Abstract

A helically-grooved copper heat pipe with ethanol as the working fluid has been fabricated and tested on a centrifuge table. The heat pipe was bent to match the radius of curvature of the table so that uniform transverse (perpendicular to the axis of the heat pipe) body force fields could be applied along the entire length of the pipe. The steady--state performance of the curved heat pipe under transverse body force fields was determined by varying the heat input (Q_in = 25 to 250 W) and centrifuge table velocity (radial acceleration a_r = 0 to 10-g). The thermal resistance decreased with increasing heat input until dryout was reached. As dryout commenced, the thermal resistance increased. Due to the geometry of the helical grooves, the capillary limit increased by a factor of five when the radial acceleration increased from $| \vec a_r|$ = 0 to 6.0-g. This important result was verified by a mathematical model of the heat pipe system, wherein the capillary limit of each groove was calculated in terms of centrifuge table angular velocity, the geometry of the heat pipe and the grooves (including helix pitch), and temperature-dependent working fluid properties.