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Ultralight heat-dissipating materials are essential for the effective thermal management of mobile devices. Graphene aerogel is a highly porous material made of thermally conductive carbon nanomaterial. Owing to aerogel's highly porous structure and graphene's high intrinsic thermal conductivity, graphene aerogel has a very low density and could be a promising ultralight thermal management material. In this study, forced convective heat transfer inside graphene aerogel is experimentally examined, and the effect of the aerogel microstructure on the heat and fluid flow characteristics of the graphene aerogel is discussed. It is established that graphene aerogel has a better convective heat transfer coefficient compared to conventional porous media. Furthermore, methods to improve the heat and fluid flow inside the aerogel are discussed. This work sheds light on the effective thermal management of various devices where lightness is critical. [Display omitted] • Forced convection inside graphene aerogel is first experimentally examined. • The effect of the aerogel microstructure on the forced convection is clarified. • Graphene aerogel shows a better convection performance than other porous media. • Methods to improve the heat and fluid flow inside the aerogel are discussed. • How to measure the permeability of anisotropic aerogels is proposed. [ABSTRACT FROM AUTHOR]

Solar thermoelectric energy-generation technology is being developed to mitigate the limitations of solar cells. Thermal management is essential to creating highly efficient and stable solar thermoelectric generators (STEGs). Phase change materials (PCMs) can be used to improve the performance of STEGs. In this study, we numerically investigate the heat transfer, thermal energy storage, and thermoelectric energy conversion in an STEG with PCMs (STEG-PCM). Based on a parametric study, we present thermal design guidelines for the configurations of an STEG-PCM and the thermal properties of PCMs by considering both the thermoelectric generation performance and thermal stability of the STEG-PCM. We also show that the PCM-impregnated structure is the most crucial component of the STEG-PCM in the thermal design based on a sensitivity analysis. To find the optimal design of a PCM-impregnated structure, topology optimization is performed for the STEG-PCM focused on daytime thermoelectric generation performance. The topology-optimized PCM-impregnated structure shows a thermoelectric generation performance close to that of an STEG-PCM whose PCM-impregnated structure is assumed to be an ideal mixture of PCM and framework material. This study explains how PCMs affect thermal energy transport and conversion in an STEG and sheds light on a highly efficient and stable STEG system. • Comprehensive thermal design guidelines for the STEG-PCM were presented based on a systematic parametric study. • The optimized STEG-PCM exhibited up to 31.3% improvement in power generation. • The maximum nighttime power generation reached 31.4% of daytime power generation. • Designing the PCM-impregnated structure was found to be most critical in the thermal design of the STEG-PCM. • A specific configuration of the PCM-impregnated structure was suggested based on topology optimization. [ABSTRACT FROM AUTHOR]