1998 Fiscal Year Final Research Report Summary
MARANGONI EFFECT ON BOILING OF MIXTURES
| Project/Area Number |
09650243
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
FUJITA Yasunobu KYUSHU UNIV., FAC.OF ENG., PROF., 工学部, 教授 (90037763)
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| Co-Investigator(Kenkyū-buntansha) |
BAI Qiang KYUSHU UNIV., FAC.OF ENG., RES.ASSO., 工学部, 助手 (00274499)
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| Project Period (FY) |
1997 – 1998
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| Keywords | MARANGONI CONVECTION / MIXTURE BOILING / CRITICAL HEAT FLUX / MENISCUS / THREE PHASE INTERFACE / EVAPORATION / BUBBLE GROWTH |
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| Research Abstract |
1. Bubble Growth Analysis Based on Meniscus Model
A numerical simulation scheme was developed to analyze the bubble growth in nucleate boiling and the effect of microlayer evaporation on bubble growth. Heat for the bubble growth was assumed as supplied through the bubble cap by convection and the meniscus by conduction. Transient Navier-Stokes and energy equations were solved using a two-dimensional arbitrary Lagrangian-Eulerian finite element method based on quadrilateral elements. It was revealed that the scheme offers a useful mean to investigate the growth process of bubble with no assumption on the bubble shape and it enables a quantitative description of flow and temperature fields around growing bubbles. It was concluded that the microlayer evaporation dominates bubble growth so that it may be substantial in boiling heat transfer.
2. Flow and Heat Transfer in Evaporating Meniscus
Evaporation from thin film is very important in heat transfer processes associated with phase change. To make it clear, a steady-state temperature distribution of a meniscus film formed on an inclined and heated cooper plate partially submerged into liquid was measured using a Mach-Zehnder laser interferometer. Water, ethanol, ethylene glycol and their mixtures were used as test fluids to investigate the effect of Marangoni convection on heat transfer in the evaporating meniscus. A numerical analysis was also performed to elucidate heat and flow characteristics in the intrinsic meniscus region and the adjacent evaporating thin film region. It was found the flow direction in the meniscus is reversed, whether mixture is positive or negative. Thus Marangoni convection is expected to play an important role in the evaporation of meniscus film for mixtures.
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