An intelligent air exhaust device with defrosting function and anti-cold air backflow function

Abstract

This invention proposes an intelligent exhaust system with defrosting function to prevent cold air backflow, belonging to the field of building HVAC technology. It solves the problems of cold air backflow affecting thermal comfort, and poor exhaust performance caused by pipe icing and blockage in winter, as well as valve failure. It includes a main air duct connected to the ventilation duct, side ducts, an inlet connected to the main air duct, and an outlet connected to the atmosphere; a fan installed in the side duct; and a temperature monitoring unit electrically connected to the fan and a switching valve installed in the main air duct. The outlet is positioned higher than the inlet; a shell is provided on the outside of the main air duct, forming a thermally insulated cavity A between the shell and the main air duct.

Description

Technical Field

[0001] This invention belongs to the field of building heating, ventilation and air conditioning technology, and in particular relates to an intelligent exhaust device for preventing cold air backflow that also has a defrosting function. Background Technology

[0002] Current building ventilation systems often combine natural and mechanical ventilation. High-rise buildings typically have shared vertical exhaust ducts, and natural ventilation is sufficient during the non-heating season. To address the issue of cold air backflow, some systems are equipped with check valves. However, in environments as cold as -30°C, condensation forms between the valve plate and seat of ordinary check valves, causing a delay of up to 15 seconds in blade movement or even complete jamming. Low-temperature contraction increases the gap in the sealing surface, making it impossible to reliably prevent backflow. Furthermore, traditional ventilation systems lack an active defrosting mechanism.

[0003] In frigid regions, the temperature difference between indoors and outdoors can exceed 40°C during the winter heating season. This creates a strong chimney effect within the vertical air ducts, causing cold air to backflow from the top vents into lower-floor rooms, keeping room temperatures consistently below 5°C. This leads to frequent freezing and cracking of toilet tanks and water supply pipes. Simultaneously, water vapor in the exhaust ducts condenses upon contact with cold air, rapidly freezing in environments below -20°C. In Harbin, many restaurant exhaust ducts have developed icicles with diameters exceeding 30 cm and lengths exceeding 1 meter, sometimes completely blocking the ducts and causing exhaust failure. The problem of frost and ice buildup on the inner walls of main ventilation ducts is particularly prominent. According to research from Harbin Institute of Technology, the asymmetric radiation temperature required for human thermal comfort in frigid regions during winter is approximately 2°C, and the temperature difference between room temperature and cold wall temperature should be limited to 3°C. Backflow of cold air causes sudden drops in localized temperatures, with temperature differences exceeding 14°C within the same building, resulting in a severe imbalance in comfort. Summary of the Invention

[0004] In view of this, the present invention aims to propose an intelligent ventilation device with defrosting function to prevent cold air backflow, so as to solve the problems of cold air backflow affecting thermal comfort, and poor ventilation effect caused by pipe icing and blockage in winter and valve failure.

[0005] To achieve the above objectives, the present invention adopts the following technical solution to provide an intelligent ventilation device for preventing cold air backflow with defrosting function, including a main air duct connected to a ventilation duct, a side duct, an inlet connected to the main air duct, and an outlet connected to the atmosphere. The fan is installed in the side duct; The temperature monitoring unit is electrically connected to the fan and the switching valve installed in the main air duct.

[0006] Furthermore, the exit is located higher than the inlet.

[0007] Furthermore, the main air duct is provided with a shell on its outer side, and a heat-insulating cavity A is formed between the shell and the main air duct.

[0008] Furthermore, the side pipe inlet is located inside the thermal insulation cavity A, and the outlet is located outside the thermal insulation cavity A.

[0009] Furthermore, the main air duct has an extension located above the housing, and the outlet of the side duct is disposed toward the extension.

[0010] Furthermore, the side pipe is provided with an insulation layer.

[0011] Furthermore, the temperature monitoring unit includes a temperature sensor and a controller. The temperature sensor is located inside the ventilation duct, and the controller receives the signal from the temperature sensor and controls the fan and switching valve to open and close.

[0012] Furthermore, the temperature sensor is positioned close to the main air duct.

[0013] Beneficial effects: 1. By measuring and comparing the temperature difference between two temperature sensors, the ventilation mode is changed. The two exhaust modes are natural exhaust in the main air duct and forced exhaust in the side duct to prevent cold air backflow when the air pressure is low.

[0014] 2. By using side ducts for forced ventilation, the hot air inside the room is forced outward. The exhausted hot air is blown towards the main air duct to heat and melt the ice on the main air duct, achieving an integrated effect of "exhausting air and defrosting at the same time", thus solving the problem of ice blockage in the main air duct from the root.

[0015] 3. The insulation layer is made of high-efficiency insulation material, which significantly reduces the loss of waste heat during long-distance transmission, prevents condensation and ice formation on the outer wall of the pipe, ensures efficient heat transfer to the target area, and improves the efficiency of waste heat utilization. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0017] In the diagram: 1. Housing; 2. Main air duct; 3. Switching air valve; 4. Side duct; 5. Fan; 6. Outlet; 7. Temperature sensor 1; 8. Temperature sensor 2; 9. Ventilation duct. Detailed Implementation Specific implementation method one: See appendix Figure 1 This embodiment provides an intelligent ventilation device for preventing cold air backflow that also has a defrosting function. It includes a main air duct 2 connected to a ventilation duct 9; a side duct 4 with its inlet connected to the main air duct 2 and its outlet 6 connected to the atmosphere; a fan 5 installed in the side duct 4; and a temperature monitoring unit electrically connected to the fan 5 and a switching valve 3 installed in the main air duct 2.

[0019] Fan 5 is a mechanical exhaust device used for forced ventilation. When used in extremely cold regions, a low-temperature resistant model should be selected, and antifreeze protection should be considered when the machine is stopped. Forced ventilation can increase the flue gas velocity and enhance the defrosting effect of the main ventilation duct.

[0020] Switching valve 3 is an electrically controlled valve used to open or close the natural ventilation channel. It must be able to operate reliably in low-temperature environments, and the valve body should be protected against freezing and heat preservation.

[0021] The lower part of the main air duct 2 is fixedly connected to the building's ventilation duct 9. In normal operation, the switching damper 3 opens. Because the main air duct 2 is vertical, has a large diameter, and a short path, exhaust air is quickly discharged through the upper part of the main air duct 2. At this time, the thermal pressure formed by the temperature difference between indoors and outdoors is sufficient to drive the air to rise naturally and be discharged. The system prioritizes natural ventilation, reducing energy consumption while meeting exhaust demand. This mode is suitable for non-severe cold periods or conditions where the indoor exhaust air temperature is relatively low.

[0022] When there is a large temperature difference between indoors and outdoors in winter, and the indoor temperature is high while the outdoor temperature is low, cold air backflow can easily occur due to low air pressure or changes in wind direction. Cold air enters the ventilation duct 9 through the main air duct 2. When the outdoor ambient temperature is lower than the air temperature inside the exhaust duct, the switching valve 3 closes the natural exhaust channel, and the fan starts forced ventilation. This is because the outdoor cold air density and pressure are high at this time, and backflow is very likely to occur if the natural channel is open. The system cuts off the backflow path by closing the switching valve 3 and starting the fan 5 to establish positive exhaust pressure, forcibly expelling indoor air, thereby blocking cold air from entering the room and preventing frost damage and thermal comfort imbalance. The temperature detection unit controls the switching valve 3 to close and then starts the fan.

[0023] In this embodiment, the outlet 6 is located higher than the inlet. The inlet of the side duct 4 is connected to the lower part of the main air duct 2, while the outlet 6 is located at the upper part of the main air duct 2 and is not connected to the main air duct 2, thus having an independent exhaust outlet.

[0024] In this embodiment, a housing 1 is provided on the outer side of the main air duct 2, and a heat-insulating cavity A is formed between the housing 1 and the main air duct 2. The outer side of the housing 1 can be fixed to the ventilation duct 9. A sealed heat-insulating cavity is formed between the housing 1 and the main air duct 2, which can reduce the direct contact between the main air duct 2 and the outside cold air, and reduce the occurrence of frost and ice.

[0025] In this embodiment, the inlet of the side pipe 4 is located inside the heat-insulating cavity A, and the outlet 6 is located outside the heat-insulating cavity A. Most of the side pipe 4 is located within the heat-insulating cavity A, which serves to insulate the space and reduce heat loss through the pipe wall when hot air flows out through the side pipe 4, ensuring efficient heat transfer to the target area and improving waste heat utilization efficiency.

[0026] In this embodiment, the main air duct 2 has an extension section located above the housing 1, and the outlet 6 of the side duct 4 is positioned facing the extension section. The extension section is the main frosting area; after passing through the outlet 6, the high-temperature flue gas directly blows the frost layer on the extension section, using residual heat to melt it. The forced exhaust by the fan increases the flue gas velocity and temperature, and the residual heat is precisely delivered to the easily frosting parts through the outlet 6, achieving an integrated effect of "exhausting air and defrosting simultaneously," thus fundamentally solving the problem of icing and blockage in the main air duct.

[0027] In this embodiment, the side pipe 4 is provided with an insulation layer. The insulation layer is made of high-efficiency insulation material, which significantly reduces the loss of residual heat during long-distance transmission and prevents condensation and icing on the outer wall of the pipe.

[0028] In this embodiment, the temperature monitoring unit includes a temperature sensor 7 and a controller. The temperature sensor 7 is disposed inside the ventilation duct 9, and the controller receives the signal from the temperature sensor 7 and controls the opening and closing of the fan 5 and the switching valve 3.

[0029] In this embodiment, the temperature sensor 7 is positioned close to the main air duct 2.

[0030] In this embodiment, the temperature monitoring unit further includes a second temperature sensor 8, which is disposed on the outside of the ventilation duct 9 and connected to the controller.

[0031] The operating temperature range of the two temperature sensors and the controller must meet the requirements for use in extremely cold regions, ranging from -40℃ to +50℃.

[0032] The controller receives temperature signals and compares the outdoor temperature with the temperature inside the pipe. The control logic is set as follows: when the outdoor temperature is higher than the pipe temperature, the valve switches to open the natural ventilation channel, and the fan shuts off; when the outdoor temperature is lower than the pipe temperature, the valve switches to close the natural ventilation channel, and the fan starts forced ventilation. The controller housing is waterproof and dustproof, and the internal circuit board is coated with conformal coating to withstand humid and low-temperature environments.

[0033] During the frosty season, a first temperature sensor located at the outdoor vent collects the outdoor ambient temperature T1 in real time, while a second temperature sensor located inside the exhaust duct collects the air temperature inside the duct in real time, T2. Taking Harbin as an example, when the outdoor temperature sensor detects T1 ≤ -16℃ (i.e., reaching the Harbin heating outdoor calculation temperature), regardless of the value of T2, the system forcibly switches to anti-backflow mode, meaning the valves are forcibly closed and the fans are forcibly turned on. When T1 > T2 (i.e., the outdoor temperature is higher than the temperature inside the duct), there is no risk of cold air backflow. At this time, the valves are switched to open the natural exhaust channel, and the fans are turned off for natural exhaust. The outdoor temperature sensor's role is to predict the risk of backflow by sensing the actual intensity of the cold air outside and determining whether natural ventilation is safe. The duct temperature sensor's role is to assess the thermal pressure and residual heat level inside the duct, determining the magnitude of the thermal pressure driving force and the amount of heat available for defrosting by monitoring the exhaust temperature. The controller uses the two temperature signals to determine whether to switch modes, enabling the system to adapt to different building types, different exhaust heat loads, and different outdoor climate conditions.

[0034] When the frosty season arrives, the temperature detector monitors the temperature inside and outside the pipe in real time, thereby switching the exhaust mode. The switching temperature can be adjusted appropriately according to the actual conditions of the region. For example, when the monitored temperature inside the pipe is >15℃, the air valve opens and the fan turns off, and the warm indoor air is discharged through the air valve and the main ventilation pipe. When the monitored temperature inside the pipe is ≤15℃, the air valve closes and the fan turns on, and the indoor air is discharged through the fan to prevent cold air backflow. The controller is electrically connected to the temperature sensor, the fan, and the switching valve, respectively. It receives the detection signal from the temperature sensor and controls the operation of the fan and the switching valve according to preset logic. The specific connection methods and control principles between the controller and each component are common knowledge in the field and will not be described in detail here.

[0035] The embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A smart ventilation device for preventing cold air backflow with defrosting function, comprising a main air duct (2) connected to a ventilation duct (9), characterized in that: The side duct (4) is connected to the main air duct (2) at its inlet and to the atmosphere at its outlet (6); The fan (5) is installed in the side pipe (4); The temperature monitoring unit is electrically connected to the fan (5) and the switching valve (3) installed in the main air duct (2).

2. The intelligent ventilation device for preventing cold air backflow with defrosting function as described in claim 1, characterized in that: The exit (6) is located higher than the inlet.

3. The intelligent ventilation device for preventing cold air backflow with defrosting function as described in claim 2, characterized in that: The main air duct (2) is provided with a shell (1) on the outside, and a heat-insulating cavity A is formed between the shell (1) and the shell (1).

4. The intelligent ventilation device for preventing cold air backflow with defrosting function as described in claim 3, characterized in that: The inlet of the side pipe (4) is located inside the heat-insulating cavity A, and the outlet (6) is located outside the heat-insulating cavity A.

5. The intelligent ventilation device for preventing cold air backflow with defrosting function as described in claim 4, characterized in that: The main air duct (2) has an extension section located above the housing (1), and the outlet (6) of the side duct (4) is disposed toward the extension section.

6. A smart ventilation device for preventing cold air backflow with defrosting function as described in any one of claims 1 to 5, characterized in that: The side pipe (4) is provided with an insulation layer.

7. The intelligent ventilation device for preventing cold air backflow with defrosting function as described in claim 6, characterized in that: The temperature monitoring unit includes a temperature sensor (7) and a controller. The temperature sensor (7) is located inside the ventilation duct (9). The controller receives the signal from the temperature sensor (7) and controls the opening and closing of the fan (5) and the switching valve (3).

8. The intelligent ventilation device for preventing cold air backflow with defrosting function as described in claim 7, characterized in that: The temperature sensor 1 (7) is located near the main air duct (2).

9. A smart ventilation device for preventing cold air backflow with defrosting function as described in claim 7 or 8, characterized in that: The temperature monitoring unit also includes a second temperature sensor (8), which is located on the outside of the ventilation duct (9) and connected to the controller.

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