Enhanced thermal performance of micro heat pipes charged with a pure ionic liquid for electronics cooling

• Ionic liquid DIMCARB enhances thermal performance of micro heat pipes. • DIMCARB shows superior wettability and lower boiling point than water and ethanol • Maximum thermal conductivity improves by 31.1% with DIMCARB-charged MHPs. • Phase-change heat transfer coefficients significantly increase using DIMCARB. This study investigates the thermal performance of micro heat pipe (MHP) using dimethylammonium dimethylcarbamate (DIMCARB), a pure ionic liquid, as a novel working fluid, and compares its thermal efficiency with conventional fluids like deionized water and ethanol. The charged MHP array is experimentally evaluated under varying heat loads (0.5 – 3.0 W) to assess the key metrics of heat transfer performance. Results demonstrated that DIMCARB significantly enhances thermal performance, achieving a peak effective thermal conductivity of 949 W/m·K and a global heat transfer coefficient of 816 W/m 2 ·K, surpassing water by 31.1 % and 32.6 %, respectively. The superior performance is attributed to the exceptional wettability (contact angle ∼ 33°) of DIMCARB and low boiling point (60 °C), which strengthen the capillary-driven fluid circulation and phase-change efficiency. Thermal resistance analysis shows that DIMCARB achieves superior evaporation (5975 W/m 2 ·K) and condensation (7750 W/m 2 ·K) coefficients, effectively reducing temperature gradients. These findings underscore the potential of ionic liquids as advanced working fluids for high-power electronics cooling, addressing the limitations of traditional fluids in microscale thermal management. The study provides critical insights into fluid selection for MHPs, emphasizing the role of wettability and boiling dynamics in optimizing heat transfer.