Low-temperature low-gas-pressure test chamber and humidity control method thereof

Abstract

The application discloses a low-temperature and low-gas-pressure test box and a humidity control method thereof. The temperature in the test box and the temperature of cooling liquid are controlled through a refrigeration system. The humidity balance is controlled by making the dew point temperature of the surface of a humidity evaporator and the dew point temperature of the temperature and humidity in the test box consistent, and the humidity is supplemented through a humidification module. The pressure value in the box body is controlled through a vacuum system, and the valve opening degree of the vacuum system is adjusted to control the pressure, so that the test box can realize different humidity environmental conditions under low temperature and high-low gas pressure.

Description

TECHNICAL FIELD

[0001] The present application relates to the humidity control technology field of test chamber, in particular to a low-temperature and low-pressure test chamber and a humidity control method thereof. BACKGROUND

[0002] The low-pressure test chamber is mainly used in the fields of aviation, spaceflight, information and electronics to determine the environmental adaptability and reliability of instruments, electrical products, materials, parts, equipment under the action of low pressure, high temperature and low temperature, and to measure the electrical performance parameters of the test piece under power supply. The test chamber adopts an integrated combined structure, which is composed of a heat preservation box body located at the front, a refrigeration and vacuum unit located at the rear, and an electrical controller located on the door of the test chamber.

[0003] However, the existing low-pressure test chamber can only control the stability of humidity in the temperature range of 10-90℃ and under normal pressure, and cannot truly simulate the low pressure and temperature and humidity environment of the aircraft at high altitude, such as the atmospheric pressure, temperature and humidity environment corresponding to the flight height.

[0004] Therefore, it is urgent to develop a test chamber and control system that can truly simulate the environmental state of the aircraft during high-altitude flight. SUMMARY

[0005] In order to solve the above technical problems, the purpose of the present application is to provide a low-temperature and low-pressure test chamber and a humidity control method thereof, so that the test chamber can maintain stable humidity under low temperature and low pressure.

[0006] In view of the above purpose, the present application provides a low-temperature and low-pressure test chamber, which comprises a chamber body, wherein the chamber body is provided with:

[0007] a humidity evaporator for controlling the stability of humidity and / or refrigeration in the chamber body;

[0008] a refrigeration system, which comprises a temperature evaporator and a humidity evaporator liquid cooler, the temperature evaporator is used to realize the refrigeration function or / and the dehumidification function, and the humidity evaporator liquid cooler is used to maintain the temperature of the cooling liquid;

[0009] a heater for temperature adjustment;

[0010] an air agitator for air circulation;

[0011] a dew point temperature sensor arranged on the surface of the humidity evaporator for real-time detection of the actual temperature value of the surface of the humidity evaporator, or for detection of the temperature inside or outside the liquid flow pipeline of the humidity evaporator;

[0012] Cooling liquid, which exchanges heat between the refrigeration system and the humidity evaporator under the power provided by the circulating pump;

[0013] A control system is configured to control the temperature in the box to be within a preset temperature range by the refrigeration system and / or the humidity evaporator and the heater, control the humidity in the box to be within a preset humidity range by the humidity evaporator and / or the temperature evaporator, and adjust the working parameters of the refrigeration system according to the actual temperature value collected by the dew point temperature sensor in real time, so that the refrigeration system adjusts the temperature of the cooling liquid.

[0014] Optionally, the box is provided with a temperature and humidity sensor and a pressure sensor, and a humidification system is connected to the outside of the box, the humidification system comprising a water tank and a water temperature sensor for detecting the water temperature of the water tank; the water tank is connected to a compressed gas source through a pipeline, and a flow meter is connected to the pipeline between the water tank and the compressed gas source;

[0015] The control system is configured to control the water temperature of the water tank and the flow of the compressed gas source according to the real-time temperature and humidity values and pressure values collected by the temperature and humidity sensor and the pressure sensor, and the water temperature value collected by the water temperature sensor and the flow value of the flow meter, so as to control the humidification amount.

[0016] Optionally, a water replenishment adjusting valve is installed on the pipeline connected between the water tank and the box, and the control system is configured to determine whether humidification is needed according to the real-time temperature and humidity values and pressure values collected by the temperature and humidity sensor and the pressure sensor, so as to control the opening and closing of the water replenishment adjusting valve.

[0017] Optionally, a vacuum system is further included, which is connected to the box to adjust the pressure in the box; a vacuum adjusting valve is installed on the pipeline between the vacuum system and the box, and the control system is configured to control the opening degree or on-off of the vacuum adjusting valve and the operation of the vacuum system according to the set pressure value in the box.

[0018] Optionally, a pressure relief adjusting valve is installed on the inner side wall of the box, and the pressure relief adjusting valve is connected to the control system; the control system is configured to control the opening degree or on-off of the pressure relief adjusting valve according to the set pressure value in the box.

[0019] Optionally, the control system comprises a controller signal collector and a PID / switching value calculation output module, and the controller signal collector is configured to collect the signals of the pressure sensor, the temperature and humidity sensor, the dew point temperature sensor and the water temperature sensor.

[0020] The PID / switching value calculation output module is configured to receive the signals and calculate and output an adjusting signal.

[0021] In addition, the application provides a control method of the low-temperature and low-pressure test box, which uses the low-temperature and low-pressure test box and comprises the following steps:

[0022] The temperature in the box is controlled to be kept in a preset temperature range by a refrigeration system, and the humidity in the box is controlled to be kept in a preset humidity range by a humidity evaporator.

[0023] An actual temperature value of the dew point temperature sensor is collected.

[0024] The working parameter of the refrigeration system is controlled and adjusted according to the actual temperature value, so that the refrigeration system adjusts the temperature of the cooling liquid until the actual temperature value of the surface of the humidity evaporator reaches the dew point temperature value range corresponding to the preset temperature and humidity value in the box.

[0025] Optionally, the application comprises the following steps:

[0026] The temperature and humidity value and the pressure value in the box are collected.

[0027] The water temperature of a water tank connected to a humidification system outside the box is detected; the water tank is connected to a compressed gas source by a pipeline, and a flow control device is connected to the pipeline between the water tank and the compressed gas source.

[0028] The control system adjusts the water temperature of the water tank and the flow of the compressed gas source according to the temperature and humidity value, the pressure value, the water temperature value and the flow control device to control the humidification amount.

[0029] Optionally,

[0030] The temperature and humidity value and the pressure value in the box are collected.

[0031] The control system determines whether humidification is needed according to the temperature and humidity value and the pressure value to control the opening and closing of the water supplementing adjusting valve.

[0032] Optionally, the control system controls the opening degree of the vacuum adjusting valve and the pressure relief adjusting valve according to the set pressure value in the box.

[0033] The application has the following beneficial effects: the low-temperature and low-pressure test box and the humidity control method thereof are provided, the temperature in the test box and the temperature of the cooling liquid are controlled by a refrigeration system, the dew point temperature of the surface of a humidity evaporator and the temperature and humidity dew point temperature in the test box are controlled by the cooling liquid to control the humidity balance, and the humidity is supplemented by a humidification module; the pressure value in the box is controlled by a vacuum system, and the valve opening degree of the vacuum system is controlled to adjust the pressure, so that the test box can simulate the low-temperature and low-pressure and humidity stable environment state of an aircraft in high-altitude flight. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0035] Figure 1 A structural schematic diagram of a low-temperature and low-gas-pressure test box provided by the embodiment of the present application is shown in the figure.

[0036] Figure 2 A structural schematic diagram of an internal system of a low-temperature and low-gas-pressure test box provided by the embodiment of the present application is shown in the figure.

[0037] Figure 3 A step flow of a control method of a low-temperature and low-gas-pressure test box provided by the embodiment of the present application is shown in the figure. Figure 1

[0038] Figure 4 A step flow of a control method of a low-temperature and low-gas-pressure test box provided by the embodiment of the present application is shown in the figure. Figure 2

[0039] Figure 5 A step flow of a control method of a low-temperature and low-gas-pressure test box provided by the embodiment of the present application is shown in the figure. Figure 3

[0040] In the figure: 1, refrigeration system; 2, cooling liquid; 3, humidity evaporator; 4, dew point temperature sensor; 5, circulating pump; 6, pressure sensor; 7, temperature and humidity sensor; 8, water temperature sensor; 9, vacuum system; 10, controller signal collector; 11, PID / switching value calculation output module; 12, temperature evaporator; 13, water tank; 14, compressed gas source; 15, flow meter; 16, water supplementing regulating valve; 17, vacuum regulating valve; 18, pressure relief regulating valve. DETAILED DESCRIPTION

[0041] The embodiment of the present application provides a low-temperature and low-gas-pressure test box and a humidity control method thereof, so that the test box can keep humidity stable under low temperature and low pressure.

[0042] ​​​In order to make the inventive purposes, features and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the following described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0043] The technical solutions of the present application will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0044] Embodiments

[0045] Please refer to Figure 1 and Figure 2 , Figure 1 A structure schematic diagram of a low-temperature and low-gas-pressure test box provided by the embodiments of the present application; Figure 2 A structure schematic diagram of an internal system of a low-temperature and low-gas-pressure test box provided by the embodiments of the present application, as shown in Figure 1 and Figure 2 A low-temperature and low-gas-pressure test box, comprising a box body, wherein the box body is internally provided with:

[0046] A humidity evaporator 3 for controlling humidity stability and / or refrigeration in the box body;

[0047] The refrigeration system 1 comprises a temperature evaporator 12 and a humidity evaporator liquid cooler (not shown in the figure), wherein the temperature evaporator 12 is used to realize refrigeration function or / and dehumidification function; and the humidity evaporator liquid cooler is used to constantly cool the temperature of the cooling liquid 2;

[0048] A heater for temperature adjustment;

[0049] An air agitator for air circulation;

[0050] A dew point temperature sensor 4 arranged on the surface of the humidity evaporator 3 for real-time detection of the actual temperature value of the surface of the humidity evaporator 3; or detection of the temperature inside or outside the liquid flow pipeline of the humidity evaporator 3;

[0051] A cooling liquid 2 for heat exchange between the refrigeration system 1 and the humidity evaporator 3 under the power provided by the circulating pump 5;

[0052] The control system is used to control the temperature in the box to be kept in a preset temperature range by the refrigeration system 1 and / or the humidity evaporator 3 and the heater, control the humidity in the box to be kept in a preset humidity range by the humidity evaporator 3 and / or the temperature evaporator 12, and adjust the working parameters of the refrigeration system 1 according to the actual temperature value collected by the dew point temperature sensor 4 in real time, so that the refrigeration system 1 adjusts the temperature of the cooling liquid 2.

[0053] Specifically, the refrigeration system 1 includes a compressor, a condenser, a throttling device and an evaporator 12, the cooling liquid 2 circulates in the refrigeration system 1 and the temperature evaporator 12, the refrigeration system 1 controls the temperature in the test box, and the temperature of the cooling liquid is kept constant by the humidity evaporator liquid cooler in the refrigeration system 1; the temperature of the cooling liquid 2 is controlled separately, so that the temperature of the cooling liquid 2 is kept constant, the preset temperature value in the box is kept, and the preset low temperature in the test box is kept.

[0054] The humidity evaporator 3 is connected with the dew point temperature sensor 4, and the cooling liquid 2 circulates in the humidity evaporator 3 by the circulating pump 5, so that the dew point temperature on the surface of the humidity evaporator 3 is kept constant.

[0055] Specifically, the dew point temperature refers to the temperature at which the air is cooled to saturation under the condition that the water vapor content and the air pressure do not change, that is, the temperature at which the water vapor in the air becomes dew is called the dew point temperature. The smaller the dew point temperature is than the temperature of the surrounding environment, the smaller the possibility of dew formation is.

[0056] Since the temperature of the cooling liquid 2 is controlled by the refrigeration system 1 to be kept constant at a low temperature, the dew point temperature on the surface of the humidity evaporator 3 is controlled by circulating the cooling liquid 2 in the humidity evaporator 3, and the constant temperature of the cooling liquid 2 corresponds to the dew point temperature value corresponding to the temperature and humidity value set in the box, the cooling liquid 2 is circulated in the humidity evaporator 3 by the circulating pump 5, the dew point temperature on the surface of the humidity evaporator 3 in the box is indirectly controlled to correspond to the dew point temperature value corresponding to the temperature and humidity value set in the box, so that the humidity in the box is kept constant at a low temperature and low air pressure, the surface of the humidity evaporator 3 is prevented from being rapidly frozen at a low temperature, and the humidity in the test box is controlled.

[0057] In a specific embodiment, since the surface temperature of the humidity evaporator 3 is kept constant near the dew point temperature set in the test box, the humidity in the test box is stable and kept at a certain humidity at a low temperature, for example, at-20℃ / 70r.h%, the surface of the humidity evaporator 3 is slowly frozen to prolong the constant time of the temperature and humidity, and the method of controlling the dew point temperature of the humidity evaporator 3 effectively prevents the surface of the humidity evaporator 3 from being rapidly frozen at a low temperature, which leads to the loss of control of the temperature and humidity.

[0058] In addition, the pressure sensor 6 is used for detecting the pressure in the box; the temperature and humidity sensor 7 is used for detecting the temperature and humidity in the box;

[0059] Specifically, the preset temperature and humidity value and the air pressure value are set in the box, the air pressure in the box is monitored in real time by the pressure sensor 6, the temperature and humidity value of the box is monitored in real time by the temperature and humidity sensor 7 and is sent to the control system, the control system calculates and controls the constant temperature of the cooling liquid 2, the dew point temperature of the surface of the humidity evaporator 3 and the dew point temperature of the temperature and humidity set in the box to keep consistent according to the temperature and humidity value and the air pressure value in the box.

[0060] Working principle: the control system controls the refrigeration system 1 to operate so that the temperature in the box and the temperature of the cooling liquid 2 are constant, and the cooling liquid 2 with constant temperature circulates in the humidity evaporator 3, the dew point temperature of the surface of the humidity evaporator 3 and the dew point temperature of the temperature and humidity set in the box are controlled to keep consistent to control the humidity in the box, which effectively avoids the rapid icing of the surface of the humidity evaporator 3 in the low-temperature state, resulting in the loss of control of temperature and humidity.

[0061] Further, the temperature and humidity sensor 7 and the pressure sensor 6 are arranged in the box, the humidification system is connected to the outside of the box, the humidification system comprises a water tank 13 and a water temperature sensor 8 for detecting the water temperature of the water tank 13; the water tank 13 is connected to the compressed air source 14 through a pipeline, and the pipeline between the water tank 13 and the compressed air source 14 is connected with a flow meter 15;

[0062] The control system is used for controlling the water temperature of the water tank 13 and the flow of the compressed air source 14 according to the real-time temperature and humidity value and the pressure value in the box collected by the temperature and humidity sensor 7 and the pressure sensor 6, and the water temperature value collected by the water temperature sensor 8 and the flow value of the flow meter 15, so as to realize the control of the humidification amount.

[0063] Specifically, compared with the traditional boiling water supplementing air method, the water temperature and flow control mode is adopted in the embodiment, the water temperature in the water tank 13 is collected in real time by the water temperature sensor 8 and is sent to the control system, the control system adjusts the water temperature of the water tank 13 according to the dew point temperature value corresponding to the temperature and humidity value set in the box and the pressure value, so that the water temperature in the water tank 13 remains constant. The compressed air source 14 takes away the saturated steam through the constant water temperature of the water tank 13 to keep the humidity of the box constant.

[0064] In addition, the water tank 13 is connected to the compressed air source 14 through a pipeline, the pipeline between the water tank 13 and the compressed air source 14 is connected with a flow meter 15, and the pipeline connected between the water tank 13 and the box is provided with a water supplementing adjusting valve 16, and the control system is used for adjusting the flow of the flow meter 15 and adjusting the opening and closing of the water supplementing adjusting valve 16.

[0065] In a specific embodiment, the humidity is controlled by adjusting the flow rate of the flow meter 15, the water tank 13 is provided with a water temperature sensor 8, and the compressed air source 14 removes saturated steam through the constant water temperature of the water tank 13 to keep the humidity of the tank constant. This method greatly reduces the temperature of the water vapor, and the heat released by the saturated steam entering the tank at low temperature is small, achieving the effect of energy saving and stable humidity.

[0066] Further, the water tank 13 is provided with a water supplementing adjusting valve 16 on the pipeline connected to the tank, and the control system judges whether humidification is needed according to the real-time temperature and humidity values and pressure values collected by the temperature and humidity sensor 7 and the pressure sensor 6 in the tank to control the opening and closing of the water supplementing adjusting valve 16.

[0067] Specifically, when the tank does not need to control humidity, the humidity control function is closed through the water supplementing adjusting valve 16.

[0068] Further, a vacuum system 9 is further included, which is in communication with the tank for adjusting the pressure in the tank; the vacuum system 9 is provided with a vacuum adjusting valve 17 on the pipeline between the tank, and the control system is used to control the opening degree or on-off of the vacuum adjusting valve 17 and the operation of the vacuum system 9 according to the set pressure value in the tank.

[0069] The tank is provided with a pressure relief adjusting valve 18 on the side wall of the tank, and the pressure relief adjusting valve 18 is connected to the control system; the control system is used to control the opening degree or on-off of the pressure relief adjusting valve 18 according to the set pressure value in the tank.

[0070] Specifically, the vacuum system 9 is in communication with the tank, and the vacuum system 9 can adjust the pressure in the tank to a preset value, such as the pressure of a simulated aircraft flying at high altitude, so as to set a low pressure in the tank.

[0071] The control system acquires the pressure value in the tank and compares it with the preset pressure value to calculate and judge whether to start the vacuum system 9, and controls the pressure drop speed or pressure relief speed through the vacuum adjusting valve 17 and the pressure relief adjusting valve 18 to keep the pressure in the tank constant.

[0072] Further, the control system includes a controller signal collector 10 and a PID / switching value calculation output module 11, and the controller signal collector 10 is used to collect the signals of the pressure sensor 6, the temperature and humidity sensor 7, the dew point temperature sensor 4, and the water temperature sensor 8.

[0073] The PID / switching value calculation output module 11 is used to receive the signals and calculate and output adjusting signals.

[0074] The PID / switching value calculation output module 11 is used for receiving the signals and calculating the deviation values of the actual parameter values of each module from the preset parameter values to control the balance and stability of the pressure, temperature and humidity, temperature of the cooling liquid and water temperature of the water tank 13 of the cabinet, and can control the opening degree of the compressed air source 14 and the water supplement adjusting valve 16 to adjust the humidification amount, and control the opening degree of the vacuum adjusting valve 17 and the pressure relief adjusting valve 18 to adjust the pressure in the cabinet.

[0075] In conclusion, the embodiment of the application provides a low-temperature and low-pressure test chamber and a test chamber control method, the temperature in the test chamber and the temperature of the cooling liquid are controlled by the refrigeration system, the humidity balance is controlled by controlling the dew point temperature of the surface of the humidity evaporator and the dew point temperature in the test chamber to be consistent, and the humidity is supplemented by the humidification module, the pressure value in the cabinet is controlled by the vacuum system, and the valve opening degree of the vacuum system is controlled to adjust the pressure, so that the test chamber can simulate the low-temperature and low-pressure environment and the stable humidity environment in which the aircraft is located when flying at high altitude.

[0076] Embodiment two:

[0077] A humidity control method is provided, and the low-temperature and low-pressure cabinet is used, as shown in the figure, comprising the following steps: Figure 2

[0078] Step 101: The temperature in the cabinet is controlled to be kept in a preset temperature range by the refrigeration system 1 and / or the humidity evaporator 3 and the heater.

[0079] Specifically, the real-time temperature and humidity values in the cabinet are collected by the control system, and the refrigeration system 1 is controlled to operate to control the temperature in the cabinet to be kept in a preset temperature range.

[0080] Step 102: The actual temperature value of the dew point temperature sensor 4 is collected; the actual temperature value of the dew point temperature sensor 4 is collected by the control system.

[0081] Step 103: The working parameters of the refrigeration system 1 are adjusted according to the actual temperature value to adjust the temperature of the cooling liquid 2, until the actual temperature value of the surface of the humidity evaporator reaches the dew point temperature value corresponding to the preset temperature and humidity value in the cabinet.

[0082] Specifically, the analog signals of the pressure sensor 6, the temperature and humidity sensor 7 and the dew point temperature sensor 4 in the cabinet are collected by the control system, and these analog signals are converted into signals, respectively, and the PID / switching value calculation output module 11 receives each signal and calculates the deviation values of each actual parameter value from the preset parameter value and outputs an adjusting signal to adjust the dew point temperature of the cabinet, the temperature of the cooling liquid 2 and the dew point temperature of the surface of the humidity evaporator 3 to be consistent, so as to control the temperature and humidity balance of the cabinet.​

[0083] Further, as shown in Figure 3 the steps include:

[0084] Step 201: Collect the temperature and humidity values and pressure values in the box; Collect the real-time temperature and humidity values and pressure values in the box through the temperature and humidity sensor 7 and the pressure sensor 6.

[0085] Step 202: Detect the water temperature of the water tank 13 connected to the humidification system outside the box; The water tank 13 is connected to the compressed air source 14, and the flow meter 15 is connected to the pipeline between the water tank 13 and the compressed air source 14; The water temperature of the water tank 13 of the humidification system is detected by the water temperature sensor 8, the water tank 13 is provided with the power of water spraying by the compressed air source 14, and the flow of the compressed air source 14 is detected by the flow meter 15 connected to the pipeline between the water tank 13 and the compressed air source 14.

[0086] Step 203: The control system adjusts the water temperature of the water tank 13 and the flow of the compressed air source 14 according to the temperature and humidity values, the pressure values, the water temperature values and the flow values of the flow meter 15 to realize the control of the humidification amount.

[0087] Specifically, the control system adjusts the water temperature of the water tank 13 and the flow of the compressed air source 14 according to the temperature and humidity values, the pressure values, the water temperature values and the flow values of the flow meter to realize the control of the humidification amount.

[0088] Further, as shown in Figure 4 the steps include:

[0089] Step 301: Collect the temperature and humidity values and pressure values in the box; Collect the real-time temperature and humidity values and pressure values in the box through the temperature and humidity sensor 7 and the pressure sensor 6.

[0090] Step 302: The control system determines whether humidification is needed according to the temperature and humidity values and pressure values to control the opening and closing of the water supplementing adjusting valve. When the humidity needs to be supplemented, the control system controls the water supplementing adjusting valve to open, and when the humidification is not needed, the control system controls the water supplementing adjusting valve to automatically close.

[0091] Step 303: The control system controls the opening of the vacuum adjusting valve and the pressure relief adjusting valve according to the set pressure value in the box. The pressure value in the box is controlled by the vacuum adjusting valve and the pressure relief adjusting valve to reach the preset pressure value in the box, so as to realize the low pressure state of the simulated aircraft flying at high altitude.

[0092] In summary, the low-temperature and low-gas-pressure test box and the humidity control method thereof provided by the embodiments of the present application can collect analog signals of the pressure sensor, the temperature and humidity sensor, the dew point temperature sensor and the water temperature sensor through the control system, convert the analog signals into signals, calculate the signals and output an adjusting signal to control the constant temperature of the cooling liquid, the dew point temperature of the surface of the humidity evaporator and the set temperature and humidity dew point temperature of the box body to be consistent, and control the humidification system and the vacuum system to supply humidity and air pressure to the box body, so that each parameter set by the box body is stably balanced or linearly changed.

[0093] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the present application. Although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent features. The modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A low temperature, low pressure test chamber, characterized by, The box is provided with: a humidity evaporator for controlling humidity stability and / or refrigeration in the box; a refrigeration system including a temperature evaporator for realizing refrigeration function or / and dehumidification function and a humidity evaporator liquid cooler for constant cooling of liquid temperature; a heater for temperature adjustment; an air agitator for air circulation; a dew point temperature sensor arranged on the surface of the humidity evaporator for real-time detection of actual temperature value of the surface of the humidity evaporator or detection of temperature inside or outside the liquid flow pipeline of the humidity evaporator; cooling liquid for heat exchange between the refrigeration system and the humidity evaporator under the power provided by a circulating pump; a control system for controlling the temperature in the box to be kept in a preset temperature range by the refrigeration system and / or the humidity evaporator and the heater, controlling the humidity in the box to be kept in a preset humidity range by the humidity evaporator or / and the temperature evaporator, and adjusting the working parameters of the refrigeration system according to the actual temperature value collected by the dew point temperature sensor in real time to make the refrigeration system adjust the temperature of the cooling liquid; the box is provided with a temperature and humidity sensor and a pressure sensor, and the control system is used to collect real-time temperature and humidity values and pressure values in the box according to the temperature and humidity sensor and the pressure sensor; the air pressure in the box is monitored in real time by the pressure sensor, and the temperature and humidity values of the box are monitored in real time by the temperature and humidity sensor and sent to the control system, and the control system calculates and controls the constant temperature of the cooling liquid, the dew point temperature of the surface of the humidity evaporator and the set temperature and humidity dew point temperature of the box to be consistent according to the obtained temperature and humidity values and air pressure values in the box.

2. The cryogenic low-pressure test chamber of claim 1, wherein, The box is connected with a humidification system, the humidification system includes a water tank and a water temperature sensor for detecting the water temperature of the water tank, the pipeline of the water tank is connected with a compressed gas source, and a flow meter is connected on the pipeline between the water tank and the compressed gas source; the control system is also used to control and adjust the water temperature of the water tank and the flow of the compressed gas source according to the water temperature value collected by the water temperature sensor and the flow value of the flow meter to realize the control of the humidification amount.

3. The cryogenic low-pressure test chamber of claim 2, wherein, A water supplement adjustment valve is installed on the pipeline connected between the water tank and the box, and the control system judges whether humidification is needed according to the real-time temperature and humidity values and pressure values in the box collected by the temperature and humidity sensor and the pressure sensor to control the opening and closing of the water supplement adjustment valve.

4. The cryogenic low-pressure test chamber of claim 3, wherein, A vacuum system is also included, which is communicated with the box for adjusting the pressure in the box, a vacuum adjustment valve is installed on the pipeline between the vacuum system and the box, and the control system is used to control the opening degree or on-off of the vacuum adjustment valve and the operation of the vacuum system according to the set pressure value in the box.

5. The cryogenic hypobaric test chamber of claim 4, wherein, A pressure relief adjustment valve is installed on the inner side wall of the box, and the control system is connected with the pressure relief adjustment valve; the control system is used to control the opening degree or on-off of the pressure relief adjustment valve according to the set pressure value in the box.

6. The cryogenic low-pressure test chamber of claim 2, wherein, The control system comprises a controller signal collector and a PID / switching value calculation output module, the controller signal collector is used for collecting signals of the pressure sensor, the temperature and humidity sensor, the dew point temperature sensor and the water temperature sensor; the PID / switching value calculation output module is used for receiving the signals and calculating and outputting an adjusting signal.

7. A humidity control method for a low-temperature low-pressure test chamber, characterized by, The low-temperature low-pressure test box as claimed in claim 5 is used, comprising the following steps: The temperature in the box is controlled to be kept in a preset temperature range by a refrigeration system and / or a humidity evaporator and a heater; the humidity in the box is controlled to be kept in a preset humidity range by the humidity evaporator; An actual temperature value of the dew point temperature sensor is collected; The working parameter of the refrigeration system is adjusted according to the actual temperature value, so that the refrigeration system adjusts the temperature of the cooling liquid until the actual temperature value of the surface of the humidity evaporator reaches the dew point temperature value range corresponding to the preset temperature and humidity value in the box.

8. The humidity control method of a low-temperature low-pressure test chamber according to claim 7, wherein Comprising the following steps: The temperature and humidity value and the pressure value in the box are collected; The water temperature of a water tank connected with a humidification system outside the box is detected; the water tank is connected with a compressed gas source through a pipeline, and a flow control device is connected to the pipeline between the water tank and the compressed gas source; The control system adjusts the water temperature of the water tank and the flow of the compressed gas source according to the temperature and humidity value, the pressure value, the water temperature value and the flow control device to control the humidification amount.

9. The humidity control method of the low-temperature low-pressure test box according to claim 7, characterized in that, The temperature and humidity value and the pressure value in the box are collected; The control system determines whether humidification is needed according to the temperature and humidity value and the pressure value to control the opening and closing of the water supplement adjusting valve.

10. The humidity control method of the low-temperature low-pressure test box according to claim 9, characterized in that, The control system controls the opening degree of the vacuum system, the vacuum adjusting valve and the pressure relief adjusting valve according to the set pressure value in the box.

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