Ren Dazhong, Wang Zhendong, Yang Fu, Zeng Hao, Zhang Zengzeng
State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083, China.
State Center for Research and Development of Oil Shale Exploitation, Beijing 100083, China.
ACS Omega. 2024 Aug 8;9(33):35600-35613. doi: 10.1021/acsomega.4c03425. eCollection 2024 Aug 20.
In situ conversion is the most potential technology for efficient and clean development of oil shale, and a downhole electric heater is key equipment for clean, efficient, and low-carbon in situ conversion. Three electric heating rods with different diameters are used to explore their influence on heater performances. The simulation results indicate that increasing the diameter of the heating rod helps to increase the minimum and maximum velocity of shell-side air, and the maximum velocity of H110-24 is 16.34 m/s, which is 1.25 and 1.13 times those of H110-16 and H110-20, respectively. In addition, the location of the local high temperature zone coincides with the area with low air flow velocity, and increasing the diameter of the heating rod can effectively reduce the heating rod surface temperature during high-power heating. Moreover, at the same heat flux, the heat transfer coefficients of H110-24 and H110-20 are 44.82-48.49% and 87.52-95.48% higher than those of H110-16, respectively. With the same heating power, the heat transfer coefficients of heaters have the same trend, indicating that the heat transfer coefficient of the heating rod can be effectively improved by increasing the diameter of the heating rod. Finally, the newly defined comprehensive performance is used to evaluate the heaters with different heating parameters. Increasing the heating power can improve the comprehensive performance of the heater, but the most effective way is to increase the diameter of the heating rod. With the same heating power, the new comprehensive performance of H110-24 and H110-20 is 48.38-52.34% and 87.29-95.19% higher than that of H110-16, respectively, and the electric heating rod with the diameter of 20 mm has the best performance.
原位转化是油页岩高效清洁开发最具潜力的技术，井下电加热器是原位转化清洁、高效、低碳的关键设备。采用三种不同直径的电加热棒来探究其对加热器性能的影响。模拟结果表明，增大加热棒直径有助于提高壳侧空气的最小和最大流速，H110 - 24的最大流速为16.34 m/s，分别是H110 - 16和H110 - 20的1.25倍和1.13倍。此外，局部高温区的位置与空气流速低的区域重合，增大加热棒直径可有效降低高功率加热时加热棒表面温度。而且，在相同热流密度下，H110 - 24和H110 - 20的传热系数分别比H110 - 16高44.82 - 48.49%和87.52 - 95.48%。在相同加热功率下，加热器的传热系数具有相同趋势，表明增大加热棒直径可有效提高加热棒的传热系数。最后，用新定义的综合性能来评估不同加热参数的加热器。提高加热功率可提升加热器的综合性能，但最有效的方法是增大加热棒直径。在相同加热功率下，H110 - 24和H110 - 20的新综合性能分别比H110 - 16高48.38 - 52.34%和87.29 - 95.19%，直径为20 mm的电加热棒性能最佳。
