In this study, we proposed and designed a pump-driven chip-level two-phase cooling system (PCTCS) and experimentally demonstrated that it can directly cool central processing units in data centres (DCs). The operation of the PCTCS involves an internal refrigerant cycle (IRC) and an external water cycle (EWC). Within the IRC, multiple mini-channel evaporators enable the dissipation of heat from the CPUs in the servers through a plate heat exchanger to initiate the EWC, which is followed by the dissipation of the heat to the environment. We performed experiments to systematically analyze the effects of key operation parameters on PCTCS performance of the IRC. The results indicated that the average and the highest core temperature of the CPUs were 76.3°C and 79.0°C, respectively, under extremely harsh heat dissipation conditions. The key driving component of the PCTCS is a refrigerant pump with high energy efficiency ratio (EERp) defined as ratio of heat dissipated by the power of the refrigerant pump. The EERp was 17–18 when the CPUs were at 0% load and 38–42 and 68–76 when the CPUs were at 50% and 100% loads, respectively. Moreover, optimizing the flow resistance of the IRC can improve the performance of the PCTCS.

As a powerful solution for heat dissipation in data centers, chip-level cooling continues to capture escalating attention in research and application domains. To accurately analyze system performance, identify potential avenues for system optimization, and inform future practical applications, we developed a steady-state, one-dimensional mathematical model for a novel pump-driven chip-level two-phase cooling system (PCTCS). This model was constructed based on our previous study and was confirmed against existing experimental data. Our simulations scrutinized PCTCS performance under default conditions and investigated the effects of key parameters, such as refrigerant type, condenser vertical positioning, and cooling water temperature. Results showed that the system could manage an 80 W power output from each CPU while maintaining CPU temperatures around 79 °C at a cooling water temperature of 45 °C. We discovered the choice of refrigerant had a significant impact on performance, with R32 outperforming R134a and R113. While the vertical position of the condenser influenced the PCTCS’s internal parameters, its overall impact on system performance was negligible. Moreover, provided the chip temperature remained within a safe range, our study found that increasing the cooling water temperature improved the energy efficiency ratio of the refrigerant pump and reduced the temperature difference between the chips and the cold source.

The energy consumption of data center cooling systems is rapidly increasing, necessitating urgent improvements in cooling system performance. This study investigates a pump-driven two-phase cooling system (PTCS) utilizing a parallel-flow heat exchanger (PFHE) as an evaporator, positioned at the rear of server cabinets. The findings indicate that enhancing the vapor quality at the PFHE outlet improves the overall cooling performance. However, airflow non-uniformity induces premature localized overheating, restricting further increases in vapor quality. For PFHEs operating with a two-phase outlet condition, inlet air temperature non-uniformity has a relatively minor impact on the cooling capacity but significantly affects the drop in pressure. Specifically, higher upstream air temperatures increase the pressure drop by 7%, whereas higher downstream air temperatures reduce it by 7.7%. The implementation of multi-pass configurations effectively mitigates localized overheating caused by airflow non-uniformity, suppresses the decline in cooling capacity, and enhances the operational vapor quality of the cooling system.

As Information Technology continues to rapidly evolve, the scale and energy consumption of data centers have seen a significant surge. Traditional air-cooling systems in data centers are notably energy intensive. This study proposes an innovative dual-cycle two-phase cooling system (DTCS) for retrofitting existing server cabinets. The system integrates the two synergistic subsystems of a pump-driven chip-level two-phase cooling system (PCTCS) and a pump-driven backplane-level two-phase cooling system (PBTCS). The PCTCS provides year-round natural cooling of high-power chips, and experimental results indicate that even under extreme outdoor conditions of up to 42 °C, the PCTCS can maintain the chip temperature at 76 °C. At the same time, the PBTCS effectively cools all components in the cabinet except the high-power chips. By efficiently controlling the chip temperature through the PCTCS, the novel DTCS ensures stable operation at data room temperatures up to 33 °C, thereby significantly reducing the energy consumption of the cooling system. The average annual pPUE of the cooling system is 1.078 at the test site in Xiangyang, Hubei province in China. The DTCS could perform well across various Chinese cities even under severe hot and moist conditions, with the average annual pPUE consistently below 1.1.