1. G  Love Kristin Brodie Jeff Colton Colin Galbraith Bushra Makiya Tiffany Santos

2. Objective To create a glove that will generate heat to help keep one’s hand warm in a cold environment What will this require? Source of heat How will they be different? Lightweight Smart Temperature Sensor/Switch Rechargeable Battery Reversible Exothermic Material

3. Heat Loss Model Cylindrical Hand Power Lost @ -10  C relative to Power Lost @ 25  C 2  rLq = 2  L(T 1 -T 3 )/R = 2.5W R = Fabric Resistance + BL Resistance Conduction Convection Glove Layers

4. Overview Battery PoweredChemical RechargeableNon-Rechargeable  Uses 2 ‘D’ batteries ReversibleNon-Reversible  Lasts 18 hours  One time use

5. Battery Operated Glove

6. Wires NiCr Alloys Stainless Steel Mechanical TestingElectrical Resistivity Testing

7. Mechanical Testing Data NiCrNiCrFeFeCrNi Diameter (mm)0.410.380.404 Stress* (ksi)12074-130~95 Extension (in)1.952.163.5 *Expected Stress

8. Electrical Resistivity Testing All wire diameters are ~40mm *R for wire wrapped around a finger **R for wire after work-hardening

9. Wire Insulators Teflon PTFE Tubing PropertyUnitsValue Resistivity  cm 10 18 Tensile Strength MPa21-34 TmTm C327 Operating Temp C260 Water Absorption <0.01% Thermal Conductivity W/m  K 0.25 Teflon Tubing Nextel Braids

10. Batteries Amp  hr Size Durability Recharge ability Serial #603672141988597980 Discharge Capacity (Ah)0.7541.3641.181 Discharge Power (Wh)2.825.104.42 Length (mm)48.988.365.5 Width (mm)34.854.936.2 Height (mm)5.303.035.50 Final OCV (V)3.763.74 Final Impedance48.839.230.3

11. Field Testing At what temperature is your hand comfortable? Tested 10 subjects Placed in freezer Dressed in winter clothes Wore gloves with heating element 1.7W of power supplied Temp recorded when subject said their hand was warm Conclusion Thermal Switch should turn power off at ~32  C TestT glove (C)T environment (C) 132.94-18.39 232.44-18.17 331.89-18.50 433.94-18.78 532.11-18.44 633.33-18.00 729.28-17.72 833.17-18.67 933.11-18.17 1032.72-18.33 AVG32.49-18.32 My hand feels warm, stop recording

12. Temperature Sensor/Switch Resistance/Current Testing BimetallicPolymer Before SwitchAfter Switch Expected Temp (  C) 32 Actual Temp (  C)32  3 Voltage (V)3.74 Resistance (  ) 0>10 6 Current (A)0.430.0012

13. Fabric Blends of Polyester/Cotton were tested Thermal Testing Input Power = 1.73 W 100cm of wire 3.7V Temperature inside and outside of glove measured Power Generated From Glove: 2  rLq=2  L(T 1 -T 3 )/R = 1.73 W L/R = 0.018 W/K Power lost using 100P* under conditions previously modeled: 2.7 W

14. Phase Change Materials (PCM) Octadecane T m = 27.2° C T c = 16.5° C  H c = 283.5 J/g Hydrophobic Polyethylene Glycol (PEG) T m = 26.6° C T c = 9.8° C  H c = 151.0 J/g Extremely hydrophilic

15. PCM Incorporation PURPOSE: To prevent leakage from glove when PCM melts. Ideal Process Microspheres to maximize surface area Polypropylene (PP) / High Density Polyethylene (PE) Can be used to encapsulate microspheres Can be drawn into fibers Extrusion of PEG/PP: phase separation Complications Different thermal properties of PEG and PE Lack of Encapsulation Capabilities Lack of Extrusion Facilities

16. Microsphere Fabrication Successfully produced both paraffin and octadecane microspheres. Complications Inefficiency of filtering process Large scale production

17. Final PCM Designs Octadecane Ground particles embedded in base material. Polydimethyl Siloxane (PDMS) Resin Thermal conductivity = 0.002W/m*K 5g octadecane in 10ml (~7.5g) PDMS PEG Melting attempts failed. Heat sealed in bags. Low Density Polyethylene (LDPE) Thermal conductivity = 0.33W/m*K 7g of PEG in ~11g LDPE -(CH 2 -CH 2 )-

18. Comparison of PCM Designs Octadecane in PDMSPEG in PE Potential Heat: 2.36 J Actual Heat: 1.16 J Efficiency: 49% Potential Heat: 0.66 J Actual Heat: 0.43 J Efficiency: 65%

19. PCM Conclusions Octadecane is more efficient than PEG. Polyethylene is more efficient than PDMS. Future Recommendations Encapsulate octadecane in polyethylene. Extrusion

20. Assembly Fabrication of Gloves Inner Lining Outer Cover Connect wires to temp. switch Connect wires to battery Encapsulation of PCMs Sew wire into glove

21. Cost Analysis Battery Powered Gloves NiCr Wire$1.50 Teflon Tubing$17.00 Li Battery$20.00 Bimetallic Temp Switch$4.00 Polyester$7.50 Labor$10.00 Production Cost$50.00 Market Price$100.00 PCM Gloves Octadecane$2.50 PDMS$5.00 Polyester$7.50 Labor$8.00 Production Cost$23.00 Market Price$46.00 Competitors: $40-$150

22. Results Battery PoweredChemical Rechargeable  Uses Li battery  Temp Sensor Non-Rechargeable  Use 2 ‘D’ batteries  More Power Reversible Octadecane > PEG  Cycle ~15min  Multiple cycles Non-Reversible  Cycle 18 hours  One cycle Better at lower temperaturesBetter at higher temperatures

23. Future Work Improvements Encapsulation process Incorporation of PCM into glove Incorporation of thermally conductive material into PCM gloves Incorporation of wire into glove Insulation Ease of access to recharge battery On/Off switch Application of Wire Insulation Field Test Prototype w/ People or Heat Model In Freezer

24. Acknowledgements Professor Ceder Professor Irvine Professor Powell Professor Roylance Toby Bashaw Erin Lavik Tim McClure Joe Parse Yin Lin Xie Test Subjects Other MIT Faculty and Students who we consulted