The data center is part of the future infrastructure. There are more and more data centers in China. Due to the characteristics of high heat load of data center, energy saving of data center has become a hot topic.Especially in the case of carbon peak and double carbon targets, the cooling methods of data center are becoming more and more abundant.This paper mainly analyzes the refrigeration methods and practical conditions of several data centers.
The first is the traditional water-cooled or air-cooled chiller, which is used in most domestic data centers.With the optimization and improvement of the refrigeration system, PUE has reached below 1.4 from more than 2.0 at the beginning.However, due to the high condensation temperature in the south, the efficiency of the refrigeration host is low, so water-cooled units should be used in places with sufficient water resources.
The second is the use of natural cold source combined with traditional refrigeration system. This system is generally used in severe cold areas and cold areas in China.Referring to the application cases of some domestic data centers, the utilization of natural cold energy in such areas accounts for more than half of the time. Half of the extra investment recovery time shall not exceed 4 years, and some areas can recover it in one year.This natural energy recovery system is not standardized, and all data centers are exploring applications.Glacier coolant is specialized in making coolant. It has certain experience in cold energy recycling and can be combined with natural energy utilization in data center.
The third is fluorinated liquid immersion refrigeration, which has been tested in Alibaba data center. They use the boiling point of fluorinated liquid at 50 ℃, phase change refrigeration to cool the CPU, and then reflux through condensation and liquefaction. At present, the test effect is good.The advantage of this method is that the unit heat flux of fluorinated liquid phase change is large, which can meet the fan heat of high heat flux of CPU.In addition, some company use fluorinated liquid as cooling system, which circulates and cools the fluorinated liquid on the basis of immersion. Its heat transfer is between convection and subcooled boiling, and the heat transfer efficiency is also high. This scheme requires a large amount of fluorinated liquid, and the initial investment cost is high.
The fourth is evaporative refrigeration. This system mainly absorbs heat and refrigeration through the evaporation of water vapor without compressor compression. The power load of the system is low, and the PUE can reach 1.1.However, this scheme has a great impact on the weather, and the place with low wet bulb temperature is more appropriate, which is affected by geographical location. In addition, the refrigeration equipment has large volume and high investment.
The fifth is absorption refrigeration, which mainly uses waste heat for refrigeration, but the temperature of the heat source has a great impact on the refrigeration efficiency.The heat source recovered in the data center is at 50 ℃, the efficiency of absorption refrigeration is very low, and it is technically difficult.If there is a waste heat source with a temperature above 90 ℃, this method is still used for energy saving. This refrigeration scheme is rarely used at present. Most scientific research institutions are still exploring absorbing materials and reducing the temperature of recovered heat source.
The sixth is to use direct cooling system for refrigeration. At present, freon is being limited due to double carbon. The transcritical cycle or supercritical cycle of carbon dioxide can be utilized, which needs to be developed with the application of many scholars.
The forms of refrigeration methods are diverse, and the ultimate goal is energy conservation, environmental protection and stability, which is the goal of the data refrigeration system. Glacier coolant focuses on the application of data center and provides professional coolant.