A visualization study of a confined vapor chamber with conical microstructure applied in data centres

With the development of the informatization technology, the scale of the data centre is expanding rapidly. The energy consumptions of the electronic equipment in the data centre are rising regularly, which lead to the thermal management becoming an argent issue to be settled. To realize the sustainable development of green data centre, the passive two-phase vapor chamber (VC) has turned into the focus of electronic cooling research. Constructing nucleation induced structures on the evaporation surface is an effective method to improve the performance of the vapor chamber. To address the problem of achieving enhanced boiling, a novel conical microstructure was designed in the vapor chamber with 50 mm height. The conical structure of 1 mm axial height was fabricated on the evaporation surface by computer numerical control (CNC) machining technology. A visualization experimental system was developed to investigate the effect of the conical microstructure on the two-phase behaviours, and the boiling heat transfer characteristics under different heating conditions (Qin = 35 W, 50 W, 65 W) in a confined vapor chamber. The high-speed camera was used to capture the bubble behaviours. Experimental results found that compared with the smooth surface, the integration of the conical structure increasing the number of bubble nucleation sites and the bubble departure frequency. The bubble growth period at stable heating stage is 162 ms shorter than initial heating stage on the evaporation surface with conical structure. The thermal resistance (Rvc) of vapor chamber with conical structure is improved by 5.85% compared to the smooth one at Qin = 65 W, which indicate that the conical microstructure can enhance the boiling heat transfer performance. This study aims to provide a reference for the design of thermal management system for green data centre.