TY - JOUR
T1 - Experimental investigations on the influence of polymerization degree in polymer-assisted pool boiling enhancement
AU - Luo, Jielin
AU - Yang, Hongxing
AU - Wen, Tao
N1 - Funding Information:
This study was supported by the Postdoctoral Hub Program (PiH/1309/21) of the Innovation and Technology Fund , The Hong Kong SAR Government.
Publisher Copyright:
© 2023 Elsevier Ltd
PY - 2023/3
Y1 - 2023/3
N2 - The addition of polymer has been widely demonstrated effective for heat transfer enhancement. However, the influence of polymerization degree is rarely studied independently. In this paper, polyvinylpyrrolidones (PVP) with different polymerization degrees were attempted to enhance nucleate pool boiling performance at the mass fraction from 100 ppm to 3200 ppm. For PVP K15, K60 and K90, their highest heat transfer coefficients were 141.88 kW/(m2·K) at 3200 ppm, 150.64 kW/(m2·K) at 3200 ppm and 141.50 kW/(m2·K) at 1600 ppm respectively, all significantly higher than 61.37 kW/(m2·K) of distilled water. The mechanism was explored by solution property measurements and bubble behavior observations. The variations of nucleate sites, bubble size and departure frequency were observed, with the detection of special behaviors including bubble repulsion, bubble leaving retardancy, bubble-bubble penetration and liquid entrainment. The mechanism on the influence of polymerization degree is comprehensively proposed. Higher polymerization degree corresponds to lower surface tension, higher local viscosity, stronger normal stress between bubble and surface, and greater repulsion force between bubbles. The findings in this paper is of great significance, not only for predicting results of present polymers, but also for providing guidance for exploration of next-generation boiling-enhanced substance in field of heat conversion and transfer.
AB - The addition of polymer has been widely demonstrated effective for heat transfer enhancement. However, the influence of polymerization degree is rarely studied independently. In this paper, polyvinylpyrrolidones (PVP) with different polymerization degrees were attempted to enhance nucleate pool boiling performance at the mass fraction from 100 ppm to 3200 ppm. For PVP K15, K60 and K90, their highest heat transfer coefficients were 141.88 kW/(m2·K) at 3200 ppm, 150.64 kW/(m2·K) at 3200 ppm and 141.50 kW/(m2·K) at 1600 ppm respectively, all significantly higher than 61.37 kW/(m2·K) of distilled water. The mechanism was explored by solution property measurements and bubble behavior observations. The variations of nucleate sites, bubble size and departure frequency were observed, with the detection of special behaviors including bubble repulsion, bubble leaving retardancy, bubble-bubble penetration and liquid entrainment. The mechanism on the influence of polymerization degree is comprehensively proposed. Higher polymerization degree corresponds to lower surface tension, higher local viscosity, stronger normal stress between bubble and surface, and greater repulsion force between bubbles. The findings in this paper is of great significance, not only for predicting results of present polymers, but also for providing guidance for exploration of next-generation boiling-enhanced substance in field of heat conversion and transfer.
KW - Heat transfer enhancement
KW - Mechanism
KW - Nucleate pool boiling
KW - Polymerization degree
KW - Polyvinylpyrrolidone
UR - http://www.scopus.com/inward/record.url?scp=85147857624&partnerID=8YFLogxK
U2 - 10.1016/j.icheatmasstransfer.2023.106650
DO - 10.1016/j.icheatmasstransfer.2023.106650
M3 - Journal article
AN - SCOPUS:85147857624
SN - 0735-1933
VL - 142
JO - International Communications in Heat and Mass Transfer
JF - International Communications in Heat and Mass Transfer
M1 - 106650
ER -