Research On Optimization Design Of Evaporative Cooling Composite Refrigeration System In Data Cente

With the continuous development of China’s digital economy,the number and scale of data centers are increasing year by year.The energy consumption of data centers is also increasing,which is becoming more and more the focus of people’s attention.Guangdong Province,as the construction and deployment of the Guangdong-Hong Kong-Macao Bay Area big data center.The construction of data centers in the province also faces the new challenge of strict control of PUE(Power Usage Effectiveness).Currently,among the data centers in Guangdong Province that have been put into operation,the percentage of data centers with PUE higher than 1.5 is over 64%,and the average PUE is 1.77.There is still a big gap with the provincial target PUE requirement of 1.25,and the task of reducing energy consumption and PUE is arduous.According to statistics,data center cooling system energy consumption accounts for up to30%～50%,occupying the majority of the proportion except for IT equipment.If data centers want to reduce energy consumption and carbon emissions,using natural cooling sources is an important way when IT equipment cannot be upgraded.Heat pipe evaporative cooling system is a form of natural cooling source that can use ambient air source for high temperature cooling.It has the characteristics of simple and flexible structure and high heat transfer efficiency.It makes it a suitable technology for energy-saving renovation of old data centers and optimal design of cooling system for new data centers in South China.Therefore,evaporative cooling heat pipe pre-cooling system is proposed in this paper.Aiming at the limitations of indirect evaporative cooling technology applied to data center energy saving,the theoretical scheme of its optimal design based on the statistical characteristics of cooling capacity is explored.As well as solving the problems of unreasonable design parameter settings and excessive capacity configurations of evaporative cooling refrigeration systems.It provides technical solutions and theoretical support for the renovation of old data centers or new data centers in Guangdong Province.The main work of this study is as follows:Firstly,the experimental platform and simulation platform of evaporative pre-cooling system are built.And the model is revised and verified by the actual measurement data of the experimental platform,and the reliability of the constructed evaporative pre-cooling simulation platform is verified.The testing process was carried out under the typical weather of hot and humid climate,and the relevant test parameters were input into the models of evaporative condenser and heat pipe backplane.The results show that after verification and correction,the deviation between the simulated and measured values is within 3%.The average error between the constructed simulation platform and the measured performance parameters is less than 2%,and the maximum error is less than ±4%.This shows that the corrected mathematical model and the built simulation system are both highly accurate and meet the needs of subsequent simulation calculations.Secondly,by building a simulation platform for the evaporative cooling composite refrigeration system,the typical annual meteorological parameters of Guangzhou were studied for the system operation throughout the year with reference to the system.The results show that the annual cooling capacity of the pre-cooling system increases with the increase of the precooling system capacity configuration ratio.When the pre-cooling system capacity is 100%ratio,the pre-cooling system has pre-cooling capacity throughout the year.The percentage of pre-cooling cooling capacity in spring and autumn is about 94.0%,and in summer,its percentage also reaches 63.8%.Finally,the optimization design study of the compound cooling system of the data center was carried out.It was carried out from three perspectives: the capacity configuration of the pre-cooling system,the chiller cooling capacity distribution of the water cooling system,and the design parameters of the composite system.The evaluation indexes are the annual operation PUE,energy consumption and economy of the composite cooling system.The results show that the pre-cooling system capacity configuration of more than 50% can meet the PUE requirements,the ratio of 50% is the most economical,and the ratio of 100% is the most energyefficient.The chiller cooling capacity allocation should be adjusted appropriately according to the different capacity configurations of the pre-cooling system,and when the ratio is 100%,the degree of impact on the system PUE is not significant.By setting different outdoor wet bulb temperatures as the switching judgment of the three modes of complete pre-cooling,mixed cooling and complete water cooling,it is found that appropriately increasing the wet bulb temperature as the switching judgment can expand the utilization of natural cold sources,reduce the energy consumption of the water cooling system and improve the energy efficiency of the composite cooling system.When the proportion of pre-cooling system configuration is 50%,the change of system operation under different switching schemes is greater,which is more flexible in actual engineering.