TRANSITION IN DROPLET STATE ON HEATED STRUCTURED HYDROPHOBIC SUBSTRATES

Venkitesh, V and Agrawal, P and Dash, S (2024) TRANSITION IN DROPLET STATE ON HEATED STRUCTURED HYDROPHOBIC SUBSTRATES. In: ASME 2024 7th International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2024, 5 August 2024 through 7 August 2024, Nottingham.

PDF MNHMT_2024.pdf - Published Version Restricted to Registered users only Download (1MB) | Request a copy

Abstract

Interaction of a droplet on a heated substrate is a subject of extensive research due to its application in spray cooling of surfaces, thermal management of micro-scale devices, water harvesting etc. Depending on the surface temperature the droplet shows nucleate, transition boiling and Leidenfrost state. The presence of surface textures gives rise to various hydrodynamic outcomes such as droplet atomization, interfacial oscillations, and lift off. When a drop is deposited on a textured surface, it typically exists in two states called Cassie-Baxter and Wenzel depending on the substrate wettability and liquid-solid contact area. In the present work we explore a unique lift off mechanism at temperature range of (140-170°C) attributed to the excessive vapor force generated due to droplet impalement into the gap between the textures followed by evaporation of the imbibed liquid. The presence of microtextures (solid fraction)offers flow resistance to the escaping vapor which leads to increase in vapor pressure underneath the drop. When the vapor force exceeds the pinning force and weight of the drop, an explosive lift off occurs. We develop a force-based model to estimate the droplet volume corresponding to lift off on substrates with different morphologies and temperatures. © 2024 by ASME.

Item Type:	Conference Paper
Publication:	Proceedings of ASME 2024 7th International Conference on Micro/Nanoscale Heat and Mass Transfer, MNHMT 2024
Publisher:	American Society of Mechanical Engineers (ASME)
Additional Information:	The copyright for this article belongs to publisher.
Keywords:	Drop formation; Hard facing; Wetting, Bubble nucleation; Droplet evaporation; Heated substrates; Hydrophobic substrate; ITS applications; Leidenfrost temperature; Lift offs; Spray-cooling; Thermal; Water harvesting, Nucleate boiling
Department/Centre:	Division of Interdisciplinary Sciences > Interdisciplinary Centre for Energy Research Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	23 Oct 2024 17:09
Last Modified:	23 Oct 2024 17:09
URI:	http://eprints.iisc.ac.in/id/eprint/86646

Actions (login required)

View Item