High-low temperature damp heat test chamber humidification and dehumidification method

The humidification method is through the generation of cold steam, usually with ultrasonic method.

, high pressure spray method, centrifugal spray, etc. They convert water into micron-sized mists that are in a metastable state. If it gets heat, it will be converted into steam. If it is not heated, it will become water droplets. In the case of heat of the sample, the heat generated by the mist absorption test sample will be vaporized, and this heat will be converted into the latent heat of water to make the water vapor inside the box. The pressure rises to the humidity required for the test. The latent heat of water vapor is released on the refrigerating evaporator, and the humidification is completed by the heat exchange of the helium. This method has proved to be very effective in practice and has been used in some test chambers.

Dehumidification methods are currently the most widely used, one is the freezing dehumidification method, and the other is the solid moisture absorption dehumidification method. The former is to condense water vapor in the air on the surface cooler to form water or frost. Since the test process of the hot and humid chamber is usually long, the frosting of the surface cooler will affect the dehumidification effect. Generally, this phenomenon should be avoided as much as possible. In order to prevent the surface cooler from frosting, the temperature of the air cooler should be controlled at 0 °C. the above. At this time, when the humidity in the tank is described by the dew point, the dew point temperature is about 5 to 7 °C. This dew point temperature has been able to meet the requirements of the current test methods, and it is very convenient to use, so it is the most widely used. When a lower dew point is required, a solid moisture absorbent is typically employed to further the moisture absorbent. The surface water vapor pressure of such a moisture absorbent is on the order of several hundred to several tens of ppm, and a dew point temperature of about -70 ° C can be obtained. This method is very inconvenient to use or expensive to purchase specialized equipment. It is only used when there are tests with special requirements. For example, when the internal combustion engine is at a low temperature or a low temperature tank for running tests, it is required to use a large amount of air in the tank for fuel combustion. In order to prevent the water vapor in the new air from affecting the refrigeration in the evaporator of the low temperature box, it is necessary to use a solid moisture absorption principle to continuously run the wheel dehumidifier. At present, the price of such a dehumidifier is very expensive.