surface tension driven water pumping by j. fraser & r.t. dobson university of stellenbosch...
TRANSCRIPT
SURFACE TENSION DRIVEN WATER PUMPING
byJ. Fraser & R.T. DobsonUniversity of Stellenbosch
Energy Postgraduate Conference 2013
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South African Heat Pipe Association Energy Postgraduate Conference EPC2013, 11-14 Aug 2013
Overview
• Introduction
• Background and Objectives
• Main Theory
• Problems
• Why it works
• Conclusion
Falling water droplet
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South African Heat Pipe Association Energy Postgraduate Conference EPC2013, 11-14 Aug 2013
Introduction
• Nature has adapted of millions of years
• Humans can learn much from nature
• Biomimicry = nature inspired design
• Examples:– Elephant trunk– Gecko feet– Shark skin– Lotus leaves– Beehive structure– Insect Nano robots – And many more
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South African Heat Pipe Association Energy Postgraduate Conference EPC2013, 11-14 Aug 2013
Introduction (cont.)
• Surface tension: similar to elastic membrane on fluid surface
• Nature found myriad of exploitations:
– Small insects stride on water– Bacteria releases surfactant for driving force– Some larva employs vector control for propulsion
• Recent applications:
– Small object propulsion– Nano-robots maneuverability– Capillary action– Micro pumping– etc
• Plant life thrived on Earth for thousands of years
• Pump water seemingly effortlessly
• Giant Redwoods grow up to 100 m tall
• Useful mechanism for water pumping
• In a time of water shortages, climate change, power consumption and emmision concerns
iThemba LABS
SAHPA®
South African Heat Pipe Association Energy Postgraduate Conference EPC2013, 11-14 Aug 2013
Background &Objectives
• Plant Leaves:– Photosynthesis: water + carbon dioxide + energy carbohydrates
+oxygen• Ingenious water transport mechanism of plants• Capillary-driven heat pipe technology mechanisms• Construct mechanical/artificial pump • First step in a larger project:
– wherein hydrogen, food (carbohydrates) and fuel are artificially produced.
• For this project:– build mechanically-constructed experimental simulation working
model of transport mechanism– Theoretical thermal-hydraulic simulation model + validation against
experimental model.
• After validation use of such a water pump in an artificial photosynthesis program to be established.
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South African Heat Pipe Association Energy Postgraduate Conference EPC2013, 11-14 Aug 2013
Main Theory Overview
• Water Transport in trees Transpiration pull
• (TACT)– Transpiration– Adhesion– Cohesion– Tension
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South African Heat Pipe Association Energy Postgraduate Conference EPC2013, 11-14 Aug 2013
Problems
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South African Heat Pipe Association Energy Postgraduate Conference EPC2013, 11-14 Aug 2013
Why it works
iThemba LABS
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South African Heat Pipe Association Energy Postgraduate Conference EPC2013, 11-14 Aug 2013
Why it works
• Secret Strong adhesion forces Strong cohesion forces Evaporation Surface tension forces
• Must prevent nucleation sites – Prevent embolisms
• Require a continuous channel of water:– Rerouting– Dissolve bubbles
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South African Heat Pipe Association Energy Postgraduate Conference EPC2013, 11-14 Aug 2013
In Conclusion
• Nature offers many lessons and techniques
• Surface tension useful mechanism
• Tree water pumping mechanism investigation
• Theory, build, experiment & validate
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SAHPA®
South African Heat Pipe Association Energy Postgraduate Conference EPC2013, 11-14 Aug 2013
Acknowledgements
•Mr. Dobson
•Family
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South African Heat Pipe Association Energy Postgraduate Conference EPC2013, 11-14 Aug 2013
END
THANK YOU