| Project/Area Number |
09450095
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 |
YOSHIDA Suguru Kyushu Univ., Grad. Sch. Of Eng., Associate Professor, 工学研究科, 教授 (30037741)
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| Co-Investigator(Kenkyū-buntansha) |
OHISHI Katsumi Kyushu Univ., Grad. Sch. Of Eng., Research Associate, 工学研究科, 助手 (00037970)
MATSUNAGA Takashi Kurume Nat. Coll. Tech., Dep. Of Mech. Eng., Associate Professor, 機械工学科, 助教授 (60117249)
MORI Hideo Kyushu Univ., Grad. Sch. Of Eng., Associate Professor, 工学研究科, 助教授 (70150505)
OHNO Masaki Kyushu Univ., Grad. Sch. Of Eng., Research Associate, 工学研究科, 助手 (30037858)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥14,100,000 (Direct Cost: ¥14,100,000)
Fiscal Year 1999: ¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1998: ¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 1997: ¥8,100,000 (Direct Cost: ¥8,100,000)
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| Keywords | Horizontal Evaporator Tube / Dryout / Post-Dryout Heat Transfer / Refrigerant / Smooth Tube / Micro-Fin Tube / Experiment / Correlation / 水平蒸発管 / ポスト ドライアウト熱伝達 / 理論解析 |
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| Research Abstract |
Experiments were made on dryout quality and local heat transfer coefficient in the post-dryout region for the flow of boiling refrigerants HFC-134a and HCFC-22 inside horizontal smooth tubes and a horizontal micro-fin tube, and prediction methods were developed for the dryout quality and the heat transfer coefficient.
1. Dryout proceeded over a certain quality range at given conditions and, therefore, two dryout qualities were discussed ; the dryout inception quality at which the heat transfer began to deteriorate and the dryout completion quality at which the heat transfer deterioration ended. The characteristics of the dryout inception and completion qualities were clarified, and each of the dryout qualities was classified into three characteristic regimes for the smooth tube and two regimes for the micro-fin tube. Dimensionless correlations of both the qualities were developed for the respective tubes, and they agreed with the measurements within ±0.03 in the absolute values for the smooth tube and within ±0.02 for the micro-fin tube.
2. In the post-dryout region of the smooth tube, the two-phase flow pattern is a dispersed one, where the vapor-liquid mixture is not in a thermodynamic equilibrium. A correlation of the actual quality in the thermodynamic nonequilibrium was developed to predict the actual vapor mass flow rate. By the use of the actual vapor flow rate, the tube wall temperature is calculated from the Gnielinski equation assuming the single-phase flow of the vapor only, and then the heat transfer coefficient is determined. The calculated heat transfer coefficient agreed within ±10% with the measured one. The post-dryout heat transfer coefficient in the micro-fin tube can be calculated as a single-phase heat transfer from the Gnielinski equation with an equation of friction factor obtained from the measured pressure drop.
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