Global characterization of innovative polymeric micro-heat sink

During the space missions, the problems related to the thermal conditioning of devices, to the personnel comfort and to the thermomechanical stresses are known and important. Furthermore for a space mission certain priorities are stressed, such as the small dimension and the lightness of thermal equipments. Due to the presence of high temperature gradients, which straightforwardly implies significant heating/cooling powers, these characteristics are sometimes difficult to obtain. Besides, miniaturized heat exchangers will have a terrestrial large industrial diffusion for electronic component cooling, in propulsion and in the power production for microsatellites, spacecrafts and airplanes and in many biomedical applications, for example, in cloth conditioning in harsh environmental conditions. Given the great value of the ratio between exchanging surface and volume of these systems, the specific thermal power per unit volume can reach extremely high values (1000 kW/m2 is a possible target). The low density, high elasticity and mechanical resistance suggest that the development of a new technology for heat sink, based on a sheet of polymeric microtubes (with a overall thickness of some tenths of millimeter) could be of great interest for space and terrestrial applications. A polymeric micro-heat sink was designed and built. Many technical problems were solved and a first prototype is available. The micro-heat sink was configured to cool an electric resistance with nitrogen and helium. An experimental set-up was built and some preliminary tests are running. For gas flow rates ranging from 3 to 26 Nl/min, a maximum heat flux of about 14 kW/m2 has been reached. The heat-sink has a surface of 6cm2 and a weight of 0.25g. The maximum pressure drop reached 3 bar. Different polymers were considered in order to test the heat sink thermal and mechanical resistances.