An efficient thermal-management system is crucial for the safe operation of lithium batteries. In this study, an embedded composite cooling plate integrating wavy flow channels with a phase-change material (PCM) and liquid cooling was designed for the thermal management of lithium batteries. From the perspective of recovering the latent heat of a thermally saturated PCM, an evaluation method was proposed to quantitatively analyze the latent heat recovery performances, pumping energy consumptions, and overall performances of different structural configurations. The optimal structural configuration was determined by comparing the overall performances. This configuration included a circular flow shape, circular cross-section, double channels, a cross-sectional area of 36 mm², and a circular arc angle of 150°. The validity of the established numerical model was experimentally verified. Based on the optimal cooling plate structure, the heat generation of lithium batteries during 3 C rate operation was simulated using a surface heat source, and the effects of several delayed-start strategies for liquid cooling based on the PCM liquid-phase fraction on cooling performance were investigated. The results showed that the best temperature performance could be achieved by switching on the liquid cooling when the PCM liquid phase fraction reached 0.6, achieving a maximum temperature for the cooling plate of 38.32 ℃ and maximum temperature difference of 1.66 ℃, while decreasing the running time of the liquid cooling by 50.50% compared with that of the continuous mode.

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.