# Experimental Study of a Novel Prototype of Dual-Cycle Two-Phase Cooling System for a Data Cabinet
The existing literature has fully demonstrated the exceptional capabilities of liquid cooling technology in high-efficiency heat dissipation. However, this technology still faces numerous challenges in practical applications. Firstly, the current research on high heat-flux cooling predominantly focuses on integrating measurement points with heat sources, neglecting the impact of internal chip thermal conduction processes and thermal interface materials (TIMs) on heat dissipation performance in real-world scenarios. Secondly, the reliability of data centers is of paramount importance, and cooling systems using water or high-pressure refrigerants as working fluids pose potential safety risks, which limits their widespread application. Thirdly, the existing research primarily concentrates on the performance analysis of components such as heat sinks and cold plates, mostly confined to theoretical studies in laboratory environments, with a lack of in-depth exploration of the practical performance of large-scale cooling systems. Currently, system-level application research mainly focuses on loop heat pipes (gravity-driven) and high-pressure refrigerant cooling systems, while studies on the application of low-pressure refrigerants in chip-level cooling for data centers remain scarce. [PERSON] et al. [35] innovatively combined loop heat pipe (LHP) technology with a water-cooling system for chip cooling. Under conditions of a 40 \({}^{\circ}\)C inlet water temperature and low flow rates, this system was able to stabilize the CPU temperature within a safe range (i.e., 61 \({}^{\circ}\)C to 70 \({}^{\circ}\)C), strongly demonstrating the efficient heat dissipation capability of LHP technology under high temperature conditions. Additionally, the annual PUE of this cooling system reached 1.152. [PERSON] et al. [36] proposed a pump-driven two-phase cooling system, which utilizes two-phase refrigerant in the inner loop and cooling water in the outer loop, thereby achieving efficient heat removal from the chip. Additionally, research on the coupling relationship between data center cooling systems and IT equipment is relatively insufficient, and the energy optimization of data centers should aim at minimizing the overall energy consumption of the entire server room, rather than focusing solely on the performance improvement of individual components. This paper introduces a novel dual-cycle two-phase cooling system (DTCS), which achieves efficient cooling of data centers through the synergistic action of the pump-driven chip-level two-phase cooling system (PCTCS) and the pump-driven backplane-level two-phase cooling system (PBTCS). The PCTCS consists of two pump-driven two-phase loops. To ensure system reliability, the internal loop utilizes a low-pressure refrigerant, while the external loop employs a high-pressure refrigerant, enabling long-distance heat transfer and year-round free cooling. The PBTCS effectively dissipates the residual heat generated beyond the chips by integrating a liquid pump with a chiller. This paper elaborates on the design methodology and operational characteristics of the system, and its energy efficiency and reliability have been validated through long-term operation. Furthermore, this study proposes and verifies the concept of minimizing overall energy consumption in data centers by increasing the operating temperature of the server room while effectively controlling chip temperatures. This approach has successfully achieved the minimization of total energy consumption in the server room.