Analysis Evaluation of Downhole Heat Exchanger for the promotion of Geothermal Energy Utilization

井下换热器促进地热能利用的分析评价

• 批准号: 16560171
• 负责人: TAGO Makoto
• 金额: $ 0.96万
• 依托单位: Akita University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16560171/
• 关键词: geothermal energy; heat extraction; direct use of heat; downhole heat exchanger; geothermal heat pump; natural convection; heat conduction; natural energy

Several types of downhole heat exchangers, for example thermosyphon type heat pipe, concentric tube thermosyphon, U-tube downhole heat exchanger, coaxial downhole heat exchanger, as well as others, have been proposed in order to extract heat directly from shallow geothermal resources. Among these downhole heat exchangers, the U-tube downhole heat exchanger is widely used in Japan as well as around the world, because of its cost performance and easy construction. Another reason it is used is because it has been reported that highly efficient heat extraction can be achieved with the downhole coaxial heat exchanger through its reverse circulation mode of working fluid in heat extraction process.The aim of this study is to estimate the heat extraction and heat release performance of the geothermal heat exchangers including single, double and triple U-tube heat exchangers and downhole coaxial heat exchangers by experiments and computer simulation.From the experimental results it was found that increasing both the flow rate and inlet temperature of the working fluid of the heat extraction increases the heat release rate with a single U-tube heat exchanger. Furthermore, the comparison of the heat extraction performance between double and triple U-tube downhole heat exchangers was made by three-dimensional numerical calculation, The finding revealed that the heat extraction rate using a triple U-tube downhole heat exchanger is greater than that using a double U-tube under a fixed flow rate of the working fluid of heat extraction. In the case of downhole coaxial heat exchanger, it was found from the computer simulation that heat extraction performance greatly depended on the factors of the inner tube material, length of heat exchanger and circulation modes of working fluid of heat extraction.

为了直接从浅层地热资源中提取热量，已经提出了几种类型的井下热交换器，例如热虹吸式热管、同心管热虹吸、U形管井下热交换器、同轴井下热交换器等。在这些井下换热器中，U形管井下换热器由于其性价比高和易于施工而在日本以及世界各地被广泛使用。采用井下同轴换热器的另一个原因是，已有研究表明，井下同轴换热器在取热过程中，通过工质的反向循环方式，可以实现高效的取热。双U和三U-通过实验和计算机模拟，对套管式换热器和井下同轴式换热器进行了研究，结果表明，提高取热器工作流体的流量和入口温度，热释放率与一个单一的U型管换热器。通过三维数值计算，对双U型管和三U型管井下换热器的取热性能进行了比较，结果表明：在取热工质流量一定的情况下，三U型管井下换热器的取热率大于双U型管。在井下同轴换热器的情况下，通过计算机模拟发现，内管材料、换热器长度和取热工质循环方式等因素对取热性能有很大影响。

项目成果

Heat extraction characteristics by coaxial heat exchanger

• DOI: 10.1002/htj.20083
• 发表时间: 2005-11
• 期刊: Heat Transfer Research
• 影响因子: 1.7
• 作者: M. Tago;K. Morita;M. Sugawara;T. Fujita

ダブルU字管型地中熱交換器による地熱エネルギー抽出

使用双U型管地下热交换器提取地热能

• 发表时间: 2005
• 期刊: 第42回日本伝熱シンポジウム講演論文集
• 作者: Hisami MURAMATUS;Masayuki KATAHIRA;Kenichi SHOUBU;S.Saitoh;田子 真
• 通讯作者: 田子 真

ダブルU字管方式による地熱エネルギー抽出

双U管法提取地热能

• 发表时间: 2004
• 期刊: 日本機械学会東北支部第40期秋季講演会講演論文集 No.041-2
• 作者: 村松久巳;片平雅之;生部賢一;Shinzaburo Umeda;田子 真
• 通讯作者: 田子 真

Heat Extraction Characteristics of a Single U-Tube Downhole Heat Exchanger with Square Cross Section

方形截面单U形管井下换热器的排热特性

• 发表时间: 2005
• 期刊: Heat and Mass Transfer (DOI 10. 1007/s00231-005-0033-2)
• 作者: H.Li;M.Takei;Y.Tomita;Y.Saito;K.Horii;Shinzaburo Umeda;Makoto TAGO;村松久巳;Makoto TAGO
• 通讯作者: Makoto TAGO

同軸型熱交換器の熱抽出特性

同轴换热器的排热特性

• 发表时间: 2005
• 期刊: 日本機械学会論文集(B編) 71巻・701号
• 作者: Kaito;A.;Sugawara;K.;Yoshikawa;H.;Ota;T.;谷口輝;Hisami MURAMATUS;田子 真
• 通讯作者: 田子 真