Analysis multi-stage heat transfer process of data center cooling system from the temperature difference

doi:10.11949/0438-1157.20201533

Abstract

Abstract:

The data center cooling system needs a multi-stage heat transfer process to dispatch the heat from the electronics equipment to the outdoor environment. This process is analyzed with the method of entransy and temperature difference, and some conclusions are drawn. Data center cooling is a process using the coolant to transport the heat generated in the chip to the outdoor under the driven temperature difference (ΔT), which includes the temperature difference of the heat acquisition from the chip (ΔT₁) and the temperature difference of the heat extraction to the outdoor environment (ΔT₂). Reducing the chip heat transfer loss, air mixing loss and heat exchanger loss can decrease the total heat transfer temperature difference (ΔT), and the cooling system can make full use of free cooling and operate in the complete free cooling mode. When the cooling system operates in the heat pipe mode in the fully free cooling area, the gravity driven heat pipe gets the highest COP, followed by the liquid pump driven heat pipe, whose COP can be as high as 40—80 generally, even more than 400, and the lowest is the gas pump driven heat pipe, whose highest COP can reach 15—30. When the temperature difference between indoor and outdoor is less than ΔT₂, the principle of the compensation temperature difference is used to make the refrigeration cycle closer to the heat pipe cycle and realize the lowest energy consumption operation of the refrigeration system. It puts forward a new solution for energy conservation and emission reduction of the data center.

Key words: data center cooling, heat transfer, temperature difference, heat pipe

摘要：

数据中心冷却系统将IT器件的产热散发到室外环境中去要经过多级传热，本文采用与温差的方法对多级传热进行分析，结论如下：数据中心冷却为在一定温差ΔT驱动下利用载体将芯片散发的热量搬运到室外的过程，过程中存在着热量采集/传热温差ΔT₁损失以及冷源系统排热温差ΔT₂损失；通过减小芯片散热损失，降低气流掺混损失与换热器损失，降低总传热温差ΔT，实现空调系统充分利用自然冷源，运行在完全自然冷却区；当空调系统在完全自然冷却区域运行热管模式时，重力热管COP最高，液泵热管次之，一般高达40～80，甚至超过400，气泵热管最低，并且气泵是现有制冷压缩机COP最高点，可达15～30；当室内外温差小于ΔT₂时，利用补偿温差原理使得制冷循环更加接近热管循环，实现制冷系统最低能耗运行，为数据中心冷却系统节能减排优化提供新的方法。

关键词: 数据中心冷却, 传热, 温差, 热管

CLC Number:

TQ 051.5

WANG Fei, WANG Jianmin, SHAO Shuangquan. Analysis multi-stage heat transfer process of data center cooling system from the temperature difference[J]. CIESC Journal, 2021, 72(S1): 348-355.

王飞, 王建民, 邵双全. 数据中心冷却系统多级传热温差分析[J]. 化工学报, 2021, 72(S1): 348-355.

Figures/Tables 6

Fig.1 Heat transfer process of data center

Fig.2 T-Q diagram of building thermal environment in computer room (free cooling)

Fig.3 T-Q diagram of building thermal environment in computer room (compression refrigeration cooling)

Fig.4 Pressure enthalpy diagram of refrigeration/idea heat pipe system

Fig.5 Operation diagram of routine rack cooling air condition

Fig.6 Analysis chart of minimum energy consumption of 37℃ return air

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