Bio-coated surfaces with micro-roughness and micro-porosity: Next generation coatings for enhanced energy efficiency

Due to growing cooling demands as well as emerging global warming and climate change issues, cooling systems should be more efficiently utilized. Boiling is an effective heat transfer mechanism, which has a critical role in many cooling systems. Surface modification is considered as the major approach for boiling heat transfer enhancement. In this study, we developed a microbial bio-coating surface modification technique for phase change cooling applications. Thermoacidophilic Sulfolobus solfataricus coating was implemented using a facile dip coating method on different metallic and non-metallic surfaces. Controlled by drying conditions, the coating exhibited rough and porous morphologies. When tested in a boiling heat transfer setup, bio-coated surfaces offered enhancements up to 76.3% in Critical Heat Flux (CHF). Next, a miniature evaporator was coated and tested for real-world air-conditioning applications, and coefficient of performance (COP) enhancements up to 11% clearly revealed the potential of bio-coated surfaces for energy saving purpose and reduction in greenhouse gasses. Furthermore, coated evaporators reduced the exergy destruction rate up to 8%. This study not only offers a new type of coating morphology, but the applicability of the proposed bio-coating is also proven in a miniature air conditioning system.