The temperature and humidity test chamber, as well as the refrigeration system, are key components of the test chamber. Their quality directly affects the quality of the test chamber and has always been a focus and difficulty in the research and design of the test chamber.

The key to a refrigeration system lies not only in its equipment cooling rate and cooling effect. More importantly, it lies in its production and after-sales service. During the pre production process of the refrigeration system, it is necessary to maintain pressure, weld, evacuate, and fill with Freon. If there are any problems in the future, the after-sales cost will be high, mainly due to the difficulty of handling. So the refrigeration system is very important.

There are different types of refrigeration systems, such as refrigerators and air conditioners used in daily life. Each type of refrigeration has its own advantages and disadvantages. Today, we will explain in detail the main refrigeration systems for temperature and humidity control. The usual refrigeration methods are divided into three types: mechanical refrigeration, liquid nitrogen refrigeration, and a combination of mechanical refrigeration and liquid nitrogen refrigeration.

Mechanical refrigeration has become quite mature in refrigeration technology, which can be divided into single-stage refrigeration and cascade refrigeration. Cooling methods are also divided into air cooling and water cooling. At present, the refrigeration of small temperature and humidity test chambers in China mostly adopts the French "Taikang" fully enclosed air-cooled single-stage/binary compressor refrigeration method. For walk-in test chambers or rapid temperature change test chambers, semi enclosed compressors such as German Gulun and German Blog are often used. However, their cooling rate is limited, generally in the range of 1-10 ℃/min, not exceeding 15 ℃/min. For those with high cooling rate requirements, liquid nitrogen refrigeration can be used, or mechanical design can be used to separate the heating chamber from the cooling chamber. Liquid nitrogen has excellent refrigeration performance, with a boiling point of -195.8 ℃ at atmospheric pressure, a refrigeration low temperature of -150 ℃, and a cooling rate of over 60 ℃/min. As an industrial accessory product, liquid nitrogen is becoming increasingly cheaper, so liquid nitrogen refrigeration technology is gradually being applied to environmental testing equipment that requires high cooling rates and ultra-low temperatures.

Above, the selection of refrigeration system and refrigeration method for the current temperature and humidity test chamber is mainly based on specific test requirements, the size of the equipment, and the requirements for temperature and cooling rate.