Experimental Investigation of Pool Boiling Heat Transfer on Cu─Al2O3 Composite Coated Patterned Surfaces Using Refrigerant R-134a

The present study investigates pool boiling heat transfer (PBHT) of R-134a on Cu─Al₂O₃ composite-coated patterned surfaces (CPS_I, CPS_II, CPS_III, and CPS_IV). Using a wire EDM method, four different types of copper patterned surfaces (PS_I, PS_II, PS_III, and PS_IV) were manufactured. Comparing the heat transfer coefficients (HTCs) of the Cu─Al₂O₃ composite-coated patterned surfaces to the uncoated Cu surfaces, a notable enhancement was observed. The maximum HTC improvements of 162%, 178%, 189%, and 211% were observed for CPS_I, CPS_II, CPS_III, and CPS_IV, respectively, when compared with bare Cu surfaces. These results demonstrate the effectiveness of these treatments in enhancing heat transfer compared to bare copper surfaces. The enhancement in PBHT is mainly due to the integration of porous Cu─Al₂O₃ composite coating with patterned surfaces which resulted in a larger heat transfer area, improved capillary action, and a substantial increase in active nucleation sites.