Performance analysis and optimization of free cooling strategies for a liquid-cooled data center

The increasing power density of IT electronics and the enormous energy consumption of data centers lead to the urgent demand for efficient cooling technology. Due to its efficiency and safety, liquid-cooled heat sink technology may gradually replace air-cooled technology over time. With the ambient or higher water supply temperature, the liquid-cooled technology shortens the operating time of the chiller and improves its coefficient of performance, while the pump power consumption may increase for satisfying the constant cooling capacity. Therefore, it is significant to study the optimal water supply temperature to achieve energy-efficient operation of data centers. A virtual 30.1 kW data center is considered as the case, the liquid-cooled system is constructed with a combination of innovative manifold microchannel heat sink with oblique fins and indirect evaporative cooling technology to minimize energy consumption. A hybrid thermal management model integrating the heat dissipation model and the power consumption model is established by TRNSYS and FLUENT software. To the highest chip-safe operating temperature premise, the energy performance is analyzed under various water supply temperatures in Guangzhou. The result shows that only 21.5-hour mechanical cooling is needed with the 30 ℃ server inlet temperature throughout the year. And the minimized power consumption occurs with the constant 29 ℃ server inlet temperature. Moreover, the temperature adaptive control strategy (TACS) is adopted to test the cooling system power consumption under different regulation frequencies, and the by-week TACS can achieve another 11.5% energy saving than the minimum power consumption of the constant temperature control strategy.