Composite latent heat storage, Phase Change materials, Optimization
An effective thermomanagement is one of the most challenging tasks in the growing field of power electronics. Within this field the cooling of electronic devices is of main interest. The cooling system should be fail-safe, low-risk, cheap, light and energy-efficient. While the heat load may vary over time, the spatial positioning of hot spots is usually constant for a given electronics component. A promising strategy for the cooling of time limited or periodic power electronic components is a composite latent heat storage (CLHS), which is a combination of a phase change material (PCM) and a thermal enhancement structure (aluminum). The thermal enhancement structure is needed, since the PCM has a very low thermal conductivity. The PCM is undergoing a phase change from solid to liquid during the cooling process while keeping a quasi-constant temperature. This leads to the question how an optimal thermal enhancement structure would look like in dependence of the spatially placement of waste heat from the power electronics. This paper presents experimental results for four composite latent heat storage devices with non-constant heat loads: The first two devices are pure aluminum and pure PCM and are used as references. The other two devices are constructed in the following way. First simulate a CLHS with pure PCM. The resulting temperature field is then averaged over time. In order to get the highest heat flux from the hot spots, fins are inserted perpendicular to isothermal contour lines. For the third device the starting points for these fins are evenly spread along the contact surface to the power electronic, for the fourth device the starting points are optimized using a genetic algorithm. The CLHS devices are cubes with boundary edge lengths of 10cm. Below the CLHS devices 5 cupper stripes are installed, that can realize independent heat loads (0-120W). The experimental time is 2400s and the temperature at the contact surface to the power electronic is monitored with 30 thermocouples.