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<p>Efficient heat transfer is crucial for improving the thermal performance and service life of downhole heaters used in in-situ oil shale extraction. In this study, a variable-pitch spiral baffle perforated-plate heater was designed, and the effects of different decreasing baffle pitches on heat transfer and flow characteristics were numerically investigated using the RNG k–ε turbulence model. The computational domain was meshed in ANSYS Workbench, with grid-independence verified through multi-scale mesh comparison. Results show that the wall temperature of the heating plate generally increases along the flow direction, while the heat transfer coefficient decreases, reaching its maximum at the inlet. Smaller baffle pitches prolong gas residence time, intensify turbulence, and enhance convective heat transfer, leading to lower wall temperatures and improved thermal uniformity. The perforated wall surface exhibits consistently lower average temperatures than the non-perforated surface, indicating more effective heat exchange. Moreover, reducing the baffle pitch significantly decreases both the mean wall temperature and the temperature difference, mitigating thermal stress and extending heater lifespan. A comprehensive performance evaluation based on the dimensionless index <i>h</i>/∆P<sup>1/3</sup> reveals that heater performance first increases and then decreases with pitch size, achieving optimal performance at a 200 mm pitch, approximately 84.6% higher than that at 100 mm. This study provides theoretical guidance for optimizing heater geometry to achieve a better balance between heat transfer enhancement and flow resistance, supporting the development of high-efficiency in-situ oil shale extraction technologies.</p>

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Numerical Study on Enhanced Heat Transfer Using Cross-Type Plate Heaters in Underground Wells for In-Situ Oil Shale Mining

  • 期刊论文

  • 发表日期：

    2026年3月1日

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  • Lihong Yang,
  • Haibo Wang,
  • Zhongwen Han,
  • Hao Zeng,
  • Zhenbin Zhang,
  • Bo Zhang,
  • Tengfei Sun,
  • Yang Zhang,
  • Shichao Wang

摘要

Efficient heat transfer is crucial for improving the thermal performance and service life of downhole heaters used in in-situ oil shale extraction. In this study, a variable-pitch spiral baffle perforated-plate heater was designed, and the effects of different decreasing baffle pitches on heat transfer and flow characteristics were numerically investigated using the RNG k–ε turbulence model. The computational domain was meshed in ANSYS Workbench, with grid-independence verified through multi-scale mesh comparison. Results show that the wall temperature of the heating plate generally increases along the flow direction, while the heat transfer coefficient decreases, reaching its maximum at the inlet. Smaller baffle pitches prolong gas residence time, intensify turbulence, and enhance convective heat transfer, leading to lower wall temperatures and improved thermal uniformity. The perforated wall surface exhibits consistently lower average temperatures than the non-perforated surface, indicating more effective heat exchange. Moreover, reducing the baffle pitch significantly decreases both the mean wall temperature and the temperature difference, mitigating thermal stress and extending heater lifespan. A comprehensive performance evaluation based on the dimensionless index h/∆P1/3 reveals that heater performance first increases and then decreases with pitch size, achieving optimal performance at a 200 mm pitch, approximately 84.6% higher than that at 100 mm. This study provides theoretical guidance for optimizing heater geometry to achieve a better balance between heat transfer enhancement and flow resistance, supporting the development of high-efficiency in-situ oil shale extraction technologies.