The air conditioning system of the data center must not only ensure reliability but also take into account energy saving. The specific air-conditioning form should be comprehensively analyzed with the meteorological parameters of the construction site, air quality, resource conditions, initial investment and operating costs, and laws and regulations to be followed.

Data center cooling

Commonly used data center air conditioning systems mainly include air-side indirect evaporative cooling systems, DX systems, water-cooled chilled water systems, air-cooled chilled water systems, and some air-conditioning systems that are used on a smaller scale, and are also partially used in data centers. Various refrigeration systems are described below.

1. Indirect evaporative cooling system

The indirect evaporative cooling unit (referred to as AHU) is the cooling capacity of the air obtained after evaporative cooling of the fresh air, which is transferred to the hot return air in the computer room through the non-direct contact heat exchanger, and then supplemented with necessary filtering, supplementary cooling and other measures to provide the computer room with Cooling air supply that meets the requirements. In the whole process, there is only the transfer of cold energy, without the exchange of substances, and will not affect the air quality and humidity of the computer room. This method realizes the close contact between the cold source and the load center and can use the wind side for natural cooling. The system has dry mode, spray mode and mixed mode operation modes, which can significantly reduce the energy consumption of the data center dispatching system.

2. Air-cooled direct expansion fluorine pump air conditioning system

The air-cooled direct expansion precision air conditioner unit itself is a small refrigeration cycle unit. The principle is similar to that of traditional air conditioners. It mainly includes compressors, evaporators, expansion valves and condensers, as well as air supply fans and control systems. It is divided into indoor units. It is connected to the outdoor unit through a copper pipe, and the connecting pipe is the refrigerant Freon.

In order to improve refrigeration energy efficiency and utilize natural cooling sources, many manufacturers have developed fluorine pump air conditioners, adding fluorine pumps to the original direct expansion refrigeration cycle system. Realize the circulation of refrigerant in the copper tube.

3. Air-cooled chilled water system

The air-cooled chilled water system is a way of chilled water preparation, mainly composed of air-cooled units and supporting facilities. The liquid refrigerant of the air-cooled unit directly evaporates (expands) in its evaporator coil to absorb heat and cool the chilled water outside the coil, and the gas refrigerant of the unit is cooled to liquid by outdoor air cooling, thus realizing the refrigeration cycle.

4. Water-cooled chilled water system

The principle of the water-cooled chilled water system is similar to that of the air-cooled chilled water system. The main difference in the system is that the water-cooled chilled water system uses a water-cooled unit. The cooling method of the condenser is water-cooled, and the cooling water of the cooling tower is used to cool the condenser. , due to the better water cooling and heat dissipation, the energy efficiency of the chiller is higher. Water-cooled chillers are placed indoors and mostly use large screw machines or centrifuges, and the cooling capacity of a single unit can be larger than that of an air-cooled unit.

5. Other refrigeration systems

Many large Internet companies, such as Google and Facebook, have achieved good energy-saving effects by changing the server power architecture, changing the CPU layout, changing the heat dissipation method, improving the high-temperature performance of the server, using distributed batteries, and using liquid-cooled servers. However, its technical measures require in-depth customization of IT equipment, which cannot be maintained without large-scale procurement, so ordinary enterprises cannot adopt it. Especially liquid cooling, the cost is relatively high, mainly used in the field of high-performance computing with high heat, the scale is not large, and the overall ecology needs to be improved, mainly leading IT companies such as Alibaba, Huawei, Inspur, and Sugon Exploration and layout on the technology.