface 23. The air channel 24 is provided with a heat exchanger air inlet 31 and a heat exchanger air outlet 32.

[0039] An air circulation system 3 is constructed around the air-to-water heat exchanger 2 and the multi-stage evaporative cooler 5. Outdoor air enters the air duct 24 through the heat exchanger inlet 31. The heat exchanger exhaust fan 33, which drives the airflow, is located in the duct. The direction of the air flowing out of the outlet 32 ​​is determined by a key controllable baffle 34. Figure 1 As shown, when the baffle plate turns to side A, the air is directed to the air supply duct leading to the room; when it turns to side B, the air is introduced into the inlet duct of the multi-stage evaporative cooler 5. The indoor air is used as secondary air for the first core 521 in the indirect evaporative cooling section core 52 through the indoor return air inlet 37, and then delivered into the building by the indoor air supply fan 35 through the indoor air supply outlet 36.

[0040] The system's central hub for cold storage and fluid distribution is the supply and return water system 4, the core of which is the tiered cold storage water tank 41. For example... Figure 1 and Figure 6As shown, the water tank is connected to the air-to-water heat exchanger 2 via two independent pipelines. The first supply and return water main 46 connects the inlet of the low-temperature water layer 414 at the bottom of the water tank to the inlet of the lower half of the water channel 22 of the air-to-water heat exchanger 2 (i.e., the air-to-water heat exchange surface 23 side). A first vacuum pump 44 and a proportional three-way valve 43 with precisely adjustable flow rate are connected in series on this pipeline. A first bypass pipeline 48 with gate valves is connected in parallel at both ends of the first vacuum pump 44. The second supply and return water main 47 connects the inlet of the high-temperature water layer 412 at the top of the water tank to the inlet of the upper half of the water channel 22 of the air-to-water heat exchanger 2 (i.e., the radiant plate-to-water heat exchange surface 21 side). A second vacuum pump 45 is connected in series on this pipeline. A second bypass pipeline 49 with gate valves is connected in parallel at both ends of the second vacuum pump 45. The outlet of the water channel 22 of the air-to-water heat exchanger 2 flows into the second supply and return water main 47 via pipelines. The water replenishment solenoid valve 42 is used to replenish the water lost through evaporation in the system. The bypass lines 48 and 49 are convenient for use during vacuum pump maintenance, initial venting of the system during startup, or when there is a specific need to reduce water resistance, thus improving the reliability and flexibility of the system.

[0041] The core of the system's advanced processing and performance breakthrough lies in the multi-stage evaporative cooler 5. Inside its casing, arranged sequentially along the airflow direction, are: an air filter 51, an indirect evaporative cooling section core 52 consisting of a first core 521 and a second core 522 connected in series, a direct evaporative cooling section packing 53, and a primary air baffle 55. The spray system includes nozzles 54 supplying water to the top of the direct section packing and the secondary air side of the indirect section core. A spray water pipe 56 connects to one outlet of a proportional three-way valve 43. The sprayed water collects in the spray water collection chamber 58 at the bottom and returns to the upper part of the chilled water tank 41 via a spray water return pipe 59. The core innovation of this module lies in its airflow design: an airflow diversion and guiding device is installed on the duct connecting the primary air outlet of the first core 521 and the primary air inlet of the second core 522. This device includes an adjustable first air valve, a diversion duct, and a second air valve and a diversion fan installed on the diversion duct. The other end of the split duct is connected to the secondary air inlet of the second core 522.

[0042] The entire system is coordinated by an intelligent control system. This system connects indoor and outdoor temperature and humidity sensors, sky radiation intensity sensors, temperature sensors for each layer of the chilled water tank, flow meters, water level gauges, etc., and communicates and controls all fans, vacuum pumps, proportional three-way valves 43, water supply solenoid valves 42, controllable wind baffles 34, and air valves and split fans in the multi-stage evaporative cooler 5 through a programmable controller.

[0043] The following will describe in detail the complete operation process of the system under various typical working conditions, including the specific actions of each component, the flow paths of air and water, and the coupling and linkage between them:

[0044] When the intelligent control system determines, based on sensor data, that the night sky is clear, outdoor conditions are suitable, and the building may have some cooling needs, it activates the system's cold storage mode. The control system first starts the second vacuum pump 45 while simultaneously shutting down the first vacuum pump 44. The second vacuum pump 45 draws relatively warm water from the upper high-temperature water layer 412 of the stratified cold storage water tank 41 and pumps it into the inlet of the water channel 22 of the air-to-water heat exchanger 2 through the second supply and return water main 47. The water first enters the upper part of the water channel 22, i.e., the radiant plate-to-water heat exchange surface 21. Because the sky radiant plate 1 radiates heat into the cold outer space at night, its temperature is lower than the ambient air. The hot water flowing through this area transfers heat to the radiant plate through the pipe wall, thus being cooled, and the water temperature can drop to far below the nighttime air temperature. This cooled water continues to flow through the lower part of the water channel 22, i.e., the air-to-water heat exchange surface 23.

[0045] Simultaneously, the control system activates the heat exchanger exhaust fan 33. Outdoor air is drawn into the air passage 24 through the heat exchanger inlet 31 and flows through the air-water heat exchange surface 23. The low-temperature pipe surface exchanges sensible heat with the air, cooling the air. The controllable baffle 34 is then adjusted to position A, directing the air into the indoor air supply duct.

[0046] The cooled air is delivered directly into the building interior through the air supply duct, driven by the indoor air supply fan 35, providing nighttime cooling. After absorbing heat from the air, the water temperature rises. This cooled water, still retaining its coldness, flows out from the outlet of water channel 22 and, through the first supply and return water main 46, is directly injected into the bottom of the stratified cold water tank 41, i.e., the lower low-temperature water layer 414, under the influence of gravity or system pressure. This process achieves "high-temperature water extraction and low-temperature water storage," efficiently converting the radiant cooling energy from the sky into sensible heat in the water for storage.

[0047] If the outdoor air is very dry at night and the building's indoor load is high, the system will activate the combined radiation-evaporation cooling / storage mode. While maintaining the aforementioned water circulation, the control system will adjust the proportional three-way valve 43 to distribute a small portion of the low-temperature chilled water flowing through the air-water heat exchanger 2 to the spray water pipe 56. Simultaneously, the controllable baffle 34 will be partially adjusted to allow some of the air pre-cooled by the air-water heat exchanger to enter the multi-stage evaporative cooler 5. Utilizing low-temperature spray water for evaporative cooling can produce even lower-temperature air for cooling.

[0048] When the building's cooling load increases during the day and the outdoor temperature rises, the system switches to the core mode of daytime combined cooling and cold energy recovery. The intelligent control system starts the first vacuum pump 44 to draw high-grade chilled water stored overnight from the low-temperature water layer 414 at the bottom of the stratified chilled water storage tank 41. After the chilled water flows out, it immediately passes through the proportional three-way valve 43. This valve dynamically adjusts its opening according to a real-time optimization algorithm (based on outdoor temperature and humidity, chilled water temperature, load demand, etc.), dividing the total chilled water volume into two paths: one path is distributed to the spray water pipe 56 of the multi-stage evaporative cooler 5 as low-temperature spray water; the other path is pumped into the inlet of the lower half of the water channel 22 (air-water heat exchange surface 23) of the air-water heat exchanger 2 through the first supply and return water main pipe 46.

[0049] Outdoor fresh air is first directed to the area where the sky radiant panel 1 is located. Although the radiant panel does not actively cool during the day, its surface temperature is usually lower than that of outdoor air exposed to direct sunlight due to its overnight cooling and material properties. When the fresh air passes over its surface or in the shaded passage, it undergoes preliminary isohumid pre-cooling, resulting in a temperature drop. Next, this air is drawn into the air passage 24 by the heat exchanger exhaust fan 33. Here, the air undergoes intense sensible heat exchange with the low-temperature chilled water flowing through the air-water heat exchange surface 23—a crucial second active pre-cooling process. This process significantly reduces the dry-bulb temperature of the air and substantially lowers its wet-bulb temperature.

[0050] The pre-cooled air enters the multi-stage evaporative cooler 5 through the controllable baffle 34, first passing through the air filter 51. This air, as primary air, enters the primary air side of the first core 521. Simultaneously, hot return air from the room, as secondary air, is introduced into the secondary air side of the first core 521. The two exchange heat through the core wall, and the primary air is humidified, its temperature dropping to T1. The indoor return air is heated and humidified before being discharged. The primary air flowing out of the first core 521 reaches the distribution point. The intelligent control system calculates the optimal recovery air volume ratio R based on an algorithm and issues a command: adjust the opening of the first air valve to reduce the main air duct flow by a corresponding proportion; simultaneously open the second air valve and start the distribution fan. Thus, air at approximately R proportion and temperature T1 is distributed and guided through the distribution duct to the secondary air side inlet of the second core 522. This "recovered cold air" is humidified and cooled by the spray water on that side before entering the second core, further reducing its wet-bulb temperature.

[0051] The remaining primary air, accounting for 1-R proportion, continues to enter the primary air side of the second core 522. Inside the second core, the primary air exchanges heat with "recovered cold air," whose inlet temperature is much lower than the indoor return air. Due to the very low wet-bulb temperature of the air on the secondary air side, the heat exchange temperature difference is extremely large, causing the primary air to be deeply and isohumidly cooled to an even lower temperature T2.

[0052] The dry air, now cooled to T2, finally enters the direct evaporative cooling section packing 53. It comes into direct contact with low-temperature spray water from the proportional three-way valve, undergoing adiabatic humidification and cooling. The air temperature decreases slightly along the iso-wet-bulb temperature line, while the moisture content increases, eventually reaching the target air supply state point, and is then delivered into the room by the indoor fan 35.

[0053] During the air pre-cooling stage, the chilled water used to cool the air absorbs heat at the air-water heat exchange surface 23, causing its temperature to rise. This water continues to flow through the upper part of the water channel 22, where it is cooled by the radiant plate-water heat exchange surface 21 and then flows back to the upper high-temperature water layer 412 of the stratified cold water storage tank 41 via the second supply and return water main pipe 47. Simultaneously, the chilled water used for spraying in the multi-stage evaporative cooler 5 absorbs heat and evaporates a portion; the remaining unevaporated water is collected by the spray water collection chamber 58 and flows back to the upper high-temperature water layer 412 of the tank via the spray water return pipe 59. This process completes the cooling cycle of "low-temperature water extraction and high-temperature water return."

[0054] When the outdoor dry-bulb temperature is low, but the humidity may be unsuitable or only a small amount of cooling is required, the system can operate in a simplified mode. For example, in the "fresh air natural cooling mode," the control system can shut down the relevant water pumps and fans of the multi-stage evaporative cooler 5, and even shut down the first vacuum pump 44. Only the heat exchanger exhaust fan 33 is operated to introduce cool outdoor air, or to allow it to flow through the air-to-water heat exchanger 2 for simple sensible heat cooling or filtration, before directly delivering it into the room through the controllable baffle 34, resulting in extremely low energy consumption.

[0055] When radiative cooling from the sky fails, and only the stored cold water in the tank and evaporative cooling through cold energy recovery remain, the intelligent control system will enter an optimized operating strategy. The proportional three-way valve 43 will prioritize the supply of cold water to the air-to-water heat exchanger 2 to maximize the dehumidification and pre-cooling of the fresh air, reducing its moisture content—a prerequisite for effective cooling in hot and humid weather. Simultaneously, the control system will meticulously calculate the cold energy recovery ratio R, achieving the optimal balance between ensuring deep cooling of the second core and the additional energy consumption of the fan, maximizing cooling duration and temperature reduction with limited stored cold energy.

[0056] In summary, this invention, through a highly integrated structural design, a unique dual-path water circulation system, a convenient vacuum pump bypass pipeline, and an innovative process for reusing internal cooling capacity within the evaporative cooling core, deeply couples sky radiation cooling, water storage cooling, and multi-stage evaporative cooling technologies to construct an intelligent, efficient, and highly adaptable passive cooling system. It details the entire process from component construction and piping connections to how air and water flow, exchange heat, and recycle under various meteorological conditions, providing a practical technical solution for achieving near-zero energy building cooling. Those skilled in the art can adaptively adjust and optimize the area and arrangement of the sky radiation panels, the volume of the chilled water tank, the form and number of stages of the evaporative cooling core, and the specific parameters of the control algorithm based on the core concept of this invention; all such modifications fall within the protection scope of this application.

[0057] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A cold storage and cooling system coupling sky radiation and multi-stage evaporative refrigeration, characterized in that, include: Sky radiation panel (1); The air-water heat exchanger (2) includes an air channel (24) and a water channel (22). The water channel (22) is divided into an upper part and a lower part. The upper part is embedded in the sky radiation plate (1) to form a radiation plate-water heat exchange surface (21), and the lower part is exposed in the air channel (24) to form an air-water heat exchange surface (23). The air circulation system (3) includes a heat exchanger inlet (31) and a heat exchanger outlet (32) connected to the air passage (24), a fan (33, 35, 38) for driving air flow, and a controllable baffle (34) disposed in the downstream air duct of the heat exchanger outlet (32) for switching airflow paths. The water supply and return system (4) includes a layered cold water tank (41), a water replenishment solenoid valve (42), a proportional three-way valve (43), a first vacuum pump (44), a second vacuum pump (45), a first water supply and return main pipe (46), and a second water supply and return main pipe (47). The layered cold water tank (41) has an upper high-temperature water layer (412), a middle heat exchange layer (413), and a lower low-temperature water layer (414) formed from top to bottom. The first water supply and return main pipe (46) connects to the lower water supply and return main pipe. The low-temperature water layer (414) is connected to the lower half of the inlet of the water channel (22) of the air-water heat exchanger (2), and the first vacuum pump (44) and the proportional three-way valve (43) are installed on it; the second supply and return water main (47) connects the upper high-temperature water layer (412) to the upper half of the inlet of the water channel (22) of the air-water heat exchanger (2), and the second vacuum pump (45) is installed on it; the outlet of the water channel (22) is connected to the second supply and return water main (47); The multi-stage evaporative cooler (5) includes an air filter (51), an indirect evaporative cooling section (52), and a direct evaporative cooling section packing (53) arranged sequentially along the airflow direction, as well as a spray system; the indirect evaporative cooling section includes a first core (521) and a second core (522) arranged in series; the spray system includes a spray water pipe (56), which is connected to one outlet of the proportional three-way valve (43).

2. The cooling system according to claim 1, characterized in that, The surface of the sky radiation panel (1) is coated with a selective coating with high infrared emissivity and low solar absorptivity, and is installed at an optimized tilt angle relative to the horizontal plane.

3. The cooling system according to claim 1, characterized in that, The upper part of the water channel (22) of the air-water heat exchanger (2) is tightly bonded to the sky radiation plate (1) by a highly thermally conductive material.

4. The passive cooling system according to claim 1, characterized in that, The controllable baffle (34) is located on the air duct downstream of the heat exchanger outlet (32) and has a first position and a second position. When switched to the first position, the airflow is directly directed to the indoor air supply duct. When switched to the second position, the airflow is directed to the air inlet of the multi-stage evaporative cooler (5).

5. The cooling system according to claim 1, characterized in that, The water supply and return system (4) further includes a first bypass pipe (48) and a second bypass pipe (49); the first bypass pipe (48) is connected in parallel with the first vacuum pump (44), the second bypass pipe (49) is connected in parallel with the second vacuum pump (45), and gate valves are provided on both the first bypass pipe (48) and the second bypass pipe (49).

6. The water supply and return system according to claim 5, characterized in that, The first bypass line (48) and the second bypass line (49) are configured to allow water to flow around the corresponding vacuum pump by opening the corresponding gate valve during vacuum pump maintenance, water hammer prevention, or specific low-resistance operation modes.

7. The cooling system according to claim 1, characterized in that, The multi-stage evaporative cooler (5) also includes a spray water collection chamber (58) and a spray water return pipe (59) for guiding unevaporated spray water back to the upper high-temperature water layer (412) of the layered cold water storage tank (41).

8. The multi-stage evaporative cooler according to claim 7, characterized in that, The indirect evaporative cooling section is configured such that outdoor air flows as primary air through the primary air side of the first core (521) and the second core (522) in sequence; indoor return air flows as secondary air through the secondary air side of the first core (521); and the core is provided with an airflow diversion and guiding device, so that a portion of the air that has flowed through the primary air side of the first core (521) and been cooled is guided to the secondary air side of the second core (522).

9. The indirect evaporation cooling section according to claim 8, characterized in that, The airflow diversion and guidance device includes a first air valve installed on the air duct between the primary air outlet of the first core (521) and the primary air inlet of the second core (522), and a diversion air duct connecting the primary air outlet of the first core (521) and the secondary air inlet of the second core (522). The diversion air duct is equipped with a second air valve and a diversion fan.

10. The cooling system according to claim 1, characterized in that, The system has two main operating modes: the first is the nighttime cold storage and cooling mode. In this mode, the second vacuum pump (45) operates, takes water from the upper high-temperature water layer (412), and after being cooled by the sky radiation in the upper part of the water channel (22), it flows through the lower part to cool the air in the air channel (24). The cooled air is sent into the room through the controllable wind baffle (34), and the low-temperature cold water flowing out from the water channel (22) is introduced into the lower low-temperature water layer (414) for storage. When the sky's radiative cooling capacity is insufficient, the proportional three-way valve (43) distributes a portion of the low-temperature cold water from the first vacuum pump (44) to the spray water pipe (56), activating the multi-stage evaporative cooler (5) to provide auxiliary cooling to the air. The second mode is a daytime combined cooling mode. In this mode, the first vacuum pump (44) draws water from the lower low-temperature water layer (414), which is then diverted by the proportional three-way valve (43), and a portion of the cold water is sent to the multi-stage evaporative cooler through the spray water pipe (56). (5) As spray water, another part of the cold water is sent to the lower half of the water channel (22) through the first supply and return water main (46) to pre-cool the air. Then the water flows through the upper half and returns to the upper high temperature water layer (412) through the second supply and return water main (47). After the outdoor air is pre-cooled by the back side of the sky radiation plate (1), it enters the air channel (24) of the air-water heat exchanger (2) and is pre-cooled by cold water. Then it enters the multi-stage evaporative cooler (5) for deep cooling and is sent into the room.

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