Utilizing Additive Manufacturing to Enhance Two-Phase Heat Transfer Devices

Two-phase heat transfer devices are among the most popular devices in thermal management systems due to their superior thermal characteristics. This paper investigates a thermosyphon for electronics cooling applications into which a freeform wick structure is inserted to enhance thermal performance. Additive manufacturing is employed to fabricate the wick structure tailored to the thermosyphon at hand using a conductive thermoplastic material. The goal of this study is to investigate how the freeform wick structure inserted into a thermosyphon affects the local liquid and vapor distributions and thus improving the thermal performance. Experiments were carried out with various heat loads and inclination angles, while the temperature distribution was recorded along the length of the thermosyphon. Thermal resistances were determined for both a conventional thermosyphon and an adapted version with an inserted wick structure in order to quantify the enhancement. The obtained experimental data demonstrate that the additively manufactured wick structure gives benefits at higher heat loads due to enhanced evaporation and boiling modes. The evaporation thermal resistance improves by 7% to 13% at heat loads above 55 W for the vertical orientation. Likewise, an improvement of about 7% to 9% was found at a heat load of 105 W for inclination angles of 30° and 60°. Both results exemplify the advantages additive manufacturing may bring to thermal management systems and in particular to two-phase heat transfer devices.