Wetting Behaviors of Liquid Nitrogen on Micro-textured Surfaces at Ultra-Low Temperatures
Abstract
Liquid Nitrogen (LN2) is used for facilitating heat transfer in numerous precision equipment, such as cryopumps, superconducting magnets, and cryosurgical guns. Due to the ultralow boiling point of LN2 (77 K at 1 atm), as it comes into contact with surfaces at normal temperature and pressure (NTP - 293 K and 1 atm), a vapor cushion is formed underneath and the drops start levitating. This is the well-known Leidenfrost phenomenon. Due to the complex heat transfer and phase change associated with this process, the present understanding of wetting of LN2 on structural surfaces remains unsatisfactory. In response, we have investigated the fate of LN2 drops placed on the following precisely temperature-controlled silica surfaces: smooth silica, surfaces with mushroom-shaped doubly reentrant pillars (DRPs), and those with cylindrical pillars. Specifically, we measured the lifetimes of LN2 drops on these surfaces as a function of ultralow temperatures. This allowed us to find out how/when LN2 transitions from a wetting liquid to the Leidenfrost state. We will also shed light on the effects of the surface wettability, liquid surface tension, and the interfacial heat transfer on the fate of LN2 drops. These findings should prove to be helpful in the rational design of LN2 applications.
- Publication:
-
APS Division of Fluid Dynamics Meeting Abstracts
- Pub Date:
- 2021
- Bibcode:
- 2021APS..DFDT12005M