Enhancing condensation with micro/nanostructured metal additively manufactured materials

• Main Author: Foo, Ru Yuan
• Other Authors: Ho Jin Yao
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/168031
• Institution: Nanyang Technological University

This report examines the dropwise condensation heat transfer performance on additively manufactured micro/nanostructured materials. Multiple studies have been conducted on surface structures, which has garnered growing interest owing to its distinct characteristics. In this project, the behaviour of water condensation on different enhanced surfaces and in the presence of surface coating has been investigated in relation to surface morphology, wettability, and heat transfer performance. Lubricant Infused Surfaces (LISs) are surfaces coated with lubricant and held by capillary forces induced by the surface micro/nanostructures thus allowing low adhesion and high mobility of droplets in contact with the surface. Dropwise condensation on LISs has shown to have properties that increases the rate of heat transfer. Such surfaces are recognised for their ability to shield materials against corrosion and icing while also providing exceptional liquid repellency. There are several studies on LISs for repelling low surface tension fluids but studies of utilising these surfaces for water condensation are lacking. Therefore, in this project, the condensation of water on LISs was conducted on the different surface materials to analyse and predict their heat transfer performance. A new experimental setup was also designed and developed based on the required parameters and conditions for the condensation experiments. The experimental setup was devised to maintain a consistent environment to obtain the droplet distribution density, from which the condensation heat transfer coefficients (h) were determined. The fabricated samples were studied for tuning surface wettability in relation to the interfacial transport mechanism for mass, momentum, and energy. The results indicate that surface morphology has a notable impact on condensation behaviour. This investigation examined the use of LISs on additively manufactured surfaces with regards to enhance the heat transfer properties on surface structures. The results demonstrated that the additively manufactured samples exhibited comparable, if not, superior heat transfer performance compared to the conventionally manufactured samples, which is evidenced from the computed heat transfer coefficient and droplet distribution density values. The heat transfer coefficient for the vertically and horizontal printed additively manufactured samples are 10.3 kW/m²·K and 8.44 kW/m²·K respectively while the conventional aluminium was computed to be 5.9 kW/m²·K at a high saturated pressure of 8 kPa. The additive manufactured samples exhibited higher heat transfer rates when compared to the conventional aluminium material. This research delves into the development of surfaces produced through additive manufacturing, with the goal of improving condensation performance. The potential benefits of such enhancements are far-reaching and can have a considerable impact on applications such as heat exchangers, electronics cooling and various practical applications.