Role of ZnO-nano-thin-film-layered micro/nanostructured surfaces on flow boiling heat transfer characteristics

• Published in: Journal of thermal analysis and calorimetry 2024-02, Vol.149 (3), p.1267-1281
• Main Authors: Gupta, Sanjay Kumar, Misra, Rahul Dev
• Format: Article
• Language: English
• Subjects: Air conditioning; Analytical Chemistry; Chemistry; Chemistry and Materials Science; Continuous flow; Copper; Distillation; Durability; Heat flux; Heat transfer; Heat transfer coefficients; Inorganic Chemistry; Measurement Science and Instrumentation; Nanostructure; Physical Chemistry; Polymer Sciences; Production methods; Sol-gel processes; Spin coating; Thin films; Water flow; Working fluids; Zinc oxide
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-023-12766-1

Numerous energy systems, including distillation, power production, air conditioning, cooling, and purification, use evaporation and flow boiling in minichannels. In this study, we show noticeably higher heat transfer coefficients and critical heat flux of 182% and 114% during DI water flow boiling in ZnO-nano-thin-film nanostructured (∼110–423 nm), industrial-scale-heated copper bottom surface. By using a combination of the sol–gel spin coating and annealing methods, we produce durable and highly conformal nanostructured surfaces that enable scale nano-manufacturing. Flow boiling experiments were carried out in 1.5 mm height bottom surface-heated minichannel using DI water as the working fluid. In order to measure the effectiveness of present method and clarify how the structural length scale affects it, the present study ZnO-nano-thin-film structured surfaces are compared with previously published micro/nano-scale fabricated surfaces, demonstrating the necessity and importance of the nanoscale properties of ZnO-nano-thin films for improvement. The surfaces of the nano-thin film were subjected to durability testing utilizing a seven-day continuous flow boiling experiment, which revealed minor deterioration. The higher boiling performance is achieved on ZnO-TF-423 is due to the proper bonding between polished copper bare surface (BS) and deposited ZnO thin films. Additionally, the rough surface on BS allows the copper and ZnO thin films to bind properly. It can be concluded that surfaces made using an efficient sol–gel spin coating process possesses superior boiling heat transfer capabilities at comparatively lower surface temperatures, suggesting a smaller chance of damaging the surface from rising temperatures.