Search

[Display omitted] Films with nanoengineered surfaces have found extensive utilization in versatile applications, such as freshwater harvesting, water purification, steam generation and thermal energy management. Herein, we develop a liquid metal (LM) nanoporous film on a copper substrate via a simple and scalable bubble-induced self-assembly method. The LM nanoporous film not only provides abundant nucleation sites of bubbles due to nanoscale pores, but also generates CuGa 2 intermetallic compound (IMC) as a thermal interface layer with low interfacial resistance due to in situ alloying with the copper substrate. When the film is used in ethanol-based boiling system, it shows a 172% enhanced heat transfer coefficient compared to the pristine copper. In addition, the metallic wetting force between the LM nanoporous film and CuGa 2 IMC results in a durable nanoporous film. When the LM nanoporous film is utilized for the phase-change thermal energy management of a high-power-density light emitting diode, it leads to a distinct decrease in temperature by 20.7 ℃ relative to the pristine copper. This work provides a strategy to combine nanoengineered surfaces with interface engineering to enhance phase-change heat transfer, which can result in efficient energy transport in various energy-related applications. [ABSTRACT FROM AUTHOR]

• We generate a stably self-dispersed crumpled graphene/water nanofluid at 100 °C. • The nanofluid enhances the heat transfer coefficient by 89.1% over deionized water. • The enhancement is due to the porous structure generated by self-assembly. Boiling can induce the self-assembly of nanomaterials in nanofluids to generate reliable micro/nanostructures for enhancing boiling heat transfer. The practical applications of most nanofluids in boiling, however, are limited by the poor thermal stability at the boiling point, and improving the thermal stability of nanofluids at such high temperature is challenging. Here, we demonstrate that the crumpled graphene can remain uniformly and stably dispersed within deionized water at the boiling point of 100 °C due to its highly wrinkled structure, while self-assembling to generate a porous structure on the substrate during boiling. Such porous structure can vary the surface micromorphology, wettability and roughness, which increases the nucleation sites and departure frequency of bubbles, thus effectively enhancing the critical heat flux and the maximum heat transfer coefficient by 80.7 and 89.1% compared to the pristine copper substrate, respectively. This in situ boiling-induced self-assembly provides a facile and low-cost strategy to achieve high-performance boiling heat transfer for a wide variety of nanomaterials. The crumpled graphene/water nanofluid used can be directly utilized as a phase change working medium in boiling systems to harvest thermal energy and generate clean steam. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A W-Cu vapor chamber (VC) improves thermal management systems at high temperature. • A Cu coating layer enhances bonding strength with wick and isolates working medium. • The lateral thermal conductivity of W-Cu VC is ~1700 W/(m∙K) under 1.6 kW/cm2. • The W-Cu VC reduces the thermal stress at the interface between the VC and chip. The electronic industry is facing pressing needs for cooling system with high-performance in heat transfer and matched coefficient of thermal expansion (CTE) with the chips. Metal composite materials (MCMs) with low CTE can be used in cooling chips to overcome the thermal expansion mismatch between the cooling substrate and chips. However, low thermal conductivity of MCMs limits their application in electronic cooling systems. Increasing the percentage of components with high thermal conductivity can enhance the thermal conductivity of MCMs, but it often leads to increase CTE as well. Here, we demonstrate that vapor–liquid phase change can improve the heat transfer performance of tungsten-copper (W-Cu) alloy-based MCMs while maintain their low CTEs. Such strategy reduces the maximum temperature and thermal resistance of MCMs, and also allows for heat spreading from concentrated heat source with high power density. The W-Cu alloy-based vapor chamber (VC) has low thermal resistance of 0.38 K/W at 100 W and high lateral thermal conductivity of ~1727 W/(m·K). The W-Cu alloy-based VC can be readily integrated with the chip and heat sink to serve as cooling substrates for dissipating the heat and simultaneously lowering the thermal expansion mismatch by using its high thermal conductivity and low CTE. [ABSTRACT FROM AUTHOR]