众所周知恒温恒湿机它的温度系统有两个子系统，分别为加湿和除湿这两个子系统，而加湿一般采用蒸汽加湿，简单来讲就是将低压蒸汽直接注入箱内进行加湿。用这种方法加湿它的速度快，加湿控制更加灵敏，尤其是在降温时能很好地实现强制加湿。

　　而恒温恒湿机的除湿又有两种，机械制冷除湿和干燥除湿。所谓的机械制冷的除湿原理是将空气冷却到露点温度以下，使大于饱和含湿量的水汽凝结析出，这样就降低了湿度。干燥器则是利用气泵将试验箱内的空气抽出，并将干燥的空气注入，同时将湿空气送入可循环利用的干燥进行干燥，干燥完后又送入试验箱内，如此反复循环进行除湿。

　　恒温恒湿机的加湿系统与加热系统大致一样;它是加热器加热水变成蒸汽过程;完成加湿目的。降湿系统也是靠制冷系统完成，蒸发器放在设备里面;里面高湿气体会见冷的物体冷凝成液体;如此反复箱体的高湿气体会很少，从而达到降湿目的

It is well known that there are two subsystems in the temperature system of constant temperature and humidity machine, namely, humidification and dehumidification subsystems. Steam humidification is generally used for humidification. Simply speaking, low pressure steam is injected directly into the box for humidification. With this method, the humidification speed is faster and the humidification control is more sensitive. Especially when the temperature is lowered, the forced humidification can be well realized.

There are two kinds of dehumidification of constant temperature and humidity machine, mechanical refrigeration dehumidification and drying dehumidification. The so-called dehumidification principle of mechanical refrigeration is to cool air below dew point temperature, so that water vapor with more than saturated moisture content condenses out, thus reducing humidity. The dryer uses an air pump to extract the air from the test box and inject the dry air into it. At the same time, the wet air is sent to the recyclable drying for drying. After drying, it is sent to the test box again and again for dehumidification.

The humidifying system of constant temperature and humidity machine is similar to that of heating system. It is the process of heating water to steam in heater and completes the purpose of humidifying. The dehumidification system is also completed by the refrigeration system, the evaporator is placed in the equipment; the high humidity gas inside meets the cold object to condense into liquid; so the high humidity gas in the repeated box body will be very few, so as to achieve the purpose of dehumidification.