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Open AccessArticle

Investigation of Start-Up Characteristics of Thermosyphons Modified with Different Hydrophilic and Hydrophobic Inner Surfaces

School of Energy and Power, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212000, China
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Energies 2020, 13(3), 765; https://doi.org/10.3390/en13030765
Received: 20 December 2019 / Revised: 5 February 2020 / Accepted: 7 February 2020 / Published: 9 February 2020
(This article belongs to the Special Issue Heat Transfer in Energy Conversion Systems)
In this paper, the influence of wettability properties on the start-up characteristics of two-phase closed thermosyphons (TPCTs) is investigated. Chemical coating and etching techniques are performed to prepare the surfaces with different wettabilities that is quantified in the form of the contact angle (CA). The 12 TPCTs are processed including the same CA and a different CA combination on the inner surfaces inside both the evaporator and the condenser sections. For TPCTs with the same wettability properties, the introduction of hydrophilic properties inside the evaporator section not only significantly reduces the start-up time but also decreases the start-up temperature. For example, the start-up time of a TPCT with CA = 28° at 40 W, 60 W and 80 W is 46%, 50% and 55% shorter than that of a TPCT with a smooth surface and the wall superheat degrees is 55%, 39% and 28% lower, respectively. For TPCTs with combined hydrophilic and hydrophobic properties, the start-up time spent on the evaporator section with hydrophilic properties is shorter than that of the hydrophobic evaporator section and the smaller CA on the condenser section shows better results. The start-up time of a TPCT with CA = 28° on the evaporator section and CA = 105° on the condenser section has the best start-up process at 40 W, 60 W and 80 W which is 14%, 22% and 26% shorter than that of a TPCT with smooth surface. Thus, the hydrophilic and hydrophobic modifications play a significant role in promoting the start-up process of a TPCT. View Full-Text
Keywords: Thermosyphon; start-up characteristics; hydrophilic and hydrophobic; contact angle Thermosyphon; start-up characteristics; hydrophilic and hydrophobic; contact angle
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MDPI and ACS Style

Ma, X.; Zhao, Z.; Jiang, P.; Yang, S.; Li, S.; Chen, X. Investigation of Start-Up Characteristics of Thermosyphons Modified with Different Hydrophilic and Hydrophobic Inner Surfaces. Energies 2020, 13, 765.

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