Research and Application Progress of Phase-Change Working Fluid for High-Heat-Flux Liquid Cooling Servers

The proportion of high-heat-flux servers has gradually increased with the increasing number and scale of data centers. Traditional air cooling cannot handle the heat dissipation and energy saving needs. In this regard, the liquid cooling technology with a large latent heat and high heat transfer coefficient has emerged. Research on liquid cooling systems primarily focuses on system efficiency enhancement, system comparison, and overall thermal management. Among them, the working fluid, as an important medium for heat exchange, is crucial for the liquid system performance. In this paper, selection principles of phase-change working fluid are proposed. The investigations and application progress of six types of phase-change working fluid (natural working medium, HFCs, HFOs, PFCs, HFEs, mixed working medium) are reviewed, summarized, and analyzed according to the contact modes (direct and indirect). The prospects for future research on phase-change liquid cooling fluids are presented.