Submicron thermal imaging of a nucleate boiling process using fluorescence microscopy. (15th August 2016)

• Record Type: Journal Article
• Authors: Sedmak, Ivan; Urbančič, Iztok; Podlipec, Rok; Štrancar, Janez; Mortier, Michel; Golobič, Iztok
• Is Part Of: Energy. Volume 109(2016)
• Page Start: 436
• Page End: 445
• Publication Date: 2016-08-15
• Subjects: Temperature-dependent fluorescence -- Erbium-doped heavy-metal glass -- Nucleate boiling -- Submicron spatial resolution -- Transient thermal imaging; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2016.04.121
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: The submicron characterization of transient heat-transfer processes at solid–liquid interfaces is of great importance in many areas of science and engineering. This paper reports on a technique that allows for the transient thermal imaging of the temperature field underneath a growing bubble during nucleate boiling with submicron spatial resolution. The boiling experiments were performed on a temperature-sensitive, erbium-doped, heavy-metal glass, Er:ZBLALiP, used as a robust sensing material for the non-invasive, transient temperature measurements. These measurements were made by analyzing the intensity variations of the fluorescence emission. The thermal imaging of an active nucleation site was performed by utilizing high-resolution, fluorescence microscopy, which enabled a maximum spatial resolution of 370 nm/pixel. The high-speed acquisition above 400 fps ensured sampling of individual bubble-nucleation events. Our transient measurements clearly revealed temperature variations underneath the growing bubble, as well as a measurable bubble-departure frequency under saturated conditions. These encouraging results suggest the need for a systematic use of the corresponding fluorescence technique on enhanced boiling surfaces in order to define the local heat-transfer characteristics and to gain a better understanding of the underlying physical processes. Highlights: Fluorescence thermal imaging of nucleate pool boiling process is presented. Non-invasive imaging of transient-temperature fields at submicron spatial resolution. Capturing of the individual microbubble-nucleation event is demonstrated. The technique allows studies of various thermal processes at the submicron level.