Two-Phase Flow, Phase Change, and Advanced Heat-Transfer Surfaces
We observe bubbles, liquid films, and wettability to understand what controls boiling and condensation.
Two-phase cooling cannot be understood from average temperature and flow rate alone. Heat transfer and pressure drop depend strongly on where bubbles nucleate, how they grow, and how much liquid film remains near the wall.
We visualize two-phase flow and phase change in micro- and mini-channels and use those observations to improve cold plates and compact heat exchangers.
Research focus
- Flow boiling in micro- and mini-channels
- Visualization of thin films and slug flow
- Wettability, microstructures, and porous media
- Low-GWP refrigerants, mixtures, and refrigerant/oil systems
Two-phase flow in micro- and mini-channels
High-speed imaging is used to study slug flow, bubbly flow, and flow boiling. We examine the influence of channel size, flow rate, surface tension, and wettability on flow patterns and pressure drop. The thin liquid film between a bubble and the wall is particularly important for heat transfer.
Designing the surface
Microgrooves, microcolumns, metal foam, and mesh structures are used to control nucleation sites, liquid replenishment, and vapor departure. Hydrophilic and hydrophobic behavior also changes liquid-film formation and dryout.
Working fluids and lubricating oil
We study low-GWP refrigerants, refrigerant mixtures, dielectric fluids, and refrigerant/lubricant mixtures. Fluid properties, oil concentration, and the temperature glide of mixtures can all affect practical heat exchanger performance.
Experiment and numerical analysis
High-speed visualization, temperature and pressure measurements, and surface observation are combined with CFD or Lattice Boltzmann analysis where useful. We place particular emphasis on connecting visible flow behavior with measured heat-transfer performance.
Selected related work
- Jie Peng et al., “Influence of microcolumn structure on flow boiling heat transfer characteristics of R454B in an open minichannel,” International Journal of Thermal Sciences (2026).
- Jing Li et al., “Experimental study of flow boiling characteristics of R454B in an open microchannel with micro-nano composite structured surfaces,” Applied Thermal Engineering (2025).
- Dengwei Fu et al., “An experimental investigation on characteristics of liquid film thickness of gas-liquid Taylor flow in square/rectangular microchannel,” IJHMT (2024).
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