Publication

Advanced Multifunctional Nanocomposite Lab

Selected Representative Publications

  • 2023
  • Giant thermal rectification efficiency by geometrically enhanced asymmetric non-linear radiation
  • Seongkyun Kim , Taeyeop Kim , Jaehyun Sung , Yongjun Kim , Dongwoo Lee and Seunghyun Baik Materials Horizons
  • Thermal rectification is an asymmetric heat transport phenomenon where thermal conductance changes depending on the temperature gradient direction. The experimentally reported efficiency of thermal rectification materials and devices, which are applicable for a wide range of temperatures, is relatively low. Here we report a giant thermal rectification efficiency of 218% by maximizing asymmetry in …
  • 2022
  • Invariable resistance of conductive nanocomposite over 30% strain
  • C. MUHAMMED AJMAL, SEOKJAE CHA, WONJOON KIM, K. P. FASEELA, HEEJUN YANG, AND SEUNGHYUN BAIK Science Advances
  • The dependence of the electrical resistance on materials’ geometry determines the performance of conductive nanocomposites. Here, we report the invariable resistance of a conductive nanocomposite over 30% strain. This is enabled by the in situ–generated hierarchically structured silver nanosatellite particles, realizing a short interparticle distance (4.37 nm) in a stretchable silicone rubber matr…
Dryout suppression and significantly enhanced flow boiling heat transfer through the two-tier vertically aligned carbon nanotube channel
Author
Jungho Ahn, Wonjae Jeon, Hyeong-Geun Kim, Sung-Min Kim, Seunghyun Baik
Journal
International Journal of Heat and Mass Transfer
Vol
214
Page
124438
Year
2023
It is crucial to design multi-functional structure to improve heat transfer characteristics. Here we report significantly enhanced saturated flow boiling heat transfer of water using the two-tier vertically aligned multiwalled carbon nanotube (VAMWNT) channel (tube diameter: 11.5 nm). The channel size is 10 × 10 × 2 mm3 (height: 2 mm). The tube aggregation-generated large voids act as micropores (10-200 µm) whereas the interstitial spaces between the tubes act as nanopores (< 72 nm). The microcavities at the periphery of aggregated nanotubes increase bubble nucleation sites while constraining bubble size. The high nanotube thermal conductivity induces more uniform bubble nucleation, and departed bubbles are swept away through the micropores. On the other hand, water is effectively replenished through the nanopores by high capillary pumping. Overall, the path separation of bubble departure and water replenish effectively prevents dryout and increases critical heat flux (CHF). The experiment is carried out at 3 different mass velocities (62, 83, and 104 kg m−2 s−1). The VAMWNT channel provides a high heat transfer coefficient (h = 100,666 W m−2 K−1 at 183 W cm−2), even before reaching CHF without any sign of local dryout, compared with microchannels and porous media in literature (under the similar heat flux and mass velocity). In contrast, the CHF condition is observed for a plain channel of the same size without the nanotubes, resulting in smaller h values than those of the VAMWNT channel. The novel two-tier structure separated liquid-vapor pathways, significantly enhancing heat transfer characteristics.