Juniorprofessur für Werkstoffmodellierung
Prof. Dr.-Ing. Ming Hu
Micro/Nanoscale thermal transport attracts significant attention because it involves rich physics and has extensive applications. The fundamental length scales associated with the basic heat carriers, such as phonons and electrons, generally fall in the range of 1 – 1000 nm. Therefore, exploring and exploiting basic nanoscale thermal transport phenomena holds the key for developing high performance materials and devices for thermal energy conversion and management. Currently Prof. Hu’s research is focused on the following two aspects:
1. Nanoscale Heat Transfer for Energy Conversion
Approximately 90% of the world's power is generated by heat engines that use fossil fuel combustion as a heat source and typically operate at 30 - 40 per cent efficiency, such that roughly 15 terawatts of heat is lost to the environment. Thermoelectric modules could potentially convert part of this low-grade waste heat to electricity. Their efficiency depends on the thermoelectric figure of merit ZT of their material components. An ideal thermoelectric material with a high thermoelectric figure of merit, ZT, should be an electrical conductor, but a thermal insulator. This conflicting requirement poses a material challenge. Nanoscale structures with at least one dimension of the order of the phonon mean free path may increase phonon scattering thereby reducing thermal conductivity. We explore new concepts of nanostructures to push the lower limit thermal conductivity in electrically conductive materials through manipulation of phonons across different length scales.
2. Modeling Thermal Transport for Thermal Management
In most modern electronics systems, the electronic device is the warmest element in the system, and waste heat is removed by conduction, spreading, and convection to an appropriate working fluid with gradual reductions in the temperature as heat travels from the source to the fluid. So far almost all existing studies are focused on improvements in heat transport and removal after the heat has exited the backside of the electronic substrate. However, in many high-power semiconductor electronic and photonic components the thermal resistance associated with the "near-junction" region can be as large as the resistance of the remaining elements of the system combined! To this end, improvements in "near-junction" thermal transport plays crucial role in the overall heat dissipation efficiency in high-power electronic cooling. Moreover, we dedicate our research effort on exploring novel approaches such as tailoring electron-phonon coupling.
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