The principle of the high and low temperature test chamber is how the huanyi instrument takes you to understand

Principle of high and low temperature test chamber:

1. Refrigeration system of high and low temperature test chamber: The refrigeration system is one of the important parts of the comprehensive high and low temperature test chamber. Generally speaking, the refrigeration methods of high and low temperature test chambers are mechanical refrigeration and auxiliary liquid nitrogen refrigeration. The mechanical refrigeration adopts vapor compression refrigeration. They are mainly composed of compressors, condensers, throttling mechanisms and evaporators. Due to the temperature of our test the low temperature must reach -55 ℃, and it is difficult to meet the requirements of single-stage refrigeration. Therefore, the refrigeration method of the test chamber generally adopts cascade refrigeration.

The refrigeration system of the high and low temperature test chamber produced by Oke Instruments consists of two parts, called the high temperature part and the low temperature part, and each part is a relatively independent refrigeration system. The evaporation of the refrigerant in the high temperature part absorbs the heat of the refrigerant from the low temperature part and evaporates; the evaporation of the refrigerant in the low temperature part absorbs heat from the object to be cooled (the air in the test chamber) to obtain the cooling capacity. The high temperature part and the low temperature part are connected by an evaporative condenser, which is both the condenser of the high temperature part and the condenser of the low temperature part. The high temperature part of the high and low temperature test chamber adopts medium temperature refrigerant, and the low temperature part adopts low temperature refrigerant, and the temperature in the chamber can reach -70-150 ℃.

2. Heating system of high and low temperature test chamber: The heating system of high and low temperature test chamber is relatively simple compared to the refrigeration system. It is mainly composed of high-power resistance wires. Due to the large heating rate required by the test chamber, the heating system power of the test chamber is relatively large, and a heater is also provided on the bottom plate of the test chamber.

3. High and low temperature test chamber control system: The control system is the core of the comprehensive test chamber, which determines the heating rate, accuracy and other important indicators of the high and low temperature test chamber. At present, most of the controllers of the test chamber use PID control, and a few use the combination of PID and fuzzy control. Since the control system basically belongs to the category of software, and this part is generally used without problems.

4. High and low temperature test chamber sensor system: The sensors of the high and low temperature test chamber are mainly temperature and humidity sensors. The most commonly used temperature sensors are platinum groups and thermocouples. There are two kinds of humidity measurement methods: dry and wet bulb thermometer method and solid-state electronic sensor direct measurement method. Due to the low measurement accuracy of the wet and dry bulb method, the current test chamber is gradually replacing the wet and dry bulb with solid-state sensors to measure humidity.

5. Air circulation system of high and low temperature test chamber: The air circulation system generally consists of a centrifugal fan and a motor that drives it.