Speaker
Description
Thermal control is a key challenge in spacecraft electronic components, particularly for compact high power density units. Given the limitation of conventional aluminium ammonia grooved heat pipes regarding the maximum heat flux density, a two-phase spreader can be utilised as a primary thermal control technology to reduce the heat flux density to acceptable levels, allowing secondary heat transport equipment to transfer the dissipation to dedicated radiators. In this context Airbus with the help of CEA, developed an experimental test bench to characterise three types of thermal spreaders; a solid aluminium spreader (benchmark), a copper / water spreader and a nickel / water two phase spreader.
The two-phase spreaders were tested over a range of saturation temperatures (30-90°C), orientations and input powers (up to 250W) that correspond to high heat flux densities up to 50 W/cm². The thermal resistance and spreading efficiency were evaluated using direct temperature measurements and numerical modelling. The aluminium reference showed the expected conductive behaviour with limited spreading performance (R_total ≈ 0.10 K/W). The copper water spreader provided significantly lower thermal resistance (down to 0.04 K/W), with better temperature homogeneity (<2°C), and a more effective redistribution of heat at the condenser. The nickel/water spreader was also characterised under the same conditions with its performance found to be inferior compared to the copper/water spreader. This paper presents the activities that allowed the characterisation of the spreading technologies including the design of the experimental apparatus, the experimental results and the efficiency calculation.