Numerical calculation of heat transfer in single medium-deep geothermal well

Authors

SHANG Hongbo, Xi'an Research Institute of Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710077, China; Shaanxi Key Laboratory of Prevention and Control Technology for Coal Mine Water Hazard, Xi'an 710077, China
ZHAO Chunhu, Xi'an Research Institute of Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710077, China; Shaanxi Key Laboratory of Prevention and Control Technology for Coal Mine Water Hazard, Xi'an 710077, China
JIN Dewu, Xi'an Research Institute of Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710077, China; Shaanxi Key Laboratory of Prevention and Control Technology for Coal Mine Water Hazard, Xi'an 710077, China
XU Shuanhai, Xi'an Research Institute of Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710077, China
WANG Xiaodong, Xi'an Research Institute of Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710077, China
ZHANG Weidong, Xi'an Research Institute of Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710077, China
HAN Yongliang, Xi'an Research Institute of Co. Ltd., China Coal Technology and Engineering Group Corp., Xi'an 710077, China

Abstract

Medium-deep geothermal single well heat transfer is a technology of developing geothermal energy to "obtain heat without extracting groundwater". This technology has the advantages of not damaging the groundwater environment and taking more heat. However, there are few studies on the numerical calculation of single well heat transfer above 3000m depth. In this paper, based on the geothermal geological conditions in Xi'an, the numerical method was used to calculate the heat transfer of a medium-deep geothermal single well with different well structures (L-shaped directional wells and cluster directional wells) under the scenario of continuous operation of a heating season. The results show that under the same flow rate and geothermal gradient, the outlet temperature, heat taken per unit time and the heat taken by the extended meter in the L-shaped directional wells are higher than that of cluster directional wells after 120 days of continuous operation. At the same flow rate, the higher the geothermal gradient, the higher the outlet temperature, and the greater the heat value per unit time and the heat by the extended meter. Under the same geothermal gradient, the higher the flow rate, the lower the outlet temperature, and the greater the heat per unit time and the heat by the extended meter are. In cluster directional wells, the outlet temperature, the heat per unit time, and the heat by extended meter at 30° inclination was higher than that at 45°inclination.With the increase of flow rate, the difference of outlet temperature, heat per unit time and heat by extended meter under two kinds of deviations decreased gradually. Considering the outlet temperature, heat per unit time and heat by extended mete, the heat transfer of L-type directional wells was better than that of cluster directional wells; from the point of view of the difficulty of drilling operation, cluster directional wells are better than L-type directional wells; in two kinds of deviation structures of cluster directional wells, cluster directional wells with 30°inclination are better than 45°inclination. Therefore, the calculated results under different working conditions can provide a reference for the development and utilization of medium-deep geotherm

Keywords

medium-deep layer, single well heat transfer, numerical method, heat transfer per-meter, cluster directional well, Xi'an area

DOI

10.3969/j.issn.1001-1986.2019.06.024

Recommended Citation

SHANG Hongbo, ZHAO Chunhu, JIN Dewu, et al. (2019) "Numerical calculation of heat transfer in single medium-deep geothermal well," Coal Geology & Exploration: Vol. 47: Iss. 6, Article 25.
DOI: 10.3969/j.issn.1001-1986.2019.06.024
Available at: https://cge.researchcommons.org/journal/vol47/iss6/25

Reference

[1] 刁乃仁,曾和义,方肇洪. 竖直U型管地热换热器的准三维传热模型[J]. 热能动力工程,2003,18(4):387-390. DIAO Nairen,ZENG Heyi,FANG Zhaohong. A quasi three-dimensional heat transfer model for vertical U-tube geothermal heat exchangers[J]. Journal of Engineering for Thermal Energy & Power,2003,18(4):387-390.

[2] 陈必光,宋二祥,程晓辉. 二维裂隙岩体渗流传热的离散裂隙网络模型数值计算方法[J]. 岩石力学与工程学报,2014,33(1):43-51. CHEN Biguang,SONG Erxiang,CHENG Xiaohui. A numerical method for discrete fracture network model for flow and heat transfer in two-dimensional fractured rocks[J]. Chinese Journal of Rock Mechanics and Engineering,2014,33(1):43-51.

[3] 曾宪斌. 地源热泵垂直U型埋管换热器周围土壤温度场的数值模拟[D]. 重庆:重庆大学,2007.

[4] SANAYE S,NIROOMAND B. Thermal-economic modeling and optimization of vertical ground-coupled heat pump[J]. Energy Conversion and Management,2009,50(4):1136-1147.

[5] 崔淑琴,高青,李明,等. 地源热泵非连续过程地下传热特性及其控制[J]. 吉林大学学报(工学版),2006,36(2):172-176. CUI Shuqin,GAO Qing,LI Ming,et al. Underground heat transfer characteristics in discontinuous operation of GSHP and its control strategy[J]. Journal of Jilin University(Engineering and Technology Edition),2006,36(2):172-176.

[6] 范蕊,马最良. 热渗耦合作用下地下埋管换热器的传热分析[J]. 暖通空调,2006,36(2):6-10. FAN Rui,MA Zuiliang. Heat transfer analysis of underground hear exchangers under coupled thermal conduction and groundwater advection conditions[J]. Heating Ventilating & Air Conditioning,2006,36(2):6-10.

[7] 杨卫波,施明恒. 地源热泵中U型埋管传热过程的数值模拟[J]. 东南大学学报(自然科学版),2007,37(1):78-83. YANG Weibo,SHI Mingheng. Numerical simulation on heat transfer process in U-bend ground heat exchanger of ground source heat pump[J]. Journal of Southeast University(Natural Science Edition),2007,37(1):78-83.

[8] 赵阳升,万志军,康建荣. 高温岩体地热开发导论[M]. 北京:科学出版社,2004.

[9] 汪集晹. 地热利用技术[M]. 北京:化学工业出版社,2004.

[10] 赵西蓉. 渭河断陷盆地地热资源赋存特征与热储分析[J]. 煤田地质与勘探,2006,34(2):51-54. ZHAO Xirong. Occurrence features of geothermal resources and geothermal bearing analysis in Weihe basin[J]. Coal Geology & Exploration,2006,34(2):51-54.

[11] 庞忠和,孔彦龙,庞菊梅,等. 雄安新区地热资源与开发利用研究[J]. 中国科学院院刊,2017,32(11):1224-1230. PANG Zhonghe,KONG Yanlong,PANG Jumei,et al. Geothermal resources and development in Xiongan new area[J]. Bulletin of Chinese Academy of Sciences,2017,32(11):1224-1230.

[12] KONG Y L,PANG Z H,PANG J M,et al. Stable isotopes of deep groundwater in the Xiongxian geothermal field[J]. Procedia Earth & Planetary Science,2017,17:512-515.

[13] 孔彦龙,陈超凡,邵亥冰,等. 深井换热技术原理及其换热量评估[J]. 地球物理学报,2017,60(12):4741-4752. KONG Yanlong,CHEN Chaofan,SHAO Haibing,et a1. Principle and capacity quantification of deep-borehole heat exchangers[J]. Chinese Journal of Geophysics,2017,60(12):4741-4752.

[14] KONG Y L,PANG Z H,SHAO H B,et al. Optimization of welldoublet placement in geothermal reservoirs using numerical simulation and economic analysis[J]. Environmental Earth Sciences,2017,76(3):118.

[15] 孔祥言. 高等渗流力学[M]. 合肥:中国科学技术大学出版社,2010.

[16] 汪集晹. 地热学及其应用[M]. 北京:科学出版社,2015.

[17] 宋伟. 单井循环地下换热系统地下水流动及其传热特性研究[D]. 哈尔滨:哈尔滨工业大学,2014.

[18] 邓杰文,魏庆芃,张辉,等. 中深层地热源热泵供暖系统能耗和能效实测分析[J]. 暖通空调,2017,47(8):150-154. DENG Jiewen,WEI Qingpeng,ZHANG Hui,et al. On-site measurement and analysis on energy consumption and energy efficiency ratio of medium-depth geothermal heat pump systems for space heating[J]. Journal of HV&AC,2017,47(8):150-154.