GLove
Kristin Brodie
Jeff Colton
Colin Galbraith
Bushra Makiya
Tiffany Santos
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
Heat Loss Model



Cylindrical Hand
Power Lost @ -10C relative to Power Lost @ 25C
2rLq = 2L(T1-T3)/R = 2.5W

R = Fabric Resistance + BL Resistance
Glove Layers
Conduction
Convection
Overview
Battery Powered
Rechargeable
Non-Rechargeable
Uses
2 ‘D’ batteries
Chemical
Reversible
Non-Reversible
Lasts 18 hours
One time use
Battery Operated Glove
Wires
NiCr Alloys
Mechanical Testing
Stainless Steel
Electrical Resistivity Testing
Mechanical Testing Data
NiCr
Diameter (mm) 0.41
Stress* (ksi) 120
Stress vs Strain
Extension (in) 1.95
for 3 wires
Stress (lbs/in)
100000
80000
60000
40000
20000
0
NiCrFe
0.005
FeCrNi
0.01
NiCr
FeCrNi
0.38
0.404
74-130
~95
2.16
3.5
*Expected Stress
120000
0
NiCrFe
0.015
Strain
0.02
0.025
Electrical Resistivity Testing
Resistance
(W /cm)
Measured Resistances
0.1
0.08
0.06
0.04
0.02
0
Expected R
Measured R
R*
R**
Condition
NiCr 80:20
NiCrFe 60:16:24
All wire diameters are ~40mm
*R for wire wrapped around a finger
**R for wire after work-hardening
FeCrNi 70:19:11
Wire Insulators
Teflon Tubing
Nextel Braids
Teflon PTFE Tubing
Property
Units
Value
Resistivity
Wcm
1018
Tensile
Strength
MPa
21-34
Tm
C
327
Operating
Temp
C
260
Water
Absorption
Thermal
Conductivity
<0.01%
W/mK
0.25
Batteries




Amphr
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
My hand feels warm,
stop recording
At what temperature is your hand
comfortable?
Test
1
Tested 10 subjects
2

Placed in freezer
3

Dressed in winter clothes

Wore gloves with heating element
4

1.7W of power supplied
5

Temp recorded when subject said their hand
6
was warm
7
Conclusion
8

Thermal Switch should turn power off at
9
~32C
10
AVG
Tglove(C) Tenvironment(C)
32.94
-18.39
32.44
-18.17
31.89
-18.50
33.94
-18.78
32.11
-18.44
33.33
-18.00
29.28
-17.72
33.17
-18.67
33.11
-18.17
32.72
-18.33
32.49
-18.32
Temperature Sensor/Switch
Bimetallic
Polymer
Resistance/Current Testing
Before Switch After Switch
Expected Temp (C)
32
32  3
Actual Temp (C)
Voltage (V)
Resistance (W)
Current (A)
3.74
0
>106
0.43
0.0012
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(T1-T3)/R = 1.73 W
L/R = 0.018 W/K
Power lost using 100P* under conditions previously modeled: 2.7 W
Phase Change Materials (PCM)
Octadecane




Tm = 27.2° C
Tc = 16.5° C
Hc = 283.5 J/g
Hydrophobic
Polyethylene Glycol (PEG)




Tm = 26.6° C
Tc = 9.8° C
Hc = 151.0 J/g
Extremely hydrophilic
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
Microsphere Fabrication
Successfully produced both paraffin and octadecane microspheres.
Complications

Inefficiency of filtering process

Large scale production
Final PCM Designs
Octadecane

Ground particles embedded in base
material.

Polydimethyl Siloxane (PDMS) Resin

Thermal conductivity =
0.002W/m*K
PEG

Melting attempts failed.

Heat sealed in bags.

Low Density Polyethylene (LDPE)
 Thermal conductivity =
0.33W/m*K
-(CH2-CH2)-

5g octadecane in 10ml (~7.5g) PDMS

7g of PEG in ~11g LDPE
Comparison of PCM Designs
Octadecane in PDMS
PEG in PE
Potential Heat: 2.36 J
Actual Heat: 1.16 J
Potential Heat: 0.66 J
Actual Heat: 0.43 J
Efficiency: 49%
Efficiency: 65%
PCM Conclusions


Octadecane is more efficient than PEG.
Polyethylene is more efficient than PDMS.
Temperature Difference vs Time
for 3 Different Gloves
T (C)
40.0
30.0
20.0
10.0
0.0
0
10
20
30
40
Time (min)
PEG

Octadecane
Control
Future Recommendations

Encapsulate octadecane in polyethylene.

Extrusion
50
60
Assembly
Sew wire into glove
Connect wires to
temp. switch
Encapsulation of
PCMs
Connect wires to battery
Fabrication of Gloves
Inner Lining
Outer Cover
Cost Analysis
PCM Gloves
Battery Powered Gloves
NiCr Wire
$1.50
Octadecane
$2.50
Teflon Tubing
$17.00
PDMS
$5.00
Li Battery
$20.00
Polyester
$7.50
Labor
$8.00
Bimetallic Temp Switch
$4.00
Polyester
$7.50
Labor
Production Cost
Market Price
$10.00
$50.00
$100.00
Production Cost
$23.00
Market Price
$46.00
Competitors: $40-$150
Results
Battery Powered
Rechargeable
Non-Rechargeable
Chemical
Reversible
Non-Reversible
Octadecane > PEG
Uses Li battery
Temp Sensor

Use 2 ‘D’ batteries  Cycle ~15min
 Multiple cycles
 More Power

Better at lower temperatures
 Cycle 18 hours
 One cycle
Better at higher temperatures
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
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