The air-cooled chiller unit has three operating modes:

·Mechanical cooling mode:

When the outdoor temperature is higher than the indoor return air temperature, the three-way valve opens normally in position A and closes in position B. The return water from the data center directly enters the generator for cooling. The compressor and air-cooled condenser are both operating in mechanical refrigeration mode.

·Mechanical cooling mode+natural cooling mode:

When the outdoor temperature is lower than the indoor return air temperature, the three-way valve opens in position B and closes in position A. The return water directly enters the natural cooling coil and is cooled by outdoor air before entering the evaporator. In some natural cooling modes, the return water is pre cooled by the natural cooling coil and then cooled by the compressor mechanical refrigeration evaporator.

·Natural cooling mode:

When the outdoor temperature is 20 ℃ lower than the indoor return air temperature, the three-way valve opens in position B and closes in position A, and the cooling work relies entirely on the natural cooling coil to stop the mechanical refrigeration of the compressor.