NiTi Project Junior Year

8/3/2019 NiTi Project Junior Year

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Jared Vidales Austin Schader

Nick WiswellMichael Turovskiy

Aaron YourilKevin Wilkins

CooliNiTTM



Product Overviewy The product is a heat pump

using the unique propertiesof superelastic nitinol wire

yThe product functions bystraining the wire around aspool in one working fluidand allowing it to release inanother

y Advantages of the designinclude hand operation andportability



Science of Superelasticityy A f > Room Temperature

y Strain causes A M

y Harvest H of

transformation

y 5% Fatigue Limit



Heat

Pump Thermodynamics

Cycle of compressor-based heatpump

Heat pumps use work to move heat energybetween thermal reservoirs

A common example of a heat pump is a

household refrigerator

Traditional systems use a compressible fluidand two heat exchangers

Nitinol wire can be used to replace the fluid

because of its superelasticity; it has a thermalresponse to strain



Theoretical Efficiencyy The theoretical efficiency (measured as Coefficient of

Performance) of a traditional compressor-based heat pump isproportional to ambient temperature

y This will also apply to the wire as the ambient temperatureincreases; eventually the heat of transformation will be overcomeby the ambient temperature difference

y A nitinol-based system can have a COP larger than 1 because

work is stored in the strain of the wire; the limiting factor is thedifference in the elastic modulus of the austenite and martensite



Early Proof Calculations

Pure bending problem:

Wire is worst possible cross-section:

10% of wire strains >.08Ensuring bulk of wire getsstrained

Percent transformation:

Assume 100% phasetransformation at .08 strain



Early CalculationsOptimal radius of curvature:

Average strain of the inner 90%:

Percent transformed on bending:

Final energy yield on bending:



Preliminary TestingReleased strained Nitinol in ~50mL H2O

Measured T = -0.5 to -1ºC



Conceptual Designs



Prototype Sketch



Final Prototype

y Simple design

y Portable

yManually driven

y Low cost

y Repeatable



Markety Portable refrigeration

y Beverages

y Portable heating

y Beverage inserts



Manufacturing & Cost

Total cost = $25.00

ABS housing = $11.00

PVC Crank = $1.00

Wooden Dowel = $1.00

SE508 Nitinol 1mm = $12.00



Resultsy Results varied

y Many variables that could affect temperature change inthe water.

y Prototype itself

y Water clinging to NiTi

y Dowel

y Mechanical Heating

y Winding and Unwinding of NiTi



Future Improvements &Recommendations

y Convert to continuous system

y Material with greater insulating properties

y Larger volume of Nitinoly Greater diameter

y Longer wire



Thank You!

Questions?

NiTi Project Junior Year

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