Reliability of Avionics Equipment

The power and heat dissipation of modern avionics equipment is increasing rapidly, and designing appropriate cooling systems is now an absolute necessity to ensure reliability. Weight minimization and space optimization are key design goals for us, and thermal management is often the main design bottleneck. We avoid using cooling fans wherever possible in order to minimize possible causes of failure, so thermal management is a major challenge from the very first design phase. Tecnobit designed a special chassis enabling the avionics to be housed in a reduced space (max dimension around 10cm). The system is totally sealed, so the task was to maximize heat transfer by conduction, radiation and natural convection from the outside surface. The preliminary design was clearly not thermally acceptable, and the internal chassis structure was modified in order to increase heat conduction from the components to the chassis walls. At the same time the outer surfaces of the chassis were modified using special fins, sandblasting treatment and electrostatic painting in order to enhance convection and radiation exchange with the external ambient. All the design options were evaluated without building prototypes, and the Flotherm simulations enabled us to optimize the thermal design rapidly and reduce component junction temperatures by 40°C compared with the initial design.