Investigation of leaf shape and edge design for faster evaporation in biomimetic heat dissipation systems

In previous projects theromodynamics of plants was identified as an interesting field delivering concept generators for technical, especially architectural application. So leaf morphology is determined by a variety of factors, and also significant for plant water and energy balance. However, how leaf design affects evapotranspiration and, consequently, leaf thermal performance and energy budget, has not been investigated in detail. Many leaf-inspired models in the literature overlook leaf hydraulics, capillarity, wetting phenomena in porous materials and the thermal properties of cellulose. To further the knowledge in this field, we have started to research on the relation between wetting, thermal dynamics and shape. We recorded with a thermal camera free convection of wetted models made of laser-cut paper tissue, soaked in water and drying naturally. Families of shapes were abstracted from leaves of deciduous trees: white oak, for their crenations and lobes; maple, for their relatively large teeth; elm, for their smaller hierarchically-ordered serrations. In this abstracted experimental setup, we observed distinct evaporation rates for models with normalized surface area but different boundary perimeters. Outward teeth prompt dewetting nucleation in shapes only differing geometrically, shedding some light on surface designs for heat dissipation versus designs for moist microclimate retention. The biomimetic approach taken will deliver a better understanding of the biological role of leaf structure and support the enhancement of fluid-assisted heat transfer systems, for which further three-dimensional exploration and scale studies are conceptualized.