Bio-inspired evaporation from shaped interfaces: an experimental study

Area of Science:

• Engineering
• Biomimetics
• Thermal Science

Background:

• Evaporative interfaces are crucial for heat and mass transfer in diverse applications.
• Surface area enhancement in packed volumes is a common strategy, but the impact of geometry on aerodynamic and thermal properties remains underexplored.
• Natural structures, like leaf protrusions, show potential for improved vapor dissipation.

Purpose of the Study:

• To investigate the design space of leaf-inspired structures with evaporating protrusions.
• To explore how geometric features influence mass transfer and thermal performance in evaporative devices.
• To assess the applicability of these designs in architectural elements for evaporative cooling.

Main Methods:

• Tested three types of water-absorbing models: paper strips with varied protrusions, 3D-extruded cellulose sponges, and ceramic tiles with grooved patterns.
• Maintained fixed evaporating surface area and unlimited hydraulic supply across all models.
• Varied protrusion shape, elongation, and groove cross-sections to analyze geometric effects.

Main Results:

• Protrusions significantly impact mass transfer rates and surface temperatures.
• For paper models, evaporation rate correlated with protrusion aspect ratio, mimicking leaf designs.
• Extruding effective 2D designs into 3D did not yield similar transfer enhancements; ceramic tile performance depended on aerodynamic roughness, pattern size, and ventilation.

Conclusions:

• Leaf-inspired structured interfaces offer a promising approach for enhancing evaporative exchange.
• Geometric design of protrusions is key to optimizing performance in low-wind conditions.
• Further research is needed to fully understand the complex environmental interactions for architectural applications.