Introduction of the liquid cooling server application
With the surge of new infrastructure, the pace of new construction and expansion of data centers is gradually accelerating. According to a survey conducted by the White Paper, as of the end of 2019, the number of data centers in use nationwide increased by 28.6% year-on-year, and the scale of data centers under construction increased by 30%, especially in first tier cities such as Beijing, Shanghai, Guangzhou, and Shenzhen, where the growth rate was significant.
The rapid development of ultra large data centers and insufficient space carriers will accelerate the rapid increase in power density of individual cabinets, with an expected average power of 25kW by 2025. The rapidly increasing power density places higher demands on heat dissipation. According to statistics, in 2019, traditional data centers represented by "air-cooled" technology consumed about 43% of their energy for IT equipment cooling, which is basically the same as the energy consumption of IT equipment itself (45%). The PUE (Energy Efficiency Index) value is generally above 1.4, indicating that reducing heat dissipation power consumption, controlling data center operating costs, and building green data centers have become urgent tasks. Data centers call for a "cooling revolution".
A liquid cooling data center refers to a data center that applies liquid cooling technology and equipment such as liquid cooling servers. Compared with traditional air-cooled servers, the heat export method of liquid cooling servers is different. Liquid cooling refers to the technology of using liquid instead of air as a refrigerant to exchange heat for heating components and remove heat. A liquid cooled server refers to a type of server that injects liquid into the server and takes away the server's heat through cold and hot exchange. Generally speaking, the industry divides liquid cooling into direct cooling and indirect cooling. At present, direct cooling is mainly achieved through immersion liquid cooling technology, which can be divided into phase change and non phase change. Indirect cooling is mainly achieved through cold plate liquid cooling technology.
Immersion liquid cooling technology is a cooling technique that uses liquid as the heat transfer medium, immerses the heating device in the liquid, and conducts heat exchange through direct contact. Liquid has a better thermal conductivity effect, 25 times that of air, with faster and better temperature transfer, and can achieve efficient cooling of IT equipment. Meanwhile, due to the large specific heat capacity of liquids, their temperature does not change significantly after absorbing a large amount of heat, so the CPU temperature can be set.
Compared with traditional air-cooled data centers, liquid cooled data centers have removed air conditioning systems and corresponding air-cooled infrastructure, and added circulating pumps, which can save construction costs. Secondly, compared with air-cooled systems, liquid cooled data centers can save about 30% of energy, effectively reducing the energy consumption ratio and lowering the PUE (energy efficiency index of data centers) to 1.05, meeting the requirements of green data centers. Finally, under the same heat dissipation conditions, the pump and coolant system used in the liquid cooling system have lower noise compared to traditional air conditioning systems.
Research, exploration, and practice are conducted on different liquid cooling technologies and solutions. Compared with other liquid cooling technologies, immersion liquid cooling has the characteristics of high energy efficiency, high density, high reliability, and high availability, making it more suitable for high reliability application scenarios in cloud computing data centers.
