Forced Convection Heat Transfer of Liquid-Gas Foam around a Circular Cylinder

液-气泡沫绕圆柱体的强制对流换热

• 批准号: 11650200
• 负责人: TOKURA Ikuo
• 金额: $ 0.7万
• 依托单位: MURORAN INSTITUTE OF TECHNOLOGY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650200/
• 关键词: Liquid-Gas Foam; Non-Newtonian Fluid; Forced Convection; Two-Phase Flow; Heat Transfer; Circular Cylinder; 熱伝達率

Water-air foam is a new material for a coolant and expected to be applied in various industrial fields in the future. To clarify thermal properties of the flowing foam, forced convection heat transfer experiments were conducted by using a heated circular cylinder. Foam with wide rage of expansion ratio and various values of foam velocity was used in this study. We can draw the following conclusions from the study conducted in the academic years of 1999 and 2000.○When the temperature of the heating surface is less than 373K.The value of mean heat transfer coefficient for foam flow ranges between those for water and the air flows. This result suggest that intermediate cooling rate between water cooling and air cooling is obtained by using a liquid-gas foam. The heat transfer coefficient increases with increasing foam velocity and with decreasing the expansion ratio of the foam. It was indicated that the-value of the coefficient extremely decreases in a condition of low velocity and high … More expansion ratio of the foam. The heat transfer coefficient increases with the temperature difference between the heating surface and the foam. This result is much different from the heat transfer characteristics of usual one-phase fluids. Numerical analysis shows that the latent heat transfer by water vapor diffusion in the foam is the one of the important factors that increases the heat transfer coefficient at higher temperature range.○When the temperature increases over 373K.When the heat flux is increased gradually, the temperature of the heating surface increases and reaches 373K, i.e., the boiling point of water. Farther increase in the heat flux result in the temperature remains 373K for a while, and then begin to increase rapidly. The rate of increase in the heat flux with the surface temperature is relatively low in a super heated region. This boiling heat transfer characteristic of the foam flow is also much different from those for one phase liquids. In the temperature range around 373K, the heat flux for the foam flow is greater then that for water. In other temperature ranges, the heat flux for foam flow is lower than that of water. Less

水-气泡沫是一种新型的冷却剂材料，有望在各个工业领域得到应用。为了阐明流动泡沫的热学性质，利用加热圆柱体进行了强迫对流换热实验。研究中采用了膨胀率范围较大、泡沫速度不同的泡沫材料。通过1999和2000两个学年的研究，得出以下结论：当受热面温度低于373K时，泡沫流的平均换热系数介于水和空气流之间。这一结果表明，采用液气泡沫可以获得介于水冷和空冷之间的中间冷却速度。换热系数随泡沫速度的增大而增大，随泡沫膨胀率的减小而增大。结果表明，在低速、高…条件下，该系数的负值极大地减小。泡沫的膨胀率更大。受热面与泡沫之间的温差越大，换热系数越大。这一结果与通常单相流体的换热特性有很大的不同。数值分析表明，在较高温度范围内，水蒸气在泡沫中的扩散潜热是提高换热系数的重要因素之一。当温度升高到373K以上时，当热流密度逐渐增大时，受热面温度升高，达到373K，即水的沸点。热流密度的进一步增加导致温度在一段时间内保持在373K，然后开始迅速升高。在过热区域，热流密度随表面温度的增加速率相对较低。泡沫流的这种沸腾换热特性也与单相液体的沸腾换热特性有很大不同。在373K左右的温度范围内，泡沫流的热流比水的热流大。在其他温度范围内，泡沫流动的热流密度低于水的热流密度。较少

项目成果

T.Matuda, I.Tokura, N.Ogawa and S.Ogahata: "Pressure Drop and Heat Transfer for Foam Flow Through a Circular Pipe"Pre-prints of Fluid Engineering Conference 2000, JSME. No.00-14. 150 (2000)

T.Matuda、I.Tokura、N.Okawa 和 S.Ogahata：“通过圆形管道的泡沫流的压降和传热”2000 年流体工程会议预印本，JSME。

戸倉郁夫 ほか3名: "流動液体泡沫の加熱円筒回りの熱伝達"日本機械学会北海道支部第40回講演会講演概要集. No.002-1. 142-143 (2000)

Ikuo Tokura 等 3 人：“流动液体泡沫加热筒周围的传热”日本机械工程师学会第 40 届北海道分会摘要第 002-143 号（2000 年）。

I,Tokura, et al.: "Heat Tranfer Characteristics of Foam Flow at Temperature up to 373K"Proceedings of 4th JSME-KSME Thermal Engineering Conference. Vol.3. 45-50 (2000)

I,Tokura, et al.：“泡沫流在温度高达 373K 时的传热特性”第四届 JSME-KSME 热工会议论文集。