The environmental aging test chamber is a device used to simulate the aging situation of products under various environmental conditions. Its basic working principle is to control the temperature, humidity, light and other environmental factors inside the chamber to subject the product to long-term testing in the simulated environment, thereby accelerating the aging process of the product and evaluating its reliability and durability in the long term.

（1） Temperature control principle

1. Heating system: Environmental aging test chambers are usually equipped with heating devices, such as electric heating wires or heating tubes. When it is necessary to increase the temperature inside the box, the control system will send instructions to the heating device to generate heat during operation. These heats are evenly distributed in the test chamber through the air circulation system, thereby raising the temperature inside the chamber to the set value.

2. Refrigeration system: In order to achieve low-temperature environment or accurate temperature control, the test chamber is also equipped with a refrigeration system. The common refrigeration method is compressor refrigeration, which compresses the refrigerant into high-temperature and high-pressure gas through the compressor, and then turns it into high-pressure liquid after passing through the condenser for heat dissipation. It is then expanded and depressurized through a throttling device to become a low-temperature and low-pressure gas-liquid mixture, which absorbs heat in the evaporator and lowers the temperature inside the box. The control system adjusts the operation of the refrigeration system based on the set temperature value to maintain stable temperature inside the box.

（2） Principle of humidity control

1. Humidification system: When it is necessary to increase the humidity inside the box, the humidification system will work. Generally, ultrasonic humidification or steam humidification is used. Ultrasonic humidification is achieved by using an ultrasonic transducer to transform water mist into tiny water droplets, which are then sent into a test chamber to increase the humidity in the air. Steam humidification is achieved by heating water to produce water vapor, which is then introduced into the test chamber to increase humidity.

2. Dehumidification system: When it is necessary to reduce humidity, the dehumidification system will be activated. Common dehumidification methods include freeze dehumidification and adsorption dehumidification. Freezing dehumidification is the use of a refrigeration system to condense water vapor in the air into water droplets, which are then discharged from the box through a drainage device to reduce air humidity. Adsorption dehumidification is the use of desiccants (such as silica gel) to adsorb moisture from the air. When the desiccant is saturated, it can be regenerated by heating to restore its moisture absorption capacity and reused.

（3） Principle of Light Control

For some products that require light aging testing, the environmental aging test chamber will be equipped with a lighting system. Lighting systems typically use light sources such as fluorescent lamps, xenon lamps, or ultraviolet lamps. The control system can adjust parameters such as light intensity, light duration, and light cycle. For example, in simulating sunlight, xenon lamps can be used as light sources because their spectral characteristics are similar to sunlight, which can better simulate outdoor lighting environments. The light generated by the lighting system shining on the product can cause photochemical reactions, thereby accelerating the aging of the product.