Thermal Investigation for Accurate Temperature Measurement

Team TCTJTruc Le

Cedric ToguemJonathan Newman

Overview•Mission Goal•Objectives•Science Background•Science Requirements•Technical Background •Technical Requirements•Staffing Plan•Scheduling

Mission GoalThe 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.

Objectives•Accurately measure the temperature of the atmosphere as a function of altitude.•Determine the effect of thermal radiation on temperature measurements

i. Shielding effectii. Distance from circuitry

•Determine the effects of conductivity on temperature measurements•Determine the effect of the boundary layer on temperature measurements

SCIENTIFIC BACKGROUND

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

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

Temperature Change Because of Heat TransferTemperature 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

Heat Transfer ModesHeat can be transferred in three

different ways:- Conduction- Convection- Radiation

http://blogs.saschina.org/morena01pd2016/files/2009/10/ccr.jpg

ConductionTransfer 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

Convection

Movement of molecules within fluidA 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

RadiationElectromagnetic 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

Science RequirementsThe 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.

Technical BackgroundThe goal of the payload design is to

determine the effects of the following on measured temperature:

o Radiation effect from the Suno Radiation effect from the payloado Conduction from the interior/exterioro Boundary layer effect

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

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

Technical BackgroundBoundary layer effectSensors are placed at different distance

from the exterior surface of the payloadDetermine how much effect the boundary

layer has on the measured temperature

http://www.google.com/imgres?imgurl=http://www.engineering.leeds

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/394sec10-15km →sample/98sec15-30km →sample/590sec

Technical RequirementPhysical 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:

i. Max weight of 500gii. Not exceed 3oz/in2 on any surface

Staffing PlanThe 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

Scheduling

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

Questions• 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