Thermal Investigation for Accurate Temperature Measurement

1. Thermal Investigation for Accurate Temperature Measurement Team TCTJ Truc Le Cedric Toguem Jonathan Newman

2. Overview Mission Goal Objectives Science Background Science Requirements Technical Background Technical Requirements Staffing Plan Scheduling

3. Mission Goal The goal of team TCTJ is to accurately measure atmospheric temperature at altitudes up to 35 km with a payload traveling at 1000 ft/s. The goal is to investigate why previous LaACES payloads have failed to correctly make temperature measurements.

4. Objectives Accurately measure the temperature of the atmosphere as a function of altitude. Determine the effect of thermal radiation on temperature measurements Shielding effect Distance from circuitry Determine the effects of conductivity on temperature measurements Determine the effect of the boundary layer on temperature measurements

5. SCIENTIFIC BACKGROUND

6. Temperature change in the Atmosphere Troposphere (0 to 12km) : lowermost atmosphere where temperature decreases from 30 to -70°C Stratosphere (12 to 48km): second lowermost part of the atmosphere where temperature increases from -70 to 0°C http://apollo.lsc.vsc.edu/classes/met130/notes/chapter1/vert_temp_all.html

7. 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

8. Temperature Change Because of Heat Transfer • Temperature change in the atmosphere affects the payload temperature and the payload’s boundary layer • Heat transfer takes place between atmosphere and payload and therefore influences the measurements around the payload

9. Heat Transfer Modes • Heat can be transferred in three different ways: - Conduction - Convection - Radiation http://blogs.saschina.org/morena01pd2016/files/2009/10/ccr.jpg

10. Conduction • Transfer of thermal energy between molecules due to temperature gradient • The energy flows from a region of higher temperature to a region of lower temperature i.e. From payload to atmosphere in the troposphere and from atmosphere to payload in stratosphere

11. Convection • Movement of molecules within fluid • A shallow layer of air in contact with a hotter surface warms by conduction, acquires buoyancy and then rises • Affects the air around the surface and can make it different from the air in the atmosphere

12. Radiation • Electromagnetic radiation emitted from the surface of an object in the form of heat due to the object 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

13. Science Requirements • The measured temperature must not be affected by the heat transfer phenomena around the payload’s boundary layer • To reduce the effect of the payload on the measured atmospheric temperature the thermistors will be placed at a distance away from the payload. • To reduce the effect of radiation from the sun, different shielding will be used.

14. Technical Background The goal of the payload design is to determine the effects of the following on measured temperature: • Radiation effect from the Sun • Radiation effect from the payload • Conduction from the interior/exterior • Boundary layer effect

15. Technical Background 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

16. Technical Background 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

17. Technical Background Boundary layer effect • 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

18. Technical Requirement • The payload will have thermistors that can make measurements at temperature range: 30 to -80˚C • The data will be stored in the B2S24 integrated circuit programmed on an EEPROM on the LaACES BalloonSat. • The data acquisition rate will have three levels with three different rates: 0-10km →sample/394sec 10-15km →sample/98sec 15-30km →sample/590sec

19. Technical Requirement Physical requirements for the payload: • Operate at pressure ranges : 0 to 1020mb • Operate at temperature ranges: 30 to -80˚C • Withstand the force of release from sounding balloon • Withstand impact from landing at 20fps • Stay within FAA no wavier regulations of: • Max weight of 500g • Not exceed 3oz/in2 on any surface

20. Staffing Plan • The team members that will have the leads for the major tasks are assigned as such: • Project Management: Truc • Science Requirements: Cedric • Electronics: Truc • Flight Software: Cedric • Mechanical: Jon • Integration: Truc • System Testing: Jon • Calibrations: Jon • Data Processing and Analysis: Cedric • Documentation: Jon

21. Scheduling

22. 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

23. Accurately measure the temperature of the atmosphere as a function of altitude. Determine the effect of thermal radiation on temperature measurements Determine the effects of conductivity on temperature measurements Determine the effect of the boundary layer on temperature measurements Questions