Closed solar water heating system

Abstract

The invention discloses a closed solar water heating system which comprises a heat collecting plate, a displacement heat exchanger and a controller. The heat collecting plate is connected with a heat exchanger heating medium inlet through a first pipeline to form a main path, a heat exchanger heating medium outlet flows back to the heat collecting plate through a second pipeline, and a closed heating medium circulating system is formed. A liquid level sensor and an air valve are arranged at the high position of the system and used for monitoring the liquid level and discharging air or excessive steam. A heat medium circulating pump, an expansion tank and a filling device are integrated in the backflow path. The controller is connected with the components and is configured as follows: 1) the circulating pump is driven to maintain heat medium circulation; and (2) when the liquid level sensor detects that the liquid level is lower than a preset threshold value, the filling device is automatically started to supplement liquid. According to the system, liquid shortage automatic detection and supply are achieved, excessive heat energy can be consumed in summer, solar energy can still be efficiently utilized under the low-sunlight condition in winter, environment friendliness and stability are achieved, and the manual maintenance requirement is reduced.

Description

Technical Field

[0001] The present invention relates to a closed solar water heating system. Background Art

[0002] The core of a solar water heating system is to absorb the heat of solar radiation through a solar collector, transfer the heat to a heat medium (a heat transfer medium, usually water or antifreeze), and then transfer the heat to a storage tank through the heat medium to heat domestic water. Under normal circumstances, when the water temperature in the storage tank reaches the set temperature, the system will stop heating or reduce the heat medium circulation to avoid overheating.

[0003] In summer during the day, people usually use less hot water, and the water in the storage tank may be in a high-temperature state for a long time (close to or reaching the upper limit of the set temperature). The storage tank no longer needs to continue absorbing heat, but the solar collector still continuously absorbs solar radiation, resulting in the heat medium being unable to transfer the heat through normal circulation. When the storage tank no longer needs heating, the heat medium is still continuously heated by the collector but cannot release the heat through hot water consumption or circulation, causing the temperature of the heat medium to continue to rise.

[0004] When the temperature of the heat medium is too high, although theoretically only evaporation causes the pressure in the pipeline to rise without heat medium loss (many people mistakenly think that a closed system has no loss at all), there are still multiple challenges in actual operation. The accumulation of high-temperature steam will cause problems such as pump cavitation and air blockage. Therefore, the system is usually equipped with a high-position exhaust valve to automatically release the residual gas at the top of the pipeline through physical gravity. At the same time, the thermal expansion and contraction effect of the heat medium further exacerbates the system pressure fluctuation: when the temperature drops at night, the heat medium cools and contracts, the pressure in the pipeline decreases, the liquid level drops, and the volume of the heat medium decreases. If the heat medium is not replenished in time, residual air may form an air block in the pipeline (the gas blocks the pipeline and hinders circulation), ultimately resulting in a decrease or stagnation of the system circulation efficiency.

[0005] When the heat medium evaporates due to high temperature, the reduction of the internal liquid volume in the system may cause multiple problems: the circulation pump cannot work properly due to lack of liquid, resulting in the inability to transfer heat and system stagnation; the gas generated by evaporation increases the system pressure, and if it exceeds the safety threshold, the safety valve will be triggered to relieve pressure, which may seriously damage components such as pipelines or valves in severe cases; long-term high temperature will also accelerate the aging or deformation of pipelines, valves, and seals, and even damage the coating and internal structure of the collector; if the heat medium is severely lost, the system may completely stop running, and at this time, the heat medium needs to be replenished manually or by equipment (i.e., "water replenishment"), usually once every 10 - 15 days.

[0006] However, existing liquid filling technologies have significant limitations: The constant-pressure water filling device relies on components such as an independent water tank, a water filling pump, and a pressure tank. It not only occupies a large amount of space and has a high initial investment cost but also is only applicable to scenarios that require a large amount of liquid filling, such as heating systems. Since a large amount of heat medium will be supplemented at once after the pump starts, it causes a sudden increase in the system pressure. However, the actual liquid filling demand of a closed solar water heating system is usually small. This characteristic makes it difficult to apply the constant-pressure water filling device to a closed solar water heating system. Although the expansion tank scheme can compensate for part of the pressure change, because the solar collector needs to be installed at a high position on the building to avoid shading, and the expansion tank needs to be placed at a higher position to maintain gravity water supply, it increases the installation and maintenance risks. In addition, when filling the expansion tank with water, high-altitude operations are required, which poses safety hazards and has a high operation complexity.

[0007] The complexity of manual liquid filling operations further exacerbates the maintenance difficulty: Liquid filling requires fine operations such as exhausting gas simultaneously (such as discharging the residual gas in the pipeline), which has high requirements for the professionalism of operators. If the owner maintains it by themselves, due to the lack of professional training, it is easy to cause liquid leakage due to operation errors, leading to on-site chaos and subsequent maintenance difficulties.

[0008] In winter, the solar altitude angle is low, and the day length is short, so the solar radiation energy received by the solar collector is significantly reduced. Even if the surface of the collector is clean and unobstructed, the heat absorbed per unit time is much lower than that in summer, resulting in the water temperature in the water tank being difficult to reach the user-set operating temperature (such as above 50°C). Some solar systems rely on a circulation pump for forced circulation. Even if the sunlight is insufficient or the water temperature does not reach the standard, the pump may still run continuously in an attempt to transfer heat. If the collector cannot provide enough heat, the continuous operation of the circulation pump only circulates in cold water and cannot effectively increase the water temperature, resulting in waste of electric energy. When the water temperature cannot reach the standard for a long time, the system may automatically start an electric heating element (such as an electric heating rod) to supplement heat, and at this time, the electric energy consumption further increases. While the circulation pump maintains circulation, the electric heating consumes additional electricity, forming an "electric energy waste superposition". If the circulation pump is inefficient due to pipeline blockage or pump failure, the heat absorbed by the solar energy cannot be effectively transferred to the water tank, and the solar energy is not fully utilized. In winter, snow, dust, or frost covering the surface of the collector further hinders the absorption of solar energy and exacerbates the waste. Summary of the Invention

[0009] At least one embodiment of the present invention provides a closed solar water heating system that can automatically detect and fill the liquid when the heat medium is lacking.

[0010] At least one embodiment of the present invention provides a closed solar water heating system that can consume or utilize the excess heat energy in a green and environmentally friendly manner when there is an excess of heat energy in summer.

[0011] At least one embodiment of the present invention provides a closed solar water heating system that can still effectively utilize solar energy in winter when the sunlight is insufficient.

[0012] According to one aspect of the embodiment, a closed solar water heating system includes a heat collecting plate, a volumetric heat exchanger, and a controller. The heat medium outlet of the heat collecting plate is connected to the heat medium inlet of the volumetric heat exchanger through a first pipeline to form a main path of the heat medium circulation. The heat medium outlet of the volumetric heat exchanger is connected to the heat medium inlet of the heat collecting plate through a second pipeline to form a return path of the heat medium circulation. The main path and the return path constitute a heat medium circulation system. A liquid level sensor for monitoring the heat medium liquid level and a gas valve for exhausting air or steam exceeding the safety threshold are provided at the high position of the heat medium circulation system. A heat medium circulation pump, an expansion tank, and a heat medium filling device are provided on the return path. The controller is respectively connected to the heat medium circulation pump, the liquid level sensor, and the heat medium filling device, and is configured to: control the operation of the heat medium circulation pump to drive the heat medium to circulate in the heat medium circulation system; when the liquid level sensor monitors that the heat medium liquid level in the heat medium circulation system is lower than a preset threshold, control the heat medium filling device to start and inject heat medium into the heat medium circulation system.

[0013] In some examples, the heat medium filling device injects heat medium into the heat medium circulation system at a speed of 80 - 120 ml / min.

[0014] In some examples, the liquid level sensor has an exhaust function.

[0015] In some examples, a temperature sensor 1T1 for detecting the heat medium temperature inside the heat collecting plate is provided on the heat collecting plate, and a temperature sensor 1T2 for detecting the stored water temperature inside the volumetric heat exchanger is provided on the volumetric heat exchanger.

[0016] In some examples, when the temperature of the heat medium detected by the temperature sensor 1T1 reaches or exceeds a preset start threshold (such as 45 °C), the controller is configured to control the heat medium circulation pump to start to drive the operation of the heat medium circulation system; when the temperature of the heat medium detected by the temperature sensor 1T1 is lower than the preset start threshold (such as 45 °C), or the temperature difference between the heat medium and the stored water is less than a preset value (such as 7 °C), the controller is configured to control the heat medium circulation pump to close to stop the operation of the heat medium circulation system.

[0017] In some examples, when the stored water temperature detected by the temperature sensor 1T2 reaches a preset upper limit (such as 60 °C), and the temperature of the heat medium detected by the temperature sensor 1T1 is lower than the safety threshold (such as 80 °C), the controller is configured to control the heat medium circulation pump to close to stop the operation of the heat medium circulation system.

[0018] In some examples, when the temperature sensor 1T2 detects that the water storage temperature is equal to or lower than a preset lower limit (such as 45 °C), the temperature sensor 1T1 detects that the heat medium temperature reaches or exceeds a preset start threshold (such as 45 °C), and the temperature difference between the heat medium and the water storage reaches a preset value (such as 7 °C), the controller is configured to control the restart of the heat medium circulation pump to drive the operation of the heat medium circulation system.

[0019] In some examples, a photovoltaic flexible panel is provided above the heat collecting plate, and the controller is configured to be able to: control the photovoltaic flexible panel to unfold to cover the heat collecting plate; wind up the photovoltaic flexible panel to expose the heat collecting plate; when the temperature sensor 1T1 detects that the heat medium temperature reaches or exceeds a safety threshold (such as 80 °C), and the temperature sensor 1T2 detects that the water storage temperature reaches a preset upper limit (such as 60 °C), the controller is configured to: control the photovoltaic flexible panel to unfold to cover the heat collecting plate, isolate direct sunlight to reduce the heat medium temperature; control the photovoltaic flexible panel to perform photovoltaic power generation; and / or when the temperature sensor 1T1 does not detect that the heat medium temperature reaches the preset start threshold for consecutive days, the controller is configured to: control the photovoltaic flexible panel to unfold for photovoltaic power generation during the day.

[0020] In some examples, an overheat protection device for cooling the heat medium is connected to the main path, and the controller is configured to: when the heat medium temperature detected by the temperature sensor 1T1 reaches or exceeds a safety threshold (for example, 80 °C), and the temperature sensor 1T2 detects that the water storage temperature reaches a preset upper limit (for example, 60 °C), control the start of the heat medium circulation pump and the overheat protection device to drive the heat medium to flow through the overheat protection device for heat dissipation, so as to reduce the heat medium temperature.

[0021] In some examples, the overheat protection device includes: a serpentine pipe connected to the main path for the heat medium to flow through; a fan disposed adjacent to the serpentine pipe to reduce the heat medium temperature by forced convection heat dissipation. Description of the Drawings

[0022] Figure 1 is a schematic diagram of a solar water heating system according to an embodiment of the present invention.

[0023] Figure 2 is a schematic diagram of an integrated solar heat collection and photovoltaic power generation panel according to an embodiment of the present invention.

[0024] Figure 3 is a schematic diagram of an overheat protection device according to an embodiment of the present invention.

[0025] Figure 4 is a schematic diagram of a heat medium filling device according to an embodiment of the present invention. Detailed Description

[0026] As shown Figure 1 in the figure, the solar water heating system includes a solar heat collection and photovoltaic power generation integrated panel 3 (abbreviation: integrated panel), an overheat protection device 4, an expansion tank 6, a heat medium filling device 7, a volume type heat exchanger 8, a heat medium circulation pump 9 and a controller. The heat medium outlet of the integrated panel 3 is sequentially connected to the overheat protection device 4 and the heat medium inlet of the volume type heat exchanger 8 through a first pipeline to form the main path of the heat medium circulation; the heat medium outlet of the volume type heat exchanger 8 returns to the heat medium inlet of the integrated panel 3 through a second pipeline, and an expansion tank 6, a heat medium filling device 7 and a heat medium circulation pump 9 are arranged on this return path to regulate the system pressure, supplement the heat medium and drive the circulation. The main path and the return path constitute the heat medium circulation path. The controller controls each part of the system to realize the thermal energy management and safety protection of the system, and ensure the coordinated operation of the heat medium in the heat collection, heat exchange, circulation and overheat protection links.

[0027] As shown Figure 2 in the figure, the solar heat collection and photovoltaic power generation integrated panel 3 includes a bracket 33, a solar heat collection panel 31 arranged thereon and a photovoltaic flexible panel 32. The photovoltaic flexible panel 32 is stored above the solar heat collection panel 31 through a reel, and the reel is driven by a motor. Under the control of the controller, the motor can drive the reel to rotate, so that the photovoltaic flexible panel 32 unfolds to cover the solar heat collection panel 31, or wind up the photovoltaic flexible panel 32 to directly expose the solar heat collection panel 31 to sunlight.

[0028] In addition, a temperature sensor 1T1 for detecting the heat medium temperature inside the heat collection panel 31 is arranged on the heat collection panel 31. A temperature sensor 1T2 for detecting the water storage temperature inside the volume type heat exchanger 8 is arranged on the volume type heat exchanger 8. An air valve 2 and a liquid level sensor 21 are arranged at the high position of the circulation system (for example, near the heat medium outlet of the integrated panel 3). The air valve 2 is used to discharge the air or steam exceeding the safety threshold in the circulation system; the liquid level sensor 21 is used to monitor the heat medium liquid level in the circulation system. When the heat medium is insufficient, the liquid level sensor 21 at the high position will first sense the liquid level drop and trigger corresponding control actions.

[0029] As shown Figure 3 in the figure, the overheat protection device 4 is used to cool the overheated heat medium. As shown Figure 3As shown, the device is connected to the main path through an electric three-way valve 5. The core component of the overheat protection device 4 is a heat dissipation box 43, inside which there are serpentine pipes and a heat dissipation fan. When it is detected that the temperature of the heat medium exceeds the set threshold, the AB ports of the electric three-way valve 5 are opened, allowing the high-temperature heat medium to flow into the serpentine pipes of the heat dissipation box 43. At the same time, the heat dissipation fan starts automatically, accelerating the heat dissipation of the heat medium through forced convection. The cooled heat medium then returns to the main circulation pipe, restoring the normal operation of the system. In one implementation, a photovoltaic panel 41 and its supporting control box 42 are also integrated on the top of the heat dissipation box 43, which are used to provide power support for devices such as the heat dissipation fan and optimize the heat dissipation efficiency through intelligent regulation.

[0030] As Figure 4 shown, the heat medium filling device 7 is an existing standard device that uses pneumatic filling technology. Its main structure is a stainless steel shell, equipped with a heat medium inlet 71 for supplementing glycerol solution. Inside, there is a cylinder 72 to compress gas to provide filling power, and a pressure valve 73 is used to monitor and maintain the pressure inside the device in real time. To ensure safe operation, the device is equipped with a safety relief valve 74 that automatically releases excess gas when the pressure exceeds the set threshold. The air pump 75 is responsible for driving gas compression to maintain the stable pressure required for filling. In addition, a steel column check valve 77 is installed in the cylinder path to prevent the heat medium from flowing back into the cylinder when it is not in the filling state. The device is connected to the second pipe of the heat medium circulation system through an electric two-way valve 76, and the electric two-way valve opens or closes the filling channel according to the controller's instructions to achieve automatic control.

[0031] Implementation schemes and working processes:

[0032] (1) Domestic hot water heating mode

[0033] At noon in summer, the temperature of the heat collection plate 31 gradually rises due to sunlight. The temperature data of the heat medium inside it is fed back to the controller in real time through the temperature sensor 1T1. When the temperature detected by 1T1 reaches or exceeds the preset start threshold (such as 45 °C), the controller will send a start command to the heat medium circulation pump 9 to start the heat medium circulation system. At this time, the heat medium in the heat collection plate 31 is driven by the heat medium circulation pump 9 and flows into the volumetric heat exchanger 8 to exchange heat with the stored water.

[0034] Due to the long sunshine time in summer and the small consumption of hot water, the temperature of the stored water in the volumetric heat exchanger 8 will continue to rise. When the temperature sensor 1T2 detects that the temperature of the stored water reaches the preset upper limit (such as 60 °C), and the temperature sensor 1T1 detects that the temperature of the heat medium in the heat collection plate 31 is lower than the safety threshold (such as 80 °C), the controller will automatically turn off the heat medium circulation pump 9 to stop the heat circulation to avoid overheating.

[0035] If the user uses hot water at this time, causing the stored water in the volumetric heat exchanger 8 to be consumed, the temperature of the stored water will drop after cold water is replenished. When the temperature of the stored water fed back by the temperature sensor 1T2 ≤ the preset lower limit (such as 45°C), and the following conditions are met simultaneously:

[0036] The temperature difference between the heat medium and the stored water in the heat collecting plate 31 reaches or exceeds the preset value (such as ≥7°C);

[0037] The temperature of the heat medium in the heat collecting plate 31 is still greater than or equal to the preset start threshold (such as 45°C);

[0038] The controller will restart the heat medium circulation pump 9, resume the heat medium circulation, and continue to heat the stored water in the volumetric heat exchanger 8 until the temperature threshold or stop condition is reached.

[0039] (2) Overheat power generation mode

[0040] When the sunlight remains sufficient and the hot water demand is extremely low, the temperature of the stored water in the volumetric heat exchanger 8 may continue to rise. At this time, the temperature sensor 1T2 feeds the real-time data back to the controller. If the following conditions are met simultaneously:

[0041] The heat medium temperature sensor 1T1 of the heat collecting plate detects that the heat medium temperature reaches or exceeds the safety threshold (such as 80°C);

[0042] The stored water temperature sensor 1T2 in the volumetric heat exchanger 8 detects that the temperature reaches the preset upper limit (such as 60°C);

[0043] The controller will perform the following operations: After receiving the instruction, the photovoltaic flexible board 32 unfolds and switches to the photovoltaic power generation mode with the heat collecting plate 31 as the support. The unfolded photovoltaic flexible board can block the surface of the heat collecting plate 31 and isolate the direct sunlight, thereby preventing the temperature from rising further. The photovoltaic power generation is used to charge and store energy for the UPS power supply of the particularly important loads in the first-level loads such as the fire control room and the information center.

[0044] (3) Overheat protection

[0045] Usually in the afternoon (such as around 14:00), due to the increase in ambient temperature, the volume of the heat medium (such as glycerol) expands, and the steam accumulates in the heat medium circulation system, causing the pressure in the expansion tank 6 to gradually rise. At this time, if the hot water usage significantly decreases (such as the user demand decreases or in the off-peak period), the heat medium cannot be cooled by natural hot water consumption, and the temperature may continue to rise and exceed the safety threshold (such as 80°C). At this time, the air valve 2 automatically releases the excess steam in the heat medium circulation system to reduce the pressure; at the same time, the electric three-way valve 5 receives the instruction, closes the AC channel and opens the AB channel, guiding the heat medium to flow to the heat dissipation box 43 for forced heat dissipation (such as a fan or air cooling). This operation quickly reduces the temperature of the heat medium through the heat dissipation box, ensuring the safe operation of the equipment, and at the same time avoiding the risk of scalding that may exist when using hot water subsequently due to high-temperature accumulation.

[0046] The pressure gauge on the expansion tank 6 monitors the pressure change in the heat medium circulation system in real time. If the liquid level drops due to the volume contraction (temperature decrease) or evaporation of the heat medium, the non-pressure gas remaining in the high position of the pipeline forms an air block, and the pressure of the heat medium circulation system will drop significantly.

[0047] (4) Nighttime energy saving

[0048] When the hot water demand increases at night, the high-temperature hot water in the volumetric heat exchanger 8 is replaced by cold water. If at the same time the temperature sensor 1T1 detects that the temperature of the heat medium in the heat collection plate 31 is lower than the preset start threshold (such as 45 °C) or the temperature difference between the heat medium and the storage water is less than the preset value (such as 7 °C), the system determines that the heat medium circulation loses the meaning of heating (due to no sunlight and too low temperature). At this time, the controller will perform the following steps: Shut down the heat medium circulation system: The electric three-way valve 5 receives the instruction, closes the connection of the AB pipe and opens the connection of the AC pipe, cutting off the flow of the heat medium to the heat dissipation box 43; The photovoltaic flexible plate 32 is retracted, stopping the photovoltaic power generation function; The heat medium circulation pump 9 is turned off, and the heat medium circulation system enters a completely static state.

[0049] (5) Liquid shortage treatment

[0050] When the liquid level sensor 21 detects that the heat medium in the circulation system is insufficient, the controller starts the following operations: Turn on the air pump 75 and the electric two-way valve 76 of the heat medium filling device 7, and press the heat medium (such as glycerol solution) stored in the device 7 into the heat medium circulation system in a slow, small-flow and stable manner. While replenishing the liquid, the gas in the circulation system will be squeezed out of the air valve 2 to ensure that the heat medium fully fills the pipeline; When the liquid level sensor 21 detects that the liquid level of the heat medium in the circulation system has returned to the preset threshold, the controller turns off the air pump 75 and the electric two-way valve 76 to complete the liquid replenishment. The heat medium filling device injects the heat medium into the heat medium circulation system at a speed of 80 - 120 ml / min, which can completely discharge the gas in the circulation system. Usually, it is necessary to replenish the liquid once every 10 - 15 days, otherwise the total loss of the heat medium may cause the system to fail to operate.

[0051] When the liquid level sensor 21 detects that the heat medium level in the heat medium circulation system is lower than the preset threshold, the controller starts the following operations: turn on the air pump 75 and the electric two-way valve 76 of the heat medium filling device 7, and press the heat medium (such as glycerol solution) stored in the heat medium filling device 7 into the heat medium circulation system in a slow, small flow rate (such as 80 - 120 ml / min) and stable manner; during the liquid supplement process, the gas in the heat medium circulation system is discharged through the gas valve 2 to ensure that the heat medium fully fills the pipeline; when the liquid level sensor 21 detects that the heat medium level in the heat medium circulation system has recovered to the preset threshold, the controller turns off the air pump 75 and the electric two-way valve 76 to complete the liquid supplement operation. By designing the liquid supplement speed of the heat medium filling device 7 to be 80 - 120 ml / min and adopting the method of daily real-time small-capacity supplement, the present invention can ensure the normal operation of the system.

[0052] After the liquid supplement is completed, if the heat medium temperature 1T1 in the heat collection plate rises back to the preset start threshold (such as 45 °C) and sunlight returns, the system will re-evaluate the current state according to the aforementioned (1), (2), and (3) and select to enter the corresponding mode (such as starting the heat medium circulation); if there is continuous lack of sunlight or the temperature is too low, the system maintains a stationary state and waits for the next demand trigger.

[0053] (6) Power generation in winter

[0054] In winter, the daytime sunlight duration is often less than one hour, and the solar heat medium temperature cannot reach 45 °C for several consecutive days. At this time, if the circulation pump is still started according to the temperature difference between the water stored in the volumetric heat exchanger 8 and the heat medium in the heat collection plate 31, it will keep circulating and doing useless work, wasting electric energy resources. Under the control of the controller, the photovoltaic flexible plate 32 is unfolded. Even if the sunlight duration on the same day is only 10 minutes, it can generate electric energy to charge and store energy for the UPS power supply (information computer room, fire control room, emergency lighting, etc.) in the building, and stop the operation of the hot water system to achieve the purpose of energy conservation.

[0055] In the scenario of insufficient sunlight in winter (such as when the daytime effective sunlight duration is lower than the preset threshold, such as 1 hour), the solar heat medium temperature may not reach the preset start threshold (such as 45 °C) for several consecutive days. At this time, if still relying on the traditional temperature difference control logic (that is, starting the circulation pump according to the temperature difference between the water temperature stored in the volumetric heat exchanger 8 and the heat medium in the heat collection plate 31), it will cause the long-term ineffective operation of the heat medium circulation system and result in waste of electric energy. To solve this problem, the controller will monitor the following conditions in real time:

[0056] Dual determination of temperature and sunlight duration: When the temperature sensor 1T1 detects that the heat medium has not reached the preset start threshold for consecutive X days (such as 3 days), and the effective sunlight duration on the same day is lower than the preset threshold, the system automatically switches to the "winter power generation priority mode".

[0057] At this time, the controller performs the following operations: Unfolding the flexible photovoltaic panel 32: The flexible photovoltaic panel is unfolded with the heat collection plate 31 as the support structure. Even if the sunshine duration on the same day is short (such as 10 minutes), the light energy can still be converted into electrical energy through photovoltaic power generation. The generated electrical energy is preferentially used to charge and store energy in the UPS power supplies of first-level loads such as information machine rooms, fire control rooms, and emergency lighting, ensuring the power supply for key equipment. Shut down the heat medium circulation pump 9 and the electric three-way valve 5, cut off the heat medium circulation path, and stop the operation of the hot water system to avoid ineffective energy consumption.

[0058] When the sunshine condition recovers (such as the continuous sunshine duration exceeds the preset threshold for Y days and the heat medium temperature rises back to the start threshold), the system will re-evaluate the current state according to the aforementioned (1), (2), (3), (4), (5) and select to enter the corresponding mode (such as starting the heat medium circulation). Through this dynamic mode switching strategy, it not only avoids the energy waste of inefficient circulation in winter but also makes full use of limited sunshine to store energy for key facilities, improving the overall energy efficiency of the system.

[0059] (7) Extended function

[0060] When it is detected that there is excess heat energy (such as the heat medium temperature T1 continuously higher than the water storage temperature T2 and the temperature difference exceeds the set threshold), the excess heat energy can be connected to other heat-consuming devices through the interface to achieve efficient energy utilization. For example: providing steam or hot water for the high-temperature disinfection equipment in the disinfection supply room; preheating the pure water circulation of the medical purification system; supplementing the heat energy requirements of the information machine room, steam generator or boiler; or providing heat energy for the humidification system of the precision air conditioner to reduce the electric heating energy consumption and achieve energy-saving operation of steam humidification. The controller dynamically adjusts the heat energy distribution ratio to ensure the stable operation of the system under heat load fluctuations.

[0061] In terms of fault warning, the system realizes automatic detection and prompt through multi-sensor linkage and algorithm analysis: If the heat medium temperature T1 ≥ 60°C and the water storage temperature T2 does not increase synchronously (or even decreases), it indicates that the heat medium circulation has stagnated. At this time, there is no current in the heat medium circulation pump 9, indicating that it has not started. The system will automatically trigger an alarm and prompt to check the power supply and control circuit; If the current of the heat medium circulation pump 9 increases abnormally but the temperature of T2 rises slowly, it is judged that the Y-type filter ( Figure 1 connected to the heat medium circulation pump 9 in the middle) is blocked. The system will prompt to clean the filter and display the blockage position and maintenance suggestions; If T1 rises abnormally and the pressure of the expansion tank 6 drops suddenly, it is determined as pipeline air block. The system will automatically stop the operation of the circulation pump 9. After the pressure stabilizes, start the liquid filling and exhaust procedure: Press the heat medium (such as glycerol solution) into the circulation system through the air pump and electric two-way valve of the heat medium perfusion device 7, and then use the high-position air valve 2 to squeeze out the air until the pressure returns to the safe range.

[0062] The system can further integrate sensor data such as pressure and flow rate to realize functions such as wear warning of pump sets and valve seal detection, and learn from historical data to predict the maintenance cycle and generate preventive maintenance plans. When a fault occurs, the system provides step-by-step solutions to reduce the manual troubleshooting time. Through the above design, the stable supply of green energy is ensured while the system life is extended.

[0063] The present invention realizes the collaborative operation of solar hot water and photovoltaic power generation, and achieves efficient utilization of resources through functional complementarity. During the heating process, the photovoltaic power generation system adjusts the temperature of the solar collector panel through shading or heat dissipation functions to prevent the heating system from suffering performance degradation or failure due to overheating; at the same time, the flexible photovoltaic panel and the collector panel share the installation space (such as the roof or wall surface), realizing the efficient utilization of land resources in high-density urban areas and reducing the system deployment cost.

[0064] The system adopts an intelligent control strategy, integrating temperature, pressure and liquid level sensors with an intelligent controller to monitor the operating status in real time and automatically perform fault diagnosis and repair (such as triggering heat dissipation or liquid replenishment for abnormal temperature), significantly reducing the need for manual intervention. In addition, by optimizing the distribution of solar thermal energy and electrical energy, the energy utilization rate is improved and the loss of abandoned light and heat is reduced.

[0065] The heat medium self-balancing liquid replenishment device of the present invention realizes automatic liquid replenishment and liquid level adaptive adjustment through the linkage of a liquid level sensor and a controller. Compared with traditional manual liquid replenishment technology, this device can accurately control the liquid replenishment flow rate (for example, 80 - 120 ml / min), forcibly discharge the air in the circulation system while stably injecting the heat medium, and ensure that the pipeline is completely filled. The system automatically replenishes the liquid every 10 - 15 days, significantly reducing the manual maintenance frequency and avoiding system failure caused by heat medium loss.

Claims

1. A closed solar water heating system, characterized in that, It includes a heat collecting plate, a volumetric heat exchanger and a controller. The heat medium outlet of the heat collecting plate is connected to the heat medium inlet of the volumetric heat exchanger through a first pipeline to form the main path of the heat medium circulation. The heat medium outlet of the volumetric heat exchanger is connected to the heat medium inlet of the heat collecting plate through a second pipeline to form the return path of the heat medium circulation. The main path and the return path constitute the heat medium circulation system. A liquid level sensor for monitoring the heat medium liquid level and a gas valve for exhausting air or steam exceeding the safety threshold are arranged at the high position of the heat medium circulation system. A heat medium circulation pump, an expansion tank and a heat medium filling device are arranged on the return path. The controller is respectively connected to the heat medium circulation pump, the liquid level sensor and the heat medium filling device, and is configured to: control the operation of the heat medium circulation pump to drive the heat medium to circulate in the heat medium circulation system; When the liquid level sensor monitors that the heat medium liquid level in the heat medium circulation system is lower than the preset threshold, control the heat medium filling device to start and inject heat medium into the heat medium circulation system.

2. The closed solar water heating system according to claim 1, wherein The heat medium filling device injects heat medium into the heat medium circulation system at a speed of 80 - 120 ml / min.

3. The closed solar water heating system according to claim 1, wherein, The liquid level sensor has an exhaust function.

4. The closed solar water heating system according to claim 1 or 2 or 3, characterized in that, A temperature sensor 1T1 for detecting the heat medium temperature inside the heat collecting plate is arranged on the heat collecting plate, and a temperature sensor 1T2 for detecting the stored water temperature inside the volumetric heat exchanger is arranged on the volumetric heat exchanger.

5. The closed solar water heating system according to claim 4, characterized in that, When the temperature of the heat medium detected by the temperature sensor 1T1 reaches or exceeds the preset start threshold, the controller is configured to control the heat medium circulation pump to start to drive the operation of the heat medium circulation system; When the temperature of the heat medium detected by the temperature sensor 1T1 is lower than the preset start threshold, or the temperature difference between the heat medium and the stored water is less than the preset value, the controller is configured to control the heat medium circulation pump to close to stop the operation of the heat medium circulation system.

6. The closed solar water heating system according to claim 4, wherein, When the temperature sensor 1T2 detects that the stored water temperature reaches the preset upper limit and the temperature of the heat medium detected by the temperature sensor 1T1 is lower than the safety threshold, the controller is configured to control the heat medium circulation pump to close to stop the operation of the heat medium circulation system.

7. The closed solar water heating system according to claim 6, wherein, When the temperature sensor 1T2 detects that the stored water temperature is equal to or lower than the preset lower limit, the temperature sensor 1T1 detects that the heat medium temperature reaches or exceeds the preset start threshold, and the temperature difference between the heat medium and the stored water reaches the preset value, the controller is configured to control the heat medium circulation pump to restart to drive the operation of the heat medium circulation system.

8. The closed solar water heating system according to claim 4, characterized in that, A flexible photovoltaic panel is arranged above the heat collecting plate, and the controller is configured to be able to: control the flexible photovoltaic panel to unfold to cover the heat collecting plate; roll up the flexible photovoltaic panel to expose the heat collecting plate; When the temperature sensor 1T1 detects that the heat medium temperature reaches or exceeds the safety threshold and the temperature sensor 1T2 detects that the stored water temperature reaches the preset upper limit, the controller is configured to: control the flexible photovoltaic panel to unfold to cover the heat collecting plate, isolate the direct sunlight to reduce the heat medium temperature; control the flexible photovoltaic panel to perform photovoltaic power generation; and / or When the temperature sensor 1T1 does not detect that the temperature of the heat medium reaches the preset start threshold for consecutive days, the controller is configured to: control the photovoltaic flexible panel to unfold for photovoltaic power generation during the day.

9. The closed solar water heating system according to claim 8, characterized in that, An overheat protection device for cooling the heat medium is connected to the main path. The controller is configured to: when the temperature of the heat medium detected by the temperature sensor 1T1 reaches or exceeds the safety threshold and the water storage temperature detected by the temperature sensor 1T2 reaches the preset upper limit, control the heat medium circulation pump and the overheat protection device to start, so as to drive the heat medium to flow through the overheat protection device for heat dissipation, and realize the reduction of the heat medium temperature.

10. The closed solar water heating system according to claim 9, wherein The overheat protection device includes: a serpentine pipe connected to the main path for the heat medium to flow through; a fan disposed adjacent to the serpentine pipe to reduce the heat medium temperature by forced convection heat dissipation.

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