| With the rapid development of information industry technology,the scale of data center is becoming larger and larger,and the thermal power consumption of electronic components is gradually increasing.A large amount of energy will be consumed for the thermal management of electronic equipment.The traditional air-cooling method has been difficult to adapt to the development requirements of green energy saving in data center.In this context,immersion liquid cooling method is favored by people because of its high heat dissipation capacity and low energy efficiency.Immersion liquid cooling is to soak the electronic components of the server in a special cooling medium,and transfer the heat through the flow of the coolant.In this paper,with the help of numerical simulation software,the single-phase immersion liquid cooling of the server is simulated,the temperature field and flow field distribution in the cabinet are obtained,the improvement measures are put forward for the uneven flow distribution and high temperature hot spots,and the coolant is also discussed.In this paper,a liquid cooled cabinet model with four servers is designed,including liquid cooled cabinet,liquid inlet,liquid outlet and server.FC-40 is selected as the cooling medium,and the numerical simulation of the whole cabinet is carried out with the help of FLUENT software.The temperature of electronic components in the cabinet and the distribution of temperature field and flow field in the cabinet are obtained.The average value of the highest temperature of GPU in each server is counted,and the temperature of each server is evaluated.When the inlet flow rate is relatively low,server 1 is closest to the outlet,and the coolant flow rate through channel 1 is the highest,so the temperature of server 1 is the lowest;server 4 is farthest from the outlet,and the coolant flow rate through channel 4 is the lowest,so the temperature is higher.With the increase of the flow rate,the coolant flows along the back wall and side wall of the cabinet due to the inertia effect after entering the bottom of the cabinet.The center of the circular vortex is the area with relatively low flow rate.The flow rate of No.2 channel and No.3 channel is relatively small,so the temperature of No.2 server is relatively high.According to the temperature difference of each server,the standard deviation of GPU temperature is used to evaluate the uniform temperature distribution of electronic components.Through the analysis,it is concluded that the non-uniformity of temperature distribution is caused by the non-uniformity of flow distribution in four channels.Aiming at the problem of non-uniformity of flow distribution,two ways are proposed to improve the flow uniformity:(a)change the layout of inlet and outlet;(b)increase the drainage baffle to improve the flow field.Changing the layout of import and export includes changing the location and quantity of import and export.The results show that with single inlet and single outlet,the temperature of No.4 server can be reduced by U-shaped layout when the inlet and outlet are on the same side;increasing the number of inlets can significantly reduce the overall temperature,and there is no significant difference between Z-shaped layout and U-shaped layout.Increasing the number of baffles can significantly improve the flow field uniformity and reduce the overall temperature of the cabinet.The total average temperature of three baffles is 0.6?lower than that of one baffle,and 1.4? lower than that of no baffle.The temperature is the highest when the baffle angle is small,and the cooling effect is the best when the angle is 30 degrees.Aiming at the problem that the temperature of high-power electronic components is too high,the orthogonal test method is used to optimize the heatsink.According to the orthogonal table,16 case models were designed,and the maximum temperature and average temperature coefficient of each case model were obtained by numerical simulation.The highest temperature of the substrate was case 1,and the lowest temperature was case 4.Through range analysis and variance analysis,the influence of heatsink structure factors on the maximum temperature and average temperature of substrate was obtained.The main factor affecting the maximum temperature of the substrate is the thickness of the fin,and the main factor affecting the uniformity of the substrate is the thickness of the substrate.Finally,considering the maximum temperature of the base plate,the average temperature of the base plate and the quality of the heatsink,the highest comprehensive score is obtained through the weighted method in case 8:the thickness of the base plate is 5mm,the number of fins is 21,the thickness of the fins is 1.5mm,and the height of the fins is 30mm.Finally,the influence of different coolant on heat dissipation performance was studied.Mineral oil,silicone oil and fluorinated liquids FC-40,FC-43,FC-77 and FC-3283 are selected to compare and analyze their cooling performance at the same coolant inlet flow rate.Among these coolant,mineral oil has the worst cooling effect,the maxium temperature is 77.7?,and the temperature difference is 3.9?;fluorinated liquid FC-3283 has the best cooling effect,the temperature is 54.5?,and the temperature difference is 2?. |
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