Leaf shapes and edge design for faster evaporation in ......Leaf design parameters Family of shapes...
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Leaf shapes and edge design for faster evaporation in biomimetic heat dissipation systems Dr. Petra Gruber, Ariana Rupp. University of Akron, Biomimicry Research and Innovation Center BRIC [email protected] . [email protected] . Summit 2017: Nature-Inspired Exploration for Aerospace (NIEA) I) Plant thermodynamics : leaf shape and margin morphology affects evapotranspiration II) Abstracting geometry principles : from leaf morphometrics to parametric design III) Qualitative and quantitative results : geometry-driven divergences in evaporation rate IV) Biomimetic application space : heat transfer systems assisted by phase-changing fluids V) Ongoing research areas : conceptual / empirical botany and thermal investigation • How to translate findings from 2D into 3D? How to transfer findings to technical devices? 45.5 45.6 45.7 45.8 45.9 46 46.1 46.2 46.3 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 time lapse (min) 49 49.5 50 50.5 51 51.5 0 10 20 30 40 50 60 70 80 90 100 110 120 130 model weight (g) dried paper time lapse (min) • Plants are good candidates for studying structural thermal adaptations • Evapotranspiration is still seen as a necessary "cost“ for photosynthesis • It has a cooling effect but its thermo(regulatory?) role is still unclear . Vogel looked closely at leaf convection with cellulose acetate models. “Heated models differing only in shape showed sun leaves to be much more effective convective heat dissipaters “ On leaf lobes : Vogel didn’t test evaporation, but aknowledged “typically broad leaves dissipate about as much energy evaporatively as they do convectively”. Oak sun leaf Oak shade leaf Shapes only differing geometrically (same perimeter, same surface area) Relative teeth area ~ 8% : small influence in evaporation Relative teeth area ~ 24% : slope shifting gap between evaporation rates / drying times Family of shapes inspired by maple, oak and elm Leaf design parameters • In a glasshouse experiment (2016), water stress led to leaf cooling differences (up to 3°C). • For many species, leaf teeth (number, area..) correlate with climate. • Temperature of growth environment can affect teeth development . • • Toothed leaves seem to have more active photosynthesis and transpiration (2006). Teeth might favor survival of juvenile leaves. (Nicotra et al. 2011) “The functional significance of leaf shape lies more often in water relations than directly in leaf thermoregulation” • Models laser-cut from commercial paper towel (leaf-scaled designs) • Uniform wetting with cold water followed by free convection drying • Water loss / temps. recorded with analytical scale / thermal camera • Models keep a uniform cooler temp. until paper finally starts dewetting • A delayed dewetting hints to slow water loss = lower evaporation rate paper model 3D printed support water in m anti-floating weight water out • Significant differences in drying times (15 - 75 min differences between designs) • Extreme cases (dissipative vs retaining design) were resilient to wetting inconsistencies • Teeth acted as dewetting nucleators • Dewetting propagates inward from boundaries Measuring and saturation (wetting) setup normalized surface area normalized perimeter Trade-off between boundary interface (perimeter) and water volume (surface area) Electronics Wearables Thermal appliances / Lighting / HVAC Air/Spacecraft Architecture Grooved heat pipes Evaporator geometry EXTRUSION FOLD - Fabrics, pads RADIAL - Heat sinks, exhausts MODULAR - Sweating facades 3D-printed supports emulate one-sided leaf evapotranspiration (stomatal side) laser-cut cellulose sponge models, soaked in water slopes = evaporation rates APPLICATION SCALE Stomata / hydathodes pinpointing microscopy Measuring local humidity/temp. over leaves and plants (3D), for boundary layer and scale studies. • • Observation of leaf tissues and transpiration-related microstructures (stomata, water pores). • • Theoretical framework for heat/mass transport models and computational simulations. • Fabrication of leaf analogues with nonwovens and hydrogels, to explore applications. Leaves and morphometric data collection, with Elliptic Fourier shape analysis. ... Focus on cold-hardy, toothed (Maple, Elm), heterophyllous (Mulberry) or sun vs. shade leaves (Oak) ... Materials research for models with differentiated marginal properties / active evaporation Wicking, porous membranes Multiscale curvature-based contour software
Transcript of Leaf shapes and edge design for faster evaporation in ......Leaf design parameters Family of shapes...
Leaf shapes and edge design for faster evaporation in biomimetic heat dissipation systems
Dr. Petra Gruber, Ariana Rupp. University of Akron, Biomimicry Research and Innovation Center BRIC [email protected] . [email protected] . Summit 2017: Nature-Inspired Exploration for Aerospace (NIEA)
I) Plant thermodynamics : leaf shape and margin morphology affects evapotranspiration
II) Abstracting geometry principles : from leaf morphometrics to parametric design
III) Qualitative and quantitative results : geometry-driven divergences in evaporation rate
IV) Biomimetic application space : heat transfer systems assisted by phase-changing fluids
V) Ongoing research areas : conceptual / empirical botany and thermal investigation
• How to translate findings from 2D into 3D? How to transfer findings to technical devices?
45.5
45.6
45.7
45.8
45.9
46
46.1
46.2
46.3
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
time lapse (min)time lapse (min)
49
49.5
50
50.5
51
51.5
0 10 20 30 40 50 60 70 80 90 100 110 120 130
mod
el w
eigh
t (g)
dried paper
time lapse (min)
• Plants are good candidates for studying structural thermal adaptations
• Evapotranspiration is still seen as a necessary "cost“ for photosynthesis
• It has a cooling effect but its thermo(regulatory?) role is still unclear
.
Vogel looked closely at leaf convection with cellulose acetate models.
“Heated models differing only inshape showed sun leavesto be much more effective convective heat dissipaters“
On leaf lobes :
Vogel didn’t test evaporation, but aknowledged “typically broad leaves dissipate about as much energy evaporatively as they do convectively”.
Oak sun leaf
Oak shade leaf
Shapes only differing geometrically(same perimeter, same surface area)
Relative teeth area ~ 8% :small influence in evaporation
Relative teeth area ~ 24% : slope shifting gap between evaporation rates / drying times
Family of shapes inspired by maple, oak and elmLeaf design parameters
• In a glasshouse experiment (2016), water stress led to leaf cooling differences (up to 3°C).
• For many species, leaf teeth (number, area..) correlate with climate.
• Temperature of growth environment can affect teeth development.
•
•
Toothed leaves seem to have more activephotosynthesis and transpiration (2006).
Teeth might favor survival of juvenile leaves.
(Nicotra et al. 2011)“The functional significance of leaf shape lies more often in water relations than directly in leaf thermoregulation”
• Models laser-cut from commercial paper towel (leaf-scaled designs)• Uniform wetting with cold water followed by free convection drying• Water loss / temps. recorded with analytical scale / thermal camera
• Models keep a uniform cooler temp. until paper finally starts dewetting• A delayed dewetting hints to slow water loss = lower evaporation rate
paper model
3D printed support
water in
manti-floating weight
water out
• Significant differences in drying times (15 - 75 min differences between designs)
• Extreme cases (dissipative vs retaining design) were resilient to wetting inconsistencies
• Teeth acted as dewetting nucleators
• Dewetting propagates inward from boundaries
Measuring and saturation (wetting) setup
normalized surface area
normalized perimeter
Trade-off between boundary interface (perimeter) and
water volume (surface area)
Electronics Wearables Thermal appliances / Lighting / HVAC Air/Spacecraft Architecture
Grooved heat pipesEvaporator geometry
EXTRUSIONFOLD - Fabrics, pads
RADIAL - Heat sinks, exhausts
MODULAR - Sweating facades
3D-printed supports emulate one-sided leaf evapotranspiration (stomatal side)
laser-cut cellulose sponge models, soaked in water
slopes = evaporation rates
APPLICATION SCALE
Stomata / hydathodespinpointing microscopy
Measuring local humidity/temp. over leaves and plants (3D), for boundary layer and scale studies.
•
• Observation of leaf tissues and transpiration-related microstructures (stomata, water pores).
•
• Theoretical framework for heat/mass transport models and computational simulations.
• Fabrication of leaf analogues with nonwovens and hydrogels, to explore applications.
Leaves and morphometric data collection, with Elliptic Fourier shape analysis. ... Focus on cold-hardy, toothed (Maple, Elm), heterophyllous (Mulberry) or sun vs. shade leaves (Oak)
... Materials research for models with differentiated marginal properties / active evaporationWicking, porous
membranes
Multiscale curvature-based contour software
