The difference between humidification and dehumidification in humidification and dehumidification 

1  Constant temperature and humidity test chamber in order to realize the testing conditions, inevitably of humidification and dehumidification of the box operation, here various approaches are currently widely used in test box with constant temperature and humidity in the analysis, pointed out their respective advantages and disadvantages and recommended conditions.

2 Many methods of constant temperature and humidity test chamber humidity representation, experimental apparatus, usually with the conceptual description of humidity relative humidity. The definition of relative humidity refers to the saturation vapor pressure of water vapor in the air pressure and the water temperature of the ratio is expressed as a percentage. By the water vapor saturation pressure nature knowable, saturated vapour pressure is a function of temperature, and water vapor may be independent of the air pressure, the people through a lot of experiments and finishing to seek to express the relationship between the water vapor saturation pressure and temperature, which has been shall be of the formula of gove project and stoichiometric amounts used. It is currently the meteorological departments humidity tables used.

3 Process test box with constant temperature and humidity humidifier is actually improving the water vapor pressure, initial humidification mode is to test the tank wall by spraying water, control the temperature of the water so that the water surface saturation pressure control. The wall of the box surface water to form larger surface, in the face through the spread box to box to join the vapor pressure to make the test box with constant temperature and humidity relative humidity increases, this method appeared in the fifty's of the last century. Because at that time the control of humidity is mainly simple adjustment by a mercury switch quantity electric contact type conductivity meter, poor adaptability for control of hot water tank of large lag and temperature control, so the transition process is longer, can not meet the needs of alternating hot and humid demands more on humidifying quantity, more important is in the tank wall spray inevitably, drops drench the formation of different levels of pollution in the sample on the sample. At the same time also has certain requirements on the drainage.

4 This method will soon be steam humidification and humidification of shallow dish replaced. But this method still has some advantages. Although the control transition process longer test box with constant temperature and humidity, but the stability of the system after the humidity fluctuation is smaller, more suitable for damp heat test. In addition to the humidification process steam is superheated does not increase the system of extra heat. Also, when the control spray water temperature which is lower than the temperature of test point requirements, spray water with dehumidifying function.

5 With the development of damp heat test by test box with constant temperature and humidity to alternating hot and humid, require humidification and quick response, spray humidification can not meet the requirements, the steam humidification and humidification of shallow dish method to be used and developed to start.