Evaluation of enhanced nucleate boiling performance through wall- temperature distributions on PDMS-silica coated and non-coated laser textured stainless steel surfaces
ID Zupančič, Matevž (Author), ID Može, Matic (Author), ID Gregorčič, Peter (Author), ID Sitar, Anže (Author), ID Golobič, Iztok (Author)

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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.

Keywords:enhanced boiling heat transfer, high-speed IR thermography, wall-temperature distributions, PDMS-silica coating, nanosecond laser texturing
Work type:Article (dk_c)
Typology:1.01 - Original Scientific Article
Organization:FS - Faculty of Mechanical Engineering
Publication status in journal:Published
Article version:Postprint, final article version, accepted into publication
Number of pages:Str. 419-428
Numbering:Vol. 111
PID:20.500.12556/RUL-105526 This link opens in a new window
ISSN on article:0017-9310
DOI:10.1016/j.ijheatmasstransfer.2017.03.128 This link opens in a new window
COBISS.SI-ID:15473691 This link opens in a new window
Publication date in RUL:04.12.2018
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Record is a part of a journal

Title:International journal of heat and mass transfer
Shortened title:Int. j. heat mass transfer
COBISS.SI-ID:3064335 This link opens in a new window

Secondary language

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


Funder:ARRS - Agencija za raziskovalno dejavnost Republike Slovenije
Project number:P2-0392, P2-0223
Name:Optodinamika, Prenos toplote in snovi

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