Reheating and Sterilization Technology for Food,
Waste and Water:
Design and Development Considerations for
Package and Enclosure
Soojin Jun, Brian Heskitt and Sudhir Sastry
The Ohio State University
Ritesh Mahna and Joseph Marcy
Virginia Tech
Michele Perchonok
NASA/JSC
Introduction
• Long-duration space missions
– Food systems to provide the crew with a palatable,
nutritious, and safe food system and minimize volume,
mass, and waste
– A thermal process in need of food reheating to serving
temperature, or sterilization during in-transit and on
evolved planetary base
– Food package to pose a disposal problem after use
Introduction
• Ohmic heating
– Electrical energy to thermal energy with higher energy
efficiency (close to 100%)
• Reusable pouch
– Sterilized to yield food quality with long shelf life
– Enabled ohmic treatment in transit
– Used to contain and sterilize waste post-food
consumption
Objectives
• Develop and optimize a pulsed ohmic heating
system and reusable pouch
– Minimize ESM
– Eliminate gas generation
– Eliminate electrode corrosion
• Numerical Approach
– Optimize electrode configuration
• Most uniform, yet rapid heating thermal profiles
– Predict and prevent worst-scenario during food
heating
Pulsed ohmic heater
JP6
1
JP4
2
15
14
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-VOUT
-VOUT
+VOUT +VOUT
-VIN
-VIN
HL02R15S15Y
JP3
2
3
4
U1
IRAMX16UP60A
JP5
4
PHASE2
1
2
Isolation
3
PHASE1
JP2
1
AC-DC CONVERTER 15V
120V_60Hz
Output
10
11
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15
14
13
24
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+VIN
NU
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+VIN
NU
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+VOUT +VOUT
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HL02R15S15Y
10
11
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1
2
3
24
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+VIN
NU
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+VIN
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1
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3
+VIN
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-VOUT
-VOUT
+VOUT +VOUT
-VIN
-VIN
HL02R15S15Y
+VIN
NU
NU
1
2
3
Isolation
10
11
12
JP1
15
14
13
IGBT output waveform
24
23
22
Circuit diagram
1
2
3
4
4
5
7
8
10
AC-DC CONVERTER 120V
12
13
14
15
16
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18
19
20
21
22
23
3
5
J
Q
U4A
4027
1
K
Q
2
VBU
VSU
V+
LEU
LEV
LEW
HINU
HINV
HINW
LINU
LINV
LINW
ITRIP
VCC
VSS
U3A
3
2
U3A
4011
4
6
5
4
OPTO ISOLATOR-A
VBV
VSV
1
CLK
R
6
ISO1
S
7
R1
RESISTOR
F_INPUT
VBW
VSW
4011
IGBT
module
Input TTL signal
Compact design
Ideal for minimizing electrochemical
reaction
Frequency: 10 kHz
Pulse duty ratio: 0.2
Ohmic heater enclosure and frame
Reusable pouch
First realized version
Flexible
package
Foil electrodes
Newly designed version
Electrode materials
• Degassing and ohmic treatment of NaCl solution to
observe likely gas generation at the interface between
solution and electrodes
• Aluminum
– Generate lots of gas
– Serious self-corrosion
• Stainless steel
– Food grade 300 series
– Little gas generation with ideal wave conditions
Secure bond in electrode-package construction
• Hot press to seal stainless steel electrode
pouches
– However, electrodes unlikely to adhere to inner PE
layer of pouches
Sealant
Stainless steel foil
PE
Aluminum foil
PE
Nylon
Multi-layered laminate
Secure bond in electrode-package construction
• PE extruded on stainless steel foil
– Contact select vendors
• Use of food grade adhesive
– Long curing time
• Etching one side of foil to enhance the surface
energy
Electrical conductivities and locations of
temperature sensors
0.027
0.024
Chicken noodle soup
0.021
1/2 L
0.018
9.18 V/cm
15.8 V/cm
28.4 V/cm
Electrical conductivity (S/cm)
0.015
0.012
Y
3
2
1
0.009
0.030
Black beans
X
0.025
1
0.020
8.4 V/cm
14.2 V/cm
0.015
0.010
10
20
30
40
50
60
o
Temperature ( C)
70
80
90
2
3
4
5
2D Electrode configuration and field distribution
Pouch A
Electrode
V/m
Pouch B
Pouch C
Comparison of temperature profiles of chicken noodle
soup between simulation and measurement data
Temperature (oC)
Pouch A
Pouch C
X
Temperature (oC)
Pouch B
Temperature (oC)
Y
X
Y
X
 : Experimental data
Y
: Simulation data
2D temperature distribution and cold zones
Pouch A
Pouch B
Pouch C
oC
80
40
12
Predicted temperature distributions and cold zone in Pouch B with
different electrode widths
Dimensionless electrode
width
Temperature distribution
Potential cold zone
0.063
0.127
0.147
0.202
0.268
: Electrode
Optimization of electrode width with respect to cold
zone ratio, power consumption, average
temperature, and temperature variation
70
1.0
65
0.8
55
300
50
250
50
45
40
0.4
35
0.2
200
150
100
30
40
50
35
0.0
0.05
0.10
0.15
0.20
0.25
25
0.30
Dimensionless electrode width
Cold zone area ratio
Average temperature (oC)
Power (W)
Temperature variation (oC)
Power (W)
55
0.6
Average temperature (oC)
45
Cold zone area ratio
Temperature variation (oC)
60
ESM estimation based on potential final
product with optimized power consumption
Mass1
(kg)
Volume2
(m3)
Power
(kWe)
Cooling
(KWth)
3.98
0.012
0.15
0.15
Volume
(kg/m3)
Power
(kg/kWe)
Cooling
(kg/kWth)
Mars Transit Vehicle
9.16
237
Mars Descent / Ascent Lander
66.7
Surface Habitat Lander
9.16
System values
Equivalencies4
Mission
Type
ESM
(kg)
Allocated ESM3
(kg)
Percentage
(%)
40
45.6
3614
1.3
228
145
60.7
705
8.6
87
145
38.9
5771
0.7
Initiated sterilization experiment
• Pressured environment
– Counterbalance internal pressures developed due to
heating
– Installed air pressure regulator
• Employed cooling system
Intentially inceased Vrms to speed up heating rate
Air pressure: ~ 30 psi
No leak on package
Preliminary data
60
RMS voltage (V)
50
40
30
20
10
Natural cooling
0
5
RMS current (A)
4
3
2
1
Natural cooling
0
Food temperature (degC)
140
120
100
Natural cooling
80
Symmetry
60
40
20
0
0
500
1000
1500
Time (sec)
2000
2500
Deliverables
• Shelf life study of food package
– Gassing, corrosion, and leakage
• Minimize cold zones to ensure the sterility of
treated product
– System optimization with numerical approach
• Study wastes related to human activities
– Microbiological analysis, sterility testing