Heat Transfer Characteristics of Carbon Dioxide at Super-critical Pressure in Minutia-channels

超临界压力下二氧化碳在细小通道内的传热特性

• 批准号: 13650225
• 负责人: KOYAMA Shigeru
• 金额: $ 2.24万
• 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: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650225/
• 关键词: Carbon Dioxide; Supercritical Pressure; Sub-critical pressure; Single Phase Flow; Two Phase Flow; Minutia Channel; Experiment; Numerical Analysis; 超臨界流体

Heat transfer coefficient and pressure drop characteristics of carbon dioxide at supercritical pressure were investigated numerically for the in-tube laminar forced convective cooling process and the following conclusions can be drawn : (1) The radial distributions of axial velocity and temperature deform continuously in the axial direction due to the change of physical properties. (2) The local heat transfer coefficients show peak values as the bulk temperatures approach the pseudo-critical temperature. (3) The average heat transfer coefficient shows a maximum value when the average bulk temperature is nearly pseudo-critical. The maximum value of average heat transfer coefficient increases when the system pressure approaches the critical pressure. (4) The total pressure drop increases slightly as the average bulk temperature approaches to pseudo-critical temperature for the case of near critical pressure. The proportion of momentum change to total pressure drop increases as the heat f … More lux increases.Both the local and average heat transfer and pressure drop characteristics of supercritical carbon dioxide in horizontal mini channels in a cooling condition were investigated experimentally. An aluminum test section (500 mm long, 20mm wide and 2mm thick), which has 10 multi-port extruded circular channels with each 1.31mm inner diameter, was tested under pressures ranging from 7.4 to 8.5MPa, temperatures from 22 to 53℃, heat fluxes from 0.8 to 9 kW m^<-2>, and mass velocities from 113.7 to 418.6kg m^<-2>s. The main conclusions are as follows : (1) Heat transfer is enhanced greatly in the near-critical region, with a maximum heat transfer coefficient obtained at the corresponding pseudocritical temperature. (2) The system pressure, the mass velocity, and the temperature of CO_2 all have significant effects on heat transfer performance, especially in the near-critical region. The maximum heat transfer coefficient decreases as the pressure increases. The larger the mass velocity, the higher the heat transfer coefficient. (3) Correlations available in the literature deviate the experimental data. Based on the experimental data, a new Dittus-Boelter type correlation was developed for forced forced convective heat transfer of supercritical carbon dioxide in horizontal mini channels in cooling case. Less

对超临界压力下CO2管内层流强制对流冷却过程的换热系数和压降特性进行了数值研究，得出以下结论：（1）由于物性的变化，轴向速度和温度的径向分布沿轴向连续变形。(2)局部换热系数随体相温度接近拟临界温度而出现峰值。(3)平均传热系数在平均本体温度接近伪临界时出现最大值。当系统压力接近临界压力时，平均换热系数的最大值增大。(4)在近临界压力下，随着平均体相温度接近拟临界温度，总压降略有增加。动量变化占总压降的比例随热流密度的增大而增大 ...更多信息 实验研究了超临界CO2在水平微小通道内的局部和平均换热及压降特性。在压力7.4 ~ 8.5MPa、温度22 ~ 53℃、热流密度0.8 ~ 9 kW·m ~（-1）、质量流速113.7 ~ 418.6kg·m ~（-1）的条件下，对长500 mm、宽20 mm、厚2 mm的10个内径为1.31mm的多孔挤压圆形通道进行了实验<-2><-2>。主要结论如下：（1）在近临界区，换热得到了极大的强化，在相应的拟临界温度下，换热系数达到最大值。(2)系统压力、质量流速和CO_2温度对传热性能都有显著影响，尤其是在近临界区。最大换热系数随压力的增加而减小。质量流速越大，传热系数越高。(3)文献中的相关性偏离了实验数据。基于实验数据，建立了超临界CO2在冷却工况下水平微小通道内强制对流换热的Dittus-Boelter型关联式。少

项目成果

S.Koyama, D.-K.Kim and E.Shinmura: "Numerical Study on In-tube Laminar Heat Transfer Characteristics of CO2 at Supercritical Condition"Proceedings of IIR Conference on Thermophysical Properties and Transfer Processes of New Refrigerants at Paderborn. CD-R

S.Koyama、D.-K.Kim 和 E.Shinmura：“超临界条件下 CO2 管内层流传热特性的数值研究”帕德博恩 IIR 新型制冷剂热物理性质和传递过程会议论文集。

S.Koyama, X.Huai, E.Shinmura, H.Kinoshita and M.Morita: "Experimental Investigation of Heat Transfer and Pressure Drop of Supercritical Carbon Dioxide in Multi-port Mini Channels"International Journal of Refrigeration. (Submitted).

S.Koyama、X.Huai、E.Shinmura、H.Kinoshita 和 M.Morita：“多端口微型通道中超临界二氧化碳传热和压降的实验研究”国际制冷杂志。

小山繁, 新村悦生, 木下英彦, 森田真樹, 淮秀蘭: "超臨界圧におけるCO_2の扁平多孔管内冷却熱伝達に関する実験"第40回日本伝熱シンポジウム講演論文集. (発表予定). (2003)

Shigeru Koyama、Etsuo Niimura、Hidehiko Kinoshita、Maki Morita、Shuran Huai：“超临界压力下扁平多孔管中 CO_2 的冷却传热实验”第 40 届日本传热研讨会论文集（待发表）。

S.Koyama, K.Kuwahara, E.Shinmura, S.Ikeda: "Experimental Study on Flow Boiling of Carbon Dioxide in A Horizontal Small Diameter Tube"Proceedings of IIR Conference on Thermophysical Properties and Transfer Processes of New Refrigerants at Paderborn. (CD-RO

S.Koyama、K.Kuwahara、E.Shinmura、S.Ikeda：“水平小直径管中二氧化碳流动沸腾的实验研究”帕德博恩 IIR 新型制冷剂热物理性质和传输过程会议论文集。

S.Koyama, K.Kuwahara, E.Shinmura and S.Ikeda: "Experimental Study on Flow Boiling of Carbon Dioxide in A Horizontal Small Diameter Tube"Proceedings of IIR Conference on Thermophysical Properties and Transfer Processes of New Refrigerants at Paderborn. CD-

S.Koyama、K.Kuwahara、E.Shinmura 和 S.Ikeda：“水平小直径管中二氧化碳流动沸腾的实验研究”帕德博恩 IIR 新型制冷剂热物理性质和传输过程会议论文集。