And the device should be simple and reliable.

Jigaot Air Conditioning Repair Q&A: How is the chiller controlled?

In an air conditioning system, the load on the air conditioner is usually continuous over time, but the load itself varies. Therefore, it is required that the chiller be able to adjust its cooling capacity widely according to changes in the load. The requirements for cooling capacity adjustment should include a wide range of adjustments, quick response to changes in load, low power consumption at low loads, and simple and reliable equipment.

In general air conditioning situations, the ultimate goal is always to maintain a certain indoor temperature or humidity. Therefore, even in simple air conditioning systems, there are cases where the energy of the chiller is directly controlled by an indoor temperature regulator or an indoor humidity regulator. However, in large-scale systems where there is significant system lag, many air-conditioned rooms, and higher precision requirements for temperature and humidity control, the above direct control method becomes very difficult. In such cases, generally, the suction pressure of the compressor or the outlet water temperature of the chilled water from the evaporator is used as the adjustable parameter for the chiller unit.

When the chiller operates automatically, there must be a reliable automatic protection device. For example, low suction pressure protection, high discharge pressure protection, low chilled water temperature protection (in shell-and-tube evaporators, to prevent the chilled water temperature from dropping below 0°C and causing ice formation which could damage the evaporator, a low water temperature protection system must be installed), and cooling water cut-off protection, etc.

Source of the article: http://blog.sina.com.cn/jigaokongtiao