| With the advent of 5G era,as a data center which is responsible for a large amount of data calculation,storage and processing,it shows a development trend of high heat flux density and high energy consumption.The high heat flux density of the server leads to an increase in chip temperature,and the increase in chip temperature will directly affect the safety and stable operation of the data center,and even lead to the paralysis of the data center.The advanced data center thermal management system on the one hand can ensure that the server chip runs at the optimal operating temperature;on the other hand,it can adjust the cooling load of the cooling system according to the working state of the server chip to reduce the energy consumption of the data center cooling system.Therefore,in order to improve the thermal management of the data center,many scholars at home and abroad have conducted various studies on this.Through the introduction of the research status at home and abroad in this article,it can be seen that some scholars have focused on the optimization of the heat sink structure inside the cabinet to improve the heat exchange efficiency between the chip and the fluid,or are committed to using different cooling mediums,such as,nanofluids,oil,etc.for server cooling.Some scholars only consider the configuration of refrigeration equipment in the refrigeration system without considering the optimization of the operating conditions of the cooling medium.In previous studies,it was found that the cooling water operating conditions of the cooling system and the temperature of the chips were not combined to comprehensively consider the thermal management of the data center,which plays a more important role in the heat dissipation of the cabinet server and the energy saving of the cooling system in data center.View of the above research,in this paper,three kinds of cooling systems based on cooling towers,air-cooled chillers,and water-cooled chillers with a thermal power of 4.8 k W of the data center were studied respectively.Finned water-cooled heat sinks are used to cool the chips in the server cabinet.First,the structure model of the water-cold dissipation unit of the cabinet chip was calculated by using the method of the thermal resistance network model.The relationship between the inlet water temperature of the cabinet,the chip temperature and the secondary cooling water flow was studied.When the inlet water temperature of the cabinet is constant,with the increase of the secondary cooling water flow,the chip temperature gradually decreases and tends to be stable.For different safety chip temperatures,there exist a highest inlet water temperature of cabinet.When the safety chip temperature is below 70 °C,the maximum inlet water temperature of the cabinet is 24 °C,and the lower the required chip temperature,the lower the inlet water temperature of the cabinet that can be satisfied.Next,TRNSYS transient simulation software was used to analyze the optimization operation conditions of cooling water based on the minimum energy consumption of the cooling system under three cooling strategies at different ambient temperatures.The maximum ambient temperature that the cooling tower can meet is 27 °C,the optimal inlet water temperature of cabinet changes linearly with the ambient temperature,and the optimal cooling water flow increases exponentially with the increase of the ambient temperature.For the cooling system of air-cooled chiller and water-cooled chiller,the minimum power consumption of cooling system is obtained when the water supply temperature of chilled water is 10 °C.The optimal operating conditions of cooling water are the same,the best primary and secondary cooling water are 2.777 L/min and 2.562 L/min,the optimal water temperature at the inlet of the cabinet is 12 °C,and the maximum ambient temperature that the air-cooled chiller can meet is 38 °C.The total power of the three cooling strategies under different ambient temperatures is compared.The results show that the cooling tower can be used when the ambient temperature is less than 27 °C,the air-cooled chiller can be used when the ambient temperature is greater than 27 °C and less than 32 °C,and the water-cooled chiller can be used when the ambient temperature is higher than 32 °C.Finally,cooling systems with three hybrid cooling modes of data center were established,and the minimum energy consumption,PUE and energy saving rate of the data center throughout the year are analyzed,and the three hybrid cooling modes are compared and analyzed.The total energy consumption of hybrid cooling mode 1 based on cooling tower,air-chiller and water-chiller is the smallest,which is 7630.7 k J and PUE is 1.18.The energy consumption of hybrid cooling mode 3 based on cooling tower and water-chiller is the largest,which is 7957.6 k J,but there is little difference among them.Compared with the single cooling strategy with air-cooled chiller of cooling system,the energy saving rates of the three hybrid cooling modes are 58.7%,58.1% and 56.9% respectively. |
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