Experimental investigation on thermal and moisture performance of direct evaporative cooling coupled with phase change plates for data centers

Direct evaporative cooling is widely used in data centers but risks elevating humidity. This study proposes a direct ventilation channel system integrating direct evaporative cooling with phase change plates. Experiments investigated effects of inlet air temperature (IAT: 28–44 °C), inlet relative humidity (IRH: 20–60%), air supply velocity (ASV: 1.0–3.0 m/s), and water flow (40–120 mL/min). Results show: (Ⅰ) The coupled system exhibits synergistic effects, achieving 31.43% cooling efficiency improvement as IAT increases from 28 °C to 44 °C. (Ⅱ) At IAT=36 °C and IRH=60%, outlet temperature reaches 27 °C with 62.3% RH, achieving 22% dehumidification rate. Dehumidification efficiency exceeds 18.8% for over 5 hours when IRH≥40%. (Ⅲ) Cooling performance factors order: IAT > ASV > IRH > WF, with IAT contributing 94.6%. Dehumidification factors order: IRH > IAT > ASV > WF, with IRH contributing 62.8% and IAT 23.9%. The system achieves EER up to 6.3 when meeting data center cooling demand (1728–3456 m 3 /h) at 30–32 °C. This study provides a feasible energy-saving cooling strategy for data centers.