Numerical Analysis of Enhanced Subcooled Boiling Heat Transfer in a Twisted Tri-Lobed Tube

Abstract

This research meticulously explores the subcooled boiling phenomena in twisted tri-lobed tubes, focusing on their significance in the design and functional application within thermal management systems. By integrating the Eulerian two-fluid model with the RPI wall boiling model, the study rigorously assesses the impact of geometric parameters and boundary conditions on heat transfer in twisted tri-lobed tubes. Validated by empirical data, the investigation covers a spectrum of mass fluxes ranging from 500 to 800 kg/(m²∙s), inlet subcooling temperatures from 25 to 55 K, heat fluxes between 0.3 and 0.6 MW/m², and outlet pressures from 5 to 8 MPa. The results indicate that altering the minor radius and straight segment length, alongside adjusting the transition radius, notably enhances secondary and helical flows without substantially influencing the increase in wall void fraction. Additionally, the study finds that raising the wall heat flux and outlet pressure, in conjunction with lowering the inlet subcooling and mass flow rate, effectively fosters subcooled boiling. This leads to a significant improvement in both the average void fraction and the convective heat transfer coefficient. Notably, a reduction in the inlet subcooling temperature to 25 K elevates the comprehensive heat transfer performance coefficient of the twisted tri-lobed tube to 2.18. These methods and insights provide a profound understanding of the subcooled boiling process in twisted tri-lobed tubes, offering significant contributions to the field.

Keywords: Twisted tri-lobed tube, Subcooled boiling heat transfer, Rensselaer polytechnic institute wall boiling model, Void fraction analysis