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International Heat Transfer Conference 16

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

INVESTIGATION ON BUBBLE DYNAMIC BEHAVIORS UNDER PULSE HEATING

S.C. Wu
Southeast University, Sipailou 2#, Xuanwu District, Nanjing 210096, China

Xiangdong Liu
Yangzhou University, 88 South University Ave., Yangzhou 225009, China

Chengbin Zhang
Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, PR China

Yongping Chen
Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, PR China; School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, PR China

DOI: 10.1615/IHTC16.bae.023676
pages 1397-1403


KEY WORDS: Boiling, Two-phase flow, Numerical simulation, Pulse heating, Bubble

Abstract

A two-dimensional model of two phase flow and boiling phase change under pulse heating in a confined microchannel is developed and numerically analyzed to investigate the bubble dynamic behaviors under pulse heating. Through lattice Boltzmann simulation, the onset of boiling, bubble dynamic behaviors (including nucleation, growth, collapse or coalescence) are investigated and discussed. Besides, the effects of heat flux and surface wettability on the bubble dynamics under pulse heating are examined and analyzed. The results indicate that three bubble growth regimes including single bubble growth, coalescence growth, and film-boiling growth are observed with the increase of pulse heat flux. Bubble growth and collapse under different pulse heat flux are all accompanied by the apparent volume oscillation. The onset of boiling in confined microchannel starts earlier with the increase of heat flux. The maximum heat flux also contributes to the highest surface temperature. However, the maximum bubble radius is obtained under a moderate heat flux for the observed bubble coalescence phenomenon, which also reduces the bubble radius oscillation during bubble growth. In addition, the bubble is stimulated earlier on the hydrophobic surface as compared with hydrophilic one. The hydrophobicity also contributes to the direct contact between the bubble and cooling surface after pulse heat is off. Thus, bubble on the hydrophobic surface shows a faster collapse rate.

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