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Thermal Investigation for Accurate Temperature Measurement. Team TCTJ Truc Le Cedric Toguem Jonathan Newman. Overview. Mission Goal Objectives Science Background Tests Overall Design Payload Design Electrical Software Mechanical Payload Development Projected Budget
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Thermal Investigation for Accurate Temperature Measurement Team TCTJ Truc Le Cedric Toguem Jonathan Newman
Overview Mission Goal Objectives Science Background Tests Overall Design Payload Design Electrical Software Mechanical Payload Development Projected Budget Schedule and Status
Mission Goal • The goal is to determine why previous LaACES payloads temperature measurements are different in comparison to NOAA temperature measurement.
Objectives • Determine the effect of the thermal boundary layer on temperature measurements • Determine the effects of material and coating of temperature sensors on temperature measurement • Have the measurements of the control temperature sensor be similar to NOAA measurements
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
Science : Boundary Layer Thin 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
Science: Radiation Electromagnetic 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
Test 1: Radiation Test 1 Radiation 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
Test 2: Radiation Test 2 Radiation 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
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
Electrical: Sensors 1µA constant current from LM134 Output voltage will then vary from 1mV to 190.8mV (Value based on device’s datasheet – Resistance V. Temperature Table)
Electrical: Sensors 7 temperature sensors Model: 44003RC Precision Epoxy NTC Thermistor -80 °C to 50 ° C 1kΩat 25 ° C
Sensor Interfacing Sensors’ 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
Sensor Interface Vref = 1.5V, R6 = 1kΩ R4 = 0.94MΩ R5 = 14.806kΩ
Power Supply 6 x 1.5V Energizer L92 Ultimate Lithium (AAA) 9V to BalloonSat 9V to Op-Amps 9V Current sources positive voltage terminal 1.5V Battery to Op-Amps Vref
Supplemental ADC Chip • Team will use 7 sensors • 4 Channel on BallonSat ADC • Team will add another ADC0834 chip • New chips’ pin connection will follow the original’s. • Ohmmeter will test pin connections
Supplemental ADC Chip (cont.) Added ADC Pin Connection
Reference • Clavius: Environment - heat transfer. http://www.xmission.com/~jwindley/heatxfer.html. November 24, 2009 • Anne E. Egger "Earth's Atmosphere: Composition and Structure," Visionlearning Vol. EAS 2003. http://www.visionlearning.com/library/module_viewer.php?mid=107 • Sad Dr Rodrigue – Introduction to physical Geaography. http://www.csulb.edu/~rodrigue/geog140/lectures/thermalstructure.html • 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