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Proceedings of the 27th National and 5th International ISHMT-ASTFE Heat and Mass Transfer Conference December 14-17, 2023, IIT Patna, Patna-801106, Bihar, India
December, 14-17, 2023, Bihar, India

Experimental Investigation on Effect of Heterogeneous Wettable Structures on Condensation Heat Transfer

Get access (open in a dialog) DOI: 10.1615/IHMTC-2023.1960
pages 1201-1206


The film wise condensation (FWC), characterized by the presence of a condensate film, exhibits poor heat transfer performance compared to dropwise condensation (DWC) with superior performance. However, in the case of vertical tubes, droplet removal transpires when the gravitational force acting upon the droplet surpasses the friction force, resulting in increased diameters of detached droplets, thereby restricting the potential for additional improvement in heat transfer. A heterogeneous wettable structure (HWS) comprising both hydrophilic and hydrophobic surfaces is proposed in the present work to mitigate the limitation. As a promising approach for enhancing condensation heat transfer, the hydrophobic surface facilitates rapid vapor droplet nucleation and growth, while the neighboring hydrophilic surface promotes droplet removal. The HWS on vertical copper tubes were created by screen printing technique with PVC ink. Three different heterogeneous wettable patterns compared with bare copper tube and fully PVC ink coated tube. Among the patterns tested, pattern P_1_1_1 exhibited the best heat transfer performance. The maximum values of heat transfer (HT) rate and heat transfer coefficient (HTC) achieved were 124.48 kW/m2 and 125.08 kW/m2k, respectively, at a subcooling temperature of 0.99 K, with an enhancement of 30.39 % compared to the performance of a bare copper surface.