Study on Heat Transfer Performance and Applications of Series-Connected Gravity Heat Pipe Systems

Abstract In the field of heavy oil extraction, heat dissipation in the wellbore leads to uneven oil temperature distribution, severely restricting extraction efficiency. Traditional viscosity reduction methods have obvious drawbacks. This study proposes a series-connected gravity heat pipe system, which uses multiple short heat pipes connected in series to enhance system reliability while maintaining heat transfer capacity. By constructing a one-dimensional steady-state heat transfer model, the temperature distribution equations of single and series-connected heat pipes are derived, and experimental verification is carried out. The results show that this system can increase the wellhead oil temperature by 10–15 °C. However, its overall heat transfer capacity is weaker than that of a single heat pipe of the same specification, with a heat transfer deviation of 20–30%. Through optimization, it is found that when three heat pipes are connected in series, the effect is the best, and the system reliability reaches 95.2%, which can effectively reduce the wear risk of the sucker rod. From an economic perspective, compared with traditional electric heating and chemical viscosity reduction technologies, this system has significant advantages in terms of operating energy consumption, maintenance costs, and environmental protection. In conclusion, the series-connected gravity heat pipe system provides an economic, efficient, and reliable solution for heavy oil extraction and has good prospects for popularization and application.