Fabrication and performance characterization of a phase-change thermal diode using scaly-finned fibers as the wick

Abstract

Efficient unidirectional heat transfer is of paramount importance in applications such as satellite thermal control systems and large-scale data centers, where conventional phase-change heat transfer devices exhibit inherent limitations. In this study, a novel phase-change thermal diode was proposed for unidirectional and self-driven thermal management. Fiber wick structure featuring periodic oblique scaly fins and unidirectional self-driven liquid transport capability was fabricated via multi-tooth cutting process and high-temperature solid-state sintering method, and was then encapsulated to construct phase-change thermal diodes. The steady-state heat transfer performance, unidirectional heat transfer characteristic, and adverse-gravity capability of the thermal diodes were evaluated by adjusting the filling ratio, heating power, and operating conditions. Experimental results revealed that a lower filling ratio correlated with higher effective thermal conductivity and enhanced unidirectional heat transfer performance, among the tested devices under horizontal operating conditions and filling ratio range of 40% to 60%. Specifically, a maximum thermal rectification coefficient of 0.56 ± 0.03 with the thermal conductivity of 4858 ± 369 W/(m·K) was achieved at a filling ratio of 40%. Under adverse-gravity conditions, the maximum effective thermal conductivity was reduced, and the unidirectional heat transfer capability was retained but weakened at low filling ratios. The tested phase-change thermal diodes exhibit high effective thermal conductivity and appreciable thermal rectification, suggesting potential for advanced thermal management applications.

The authors' abstract, as published at the source. Energy Conversion and Management, 2026 · DOI ↗