Multiscale Thermal and Mass Transport

Multiscale Thermal and Mass Transport

At EIL, we investigate the fundamental mechanisms governing phase change processes, condensation, evaporation, and boiling, across different media, from porous solids to polymer networks. Our research is rooted in multiscale transport modeling and experimental diagnostics that capture heat and mass transfer dynamics at the interface, including in metastable and confined regimes. We study phase change phenomena not only in classic fluid-solid systems, but also in emerging materials such as hydrogels/salt composites and solid sorbent-coated substrates. Specific areas of interest include bubble dynamics during nucleate boiling, heat conduction in sorption materials, thermal time-of-flight flow sensing, and salt crystallization dynamics under evaporation-driven transport.

Adsorption materials are vital for energy storage, water harvesting, and carbon capture, but their performance is often limited by slow transport through disordered sorbent layers. We have developed a boiling-assisted channel-templating (BACT) process that uses vapor flow during boiling to align sorbent particles into ordered, low-tortuosity pathways. Using zeolite coatings on copper foams, the team achieved a 2× improvement in effective diffusivity and reduced tortuosity to ≈ 1.09 in AQSOA-Z02 layers, leading to a 1.7× boost in adsorption–desorption cyclability compared with conventional coatings. BACT offers a simple, scalable, and low-cost route to speed up sorption kinetics and unlock more efficient, sustainable systems across the energy–water–carbon landscape.

Dropwise condensation visualization

Modern thermo-fluid engineering is approaching the fundamental limit where heat and mass transport at the liquid–vapor interface control evaporation and condensation. While kinetically limited evaporation has been demonstrated, reaching this regime in condensation has remained elusive, until now. Using high-resolution light microscopy in a controlled pure-vapor environment, we observed dropwise condensation of water under conditions where 10–40 % of the total thermal resistance arose from the Knudsen-layer kinetics. The results indicate that the accommodation coefficient of water is at least 0.5 and likely near unity, challenging long-standing assumptions about interfacial transport. These experiments also revealed a previously unreported regime in which droplet–droplet interactions significantly influence condensation dynamics, offering new insight into the ultimate limits of phase-change heat transfer.

Related References

  • B. El Fil*, X. Li, C. Jacobucci, C. D. Díaz-Marín, L. Zhang, “Significant Enhancement of Sorption Kinetics via Boiling-Assisted Channel Templating.” Cell Reports Physical Science, Volume 4, Issue 9, (2023) 101549. https://doi.org/10.1016/j.xcrp.2023.101549
  • B. El Fil and S. Garimella, “Waste heat recovery in commercial gas-fired tumble dryers.” Energy, 218 (2021) 119407. https://doi.org/10.1016/j.energy.2020.119407.
  • B. El Fil, G. Kini, S. Garimella, “A Review of Dropwise Condensation: Theory, Modeling, Experiments, and Applications.” Int. J. Heat Mass Transfer, 160 (2020): 120172. https://doi.org/10.1016/j.ijheatmasstransfer.2020.120172
  • K. Keniar, B. El Fil, S. Garimella, “A critical review of analytical and numerical models of condensation in microchannels.” International Journal of Refrigeration, 120 (2020): 314–330. https://doi.org/10.1016/j.ijrefrig.2020.08.009
  • B. El Fil, A. J. Mahvi, and S. Garimella, “Unsteady two-dimensional analytical model for a thermal time-of-flight flow sensor.” International Journal of Heat and Mass Transfer, 134 (2019): 329–337. https://doi.org/10.1016/j.ijheatmasstransfer.2018.12.128