The thermal shock chamber can simulate the transient environment between high and low temperatures. In order to judge whether the product reliability and stability and other parameters are qualified. It will provide you with a basis for predicting and improving the quality and reliability of your product. The hot and cold impact test chamber is used to detect the resistance of products such as electronics, automobiles, rubber, plastics, aerospace and advanced communications equipment under repeated changes of heat and heat.

In order to realize the test conditions, the cold and heat shock test chambers are inevitably required to perform humidification and dehumidification operations on the test chamber. This paper intends to analyze a large number of various methods used in the damp heat test chambers at present and points out their respective advantages and disadvantages. And recommended conditions.

Humidity is represented in many ways. For experimental equipment, the concept of relative humidity is often used to describe humidity. Relative humidity is defined as the ratio of the partial pressure of water vapour in the air to the saturated vapour pressure of water at that temperature and expressed as a percentage. According to the saturated pressure properties of water vapor, the saturation pressure of water vapor is only a function of temperature. Regardless of the air pressure at which water vapor can be exposed, people have sought to express the relationship between water vapor saturation pressure and temperature through a large amount of experimentation and consolidation. Measured in large quantities should be Goff Gretchen's formula. It is used by the current meteorological department to prepare the humidity checklist.

The process of humidifying the hot and cold shock test chamber is actually increasing the water vapor partial pressure. The initial method of humidifying is spraying water to the wall of the test chamber. By controlling the water temperature, the saturation pressure of the water surface is controlled. The water on the surface of the tank wall forms a large surface, and in this surface, the relative humidity in the test chamber is increased by adding vapor pressure to the inside of the tank through diffusion. This method appeared in the 1950s. Since the control of humidity at the time was mainly a simple switch quantity adjustment using a mercury-electricity contact type conductivity meter, the adaptability to the control of the water temperature of the large delay hot water tank was poor, so the control transition process was long and could not meet the alternating damp heat The need for more humidification requirements, more importantly, when spraying on the wall, there is inevitably water droplets on the test sample to form different levels of pollution. At the same time there are certain requirements for the drainage inside the box. Therefore, we used steam humidification and shallow water tray humidification at an early stage. Although its control transition process is long, the humidity fluctuation is small after the system is stable, and it is suitable for a constant damp heat test. In addition, the heat of vaporization during humidification does not increase the extra heat in the system. Also, the spray water has a dehumidifying effect when the temperature of the spray water is controlled to be lower than the point temperature required by the test.