GLove

Kristin BrodieJeff Colton

Colin GalbraithBushra MakiyaTiffany Santos

Objective

To create a glove that will generate heat to help keep your hand warm in a cold environment

What will this require? Source of heat generation

How will they be different? Lightweight Re-usable Smart

Temperature Sensor/Switch Reversible Exothermic Material

Heat Loss Model Cylindrical Hand Power Lost @ -10C relative to Power Lost @ 25C 2rLq = 2L(T1-T3)/R = 2.5W

R = Fabric Resistance + BL Resistance

Conduction

ConvectionGlove Layers

Overview

Battery Powered Checmical

Rechargeable Non-Rechargeable

Uses 2 ‘D’ batteries

Reversible Non-Reversible

Lasts 18 hoursOne time use

Battery Operated Glove

Wires

NiCr Alloys Stainless Steel

Electrical Resistivity Testing Mechanical Testing

Mechanical Testing DataNiCr NiCrFe FeCrNi

Diameter (mm) 0.41 0.38 0.404

Stress* (ksi) 120 74-130 ~95

Extension (in) 1.95 2.16 3.5

*Expected Stress

Stress vs Strainfor 3 wires

0

20000

40000

60000

80000

100000

120000

0 0.005 0.01 0.015 0.02 0.025

Strain

Stress (lbs/in)

NiCrFe FeCrNi NiCr

Electrical Resistivity Testing

All wire diameters are ~40mm*R for wire wrapped around a finger**R for wire after work-hardening

Measured Resistances

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

Expected R Measured R R* R**

Condition

Resistance (

Ω/ )cm

NiCr 80:20 NiCrFe 60:16:24 FeCrNi 70:19:11

Wire Insulators

Teflon PTFE Tubing

Property Units Value

Resistivity Ωcm 1018

Tensile Strength

MPa 21-34

Tm C 327

Operating Temp

C 260

Water Absorption

<0.01%

Thermal Conductivity

W/mK

0.25

Teflon Tubing

Nextel Braids

Batteries

Amphr Size Durability Recharge ability

Serial # 603672 141988 597980

Discharge Capacity (Ah)

0.754 1.364 1.181

Discharge Power (Wh) 2.82 5.10 4.42

Length (mm) 48.9 88.3 65.5

Width (mm) 34.8 54.9 36.2

Height (mm) 5.30 3.03 5.50

Final OCV (V) 3.76 3.74 3.74

Final Impedance 48.8 39.2 30.3

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

~32C

Test Tglove(F)

Tenvironment(F)

1 91.3 -1.1

2 90.4 -0.7

3 89.4 -1.3

4 93.1 -1.8

5 89.8 -1.2

6 92.0 -0.4

7 84.7 0.1

8 91.7 -1.6

9 91.6 -1.1

10 90.9 -0.7

AVG 90.5 -1.0

My hand feels warm, stop recording

Temperature Sensor/Switch

Resistance/Current Testing

Bimetallic Polymer

Before Switch

After Switch

Expected Temp (C)

32

Actual Temp (C) 32 3

Voltage (V) 3.74

Resistance (Ω) 0 >106

Current (A) 0.43 0.0012

PICTURE HERE

FabricBlends of Polyester/Cotton were tested

Thermal Testing Input Power = 1.73 W

100cm of wire 3.7V

Temperature inside and outside of glove measured

2rLq=2L(T1-T3)/R = 1.73 W

L/R = 0.018 W/k

Power required using 100P* under same conditions as slide 3: 4.95 W

Temperature Difference vs Time

0

5

1015

20

25

3035

40

45

0 2 4 6 8 10 12

Time (min)

Δ

100P 100P* 20C 80P 80C 20P

Phase Change Materials

Octadecane

Tm = 27.2° C Tc = 16.5° C ΔHc = 283.5 J/g Hydrophobic Soft, waxy material

Polyethylene Glycol (PEG)

Tm = 26.6° C Tc = 9.8° C ΔHc = 151.0 J/g Extremely hydrophilic Soft, waxy material

Differential Scanning Calorimetery

Octadecane Polyethylene Glycol (PEG)

PCM Encapsulation 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 Lack of Encapsulation Facilities Lack of Extrusion Facilities Different thermal properties of PEG and PE

Microsphere Fabrication Successfully produced both paraffin and octadecane

microspheres.

Complications Inefficiency of filtering process Large scale production

PCM Encapsulation

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

-(CH2-CH2)-

Comparison of PCMs

Octadecane in PDMS PEG in PE

Potential Heat: 2.36 JActual Heat: 1.16 J

Reduction in Efficiency: 51%

Potential Heat: 0.66 JActual Heat: 0.43 J

Reduction in Efficiency: 35%

PCM Conclusions Octadecane is more efficient than PEG. Polyethylene is more efficient than PDMS.

Future Recommendations Encapsulate octadecane in polyethylene. Extrusion

Temperature Difference vs Timefor 3 Different Gloves

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

0 20 40 60 80 100 120

Time (min)

PEGOctadecaneNothing

Power Generated Wire

P = V2/R V = 3.74V, R = 8.3Ω 1.7 W for 156 min

Octadecane 5 g 1417 J 1.7 W for 12.5 min

PEG 7 g 1057 J 1.7 W for 9.4 min

Field Testing Battery Powered Octadecane

PEG

Assembly Connect wires to temp switch Connecting wires to battery

Mechanical Strengthening of Contacts Discharge battery

Encapsulation of PCM Fabrication of Gloves

Future Work Improvements

Encapsulation process Incorporation of wire into glove Ease of access to recharge battery On/Off switch Insulation of Wire