Study on model parameters of focal cooling device using a Peltier element for a living body

Applied Medical Engineering Science, Graduate School of Medicine
Internal Mechanical Engineering Congress & Exposition 2016
2016.11.17
Study on Model Parameters of Focal Cooling Device
Using a Peltier Element for a Living Body
○Kenyu UEHARA∗1 Kentaro MIYAGO∗2 Koji MORI∗2 Takashi SAITO∗2
∗1Graduate school of Medicine, Yamaguchi University, in JAPAN
∗2Graduate school of Science and Technology for Innovation, Yamaguchi University , in JAPAN

Brain
waves(mV)
Temperature
(oC)
Time (s)
Cooling
15℃
NormalAbnormal
(epilepsy)
Abnormal
(epilepsy)
Seizure stop!Seizures Seizures
Introduction
Applied Medical Engineering Science,
Graduate School of Medicine
What is COOLING TREATMENT ??
• It can help provide relief for some disease or symptoms
• Easy, Quick, Safe
Epilepsy（Brain cooing） Problem with the brain’s electrical System ⇒ Seizures
Focal Cooling
Yamaguchi
university
Cooling is applied to intractable diseases
Cooling draws out the potential which human originally possess

Brain
waves(mV)
Temperature
(oC)
Time (s)
Cooling
15℃
NormalAbnormal
(epilepsy)
Abnormal
(epilepsy)
Seizure stop!Seizures Seizures
Introduction
What is COOLING TREATMENT ??
• It can help provide relief for some disease or symptoms
• Easy, Quick, Safe
Epilepsy（Brain cooing） Problem with the brain’s electrical System ⇒ Seizures
Focal Cooling
Yamaguchi
university
Cooling is applied to intractable diseases
Cooling draws out the potential which human originally possess
Requirement
Optimum cooling level exists
⇒ temperature control (thermal management)

Two semiconductors
(N-type & P-type)
Introduction
What is a PELTIER ELEMENT ??
P
N
P
N
P
N
Metal plate
cooled
Heated
Peltier element is considered as a great tool for temperature controller
Electric powerThermally in parallel
Electrically in series
• Rapid thermal response
• No vibration
• Compactness
advantages
These characteristics make this element as the most suitable
cooling device to be used in human for medical purpose

Introduction
DC
Heated
Cooled
water
Heat sink
Brain（Cooled object）
Designing of a focal cooling device
(Implant)
1. Peltier effect, Joule heat, Inside heat conduction
2. Thermal conductivity of the Heat sink, Cooled object
3. Environmental condition （Open air, Cooling water）
The solution is a “MATHEMATICAL ANALYSIS”
What should be considered in designing a cooling device??
Joule Heat
Heat
conduction

Previous Research
1. Produced a focal cooling device using a Peltier element
2. Modeling of the device
3. Evaluation of the model (Proportional control)
Our previous research
Heat sink
Peltier
(6×6 mm)
150mm
Water path
Focal cooling device
Heat side / Cool side of the Peltier
Heat sink

Previous Research
Heat sink
Peltier
(6×6 mm)
150mm
Water path
Heat sink
We identified these seven parameters experimentally

Previous Research
The usefulness of our proposed model
Kenyu UEHARA, Yasumi UKIDA, Takahiro MURAKAMI, Koji MORI and Takashi
SAITO, “INVESTIGATION ON TEMPERATURE CONTROL MODEL OF
THE FOCAL COOLING HUMAN PHYSIOLOGICAL SYSTEM”,
IMECE2015, Paper No. IMECE2015-52641, pp. V003T03A104 (2015).
time (s)
0 10 20 30 40 50
26
28
30
32
34
Temperature(
O
C)
Simulation
Experiment
Temperature(oC)
It is necessary to investigate the model parameters
in order to design effective focal cooling device
Good agreement

Previous Research
Investigation of the Model parameters
Heat sinkHeat sink
Peltier
(6×6 mm)
150mm
Water path
Our questions
If the performance or the size of the device changes,
How will these 7 parameters change ???

We identify the model parameters experimentally at constant voltage
using three focal cooling devices of different sizes and cooling performances
② Model parameters identification
③ Discussion
• Experimental set-up
• Identification method
• Result
Purpose
To elucidate the characteristics of the
parameters in the mathematical model
① Three focal cooling devices and Its model

③ Discussion
• Result
Purpose

Thermocouple
Heat sink
Peltier element
Ag plate
Water path
Power supply connector
150mm
Device name
(Peltier size)
Basic construction
Focal cooling devices using a Peltier element
Device A (B)
(Peltier 6×6mm)
Device C
(Peltier 15×15mm)
Three kind of devices (A,B and C)

Heat side ：
Cool side :
Modeling
Cooling object
Peltier
Heat sink
ITh
ITc 2
2
RI
2
2
RI
( )chpp TTK −
( )hhsph TTK −
( )cmpa TTK −
Peltire
effect
Joule
heat
Heat transfer
Hot temperature
Cold temperature
cQ
hQ
Amount of Heat
The Changing of the amount of heat of the Peltier and Heat sink

Heat side ：
Cool side :
Modeling
Cooling object
Peltier
Heat sink
ITh
ITc 2
2
RI
2
2
RI
( )chpp TTK −
( )hhsph TTK −
( )cmpa TTK −
Peltire
effect
Joule
heat
Heat transfer
Hot temperature
Cold temperature
Amount of heat
Heat energy rate bp × Time changing of the temperature
Density, volume, specific heat
cQ
hQ
Amount of Heat

Heat side ：
Cool side :
Modeling
Cooling object
Peltier
Heat sink
ITh
ITc 2
2
RI
2
2
RI
( )chpp TTK −
( )hhsph TTK −
( )cmpa TTK −
Peltire
effect
Joule
heat
Heat transfer
Hot temperature
Cold temperature
cQ
hQ
Amount of Heat
Caused by an electrical action I
 : thermo-electric conversion coefficient
（Temperature difference Input electrical power）
: Internal resistanceR
Equally loaded
Main effect

Heat side ：
Cool side :
Modeling
Cooling object
Peltier
Heat sink
ITh
ITc 2
2
RI
2
2
RI
( )chpp TTK −
( )hhsph TTK −
( )cmpa TTK −
Peltire
effect
Joule
heat
Internal
Heat transfer
Hot temperature
Cold temperature
cQ
hQ
Amount of Heat
Due to the temperature difference （Th-Tc）
Thermal conductance (W/K)
(coefficient of heat transfer)
Natural reaction

Heat side ：
Cool side :
Modeling
Cooling object
Peltier
Heat sink
ITh
ITc 2
2
RI
2
2
RI
( )chpp TTK −
( )hhsph TTK −
( )cmpa TTK −
Peltire
effect
Joule
heat
External
Heat transfer
Hot temperature
Cold temperature
cQ
hQ
Amount of Heat
¥
Heat
Cool
: Thermal conductance (Peltier – Heat sink)
: Thermal conductance (Peltier – Cooled object)
Peltier – Heat sink
Peltier – Cooled object

Modeling
Heat sink ：
( )hshph TTK −
( )hswhw TTK − ( )hsaha TTK −
Heat sink
Water
External heat transfer
: Peltier Th - Heat sink Ths
Thermal conductance
Only heat transfer since there is no effect by currentCooling object
Peltier
Heat sink The Changing of the amount of heat of the Peltier and Heat sink
: Heat sink Ths - Water Tw
: Heat sink Ths - Air Ta
Peltier – Heat sink
Heat sink - Water
Heat sink - Air

Heat sink
Peltier
150mm
Heat sink
Input current
Mathematical model of the Focal cooling device
Cooling device
Modeling
Counter electromotive force
by temperature difference

Heat sink
Peltier
150mm
Heat sink
Input current
Cooling device
Modeling
Device
number
A (B) C C/A (-)
βp (J/K) 0.04437 0.2810 6.30
βhs (J/K) 0.3582 1.882 5.25
Heat energy rate
Density, volume, Specific heat

Heat sink
Peltier
150mm
Heat sink
Input current
Cooling device
Modeling
7 parameters
These are identified experimentally by solving inverse problem

③ Discussion
• Result
Purpose

23
Identification of the Parameters
Cooling experiment
Voltage 0.1 ~ 1.7V （every0.1V） 180 sec
Input
Heat side
Cool side
Vegetable gelatin（37℃）
water
（34℃）
air
（26℃）
Device A （6×6 mm）
Device B （6×6 mm）
Device C （15×15 mm ）
Temperature controlling bath

-90 -60 -30 0 30 60 90 120 150 180
0
10
20
30
40
50
Temperature(
O
C)
Time (s)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0
10
20
30
40
50
Temperature(
o
C)
Input voltage E (V)
26
Cooling experiment (Voltage 0.1 ~ 1.7V （every0.1V） 180 sec)
VS
example > 0.9V constant
Device A
Device B
At 180 sec
temperature
Hot side
Cool side
Hot side
Cool side
0.9180
The difference of performance between A and B
A has a better cooling performance

-90 -60 -30 0 30 60 90 120 150 180
0
10
20
30
40
50
Temperature(
O
C)
Time (s)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0
10
20
30
40
50
Temperature(
o
C)
Input voltage E (V)
27
VS
Device C （15×15 mm）
Device A
Device C At 180 sec
temperature
Hot side
Cool side
Hot side
Cool side
0.9180
6.25 times bigger than A
Device C shows the best cooling performance in high voltages
Heat transferring from hot side to heat sink is working well
Not increase
so much

-90 -60 -30 0 30 60 90 120 150 180
0
10
20
30
40
50
Temperature(
O
C)
Time (s)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0
10
20
30
40
50
Temperature(o
C)
Input voltage E (V)
28
Device A
Device B
At 180 sec
temperature
Hot side
Cool side
Hot side
Cool side
0.9180
Device C （15×15 mm ）
Device C
We identified seven unknowns using these experimental results
(17 voltages data × 3 devices)

0 30 60 90 120 150 180
10
15
20
25
30
35
40
Temperature(
O
C)
Time (s)
Experimental heat
Experimental cool
Parameter Identification
Simulation
How to identify the parameters
parameters x were identified by solving the minimum problem
We used the Downhill Simplex method
Simulation
Mathematical model
An example
We would like to get parameters to simulate
the experimental value as much as possible

Parameter Identification(Device A)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.000
0.001
0.002
0.003
0.004
0.005
(V/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
R(V/A)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.000
0.004
0.008
0.012
0.016
0.020
Kpp(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Kph(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.00000
0.00005
0.00010
0.00015
Kpa(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
Khw(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.00
0.04
0.08
0.12
0.16
Kha(W/K)
E (V)
Device A
(6×6)
Device C
(6×6)
Device C
(15×15)
Thermo-electric coefficient Internal resistance Internal thermal
conductance
Almost all identified parameters have
a certain tendency on the input voltages
( monotone increase, decrease)

Parameter Identification(Device A & B)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.000
0.001
0.002
0.003
0.004
0.005
(V/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
R(V/A)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.000
0.004
0.008
0.012
0.016
0.020
Kpp
(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Kph
(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.00000
0.00005
0.00010
0.00015
Kpa(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
Khw(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.00
0.04
0.08
0.12
0.16
Kha(W/K)
E (V)
conductance
In Device A(red) and B(blue),
Some parameters have a same tendency
Internal resistance R & Thermal conductance Kpp
⇒ possibly relate to cooling performance
Device A
(6×6)
Device C
(6×6)
Device C
(15×15)

Parameter Identification(Device A, B & C)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.000
0.001
0.002
0.003
0.004
0.005
(V/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
R(V/A)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.000
0.004
0.008
0.012
0.016
0.020
Kpp
(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Kph
(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.00000
0.00005
0.00010
0.00015
Kpa
(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
Khw
(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.00
0.04
0.08
0.12
0.16
Kha
(W/K)
E (V)
conductance
In device C, most of the parameter values are
larger than others (except : internal resistance R)
Device A
(6×6)
Device C
(6×6)
Device C
(15×15)

0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
R(V/A)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.000
0.004
0.008
0.012
0.016
0.020
Kpp
(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.000
0.001
0.002
0.003
0.004
0.005
(V/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Kph
(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.00000
0.00005
0.00010
0.00015
Kpa
(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
Khw
(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.00
0.04
0.08
0.12
0.16
Kha
(W/K)
E (V)
を検討
In Device A(red) and B(blue),
Some parameters have a same tendency
Internal resistance R & Thermal conductance Kpp
⇒ possibly relate to cooling performance
Discussion
conductance
Device A
(6×6)
Device C
(6×6)
Device C
(15×15)

0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
R(V/A)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.000
0.004
0.008
0.012
0.016
0.020
Kpp
(W/K)
E (V)
Discussion
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0
10
20
30
40
50
Device A
Device B
Device C
Temperature(
o
C)
Input voltage E (V)
Heat cool
Hot side
Cool side
Equilibrium temperature of
both side of Peltier vs. input voltage
Cooling performance
Device B << Device A
Device A and Device B are the same size But….
Cooling device with bad performance has a large resistance R value
and large internal thermal conductance Kpp
If R is high, Joule heat is also high
If Kpp is high, cool side is very affected by hot side
bad performance
Device A
(6×6)
Device C
(6×6)
Device C
(15×15)

0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Kph
(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.00000
0.00005
0.00010
0.00015
Kpa
(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
Khw
(W/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.00
0.04
0.08
0.12
0.16
Kha
(W/K)
E (V)
を検討
Device A（6×6 mm）
Investigation of the Device size
Discussion
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.000
0.001
0.002
0.003
0.004
0.005
(V/K)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
R(V/A)
E (V)
0.0 0.3 0.6 0.9 1.2 1.5 1.8
0.000
0.004
0.008
0.012
0.016
0.020
Kpp
(W/K)
E (V)
conductance
Device A
(6×6)
Device C
(6×6)
Device C
(15×15)

Parameters
Discussion
Thermo-electric coefficient  (V/K) 1.46
Internal resistance R (V/I) 0.865
Internal thermal conductance Kpp (W/K) 3.62
↓External thermal conductance↓
Kph (Peltier – Heat sink) 3.14
Kpa (Peltier – Object) 2.27
Khw (Heat sink – water) 3.45
Kha ( Heat sink – Air ) 2.22
Average value of
•  & R have little dependent on the device size
• 5 thermal conductance parameters are strongly
dependent on the size
When the device size increase…..
Heat is more
easily transmitted
But…these parameters wouldn’t only be related simple dimensional
ratio (Volume of the Device C is 6 times bigger than the Device A)

Parameters
Discussion
Thermo-electric coefficient  (V/K) 1.46
Internal resistance R (V/I) 0.865
Internal thermal conductance Kpp (W/K) 3.62
↓External thermal conductance↓
Kph (Peltier – Heat sink) 3.14
Kpa (Peltier – Object) 2.27
Khw (Heat sink – water) 3.45
Kha ( Heat sink – Air ) 2.22
Average value of
How about contact surface of two material…
(Volume of the Device C is around 6 times bigger than the Device A)
Heat is more
easily transmitted
×3.58
Air
×6.25 Peltier
Heat sink
Water
×7.21
Biggest one
Biggest one
Model parameters have a validity
of physical phenomena
Smallest
Smallest

The model parameters were experimentally identified.
Three focal cooling device with different size and cooling
performance were compared
Conclusion
◆Most of the parameter values are increased in the device C (largest one)
◆The internal resistance R and the internal heat conductance Kpp are
dependent on the cooling performance.
◆The Thermo-electrical coefficient  & internal resistance R have little
dependent on the device size while the other heat conductance K are
strongly dependent upon the size.

Study on model parameters of focal cooling device using a Peltier element for a living body

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