A climate chamber for detecting volatile organic compounds

Abstract

The application relates to the technical field of environment detection equipment, in particular to a climate chamber for volatile organic compound detection, which comprises an experimental cabin and a main air supply gas path, the main air supply gas path comprises, in sequence along a gas flow direction, a carbon filter tank, a diaphragm pump and a high-efficiency particle filter tank, forms a purification sequence of 'coarse filtration, power and fine filtration', and prevents secondary pollution; the climate chamber is provided with a drying machine, a humidification saturation barrel, a gas mixing barrel and a proportional valve, realizes humidity decoupling control of 'drying and returning to zero first and then accurate humidification', and is internally provided with an internal circulation air duct system composed of a motor, an axial flow fan and an up-down bidirectional return air duct, forms symmetrical air flow of middle return air and up-down bidirectional air outlet, and realizes one-key switching of normal operation, high-temperature cleaning and sampling analysis modes through an electromagnetic valve group. The application meets the requirements of GB / T31107-2014, and improves the accuracy of VOC detection and the stability of long-term operation of the equipment.

Description

Technical Field

[0001] This application relates to the technical field of environmental monitoring equipment, and in particular to a climate chamber for detecting volatile organic compounds. Background Technology

[0002] Climate chambers for detecting volatile organic compounds (VOCs) in furniture are core equipment for simulating indoor environments and conducting non-destructive testing of VOC emissions from furniture or building materials. The national standard GB / T31107-2014, "General Technical Conditions for Climate Chambers for Detecting Volatile Organic Compounds in Furniture," sets strict performance requirements for climate chambers, including background concentration, permissible temperature and humidity deviations, airflow velocity, and continuous operating time.

[0003] A search revealed Chinese Patent Publication No. CN203561001U, which discloses an air handling system for environmental chamber testing. This system includes a filtration system for filtering gas components that may affect the test results, and a temperature and humidity control system for controlling the gas temperature and humidity. Outside air is pumped into the filtration system, and the outlet of the filtration system is connected to the inlet pipe of the temperature and humidity control system. The outlet pipe of the temperature and humidity control system is connected to the inner chamber of the environmental chamber.

[0004] Regarding the aforementioned technologies, the inventors have discovered the following drawbacks: In existing technologies, diaphragm pumps (or air pumps) are typically placed at the front end of the filtration system or as part of the filtration chain. This causes minor wear and tear on the diaphragm pump's membranes, valves, and other mechanical components during long-term operation, resulting in the shedding of fine particulate matter. While some of this particulate matter may be intercepted in the downstream filtration system, some trapped on the filter media may still detach, causing secondary pollution. If the pump is placed after all the filtration elements, the particles generated by the pump itself will directly enter the experimental chamber, completely negating the effect of pre-filtration. Furthermore, when the climate chamber operates under long-term high humidity (30%~80%RH) conditions, condensation inevitably forms on the chamber walls and in the piping. However, most designs lack automatic condensate drainage devices, relying on periodic manual cleaning. This leads to condensate accumulation, forming a "water reservoir," which not only violates the national standard requirement that "the chamber walls should be smooth and free of condensate water reservoirs," but also adsorbs VOCs or promotes biofilm growth, severely interfering with the accuracy of VOC detection data. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this application provides a climate chamber for detecting volatile organic compounds.

[0006] This application provides a climate chamber for detecting volatile organic compounds, employing the following technical solution: it includes an experimental chamber and a main air supply path for supplying clean air to the experimental chamber. The main air supply path, along the gas flow direction, sequentially includes, via pipelines: a carbon filter canister for coarse filtration of the incoming gas; a diaphragm pump, whose inlet is connected to the outlet of the carbon filter canister, for providing power for gas transport; and a high-efficiency particulate filter canister, whose inlet is connected to the outlet of the diaphragm pump, for fine filtration of the gas.

[0007] Optionally, the main gas supply circuit further includes: a dryer, whose inlet is connected to the outlet of the high-efficiency particulate filter canister for outputting dry gas; a secondary filter of the dryer, whose inlet is connected to the outlet of the dryer for secondary filtration of the dry gas; a humidification saturation tank, whose inlet is connected to the outlet of the high-efficiency particulate filter canister for outputting humidified gas; a gas mixing tank, whose inlet is connected to the outlets of the secondary filter of the dryer and the humidification saturation tank respectively for mixing dry gas and humidified gas, and whose outlet is connected to the inlet of the experimental chamber; a first proportional valve and a second proportional valve, respectively disposed between the secondary filter of the dryer and the gas mixing tank, and between the humidification saturation tank and the gas mixing tank, for precisely regulating the flow rates of dry gas and humidified gas entering the gas mixing tank.

[0008] Optionally, the system also includes an internal circulation air duct system installed inside the experimental chamber. The internal circulation air duct system includes: a motor fixed to the inner wall of the experimental chamber; an axial fan connected to the output shaft of the motor, with the return air side of the axial fan facing the central area of ​​the experimental chamber; an outlet air duct connected to the outlet side of the axial fan, extending upwards and downwards to form an upper outlet and a lower outlet; and a return air duct connected to the upper and lower return air sides of the axial fan to form an intermediate return air duct.

[0009] Optionally, it also includes an electric heating tube installed inside the experimental chamber for heating the experimental chamber to a preset cleaning temperature (e.g., 200°C) in cleaning mode.

[0010] Optionally, it also includes an automatic condensate drainage device, which includes a drain outlet located at the bottom of the gas mixing tank and a timed drain valve connected to the secondary filter of the dryer. The timed drain valve is electrically connected to the control system and is used to automatically drain the condensate accumulated in the gas path at regular intervals.

[0011] Optionally, it also includes a main water supply circuit, which includes a chiller and a water pump connected in sequence through pipelines. The outlet of the water pump is connected to the inlet of the first coil located inside the gas mixing tank through an electric ball valve, for precisely regulating the temperature and humidity inside the gas mixing tank.

[0012] Optionally, the main gas supply circuit is also equipped with a pressure transmitter and an exhaust safety valve, which are used to monitor the system pressure in real time and automatically release pressure when the pressure exceeds a preset threshold.

[0013] Optionally, the main gas supply circuit is also equipped with a one-way valve to prevent gas backflow and maintain the experimental chamber at a positive pressure of 10 Pa to 20 Pa.

[0014] Optionally, it also includes a control system, which enables one-button switching between normal operation mode, high-temperature cleaning mode and sampling analysis mode via a solenoid valve group.

[0015] Optionally, the experimental chamber is equipped with a temperature and humidity sensor, which is electrically connected to the control system to monitor the temperature and humidity inside the chamber in real time and send signals back to the control system.

[0016] In summary, this application includes the following beneficial technical effects: 1. This invention achieves the following effects by sequentially configuring the main gas supply path along the gas flow direction as a carbon filter canister, a diaphragm pump, and a high-efficiency particulate filter canister, i.e., adopting a specific order of "coarse filtration by the carbon filter canister → fine filtration by the diaphragm pump → fine filtration by the high-efficiency particulate filter canister": the carbon filter canister pre-filters the incoming gas, effectively protecting the diaphragm pump and extending its service life; the high-efficiency particulate filter canister, located at the rear end of the diaphragm pump, can filter and remove the tiny particles that are worn off during the operation of the diaphragm pump, eliminating secondary pollution paths by design and ensuring that the background concentration of the experimental chamber meets the national standard GB / T31107-2014 for formaldehyde background ≤0.006mg / m³. 3 TVOC ≤ 0.05 mg / m³ 3 Extremely low requirements.

[0017] 2. This invention, by incorporating a dryer, a humidification saturation tank, a gas mixing tank, and a first and second proportional valve, establishes a decoupled temperature and humidity control structure that achieves "drying to near zero humidity followed by precise humidification." This structure achieves the following effects: external air, after fine filtration, enters the dryer to thoroughly remove moisture to near-zero humidity and then enters the humidification saturation tank to generate saturated humidity gas. The two gas streams are then precisely controlled by the proportional valves and mixed in the gas mixing tank, thereby achieving independent temperature and humidity regulation. This fundamentally reduces the coupling effect between temperature and humidity, avoids condensation inside the chamber, and ensures that the temperature and humidity control accuracy meets and exceeds the national standard deviation requirements of ±1℃ and ±3%RH.

[0018] 3. This invention utilizes an internal circulation airflow system within the experimental chamber, consisting of a motor, an axial fan, and exhaust ducts. The axial fan's inlet faces the central area of ​​the chamber, while the exhaust ducts extend upwards and downwards to form upper and lower exhaust outlets. This achieves a symmetrical circulating airflow organization with "central return air and bidirectional airflow from top to bottom," effectively eliminating dead zones in the chamber's airflow and significantly improving the uniformity of temperature, humidity, and VOC concentration. Even when large samples obstruct the airflow, basic airflow circulation is maintained, ensuring the representativeness and accuracy of the test results. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of the experimental chamber in the embodiments of this application; Figure 3 This is a first-view schematic diagram of the internal structure in an embodiment of this application; Figure 4 This is a second-view schematic diagram of the internal structure in an embodiment of this application; Figure 5 This is a third-view schematic diagram of the internal structure in an embodiment of this application; Figure 6 This is a schematic diagram of the axial fan drive in an embodiment of this application; Figure 7 This is a schematic diagram of the overall operating logic in the embodiments of this application.

[0020] Reference numerals: 1. Carbon filter canister; 2. Diaphragm pump; 3. High-efficiency particulate filter canister; 4. Dryer; 5. Humidification saturation tank; 6. Gas mixing tank; 71. First proportional valve; 72. Second proportional valve; 73. Electric ball valve; 8. Experimental chamber; 9. Motor; 10. Axial flow fan; 11. Air outlet duct; 12. Heating element; 14. Timed drain valve; 15. Chiller; 16. Water pump; 18. Second coil; 19. Return air duct. Detailed Implementation

[0021] The following is in conjunction with the appendix Figures 1-7 This application will be further described in detail below. The technical solutions in the embodiments of this application will be clearly described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0022] This application discloses a climate chamber for detecting volatile organic compounds (VOCs), used to detect VOC emissions from samples such as furniture and decorative materials. Figure 1 As shown, the system includes experimental chamber 8, main air supply path, internal circulation air duct system, main water supply path, high-temperature cleaning branch path, automatic condensate drainage device, safety protection components, and control system. This embodiment optimizes the purification sequence of the main air supply path, employing a specific architecture of "coarse filtration in a carbon filter canister → diaphragm pump → fine filtration in a high-efficiency particulate filter canister," thus eliminating secondary pollution from the design stage. It adopts a decoupled temperature and humidity control strategy of "drying to zero first, then precise humidification," combined with precise adjustment by a proportional valve, achieving independent high-precision control of temperature and humidity. This embodiment uses a solenoid valve assembly to achieve one-button switching between multiple modes such as normal operation, high-temperature cleaning, and sampling analysis. Combined with the "central air intake, bidirectional air outlet" structure of the internal circulation air duct system, it improves the uniformity within the chamber. A timed drain valve automatically discharges condensate, meeting the requirements for long-term unattended operation.

[0023] Please see Figure 3 , Figure 4 The main air supply path provides clean air to experimental chamber 8. Along the gas flow direction, the main air supply path includes, in sequence, a carbon filter canister 1, a diaphragm pump 2, and a high-efficiency particulate filter canister 3, connected by pipelines. The inlet of the carbon filter canister 1 is connected to an external air source. Its interior is filled with adsorbent materials such as activated carbon to coarsely filter the incoming gas, removing large particles, oil mist, and adsorbing some VOCs. The outlet of the carbon filter canister 1 is connected to the inlet of the diaphragm pump 2. The diaphragm pump 2 provides the gas delivery power for the entire main air supply path. The outlet of the diaphragm pump 2 is connected to the inlet of the high-efficiency particulate filter canister 3. The high-efficiency particulate filter canister 3 is equipped with HEPA filter material or a filter medium of equivalent precision for final fine filtration of the gas, removing all particles larger than 0.3 μm, including tiny particles that may detach during the operation of the diaphragm pump 2. The vacuum diaphragm pump is an oil-free dry vacuum pump that uses the reciprocating motion of an elastic diaphragm to draw in and expel gas. Because it can provide a clean, pollution-free, and corrosion-resistant vacuum environment, it is widely used in laboratories and many industrial production scenarios.

[0024] By setting up the sequence of "carbon filter 1 → diaphragm pump 2 → high-efficiency particulate filter 3" as described above, the carbon filter 1 protects the diaphragm pump 2 in front, extending its lifespan; the high-efficiency particulate filter 3 captures the particles generated by the pump itself in the rear, eliminating the path of secondary pollution.

[0025] Please see Figure 3 , Figure 4 , Figure 5 and Figure 7The main gas supply circuit also includes a temperature and humidity control component. The outlet of the high-efficiency particulate filter 3 is divided into two paths: one connects to the inlet of the dryer 4, and the other connects to the inlet of the humidification saturation tank 5. The dryer 4 is used to remove moisture from the gas, outputting dry gas with a relative humidity close to 0%. The outlet of the dryer 4 is connected to the inlet of the secondary filter 20 of the dryer. The secondary filter 20 is used to perform secondary filtration on the dry gas, further removing any trace impurities or particulate matter that may be entrained in the dry gas, ensuring that the dry gas entering the gas mixing tank 6 has extremely high cleanliness. The humidification saturation tank 5 is filled with pure water and equipped with a heating element to generate saturated humidity gas. The outlet of the secondary filter 20 of the dryer is connected to one inlet of the gas mixing tank 6 through a first proportional valve 71; the outlet of the humidification saturation tank 5 is connected to the other inlet of the gas mixing tank 6 through a second proportional valve 72. The gas mixing tank 6 is used to buffer and mix the dry gas from the secondary filter 20 of the dryer with the humidified gas from the humidification saturation tank 5. The mixed gas is then sent into the experimental chamber 8 through a pipeline. By adjusting the opening ratio of the first proportional valve 71 and the second proportional valve 72, the relative humidity of the mixed gas can be precisely controlled, achieving decoupled control of "drying to zero first, then precise humidification".

[0026] Please see Figure 3 , Figure 4 , Figure 5 and Figure 7 An internal circulation air duct system is installed inside the experimental chamber 8 to promote gas circulation and improve the uniformity of temperature, humidity, and VOC concentration. The internal circulation air duct system includes a motor 9, an axial fan 10, an exhaust duct 11, and a return duct 19. The motor 9 is fixedly installed on the back of the inner wall of the experimental chamber 8 (e.g., at the center of the rear wall). The axial fan 10 is driven by the output shaft of the motor 9, with its inlet side facing the central area of ​​the experimental chamber 8 to draw in gas from the center. The exhaust duct 11 is connected to the exhaust side of the axial fan 10, extending upwards and downwards to form an upper exhaust port and a lower exhaust port. The return duct 19 is connected to the return side of the axial fan 10, forming a central return port, which, together with the return side of the axial fan 10, achieves central return air circulation.

[0027] During operation, the motor 9 drives the axial fan 10 to rotate. The gas inside the chamber is drawn in from the middle through the return air duct 19, pressurized by the fan, and then enters the outlet air duct 11. It is then evenly returned to the experimental chamber 8 from the upper and lower air outlets, forming a symmetrical circulating airflow. This structure effectively eliminates dead zones in the airflow inside the chamber. Even if a large sample is placed inside the chamber and obstructs part of the airflow path, the bidirectional air outlet design can still maintain basic gas circulation.

[0028] Please see Figure 3 , Figure 4 , Figure 5 and Figure 7 To meet the national standard requirements for high-temperature cleaning, the experimental chamber 8 is equipped with an electric heating element 12. The electric heating element 12 can be located at the back or bottom of the experimental chamber 8 and is electrically connected to the control system. In cleaning mode, the control system controls the electric heating element 12 to generate heat, raising the internal temperature of the experimental chamber 8 to above 200°C and maintaining this temperature for a preset time (e.g., 2 hours). This process performs thermal desorption cleaning of residual VOCs on the inner walls and pipes of the chamber, and the desorbed pollutants are then discharged through exhaust ventilation.

[0029] Please see Figure 3 , Figure 4 , Figure 5 and Figure 7 The main water supply circuit provides constant-temperature chilled water to the gas mixing tank 6 and the experimental chamber 8 to achieve humidity and temperature control. The main water supply circuit includes a chiller 15 and a water pump 16 connected sequentially via pipelines. The chiller 15 provides low-temperature water at the required constant temperature (e.g., temperature controlled between 5°C and 25°C). The inlet of the water pump 16 is connected to the outlet of the chiller 15, providing the power for water flow throughout the main water supply circuit.

[0030] The water pump 16 has two outlets. One outlet is connected to the inlet of the first coil inside the gas mixing tank 6 via an electric ball valve 73. The outlet of the first coil returns to the chiller 15, forming a loop. By adjusting the opening of the electric ball valve 73, the flow rate of chilled water through the first coil can be precisely controlled, thereby controlling the gas temperature inside the gas mixing tank 6 and indirectly achieving fine adjustment of the humidity of the mixed gas.

[0031] The second coil 18 is preferably in two sets, respectively located at the upper and lower parts of the experimental chamber 8, for cooling the air inside the chamber. When heating is required, the electric heating tube 12 is activated for auxiliary heating.

[0032] Please see Figure 3 , Figure 4 , Figure 5 and Figure 7When experimental chamber 8 operates under high humidity conditions for extended periods, condensation will form on the inner walls and coil surfaces. To address this issue, a drain outlet is located at the bottom of the gas mixing tank 6, connected via a pipeline to a timed drain valve 14. The timed drain valve 14 is preferably a solenoid valve, electrically connected to the control system. The control system can set a drainage cycle (e.g., every 10 minutes, 20 minutes, 40 minutes, or 60 minutes). Upon reaching the set time, the timed drain valve 14 automatically opens (e.g., for 2 seconds, 4 seconds, 6 seconds, or 8 seconds), draining the accumulated condensate from the gas mixing tank 6 to an external collection container or sewer. The opening time lasts for several minutes (adjustable depending on the condensate level) before automatically closing. This device achieves automatic condensate drainage, meeting the national standard requirement of "no condensate storage tank inside the chamber," and ensuring the cleanliness of the chamber during 28 days of continuous unattended operation.

[0033] Please see Figure 3 , Figure 4 , Figure 5 and Figure 7 To ensure the safe operation of the system under abnormal conditions, a pressure transmitter and an exhaust safety valve are installed in the main gas supply circuit. The pressure transmitter monitors the gas system pressure in real time. When the pressure exceeds a preset threshold (e.g., 0.2 MPa), the control system automatically opens the exhaust safety valve to release pressure and prevent pipeline rupture. In addition, a one-way valve is also installed in the main gas supply circuit to prevent gas backflow and ensure that a slight positive pressure of 10 Pa to 20 Pa is maintained inside the experimental chamber 8, effectively preventing unpurified external air from seeping into the chamber through gaps and causing contamination.

[0034] Please see Figure 7 The climate chamber in this embodiment of the invention also includes a control system, preferably an imported programmable logic controller (PLC) or a microcontroller control system. The control system is electrically connected to the aforementioned proportional valves (71, 72, 73), timed drain valve 14, electric heating element 12, motor 9, diaphragm pump 2, water pump 16, chiller 15, pressure transmitter, exhaust safety valve, and multiple solenoid valves located at key nodes in the gas path. The experimental chamber 8 is also equipped with a temperature and humidity sensor, which is electrically connected to the control system. This sensor monitors the temperature and humidity inside the chamber in real time and feeds back signals to the control system. Based on the deviation between the feedback signal and the set value, the control system adjusts the opening of the first proportional valve 7.1 and the second proportional valve 7.2 respectively, achieving a precise ratio of dry gas and humidified gas flow rates, thereby forming a closed-loop control.

[0035] The control system controls the on / off state of each solenoid valve through a program, enabling one-button switching between the following three operating modes: Normal operating mode: The main air supply path is unobstructed, the internal circulation air duct system is in operation, the temperature and humidity control components work according to the set parameters, and clean air with constant temperature and humidity is introduced into the experimental chamber 8.

[0036] High-temperature cleaning mode: The control system closes the intake valve of the main air supply circuit, opens the exhaust valve, and starts the electric heating tube 12 to heat the interior of the experimental chamber 8 to above 200°C, maintaining this temperature for a preset time (e.g., 2 hours) to allow residual VOCs to undergo thermal desorption and desorption, and then be discharged outside the chamber through the exhaust system. In this mode, the internal circulation air duct system continues to operate to maintain a uniform temperature.

[0037] Sampling and analysis mode: The control system can shut off the main gas supply line or maintain a low gas flow rate, while simultaneously starting the sampling pump and valve connected to an external sampling instrument (such as GC-MS) to draw the gas inside the chamber into the analyzer for VOC concentration measurement.

[0038] The implementation principle of a climate chamber for detecting volatile organic compounds in this application embodiment is as follows: After the system is started, diaphragm pump 2 operates, and external air is sequentially filtered through carbon filter canister 1 (coarse filtration), pumped by diaphragm pump 2, and finely filtered through high-efficiency particulate filter canister 3 to obtain clean air. The clean air is divided into two paths: one path enters dryer 4 to produce dry gas, which is then filtered a second time by the dryer's secondary filter before being output; the other path enters humidification saturation tank 5 to produce saturated humidity gas. The first proportional valve 71 and the second proportional valve 72 adjust their openings according to the set humidity requirements, ensuring that the dry gas and humidified gas are mixed in proportion within gas mixing tank 6 to form air with the desired humidity. Simultaneously, chiller 15 provides constant-temperature chilled water, and water pump 16 sends the chilled water through electric ball valve 73 into the first coil 17 within gas mixing tank 6 to regulate the temperature of the mixed gas. The uniformly mixed clean air enters experimental chamber 8. Simultaneously, the motor 9 of the internal circulation air duct system drives axial fan 10 to operate, drawing air from the center of the chamber and returning it to the chamber through upper and lower air outlet ducts 11, forming a circulating airflow to ensure uniform temperature, humidity, and VOC concentration within the chamber. The timed drain valve 14 automatically opens according to a set cycle to drain condensate from the chamber. A pressure transmitter monitors the gas pressure in real time; in case of abnormality, the exhaust safety valve automatically releases pressure. The system can operate continuously for more than 28 days, meeting national standards.

[0039] When cleaning is required, the operator can switch to the high-temperature cleaning mode with one click. The system will automatically shut off the main gas supply circuit, start the electric heating element 12 to heat to above 200°C, and automatically cool down after completing the thermal desorption cleaning, then switch back to normal operation mode.

[0040] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A climate chamber for detecting volatile organic compounds, characterized in that, include: Experimental chamber (8); The main air supply line is used to provide clean air to the experimental chamber (8); The main gas supply line, along the gas flow direction, includes, in sequence, the following components connected by pipelines: Carbon filter canister (1) is used for coarse filtration of incoming gas; A diaphragm pump (2) has its inlet connected to the outlet of the carbon filter canister (1) to provide power for gas delivery; The high-efficiency particulate filter canister (3) has its inlet connected to the outlet of the diaphragm pump (2) for fine filtration of gas.

2. The climate chamber for detecting volatile organic compounds according to claim 1, characterized in that: The main gas supply circuit also includes: The dryer (4) has its air inlet connected to the air outlet of the high-efficiency particulate filter (3) for outputting dry gas; The secondary filter of the dryer has its inlet connected to the outlet of the dryer (4) and is used to perform secondary filtration of the drying gas. The humidifying saturation tank (5) has its air inlet connected to the air outlet of the high-efficiency particulate filter tank (3) for outputting humidified gas; The gas mixing tank (6) has its inlet connected to the outlet of the secondary filter of the dryer and the outlet of the humidification saturation tank (5) respectively, for mixing dry gas and humidified gas, and its outlet is directly connected to the inlet of the experimental chamber. The first proportional valve (7.1) and the second proportional valve (7.2) are respectively located between the secondary filter of the dryer and the gas mixing tank (6), and between the humidification saturation tank (5) and the gas mixing tank (6), to precisely adjust the flow rate of the dry gas and the humidified gas entering the gas mixing tank (6), thereby controlling the temperature and humidity required by the experimental chamber (8).

3. A climate chamber for detecting volatile organic compounds according to claim 1 or 2, characterized in that, It also includes an internal circulation air duct system installed inside the experimental chamber (8), the internal circulation air duct system comprising: The motor (9) is fixed to the inner wall of the experimental chamber (8); An axial fan (10) is driven to the output shaft of the motor (9), and the return air side of the axial fan (10) faces the central area of ​​the experimental chamber (8). The air outlet duct (11) is connected to the air outlet side of the axial fan (10). The air outlet duct (11) extends to the top and bottom of the experimental chamber (8) respectively to form an upper air outlet and a lower air outlet. The return air duct (19) is connected to the return air side of the axial fan (10) to form an intermediate return air.

4. The climate chamber for detecting volatile organic compounds according to claim 1, characterized in that, It also includes an electric heating tube (12) installed inside the experimental chamber (8) for heating the experimental chamber (8) to a preset cleaning temperature of 200°C in cleaning mode.

5. A climate chamber for detecting volatile organic compounds according to claim 1, characterized in that, It also includes an automatic condensate drain device, which includes a drain outlet located at the bottom of the gas mixing tank (6) and a timed drain valve (14) connected to the secondary filter of the dryer. The timed drain valve (14) is electrically connected to the control system and is used to automatically drain the condensate accumulated in the gas path at regular intervals.

6. A climate chamber for detecting volatile organic compounds according to claim 2, characterized in that, It also includes a main water supply circuit, which includes a chiller and a water pump (16) connected in sequence through pipelines. The outlet of the water pump (16) is connected to the inlet of the first coil located inside the gas mixing tank (6) through an electric ball valve (7.3).

7. The climate chamber for detecting volatile organic compounds according to claim 1, characterized in that, The main gas supply circuit is also equipped with a pressure transmitter and an exhaust safety valve, which are used to monitor the system pressure in real time and automatically release pressure when the pressure exceeds a preset threshold.

8. The climate chamber for detecting volatile organic compounds according to claim 1, characterized in that, The main gas supply circuit is also equipped with a one-way valve to prevent gas backflow and maintain the experimental chamber (8) at a positive pressure of 10 Pa to 20 Pa.

9. The climate chamber for detecting volatile organic compounds according to claim 1, characterized in that, It also includes a control system, which enables one-click switching between normal operation mode, high-temperature cleaning mode and sampling analysis mode through a solenoid valve group.

10. The climate chamber for detecting volatile organic compounds according to claim 1, characterized in that, The experimental chamber (8) is equipped with a temperature and humidity sensor, which is electrically connected to the control system and is used to monitor the temperature and humidity inside the chamber in real time and send a signal back to the control system.

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