Development of Numerical Experimental Model for Heat Transfer in High Quality Region of Flow Boiling in Tube Evaporator with Twisted Tape-Insert

扭带嵌件管式蒸发器流动沸腾高质量区域传热数值实验模型的建立

• 批准号: 10650216
• 负责人: YOSHIDA Keisuke
• 金额: $ 2.11万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650216/
• 关键词: Twisted Tape-Insert; Heat Transfer Enhancement; Flow Boiling; Tube Evaporator; High Quality Region; Post-Dryout Region; Droplets; Numerical Simulation; 管内沸騰; 高クオリティ域熱伝達; ポストドライアウト; 液滴熱伝達; 電熱促進

This research aimed to develop a numerical experimental mode which can simulates behavior of droplets in the post-dryout region of flow boiling in tube evaporator, in order to find the way to the heat transfer enhancement in this region effectively by twisted tape-insert, which contributes to reducing the tube length required. The research was performed by experimental studies on heat transfer and critical heat flux(CHF)of the flow boiling, and by numerical analysis using computer.In the experiments data for refrigerant HFC134a were obtained for the horizontal flow conditions (mass flux 100-600 kg/mィイD12ィエD1s). The following results were clarified : (1)The heat transfer characteristics and the relation between CHF and the critical quality for a smooth tube(O. D. 7mm, I. D. 6.34mm)showed the similar tendencies to the results which had been obtained previously for the different flow conditions and refrigerants by the investigators. (2)Magnitude of the heat transfer enhancement by the twi … More sted tape inserted into the smooth tube in the post-dryout region agreed qualitatively with the experimental results which had been obtained for refrigerant CHF113 by the head investigator.In the numerical analysis a simulation of behavior of a single droplet in vapor flow which collides with heated wall was carried out by the modified VOF method which is taking account of phase change at the vapor-liquid interface. The results showed that the calculation could simulate behavior of the droplet until it collided with the wall, and the definition of temperature of the cell which included the interface affected the complexity of calculation beyond the investigators' expectation. However the most relevant condition at which the droplet departs form the wall has not been found.In addition, a simple method using Thermo-Paint(temperature sensing paint), which changes its color with temperature, was proposed to measure the surface temperature profile outside the tube, and was confirmed its usefulness by another experiment. Less

本研究旨在建立一种能够模拟管式蒸发器流动沸腾干后区域液滴行为的数值实验模式，以寻找通过扭曲带插入有效增强该区域换热的方法，从而减少管长。通过对流动沸腾的传热和临界热流密度的实验研究，以及计算机数值分析进行了研究。实验中获得了制冷剂HFC134a在水平流动条件下（质量流量100-600 kg/m μ l - 12 μ l - 1 μ l - 1）的数据。结果表明：(1)光滑管的传热特性及CHF与临界质量的关系。直径7mm，内径6.34mm)与研究者在不同的流动条件和制冷剂下得到的结果相似。(2)在干后区光滑管内插入双丝带的换热增强幅度与首席研究员对CHF113制冷剂的实验结果定性一致。在数值分析中，采用考虑气液界面相变的改进VOF方法，对单个液滴在蒸汽流动中与加热壁面碰撞的行为进行了模拟。结果表明，计算可以模拟液滴与壁面碰撞之前的行为，而包含界面的细胞温度的定义对计算复杂性的影响超出了研究人员的预期。然而，液滴离开壁面的最相关条件尚未找到。此外，还提出了一种简单的方法，即利用随温度变化颜色的thermopaint来测量管外表面的温度分布，并通过另一个实验验证了该方法的有效性。少

项目成果

H. Mori: "Dryout Quality and Post-Dryout Heat Transfer Coefficient for a Refrigerant Flowing in Horizontal Evaporator Tubes"20th Int. Congress of refrigeration. (in press). (2000)

H. Mori：“水平蒸发器管中流动的制冷剂的干燥质量和干燥后传热系数”20th Int。

H. Mori: "Dryout Quality and Post-Dryout Heat Transfer Coefficient for a Refrigerant Flowing in Horizontal Evaporator Tubes"20th Int. Congress of Refrigeration. (印刷中). (2000)

H. Mori：“水平蒸发器管中制冷剂的干燥质量和干燥后传热系数”第 20 届国际制冷大会（2000 年出版）。

K.YOSHIDA: "Convective Heat Transfer Enhancement of a Rotating Drum for the Permanent Magnet Type Eddy Current Retarder"Proc. of 1999 National Heat Transfer Conference, ASME. NHTC99-115. 1-6 (1999)

K.YOSHIDA：“用于永磁型涡流减速器的旋转滚筒的对流传热增强”Proc。

H.Mori: "Dryout Quality and Post-Dryout Heat Transfer Coefficient for a Refrigerant Flowing in Horizontal Evaporator Tubes"Proc. of the 20th Int. Congress of Refrigeration. (印刷中). (2000)

H.Mori：“水平蒸发器管中制冷剂的干燥质量和干燥后传热系数”，第 20 届国际制冷大会论文集（2000 年）。

森 英夫: "管内流れにおける限界熱流束" 日本機械学会75期通常総会講演会資料集. 4. 518-519 (1998)

Hideo Mori：日本机械工程师学会第 75 届普通大会的“管流中的临界热通量”材料。4. 518-519 (1998)