Protective measures of test chamber
2020-08-18
The test box is used to radiate a large amount of heat from the power product of the fast thermal cycle of the static fixed temperature test product for many different purposes. According to the designated room will not be able to perform the task correctly, and a pair of designated chambers will cost more than necessary. Each type of application requires a different design room for optimal performance, if it is to be achieved. The simplest is basically an insulated box with a heater and convection relying on the heat of the entire distribution chamber. Although the temperature does not exceed the total chamber volume very much, it may not be important if only a single product is being tested occupying a small part of the chamber. The temperature is required by using a basic level/off temperature controller. Better temperature control can be achieved by using heater proportional control.
The test box makes full use of where it is necessary to make a stricter temperature distribution in the chamber. This can only be made faster by using forced air circulation. Axial fans are light-loaded, but higher high-pressure centrifugal fans need to be properly loaded in densely populated conditions. The faster the air circulation between the load increase and the decrease of indoor air, so the heat transfer rate after the arrival time, the thermal stability of the load. Some means that the laboratory will need to be cooled below the ambient temperature. The choice is mechanical and cryogenic cooling. The refrigerant evaporative cooling compressor used in the mechanical system, the heat exchanger chamber converts the gas back to the liquid in a closed loop, forming an independent system. A typical single-stage system will achieve a temperature drop of about -40degC while a multi-stage cascade system is provided at a lower temperature. The cryogenic system also evaporates the liquid, but at the time the gas is discharged into the atmosphere, resulting in a simple but powerful system. Very low temperatures are easily reached due to the low boiling point of liquid nitrogen at room temperature or the temperature of liquid carbon dioxide used in these systems. But special transportation, storage and distribution arrangements are necessary for cryogenic liquids and high operating costs.
