sothermal Shock Tester Humidification and dehumidification principle
In this paper, the method of humidification and dehumidification of sothermal Shock Tester is studied and discussed in detail, which is helpful to the engineering application of humidification and dehumidification method in the development of new sothermal Shock Tester.
Sothermal Shock Tester In order to achieve the test conditions, it is unavoidable to humidify and dehumidify the sothermal Shock Tester. This paper intends to use a variety of methods in the hot and hot sockmal Shock Tester to analyze their respective advantages and disadvantages And the recommended conditions.
The process of humidification is actually to increase the water vapor pressure, the initial way of humidification is to spray the water to the sothermal Shock Tester, by controlling the water temperature to the water surface saturation pressure control. The surface of the wall of the water to form a larger surface, in this side of the box through the proliferation of the way to the box by adding water vapor pressure so that sothermal Shock Tester relative humidity increased, this method appeared in the fifties of last century. Because the control of the humidity at that time is mainly based on the mercury-electric contact type conductive table for the simple switch adjustment, for the large lagging hot water tank water temperature control adaptability is poor, so the control of the transition process is longer, can not meet the alternating hot and humid The demand for more humidification requirements, more importantly, when the spray on the wall of the box, inevitably there are drops of water on the test sample to the formation of different levels of pollution. At the same time on the tank drainage also has certain requirements.
With the development of sothermal wetting to alternating damp heat, the requirements for faster humidification reactivity, spray humidification has been unable to meet the requirements, steam humidification and shallow water dish humidification method began to be used and developed.
The saturated pressure of the water vapor increases as the water temperature rises, and when the water temperature is as high as the boiling point, the water vapor saturation pressure will exceed 100 kPa at a standard atmospheric pressure, and a special humidification steam boiler will spit steam to the sothermal Shock Tester humidification. The role will produce dehumidification effect, so that the humidity inside the box, in order to maintain the test conditions will increase the amount of humidification, and further increase the additional heat inside the box. And even there will continue to humidification, cooling and at the same time continue to dehumidification phenomenon.
The use of steam humidification with humidification fast, able to adapt to sothermal Shock Tester in the warming section on the need for large demand for humidification. So the method is widely used. The main drawback is the introduction of superheated steam into the box, increasing the heat inside the box. In the design to pay special attention to the impact of superheated steam on the system.
The shallow water dish humidifier has the advantages of two methods of steam humidification and spray humidification. The shallow water tray is designed with a sufficiently large water tray in the sothermal Shock Tester, where the heater is placed. The water vapor pressure of the water surface can continuously replenish water vapor into the air by diffusion and exchange of liquid, and by this type of humidified water vapor is not overheated. But because the water tray area can not be large, so the diffusion and exchange of liquid is not very intense. By appropriately heating the water of the water tray to be higher than the test temperature in the tank, the surface of the water tray increases with the temperature, the water vapor pressure rises high, and the difference between the water vapor pressure in the tank increases The diffusion of water vapor and the exchange of liquid. In order to meet the requirements of the sothermal Shock Tester humidification, the water temperature in the water tray does not require too much, and the excess heat of the water vapor is significantly reduced. This is more direct steam humidification method is better, the shortcomings of this method is to do low-humidity test due to the diffusion of water tray and the existence of the exchange of fluid, to get low humidity more difficult. Reduce the water temperature by cooling to reduce the humidity. As the current hot and humid box has been made with the incubator, in order to prevent the water tray to do low temperature test caused by the adverse, usually to the water out of the box, the use of equipment to increase the trouble. Also when the sothermal Shock Tester is not used for a long time, the water dish is easy to breed the microbiological effects of the equipment clean.
As the test requirements continue to change, the test sample in the test process to work and send a lot of heat, then usually use the compressor to its cooling, in the process of cooling the evaporator and the air to heat and mass exchange, The greater the heat, the more intense heat and mass exchange, sothermal Shock Tester water vapor will be removed by the evaporator, if the use of steam humidification difficult to achieve the test requirements of the high humidity conditions, so to meet the test requirements, there was another supercooled steam humidification law.