Next-Generation Heat Pumps and Frost/Defrost Control
We study refrigerants, heat exchanger surfaces, frost growth, and defrosting as parts of the same heat-pump problem.
Heat-pump performance depends not only on the thermodynamic cycle but also on refrigerant properties, boiling and condensation, and the condition of heat exchanger surfaces. In air-source heat pumps, frosting and defrosting are major sources of winter performance loss.
Our work covers both phase-change heat transfer of low-GWP, natural, and mixed refrigerants and the physics of frost formation and removal.
Research focus
- Low-GWP, natural, and mixed refrigerants
- Boiling, condensation, and lubricating-oil effects
- Wettability, frosting, and meltwater drainage
- Cold-climate heat pumps and EV thermal management
Low-GWP and mixed refrigerants
We investigate HFO refrigerants, natural refrigerants, and zeotropic mixtures, including boiling, condensation, pressure drop, and the effect of lubricating oil. Replacing the refrigerant alone is not enough; the heat exchanger and cycle must be considered together.
How frost grows
When cold, humid air passes through an outdoor heat exchanger, frost builds up on fins and surfaces, increasing both airflow resistance and thermal resistance. We study how wettability, surface orientation, and channel geometry change frost morphology and growth rate.
Finishing defrost quickly
Good defrosting requires not only melting frost but also removing the meltwater. We therefore study wettability-based drainage, surface microstructures, and photothermal surfaces for anti-icing, ice melting, and rapid deicing.
Cold-climate and EV applications
Cold-climate heat pumps and EV thermal systems must provide heating and defrosting with limited available energy. We therefore evaluate heat exchangers and systems under operating conditions close to practical use.
Selected related work
- Yuan Hao et al., “Experimental study on frosting and defrosting characteristics of inclined cold surfaces considering surface wettability,” IJHMT (2026).
- Liwei Dong et al., “Copper-based photothermal superhydrophobic surfaces with multi-level structures for applications of anti-icing, ice-melting and rapid deicing,” Applied Thermal Engineering (2026).
- Qing Miao et al., “Wide operating temperature range vapor compression/auto-cascade heat pump air conditioning system adopting zeotropic mixtures,” Energy and Buildings (2026).
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