Numerical and analytical investigation of vapor flows in a flat plate heat pipe: Effects of length ratio and Reynolds number

Heat pipes are crucial in a wide range of applications, ranging from space satellites and industrial systems to electronic cooling and X-ray tube thermal management. This study introduces a method investigation into vapor flows within a flat plate heat pipe, utilizing the collocation method (CM) and the fourth-order Runge-Kutta-Fehlberg (RKF45) method. Building on previous efforts, this work explores the effects of the evaporator-to-condenser length ratio and Reynolds number on velocity and pressure distributions along the entire heat pipe. The significance of this research lies in its ability to elucidate critical parameters that directly influence heat pipe performance, offering deeper insights that are vital for optimizing design and efficiency. The primary motivation of this study is to fill existing gaps in the literature by developing a comprehensive analytical model that accurately characterizes vapor and liquid flow in asymmetrical flat plate heat pipes. The model's validity is confirmed through a satisfactory agreement with numerical results, underscoring the reliability of the methods used. Notably, the findings reveal that higher Reynolds numbers reduce pressure drop and shift the maximum velocity toward the bottom wick in the evaporation section, providing valuable guidance for future design improvements. Additionally, this research presents a powerful method for solving non-linear ordinary differential equations, offering significant time savings and enabling predictive functions. These contributions are poised to enhance the performance of thermal management systems across various engineering disciplines.