Evaluation of enhanced nucleate boiling performance through wall- temperature distributions on PDMS-silica coated and non-coated laser textured stainless steel surfaces

Zupančič, Matevž (author), Može, Matic (author), Gregorčič, Peter (author), Sitar, Anže (author), Golobič, Iztok (author)

Nucleate boiling was examined on Joule heated stainless steel foils, functionalized by PDMS-silica coating and/or nanosecond-laser texturing. The nucleating bubbles and transient temperature fields were visual- ized through high-speed IR and video recordings. The differences in boiling performance were evaluated through wall-temperature distributions. Results confirmed that smooth surfaces require high activation temperatures and produce larger bubbles, while wall-temperature distributions display higher standard deviations, higher local superheats, and bimodal shapes. Similarly, relatively high activation temperatures were observed on the superhydrophilic surface, where the enhanced liquid replenishment on the active nucleation sites reduces the bubble departure diameters and prevents formation of local hotspots. Consequently, the analyzed temperature distributions have negative skewness and decreased standard deviation. The highest heat transfer coefficient was achieved on a laser textured surface with nonuniform wettability and multi-scale microcavities. Here, nucleation site density was as high as 200 cm-2 at 300 kW/m2 , while wall-temperature distributions demonstrated by far the lowest standard deviation. The temperature distributions also proved that annealed PDMS-silica coating significantly increased the thermal resistance of the entire heater. On the contrary, laser textured surfaces provided an even better boiling performance compared to coated surfaces and did not increase heater's thermal resistance. This additionally endorses the coating-free, direct laser texturing method as a cutting-edge technology in the development of surfaces capable of significantly enhanced boiling heat transfer.

• Language: English
• Keywords: enhanced boiling heat transfer, high-speed IR thermography, wall-temperature distributions, PDMS-silica coating, nanosecond laser texturing
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Author Accepted Manuscript
• Year: 2017
• Number of pages: Str. 419-428
• Numbering: Vol. 111
• PID: 20.500.12556/RUL-105526
• UDC: 536.24(045)
• ISSN on article: 0017-9310
• DOI: 10.1016/j.ijheatmasstransfer.2017.03.128
• COBISS.SI-ID: 15473691
• Publication date in RUL: 04.12.2018

Record is a part of a journal

• Title: International journal of heat and mass transfer
• Shortened title: Int. j. heat mass transfer
• Publisher: Elsevier
• ISSN: 0017-9310
• COBISS.SI-ID: 3064335

Secondary language

• Language: Slovenian
• Keywords: izboljšan prenos toplote pri vrenju, hitrotekoča IR termografija, temperaturna porazdelitev na grelni površini, PDMS-silika premaz, strukturiranje z nanosekundnimi laserskimi bliski

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0392, P2-0223
• Name: Optodinamika, Prenos toplote in snovi