Thermal Investigation for Accurate Temperature Measurement
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Transcript of Thermal Investigation for Accurate Temperature Measurement
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Thermal Investigation for Accurate Temperature Measurement
Team TCTJTruc Le
Cedric ToguemJonathan Newman
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Overview•Mission Goal•Objectives•Science Background•Tests •Overall Design•Payload Design
• Electrical• Software • Mechanical
•Payload Development•Projected Budget•Schedule and Status
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Mission GoalThe goal is to determine why previous LaACES payloads temperature measurements are different in comparison to NOAA temperature measurement.
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ObjectivesDetermine the effect of the thermal boundary layer on temperature measurementsDetermine the effects of material and coating of temperature sensors on temperature measurementHave the measurements of the control temperature sensor be similar to NOAA measurements
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Science Background • Troposphere (0 to 12km) : lowermost atmosphere where temperature decreases from 30 to -80°C• Stratosphere (12 to 48km): second lowermost part of the atmosphere where temperature increases from -80 to 0°C
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter1/vert_temp_all.html
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Science : Boundary LayerThin layer of fluid in contact with a solid
body that flows more slowly than the rest of the fluid
As the payload gains altitude in fluid air, the boundary layer around it will be affected by heat transfer processes
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter1/vert_temp_all.html
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Science: RadiationElectromagnetic radiation emitted from the
surface of an object in the form of heat due to the objects temperature
If an object is warmer than its surrounding environment, it will emit more radiation in the form of heat into the surrounding environment than it will absorb in order to attain thermal equilibrium
http://www.tsc.com/irgen/Image7.gif
Science: Previous Data
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Test 1: Radiation Test 1Radiation test:
Sun →Electromagnetic radiation → Space →Sensors
The test will consist of different color shielding to reflect the electromagnetic radiation from the sun
http://image.tutorvista.com/content/dispersion
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Test 2: Radiation Test 2Radiation Test:The payload circuitry will emit radiation
to the sensor.Distance from the radiation source will
determine the amount of heat dissipated
http://images.google.com/imgres?imgurl=http://www.uos.harvard.edu/images/ehs/radiation
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Test 3: Boundary Layer Test
Sensors are placed at different distance from the exterior surface of the payload
Determine how much effect the boundary layer has on the measured temperature
http://www.google.com/imgres?imgurl=http://www.engineering.leeds
Overall Design
Control Subsystem 1BalloonSat
Main PowerSubsystem
Power Source(9V DC)
ControlSubsystem 2
(BASIC Stamp2p 24-PinModule)
Data ArchiveSubsystem
Memory(EEPROM)
Analog to digitalconverters(ADC0834)
ElectricalSubsystem 2
Op Amps(AD820)
Sensors(44003RC
Precision EpoxyNTC Thermistor)
ElectricalSubsystem 1
Current Sources(LM134)
AnalogAnalog
Digital
9V DC
Real Time Clock
1 μA
Dig
ital
RS
-232
Ground ControlSubsystem(PersonalComputer)
Backup PowerSubsystem
(2) AA batteries
MechanicalSubsystem
Foam Enclosure
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Electrical: Sensors 1µA constant current from LM134Output voltage will then vary from
1mV to 190.8mV (Value based on device’s datasheet – Resistance V. Temperature Table)
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Electrical: Sensors7 temperature sensorsModel: 44003RC Precision Epoxy NTC Thermistor -80 °C to 50 ° C 1kΩat 25 ° C
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Sensor InterfacingSensors’ output voltage will vary
from 1mV to 190.8 mV
Payload ADC, from 0 to 3V
Will use AD820 op-amp to amplify each sensors’ output
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Sensor Interface
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Sensor Interface
Vref = 1.5V, R6 = 1kΩR4 = 0.94MΩR5 = 14.806kΩ
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Power Supply6 x 1.5V Energizer L92 Ultimate
Lithium (AAA)9V to BalloonSat 9V to Op-Amps9V Current sources positive
voltage terminal1.5V Battery to Op-Amps Vref
Supplemental ADC ChipTeam will use 7 sensors4 Channel on BallonSat ADCTeam will add another ADC0834
chipNew chips’ pin connection will
follow the original’s.Ohmmeter will test pin
connections
Supplemental ADC Chip (cont.)
ADC pin Connection
2 P03 CH44 CH55 CH66 CH77 GND8 GND
10&13 P13
12 P1414 Vcc
Added ADC Pin Connection
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Power budget
Component Current (mA) Duration CapacityBalloonSat 51 (measured) 4 204mA-hThermistors (x7)
≤ 0.7 (desired) 4 2.8mA-h
AD820 op-amp (x7)
≤ 25 E-9 4 0.001mA-h
LM134 ≤0.7 (desired) 4 2.8mA-hMax Total 53.4 4 213.6mA-h
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Software: Data Format Table
Description ByteExtra variables 2Time-Hour 1Time-Minute 1Time-Seconds 1Sensor-Inside wall 1Sensor-Outside wall 1Sensor-Control sensor 1Sensor-Inside B.L. 1Sensor-Outside B.L. 1Sensor-Black coating 1Sensor-White coating 1Total per Loop 12Total Estimated Bytes 2880 bytes
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Software: Flowchart
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Software: Flight Flowchart
Software: Ground System
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Exterior Mechanical Design
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Interior Mechanical Design
Mechanical/electronics interface
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Weight BudgetComponent Weight (g)Batteries ~91BalloonSat 60.4Op amp Board ~30.2Foamular structure 64.1BalloonSat/Op-amp board attachments ~9
Wiring ~10Booms (Plexiglas Straws) ~20Boom attachments ~25Sensors ~1.5Total ~311.2
Thermal TestActivity Time (min)
1. Acquire dry ice and place it in a cooler 2
2. Initialize software 1
3. Place payload in refrigerator 5
4. Place payload in freezer 15
5. Place payload in dry ice cooler 30
6. Place payload in freezer 60
7. Place payload in dry ice cooler 15
8. Return payload to room temperature .5
9. Run program to ensure payload worked 5
Vacuum TestActivity Time (min)
1. Initialize software 2
2. Place payload in vacuum chamber .25
3. Begin evacuating chamber (10 mb/min) 1
4. Allow chamber to reach 5mb ~100
5. Begin re-pressurizing chamber (35mb/min) ~30
6. Run program to ensure payload worked 5
Impact TestActivity Time
(min)
1. Initialize software 2
2. Go outside with a tape measure and the payload 2
3. Put payload at a height of 3 meters and drop .5
4. Analyze damage to determine if current structure is sufficient 20
BudgetItem Part Retailer Qty. Unit
PriceTotal Price
Sensors x7 44003RC Precision Epoxy NTC Thermistor
http://www.newark.com/measurement-specialties
10 $15.17 $152.00
Batteries Energizer L92 Ultimate Lithium (4 pack)
www.Zbattery.com or local Wal-Mart or Radio Shack
4 10.00 $40.00
Constant Current x7
LM234 In house 7 ---------- ---------
ADC ADC0834 In house 1 ---------- ---------
Op-amp AD820 In house 10 ---------- --------
Resistors Varying values In house ???? ---------- --------
Booms Plexiglas straws http://www.amazon.com 1 pack
$20.00 $20.00
Op-amp Board Stripboard http://www.futurlec.com/ProtoBoards.shtml
1 $2.00 $2.00
Payload Structure
Foamular In House ------ ---------- --------
Total $214.00
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Reference1. Clavius: Environment - heat transfer.
http://www.xmission.com/~jwindley/heatxfer.html. November 24, 2009
2. Anne E. Egger "Earth's Atmosphere: Composition and Structure," Visionlearning Vol. EAS 2003. http://www.visionlearning.com/library/module_viewer.php?mid=107
3. Sad Dr Rodrigue – Introduction to physical Geaography. http://www.csulb.edu/~rodrigue/geog140/lectures/thermalstructure.html
4. BASIC Stamp 2p 24-Pin Module. http://www.parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/ProductID/7/List/1/Default.aspx?SortField=UnitCost,ProductName. November 25, 2009
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Questions?