Can You Heat Me
Now?
Formal Design Review
Brie Frame
Sandra Gonzalez
Angela Tong
Chenny Zhu
Department of Materials Science • 3.082 • Advisor: Hao Wang •
March 11, 2004
Outline of Presentation
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Objective
Overview of Components of Device
Phase Change Materials and Data
Melting Energy Calculations
Battery Selection
Power Calculations
Hybrid vs. Electrical Design
Proposed Circuit
Future Work
Proposed Schedule
Objective

Design and fabricate a heat therapy
device for lower back pain with a future
use for transdermal drug delivery.
Components of Device
Battery
High Insulating Layer
Heating Core
Outer Covering
Body
Average Body Dimensions
Waist Circumference: 37.48” (men) 34.88” (women) 36.18” (average)
Back Width (at shoulder): 15.75”
Back Length: 15.77”
Waist to Hip: 3.93”
42”
12”
6”
4”
Heating element volume: 6x4x0.25” = 6in3 or 10x16x0.5cm = 80cm3
Heating Core
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Potential Materials


Tetradecanol

X
2,6-Di-tert-butylphenol
(liquid at room temperature)

X
Cis-Cyclohexane-1,2-dicarboylic
anydride
(toxic)

Benzylideneacetone
Ethylene Carbonate
PCM: Temperature vs. Time
41
39
Temperature (C)
37
Benzilideneac etone
35
Tetradec anol
Ethylene c arbonate
33
31
29
0
5
10
15
20
25
Time (min)
30
35
40
45
50
Melting Energy
Material
Molecular
MW
density
Weight
Enthalpy of Fusion
Energy
Electric Energy
Units
Formula
(g/mol)
(g/cm3)
g
(kJ/mol)
(J)
(W*h)
Tetradecanol
C14H30O
214.39
0.823
65.84
49.4
15170.93
4.214
Ethylene Carbonate
C3H4O3
88.06
1.32
105.6
13.3
15949.13
4.430
2,6-Di-tert-butylphenol
C14H22O
206.32
0.91
72.8
16.57
5846.724
1.624

Equation: Energy (W*h) = (ρ*V*ΔHf) / (MW)
Battery Selection
Battery Specimen
Voltage weight (g) volume (cm3) joules
Wh
Wh/kg
Wh/cm3
Saft Batteries
Li-ion rechargeable
MP144350
3.6
70
28.96344
29808
8.28 118.2857 0.285878
MP174865
3.6
121
56.7987
59616
16.56 136.8595 0.291556
MP176065
3.6
150
71.1177
77760
21.6
144 0.303722
VL34480
3.6
103 43.44743572
46656
12.96 125.8252 0.298291
VL34570
3.6
126 51.42757697
58320
16.2 128.5714 0.315006
Sanyo Batteries
Li-ion rechargeable
UF103450P
3.7
39.5
17.31912
22644
6.29 159.2405 0.363182
UR18650P
3.7
41.5 15.71619353
22644
6.29 151.5663 0.400224
UR18650H
3.7
46 16.64757365
25308
7.03 152.8261 0.422284
UR18650F
3.7
46.5 16.64757365
27972
7.77 167.0968 0.466735
Li Polymer
UPF574199
3.7
46
23.1363
28638
7.955 172.9348 0.343832
UPF386369
3.7
34
16.614675
19980
5.55 163.2353 0.334042
Thunderpower Lithium Polymer
2100mAh Thun.Pow
11.1
130
58.4064
83916
23.31 179.3077
0.3991
1300mAh Double
7.4
55
25.33986
34632
9.62 174.9091 0.379639
1300mAh Triple
11.1
81
38.3292
51948
14.43 178.1481 0.376475
Power Estimation
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Heat loss to environment
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q=-k dT/dx
q=-0.0037*(16°C/0.005m)
q=8.88W/m2
q*A = P = 8.88 * 0.016m2
P = 0.142W
Heat loss to body

q= -0.025*(6°C/0.001m)
 q=150W/m2
 q*A = P = 150 * 0.016m2
 P = 2.4W
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q=heat flux W/m2
k=thermal conductivity W/mK
 Solid Silicone Rubber = 0.0037 W/mK
 Cotton = 0.025 W/mK
T=temperature
 Heat Pack = 41°C
 Environment = 25°C
 Body Surface Temperature = 35°C
x=thickness = 0.005m
A = area = 0.016m2
P = power (W)
Total heat loss

0.10m
P = 0.142 + 2.4 = 2.542 W
0.005m
0.16m
Hybrid vs. Electrical
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Power needed to keep temperature at 41°C in air =
2.56W
4.43 Whr to melt 105.6g of Ethylene Carbonate (EC)
1.73hrs to melt 105.6g (EC)
15min for 10g Ethylene Carbonate to cool to 35°C
Assuming cooling rate is at steady state, would take
~150min (2.5hrs) for ethylene carbonate to cool to 35°C
2.5hrs + 1.73hrs = 4.23 hrs for one cycle
Save 2.5hrs of electrical energy per cycle = 6.48Whr
Hybrid vs. Electrical
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Electrical
 Lighter
 Constant
Heat
 Uses more energy
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Hybrid
 More
energy efficientuse electrical energy
to both heat body and
PCM
 Staggered Heating
Switch

Programmable Thermostatic Switch –
Analog Devices AD22105
 Control
temperature by adding resistors
 Small – about 5mmx5mmx2mm
 Cheap ~ $1 - $3 per switch depending on how
many bought
Circuit
Insulating Material
Potential Materials
 COHRlastic Solid Silicone Rubber
 Thermally Conductive R10404
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Low Thermal Conductivity 0.0037W/mK
Very Thin
R10480
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Low Thermal Conductivity
Flexible
Future Work

Differential Scanning Calorimetry
 Properties
of 2,6-Di-tert-butylphenol
Polymer Gel combined w/ PCM for comfort
 Fire resistant wire coating
 Finding resistance for thermal regulation
switch
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Proposed Schedule
Feb 2004
ID
Task Name
Start
2/1
1
Formal Design Review Presentation
2
Obtaining Materials
3/11/2004
3/11/2004
2/5/2004
3/18/2004
3
Wires
3/2/2004
3/4/2004
4
PCM
3/2/2004
3/11/2004
5
Thermal Switch
3/9/2004
3/11/2004
6
Polymer Gel
3/9/2004
3/11/2004
7
Insulating Material
3/9/2004
3/16/2004
8
Battery
3/9/2004
3/16/2004
9
Outside Material
3/9/2004
3/16/2004
Wire Coating
3/9/2004
3/16/2004
3/9/2004
3/18/2004
10
11
Processing
12
Polymer Gels
3/11/2004
3/18/2004
13
Wire Coating
3/11/2004
3/18/2004
3/2/2004
4/1/2004
14
Testing Materials
Mar 2004
Apr 2004
May 2004
Finish
15
Wire
3/2/2004
3/9/2004
16
PCM
3/4/2004
3/18/2004
17
Thermal Switch
3/16/2004
3/25/2004
18
Polymer Gel
3/18/2004
4/1/2004
3/18/2004
4/6/2004
19
Prototype Assembly
20
Initial Prototypes
4/6/2004
4/6/2004
21
Testing and Troubleshooting Prototype
4/6/2004
5/6/2004
22
Last Day of Lab Work
5/6/2004
5/6/2004
23
Final Presentation/Posters Due
5/13/2004
5/13/2004
2/8
2/15
2/22
2/29
3/7
3/14
3/21
3/28
4/4
4/11
4/18
4/25
5/2
5/9
5/16