Experimental study and energy-efficiency analysis of a micro-heat-pipe-array-enhanced two-phase immersion cooling system for data centre server chips

• Proposed a novel two-phase immersion chip cooling system based on MHPA. • Demonstrated enhanced boiling and reduced thermal resistance. • Analyzed effects of inlet cooling water temperature. • Revealed MHPA-driven enhancement mechanisms. • Evaluated the energy-saving potential for data center. Cooling systems consume a substantial fraction of the total energy in data centres, while the rising heat flux of server chips challenges conventional air cooling and single-phase liquid cooling technologies. This study proposes a micro heat pipe array (MHPA)-enhanced two-phase immersion cooling system for high heat flux data centre server chips. The MHPA is integrated with a simulated chip heat source to redistribute localized heat input over a larger boiling surface, thereby enhancing the pool boiling heat transfer of Novec 7100. An experimental platform was established to investigate the boiling heat transfer characteristics, critical heat flux, thermal resistance, and the influence of condenser inlet water temperature. The results show that the MHPA significantly improves the cooling performance. Compared with direct pool boiling on a smooth copper surface, the critical heat flux increases from 27.76 W/cm 2 to 106 W/cm 2 , while the overall thermal resistance is reduced by approximately 30%, with a minimum value of 0.36 ℃/W. Varying the condenser inlet water temperature from 20℃ to 35℃ has only a limited effect on the cooling performance. Furthermore, energy-performance simulations for six representative Chinese cities show that the annual average PUE remains within 1.046–1.064, and the annual average COP reaches 30.93–35.24. These results demonstrate the potential of the proposed system for efficient cooling of next-generation high-heat-flux data centres.