干热岩热能的热管开采方案及其技术可行性研究
收稿日期: 2017-07-29
修回日期: 2017-11-04
网络出版日期: 2017-12-29
基金资助
广东省自然科学基金-重大基础研究培育项目(2014A030308001);
国家自然科学基金-广东省联合基金项目(U1401232)
Mining Hot Dry Rock Geothermal Energy by Heat Pipe: Conceptual Design and Technical Feasibility Study
Received date: 2017-07-29
Revised date: 2017-11-04
Online published: 2017-12-29
蒋方明 , 黄文博 , 曹文炅 . 干热岩热能的热管开采方案及其技术可行性研究[J]. 新能源进展, 2017 , 5(6) : 426 -434 . DOI: 10.3969/j.issn.2095-560X.2017.06.003
In conventional enhanced geothermal systems (EGS), heat is extracted from earth-deep by circulating fluid through fractured-rock heat reservoir. This process generally consumes large amount of pump work, and has problems like fluid loss and pipe scaling etc. Moreover, it often encounters failure due to the bad downhole connectivity of fracture network in the reservoir. To circumvent these problems, conceptual design about mining heat from earth-deep hot dry rock by heat pipe is presented for the first time. Hoping to have strong natural convection of CO2 in the reservoir to enhance the heat transfer between rock and heat pipe, filling the reservoir with CO2 fluid is specially proposed. Further, numerical modeling and theoretical analysis are performed to explore the technical feasibility of the new HDR heat extraction concept. The numerical model considers CO2 of temperature- and pressure- dependent thermophysical properties. Effects of natural convection of CO2 in the target reservoir on the heat extraction by heat pipe are studied; heat extraction rates by different conditioned heat pipes are compared. The results indicate that lowering the working temperature of heat pipe can significantly increase the heat extraction rate and notable increase at the heat extraction rate will be caused by the natural convection of CO2 if the reservoir permeability is higher than 1 × 10−9 m2. It is found from numerical results also that an increase of 1.5 ~ 3 times at the heat extraction rate can be achieved if the heating section of the heat pipe is arranged horizontally compared to all vertically aligned heat pipe. Additionally, the carrying limit and steam flow resistance for water thermosyphon are analyzed numerically under realistic geothermal conditions.
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