Design, fabrication, and characterization of a multi-condenser loop heat pipe

Abstract

A condenser design was characterized for a multi-condenser loop heat pipe (LHP) capable of dissipating 1000 W. The LHP was designed for integration into a high performance aircooled heat sink to address thermal management challenges in advanced electronic systems. The multi-layer stack of condensers utilizes a sintered wick design to stabilize the liquidvapor interface and prevent liquid flooding of the lower condenser layers in the presence of a gravitational head. In addition a liquid subcooler was incorporated to suppress vapor flashing in the liquid return line. The condensers were fabricated using photo-chemically etched Monel frames with Monel sintered wicks with particle sizes up to 44 pm. The performance of the condensers was characterized in a custom experimental flow rig that monitored the pressure and temperatures of the vapor and liquid. Two condensers arranged in parallel were demonstrated to dissipate the required heat load while maintaining a stable liquidvapor interface with differences in liquid and vapor side pressures in excess of 6.2 kPa. The experimental results defined the stable operating limits of multiple condensers within a LHP given a range of convective heat transfer coefficients and differences in liquid and vapor side pressures. The inclusion of a wicking element in the condenser of the LHP increases the flexibility in design by allowing a modular construction with multiple condensers which can be integrated into air-cooled heat exchangers to cool devices with high power density.