A high capacity re-entrant groove heat pipe for cryogenic and room temperature space applications

Abstract

A high capacity heat pipe has been developed for use in both the cryogenic and room temperature range. The configuration consists of 24 re-entrant axial grooves extruded in a 1-in. (25.4 mm) diameter 6063-T6 aluminium pipe. Using methane, the pipe demonstrated transport capacities as high as 6500 W in. (165 W m) in a level orientation at 115 K. This is an order of magnitude higher than state-of-the-art cryogenic heat pipe technology. Being a derivative of conventional rectangular axial groove heat pipes that have had extensive flight experience, the re-entrant design offers the same high reliability and ease of fabrication. Other benefits include: low fluid charge resulting in reduced internal pressure at ambient temperature, tolerance to the presence of non-condensible gas, and the capability to be bent to fit within tight spacecraft envelopes. The extrusion can also be used at other temperatures with appropriate working fluids, having been tested with ammonia to yield a transport capacity of 29 000 W in. at 283 K. The design lends itself to optimization for specific loads and temperatures, within the constraints of the extrusion process.