CORESTA 10.24.2018
Frank S. Higgins, Jim Skapars, and Mark J. Rusyniak
Infrared Thermal Imaging Applied to E-Cigarette Heater Core Temperature Measurement
Altria Client Services l Frank Higgins | I 10/11/2018 I CORESTA 2018 1
Introduction
▪ FDA PMTA Draft Guidance for ENDS* recommends providing information on “design
parameters that would be affected by and that would affect aerosolizing apparatus
performance”
▪ Characterization of device temperatures is important, as changes in temperature can
result in changes in aerosol ingredients
▪ It is difficult to accurately measure temperature in ENDS devices using standard
methodologies (e.g. thermocouples)
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*FDA, May 2016. Premarket Tobacco Product Applications for Electronic Nicotine Delivery Systems, Guidance for Industry, Draft Guidance.
Page 39, line 1569-1571, Food and Drug Administration, Rockville, MD.
Limitations of Thermocouple (TC) Heater Core Measurement
▪ Difficult to position TC in heater core (heater assembly)
- TC’s are Fragile
- Time consuming to insert TC and prevent movement
- Location reproducibility of the TC is a problem
▪ TC is single point measurement
▪ TC mounted in heater assembly acts as a heat sink to
surrounding areas
▪ Presence of TC in heater assembly may disturb airflow and
interfere with wicking
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FLIR® Imaging
▪ Profiles entire heater core
▪ Realtime measurement
- Fast response time (30 frames per second)
- Captures the hottest point of a puff (i.e. hottest frame)
▪ Capable of auto triggering
▪ Labview automation for pump puff activation and FLIR® activation
- Any sequence of puffs can be recorded
- Puff duration and volume can be changed
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ENDS Schematic
Infrared thermal imaging through the front of the cartridge
Heated coil
Air Channel
Mouthpiece
CartridgeBattery Assembly
Optical Resolution – FLIR® E-cigarette Setup
▪ Optimized optical resolution allows for high spatial resolution of
temperature measurements
- 45µm/pixel
▪ Working distance = 0.04m
- Using 0.5in extension ring
- 25mm Lens
- Focal plane array detector pixels (frame size) = 640x512
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Emissivity Determination▪ IR cameras (FLIR®) measure radiance
▪ FLIR® calibrations convert radiance to temperature
▪ Uses known constants and input parameters
▪ Emissivity
▪ Reflected temperature (environment)
▪ Working distance
▪ Ambient air temperature
▪ Relative Humidity
▪ External optics temperature
▪ Emissivity is the most critical parameter
▪ Opaque target objects
▪ Radiance = Emissivity + ReflectivityAltria Client Services l Frank Higgins | I 10/24/2018 I CORESTA 2018 7
Emissivity Determination
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▪ ASTM E1933-14, "Standard Practice
for Measuring and Compensating for
Emissivity Using Infrared Imaging
Radiometers," 2014.
▪ Surface modification
▪ Heater core is half painted with a
high emissivity paint
▪ Black Header Paint (704-1093°C,
Flame Proof, Silica-Ceramic
Coating), recommended by
FLIR®
▪ Emissivity = 0.99
Emissivity Determination
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▪ Custom built emissivity fixture
▪ Temperature controlled aluminum block
▪ Allows heater core materials to be mounted
securely in direct contact with block
▪ TC and heating elements are connected to
a temperature controller
Heating
Elements
TC
Heater Core Temp Measurement
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Atomizer Cross-sectioned to
expose heater coreFLIR® Image of a heater core
FLIR® Movie – Puff Duration (5s) & Volume (55cc), w/ TC Mounted
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Significant cooling of areas surrounding the thermocouple
Temporal Plot – Puff Duration (5s) & Volume (55cc), w/ TC Mounted
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Hottest Frame:
202.2°C
Tem
pera
ture
(°C
)
Relative Time (s)
202.2
195.5
190.2
184.8
179.5
174.2
168.9
163.6
158.3
152.9
150.3
0.1
83
0.4
73
0.7
62
1.1
47
1.3
40
1.6
30
1.9
19
2.2
08
2.4
97
2.7
87
3.0
76
3.3
61
3.6
45
4.2
24
4.2
24
4.5
13
4.8
02
4.9
95
5.3
81
5.5
73
5.8
63
6.1
52
6.4
42
6.7
21
7.0
11
7.3
00
7.5
89
7.8
78
8.1
68
8.4
57
8.7
46
9.0
35
9.2
28
9.6
14
Hottest Frame #161 – TC Mounted
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TC in contact with heater
core, TC Temp = 230.0°C
Hottest Pixel = 248.7°C
Adjacent Pixel to
TC = 230.7°C
▪ TC temperature
agrees with FLIR®
Mean Temperatures
▪ Pixels adjacent to
the TC
▪ TC does not measure
the hottest
temperatures
▪ Heat sinking
▪ Positioning
Apparatus Setup – FLIR® w/ Pump
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Setup for FLIR® Imaging
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Stream of
nitrogen gas is
used to
prevent
condensation
of vapors onto
the FLIR® lens
FLIR® Imaging Parameters
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▪ CORESTA Puff Profile*:▪ 55cc Puff Volume*
▪ 3s* and 5s Puff Durations
▪ Square Wave Puff Profile*
▪ 30s Puff Interval*
▪ Positive pressure
▪ Max = Peak temperature attained in the heater zone at the hottest point during
the puff (hottest spot of heater zone)
▪ Mean = Average temperature attained in the heater zone at the hottest point
during the puff
▪ FLIR® factory default calibration range is 150-350°C
▪ We employ a custom calibration with a neutral density filter to extend the
temperature range (180-464°C)
▪ Segmentation is used to only include the heater zone in mean
temperature calculations, values >181°C
*CORESTA Recommended Method N° 81, Routine Analytical Machine for E-cigarette Aerosol Generation and Collection – Definitions and Standard Conditions, June 2015.
Summary Averaged Temps – Single Cartridge thru One Charged Battery
17Altria Client Services l Frank Higgins | I 10/24/2018 I CORESTA 2018
▪ Same e-liquid, N=3
▪ Single battery for each replicate,
140 puffs
▪ Puff duration: 3s and 5s
▪ Prototype batteries:
▪ B1 (no temperature cutoff)
▪ B2 (with temperature cutoff)
▪ Both batteries are far below
carbonyl forming temps, 350-400°C
▪ Mean temperatures 212-217°C
▪ Max temperatures 247-265°C
150.0
170.0
190.0
210.0
230.0
250.0
270.0
290.0
E-liq 1 B1 3s E-liq 1 B2 3s E-liq 1 B1 5s E-liq 1 B2 5s
Average Mean
Average Max
Te
mp
era
ture
(°C
)
Summary Averaged Temps, Single Cartridge thru Two Fully Charged Batteries
18Altria Client Services l Frank Higgins | I 10/24/2018 I CORESTA 2018
150
200
250
300
350
400
450
500
E-liq 1 B1 3s E-liq 1 B2 3s E-liq 1 B1 5s E-liq 1 B2 5s
Average Mean
Averaged Max
Tem
pera
ture
(°C
)
▪ Simulating dry wicking
▪ Same e-liquid, N=3
▪ Two batteries for each replicate
▪ First Battery (puffs 1-140)
▪ Second battery (puffs 141-
220)
▪ B1 batteries indicate max temps
>350°C
▪ B2 with 3s puff duration <350°C
▪ B2 with 5s puff exceeds 350°C
briefly
▪ How long and how much?
Thermal Imaging Video Capture–B1 and B2 Batteries
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▪ Hottest point of
puff 160 for each
battery
▪ 5s puff
duration
No cutoff B1 battery,
captured image
near the end of the
5s puff
Temp cutoff B2
battery, captured
image prior to cutoff
(~2.2s)
E-liquid 1 Mean Temperature vs. Time, Puff 160
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170
220
270
320
0 1 2 3 4 5 6 7
Te
mp
era
ture
(C
)
Relative Time (s)
e-liquid 1-B1
e-liquid 1-B2
• B1 continues to increase
in temperature thru the
full 5s of puff
• Puff profiles indicate B2
battery cutoff at 2.2s into
a 5s puff
E-liquid 1 Max Temperature vs. Time, Puff 160
21Altria Client Services l Frank Higgins | I 10/24/2018 I CORESTA 2018
170
220
270
320
370
420
470
0 1 2 3 4 5 6 7
Te
mp
era
ture
(C
)
Relative Time (s)
e-liquid 1 - B1
e-liquid 1 - B2
170
220
270
320
370
420
470
0 1 2 3 4 5 6 7
• B1 exceeds 350˚ C for
2.8s during the 5s puff ~
60%
• B2 exceeds 350˚ C for
0.63s ~ 13%
Further analysis of the data
can show the area (pixel)
percentage above 350˚ C
B1 ~ 27% of pixels >350˚ C
B2 ~ 2% of pixels >350˚ C
Simultaneous FLIR® & FTIR Formaldehyde Analysis
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Vapors produced
during each puff
are simultaneously
measured by FLIR
thermal imaging
and FTIR for
formaldehyde
concentration
▪ Vapors drawn
into FTIR using
temperature
controlled
tubing
FLIR Heater Zone Temp w/ Real-Time FTIR Formaldehyde
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0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
55.0
60.0
65.0
70.0
75.0
80.0
85.0
90.0
95.0
100.0
105.0
110.0
115.0
120.0
125.0
130.0
135.0
140.0
145.0
150.0
155.0
160.0
175
200
225
250
275
300
325
350
375
400
425
450
475
500
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 175 180 185 190 195 200
Form
ald
eh
yde
(pp
m)
Tem
pe
ratu
re (°
C)
Puff Number
FLIR Heater Zone Temperatures, with Recharged Battery After 100puffs, ND Filter Puffs 101-200, E-liquid 3, Puff Profile: 55 cc, 5 sec, 30 sec Interval
E-liquid 3 Mean Temp
E-liquid 3 Max Temp
Formaldehyde (ppm)
In this example,
Formaldehyde
begins to evolve
between 350-
400°C, using B1
battery.
Conclusions
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▪ FLIR® imaging overcomes drawbacks of thermocouple heater
core measurements of ENDS devices.
▪ FLIR ® imaging provides real time puff by puff temperature data,
which can be automated.
▪ Emissivity and other parameters can be determined using ASTM
methods and confirmed using thermocouple measurements.
▪ FLIR ® measurements of the heater zone mean and max
temperatures from the hottest frame during a puff provides
consistent comparison of different e-liquids and ENDS devices.
▪ FLIR ® imaging and FTIR gas analysis can be simultaneously
used to provide real-time formaldehyde measurements and
heater core temperatures.
Acknowledgments
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• Mike Ward
• David Cohen (NuMark Innovations)
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For copies of this presentation visit the Altria’s Science Website at
www.altria.com/alcs-science
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