Numerical Simulation Research On The Immersion Cooling With Phase Change Liquid For Servers

The new generation of information and communication technologies such as 5G,artificial intelligence,cloud computing,and blockchain are developing vigorously.As an important carrier of information and communication technologies,data centers have an important strategic position.The development trend of data centers is becoming larger,the heat flux of a single machine is gradually increasing,the demand for heat dissipation is also increasing,and the energy consumption problem brought by it has become more and more obvious.At present,more than 40%of energy consumption is used for heat dissipation of IT equipment,so there is an urgent need for efficient data center cooling solutions.Compared with traditional air cooling,liquid cooling has superior performance.The application of liquid cooling technology can not only reduce energy consumption and expenditure costs,but also save energy and environmental protection,and at the same time lower noise standards.Immersion phase change liquid cooling belongs to direct contact liquid cooling.Electronic components are immersed in an insulating cooling liquid,and the insulating liquid undergoes a phase change on the surface of the component,thereby enhancing heat transfer and improving efficiency.In this paper,a numerical simulation study is carried out for the immersion phase change liquid-cooled server.Three insulating coolants FC40,FC72 and Novec649 are selected as refrigerant carriers,and compared with water under the same working conditions.The results show that FC40 and water,which can only transfer heat in a single phase,cannot meet the heat dissipation requirements of the components without adding other heat sinks;FC72 and Novec649,which undergo phase change heat transfer,can keep the components running safely below the limit temperature.However,FC72 has a potential threat to the environment.Moreover,Novec649 has the highest heat transfer efficiency when used as a coolant,and at the same time has good environmental protection characteristics.Furthermore,Novec649 is used as the cooling liquid to study the cooling of each component in a single server.This paper establishes a single server model,observes the changes in the temperature,heat flux,heat transfer coefficient,etc.of each component,and compares the pressure difference between the inlet and outlet and the flow of coolant in the horizontally placed and vertically placed servers.The influence of the inlet flow rate,the degree of fluid subcooling and the power of the components on the cooling effect is analyzed.The results show that there is the best inlet flow rate,the best degree of fluid subcooling and the maximum safety element power during the cooling process.Finally,a single cabinet containing multiple servers is studied.A cabinet model containing 4 servers is constructed,and two liquid inlet and outlet arrangements are designed,one is the Z type with the opposite side of the inlet and outlet,and the other is the I type with the same side of the inlet and outlet in the middle of the cabinet.The flow characteristics of liquid in the cabinet,and the heat dissipation of the surface heat dissipation of different server components are analyzed.At the same time,the influence of server spacing on heat transfer flow is also analyzed.Studies have shown that the flow vortex between the servers in the cabinet causes the flow field to become unstable.As the distance between the servers increases,the fluid flow rate in the cabinet becomes more uniform,but the heat transfer characteristics become worse,the component temperature rises,and the larger spacing will increase the volume of the cabinet.