Thermoelectric hotspot cooling using thermally conductive fillers

Abstract

The commercial application of thermoelectric coolers (TECs) is limited to niche markets because of their low cooling efficiency. The cooling efficiencies of TECs have been optimized by improving power factors or by decreasing thermal conductivities of constituent materials for refrigeration applications in which the Peltier heat flux is compensated for by the Fourier heat flux in the opposite direction. In contrary, for hotspot cooling, in which the Fourier heat is added to the Peltier heat flux, TE materials with large power factors and high thermal conductivities are required, posing developmental challenges owing to the interdependence between the TE properties of materials. This further complicates the simultaneous optimization of the power factor and thermal conductivity at the material level. Herein, we provide a novel solution at the device level to overcome these material challenges by utilizing a filler-embedded–thermally-conductive TEC (F-TEC) that enables the simultaneous optimization of the power factor and thermal conductance. As proof of concept, we demonstrated the F-TEC by embedding polymer–ceramic composites into a commercially available TEC, which increased the thermal conductance of TEC by over 120% at 300 K without affecting the TE properties. Using the F-TEC, the hotspot temperature under a heat flux of 56 250 W/m² decreased by 14.8 K for an electrical current flow of 1 A owing to the 42.5% improvement in effective thermal conductance at DT = 100 K. Additionally, infrared imaging and numerical analyses revealed that the filler can release thermal stress of the TE legs to a considerable extent, which extends the thermal stability of the TECs and the maximum heat flux range, over which TECs can be applied. We envision that the proposed F-TEC concept can facilitate the development of an effective TEC device that can be widely used in hotspot cooling applications, such as microprocessors and batteries.