CIESC Journal ›› 2021, Vol. 72 ›› Issue (3): 1302-1313.DOI: 10.11949/0438-1157.20200639

• Fluid dynamics and transport phenomena • Previous Articles     Next Articles

Numerical study and economic analysis of gravity heat pipe hot dry rock geothermal system

HUANG Wenbo1,2,3(),CAO Wenjiong1,2,3,LI Tingliang1,2,3,4,JIANG Fangming1,2,3()   

  1. 1.Laboratory of Advanced Energy Systems, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, Guangdong, China
    2.Key Laboratory of Renewable Energy, Chinese Academy of Sciences, Guangzhou 510640, Guangdong, China
    3.The Guangdong Provincial Key Laboratory of New and Renewable Energy, Guangzhou 510640, Guangdong, China
    4.University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2020-05-25 Revised:2020-09-30 Online:2021-03-05 Published:2021-03-05
  • Contact: JIANG Fangming

干热岩热能重力热管采热系统数值模拟研究与经济性分析

黄文博1,2,3(),曹文炅1,2,3,李庭樑1,2,3,4,蒋方明1,2,3()   

  1. 1.中国科学院广州能源研究所先进能源系统研究室,广东 广州 510640
    2.中国科学院可再生能源重点实验室,广东 广州 510640
    3.广东省新能源和可再生能源研究开发与应用重点实验室,广东 广州 510640
    4.中国科学院大学,北京 100049
  • 通讯作者: 蒋方明
  • 作者简介:黄文博(1990—),男,博士,助理研究员,huangwb@ms.giec.ac.cn
  • 基金资助:
    国家重点研发计划项目(2018YFB1501804);中国科学院A类战略性先导科技专项(XDA21060700);国家自然科学基金青年基金项目(41702206)

Abstract:

The use of ultra-long gravity heat pipes to extract thermal energy from hot dry rocks can avoid the problems of working fluid loss, corrosion and scaling, and difficulties in underground communication in enhanced geothermal systems. Moreover, compared with downhole heat exchanger (DHE) geothermal system, the evaporation and condensation process in heat pipe can increase the temperature difference between heat pipe and heat reservoir, probably leading to a much higher heat extraction rate. The present work develops a numerical model that couples the phase transition and flow process in heat pipe with the seepage flow and heat transfer process in fractured reservoir. The operation of a 4500 m heat pipe geothermal system is thus simulated and compared with single-well DHE geothermal system. The influence of nature fluid flow in fractured reservoir is particularly analyzed. Furthermore, the electricity-production cost of heat pipe geothermal system is calculated and compared with that of the DHE geothermal system and the traditional enhanced geothermal system (EGS). The results show that the capacity of heat pipe geothermal power plant is about 240 kW and the cost of electricity-production is 1.124 CNY/(kW·h), which is almost the same as that for the EGS and much lower than that for the DHE. If abandoned oil and gas wells are used to construct a gravity heat pipe geothermal system, the cost of power generation is only 0.644 CNY/(kW·h).

Key words: renewable energy, thermodynamics process, numerical study, hot dry rock, gravity heat pipe, electricity cost

摘要:

利用超长重力热管开采干热岩热能可以避免增强型地热系统存在的工质损失、腐蚀结垢和井下连通困难等问题;相比于单井井下换热器系统,热管管内液-气相变使得管壁与热储之间的传热温差增大,使用重力热管开采地热能有望获得更高的单井采热量。本文开发了能对重力热管内部过程与裂隙热储渗流过程进行耦合求解的数值模型,模拟了管长4500 m的重力热管地热系统运行过程,研究了裂隙热储中的流体自然对流对地热系统性能的影响,并与套管式井下换热器地热系统进行了对比研究。进一步分析比较了重力热管、套管井下换热器、增强型地热系统电站的发电成本。研究结果表明,重力热管地热系统单井发电量可达240 kW以上,发电成本约为1.124 CNY/(kW·h),与增强型地热系统电站发电成本接近,优于井下换热器式地热系统;如果利用废弃油气井建设重力热管地热系统,发电成本仅0.644 CNY/(kW·h)。

关键词: 再生能源, 热力学过程, 数值模拟, 干热岩, 重力热管, 成本电价

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