System and principle of constant temperature and humidity test chamber

NOKI Chamber pm5:36

The constant temperature and humidity test chamber mainly has five systems, namely control, heating, cooling, humidity and air circulation systems. The following is a brief introduction to the Cobb test equipment system and the principle of the constant temperature and humidity test box, I hope it will be helpful for everyone to understand and use the constant temperature and humidity test box.

Control system:

The control part is the core of the constant temperature and humidity test box, which determines the important indicators such as the temperature and accuracy of the test box. The controllers of the existing constant temperature and humidity test chambers mostly adopt PID control, and a few adopt the control method that combines PID and fuzzy control.

Heating system:

The heating system of the constant temperature and humidity test chamber is mainly composed of high-power resistance wires, which is simpler than the refrigeration system. Because the constant temperature and humidity test box requires a higher heating rate, the heating system power is relatively large, and the bottom plate of the test box is also equipped with a heater.

Refrigeration system:

The refrigeration system is one of the important parts of the constant temperature and humidity test chamber. Generally speaking, the refrigeration method of the test chamber is mechanical refrigeration and auxiliary liquid nitrogen refrigeration.

Vapor compression refrigeration is a widely used and economical refrigeration method in artificial refrigeration.

Vapor compression refrigeration includes single-stage refrigeration, multi-stage refrigeration and compound refrigeration, mainly composed of compressor, condenser, throttling mechanism and evaporator.

Since the test temperature is as low as -55°C, single-stage refrigeration is difficult to meet the requirements, and the constant temperature and humidity test box generally uses compound refrigeration.

Humidity system:

The humidity system is divided into two subsystems: humidification and dehumidification. The constant temperature and humidity test box has two dehumidification methods: mechanical freezing dehumidification and dryer dehumidification.

(1) The dehumidification principle of mechanical freezing and dehumidification is to cool the air below the dew point temperature, condense and precipitate water that exceeds the saturated humidity, and reduce the humidity.

(2) Dryer dehumidification is to use an air pump to extract the air in the test box, inject dry air, and at the same time send the moisture to a recyclable dryer for drying, and then send it to the test box after drying, and repeat the cycle of dehumidification.

(3) At present, most comprehensive test chambers use the former dehumidification method. The latter dehumidification method can make the dew point temperature lower than 0°C, which is suitable for occasions with special requirements, but the cost is higher.

Air circulation system:

Provides air circulation in the constant temperature and humidity test chamber, which is generally composed of a centrifugal fan and a driving motor.

Principle of constant temperature and humidity test chamber

The temperature adjustment of the constant temperature and humidity box is to collect data through the temperature sensor, adjust it through the temperature controller (micro-information processor), increase the temperature through the air heating unit or reduce the temperature through the cooling solenoid valve, so as to achieve the temperature required for control The adjustment of the tank is through the built-in adsorption and absorption data, through the control (micro-information processor adjustment), connect the heating element of the water tank, increase the blood in the water tank by evaporating the water in the water tank or adjust the cooling solenoid valve to achieve dehumidification, so as to achieve the control. Required capacity.

The constant temperature and humidity test box is used to test the performance of materials in the environment, and test the heat resistance, cold resistance, dry resistance and moisture resistance of various materials. It is suitable for the quality inspection of electronics, electrical appliances, mobile phones, communications, instruments, vehicles, plastics, metals, food, chemicals, building materials, medical care, aerospace and other products.

The contents mentioned above are related to the principles of the constant temperature and humidity test chamber. If you want to know more about the constant temperature and humidity chamber, I hope Shiva can be helpful to you. You can contact online customer service, we will serve you wholeheartedly.

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