Design of the Brazilian cryogenic heat pipes

Abstract

Cryogenic heat pipe is a satellite thermal control device that is used mainly for the thermal control of optical surfaces, infrared scanning systems, or large superconducting magnets in the space environment. Actually, investigations are being conducted to include other applications of cryogenic heat pipes, such as the cooling of electronic devices, particularly in microgravity environments. The most recent theoretical development on cryogenic heat pipe technology, carried out at the Satellite Thermal Control Laboratory (NCTS), at the Federal University of Santa Catarina (UFSC), is presented. This research project is funded by the Brazilian Space Agency, as part of the Uniespa£o Program. The heat transfer limitations of these heat pipes are focused here. Four configurations of stainlesssteel/nitrogen cryogenic heat pipes are proposed for future experimental ground testing. An experimental setup is under construction at NCTS, and a description of the apparatus is given at the conclusion. Descriptions of the researches that are still under development at NCTS are also presented. This research is part of a Ph. D. thesis, currently under development at NCTS, and it will provide a significant insight on the startup phenomena at cryogenic temperatures. Nomenclature A area Cp specific heat [J/kg K] d mesh wire diameter [m] F friction parameter [s/m4] / friction factor L length [m] Leff effective length of the heat pipe [m] g Earth's gravitational acceleration [9.81 m/s2] % latent heat [J/kg] K permeability [m2]