Visualization Study of Startup Modes and Operating States of a Flat Two-Phase Micro Thermosyphon

Liangyu Wu, Yingying Chen, Suchen Wu, Mengchen Zhang, Weibo Yang and Fangping Tang
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Liangyu Wu: School of Hydraulic, Energy and Power Engineering, Yangzhou University, Yangzhou 225127, China
Yingying Chen: School of Hydraulic, Energy and Power Engineering, Yangzhou University, Yangzhou 225127, China
Suchen Wu: Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China
Mengchen Zhang: Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China
Weibo Yang: School of Hydraulic, Energy and Power Engineering, Yangzhou University, Yangzhou 225127, China
Fangping Tang: School of Hydraulic, Energy and Power Engineering, Yangzhou University, Yangzhou 225127, China

Energies, 2018, vol. 11, issue 9, 1-15

Abstract: The flat two-phase thermosyphon has been recognized as a promising technique to realize uniform heat dissipation for high-heat-flux electronic devices. In this paper, a visualization experiment is designed and conducted to study the startup modes and operating states in a flat two-phase thermosyphon. The dynamic wall temperatures and gas–liquid interface evolution are observed and analyzed. From the results, the sudden startup and gradual startup modes and three quasi-steady operating states are identified. As the heat load increases, the continuous large-amplitude pulsation, alternate pulsation, and continuous small-amplitude pulsation states are experienced in sequence for the evaporator wall temperature. The alternate pulsation state can be divided into two types of alternate pulsation: lengthy single-large-amplitude-pulsation alternated with short multiple-small-amplitude-pulsation, and short single-large-amplitude-pulsation alternated with lengthy multiple-small-amplitude alternate pulsation state. During the continuous large-amplitude pulsation state, the bubbles were generated intermittently and the wall temperature fluctuated cyclically with a continuous large amplitude. In the alternate pulsation state, the duration of boiling became longer compared to the continuous large-amplitude pulsation state, and the wall temperature of the evaporator section exhibited small fluctuations. In addition, there was no large-amplitude wall temperature pulsation in the continuous small-amplitude pulsation state, and the boiling occurred continuously. The thermal performance of the alternate pulsation state in a flat two-phase thermosyphon is inferior to the continuous small-amplitude pulsation state but superior to the continuous large-amplitude pulsation state.

Keywords: thermosyphon; two-phase flow; startup; phase change; operating state; visualization (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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