Hygrothermal test operation method for high-low temperature damp heat test box
Hygrothermal test operation method of high-low temperature damp heat test box The high/low temperature damp heat test box is through what kind of method to carry out the damp heat aging test, what is the working principle of the high/low temperature damp heat test box, and what is the operation mode of the high/low temperature damp heat test box. Let us take these doubts to explain in detail the analysis of the most professional high-low temperature heat and humidity chamber manufacturers in China:
Gutter Downspout Roll Forming Machine
Gutter Downspout Roll Forming Machine is the special equipment for continuous rolling and cold-forming on steel sheet. It adopts coiling steel sheet as the raw material, decoiling the coil, continuous rolling and cold-forming, automatically cut to the size and output the finished panel. The equipment adopts PLC control, AC frequency and adjusting the speed technology, and it realizes the continuous automatically production, therefore, it is really a new type of energy-saving and high-effective producing equipment for steel structure.
Main parameters of rain water gutter roll forming machine
Suitable to process: Color steel plate, galvanized sheet, aluminum coils,etc.
Width of the feeding material:According to the profile.
Rollers station: 18 rows.
Thickness of feeding material:0.3-0.8mm
Power:4+4kw
Size:8500*800*1500mm
Productivity: 8-12m/min
Diameter of shaft: 60mm
Weight: About 4.8 Tons
Voltage: 380V 50Hz 3phases
Roller material:Carbon Steel 45#
Material of the cutting : Cr12
Wall thickness of main forming machine: 16mm steel plate
Main frame of the machine:300 H steel
Components of line
1.Decoiler 1 unit
2.Roll Forming System 1 unit
3.Cutting Device 1 unit
4.Hydraulic Station 1 unit
5.PLC control system 1 unit
Working Flow:
Loading coil – decoiling – guide feeding – main roll forming – PLC system - hydrarlic cutting – finished products
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The high-low temperature hot and humid test chamber, as its name suggests, is an experimental instrument for aging products by simulating moisture heating gas. In the low-temperature and high-humidity case, the high-low temperature damp-heat test chamber will not only reduce the amount of added steam, but also cause the humid air inside the box because the added steam and air are not fully mixed, or the partial condensation occurs due to contact with the wall of the box. As the temperature rises and the previously described humidification process is not an isothermal process, the temperature in the chamber will increase.
The high-low temperature hot and humid test chamber produced by Jereh uses the principle of the exchange of moist heat and air directly in contact with the water surface:
High-low temperature wet heat test box steam humidification, such as using electric heating humidification, is divided into open and closed type. The response of the open type is slower, often with hysteresis, so humidity fluctuations are large, but the structure is simple and reliable. Closed steam pressure is greater than atmospheric pressure, between 0.1 ~ 0.3MPa, no lag, but need to be equipped with pressure reducing valve, solenoid valve, drain pipe, etc., the structure is complex, mostly used in large artificial climate chamber. Open type is mostly used in small and medium size.
When the air passes through the open water surface, heat and moisture exchange occurs with the water surface. According to the different water temperature, the high-low temperature damp-heat test chamber may only have damp heat exchange; it may also have both heat and moisture exchange, but also wet exchange, as well as moist heat exchange. Moist heat exchange is a temperature difference between air and water, heat exchange due to heat conduction, convection and radiation, and latent heat exchange is the result of evaporation (or condensation) of water vapor in the air and absorption (or release) of latent heat of vaporization. The total heat exchange amount is the algebraic sum of the heat exchange amount and the latent heat exchange amount.
When the air is in direct contact with the water surface, close to the water surface, due to the irregular movement of water molecules, the high-low temperature damp heat test chamber forms a saturated air boundary layer whose temperature is equal to the water surface temperature, and the concentration of water vapor molecule or vapor fraction. The pressure depends on the saturated air temperature of the boundary layer.
High-low temperature damp heat test box The wet-heat principle heats the water in the water tank by heating the water. The steam enters the damp heat box through the spray tube and humidifies the air in the box.
If the temperature of the boundary layer is higher than the temperature of the air above it, heat is transferred from the boundary layer to the air; otherwise, heat is transferred from the air to the boundary layer. If the molecular concentration of water vapor in the boundary layer is greater than the concentration of water vapor in the air above it (ie, the partial pressure of water vapor in the boundary layer is greater than the partial pressure of water vapor in air), the number of molecules of water vapor in the air will increase, and vice versa. . The former is called "evaporation" and the latter is called "condensation." During the evaporation process of the damp heat test chamber, the reduced water vapor molecules in the boundary layer are replenished by water molecules that jump out of the water surface; during the condensation process, excessive moisture molecules in the boundary layer will return to the water surface.
The air flow in the high-low temperature damp heat test box passes through the surface of the shallow water tray in the box, and this temperature is equal to the saturated air boundary area of ​​the water surface temperature for the wet heat exchange. When the concentration of vapor molecules in the boundary zone is greater than the molecular concentration of water vapor flowing through the gas stream, it is humidified, and vice versa.
It can be seen that the heat exchange between air and water depends on the temperature difference between the boundary layer and the air above it. The wet exchange and the resulting latent heat exchange depend on the concentration difference or partial pressure of water vapor molecules between the two. difference.
