Thermopile Test BenchDetailed Design Review

Team Thermopilers

Adrian Aspinall, David Eld, Tyler Merritt, Paul Sowinski, Michael Sotolongo

1

Overview

• Updated Specifications• Drawing Package• System Design

o Thermal Subsystemo Structural Subsystemo Vacuum Subsystemo Electrical Subsystemo Software & Data

 Acquisition Subsystem• Bill of Materials & Budget• Schedule• Questions

2

Experimental Test Stand

Updated Specs

• Measure Electrical Characteristics• Measure Heat Transfer and Efficiency• Adjust Axial Loading• Display and Record Data• Test in Vacuum

 See Specification Table for Specifics

3

Drawings

See Drawing Package Handouts

4

System Design

• Thermal Subsystem • Structural Subsystem

 • Vacuum Subsystem

 • Electrical Subsystem

 • Software & Data Acquisition Subsystem

5

Thermal Components

• Heat Flux Sensors  • Thin Film Thermocouples

 • Peltier Cooler

 • Thermostone Heater

 • Water Block

 • Radiator

  

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Heat Flux Sensors

Size:                          10 mm x 10 mmThichness:                 1 mmWire Length:              1 mSensitivity:                 3 mV/(W/cm^2) Max Temperature:      ~200 C

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Thin Film Thermocouples

Size:                        13 mm x 9 mmThickness:               0.13 mm                        Type KWire Length:            1 mMax Temperature:    260 C

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Peltier Cooler

Size:                        40 mm x 40 mmThickness:               3 mmResistance:             1.5 ohms @ 25CMax Temperature:    138 CQmax :                     71 WDelta Tmax:             66 degreesPower in max:         130 W @ 15.4V , 8A

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Thermostone Heater

Size:                        1 in x 1 inThickness:               0.040 inResistance:             33 ohmsWire Length:            1 mMax Temperature:    250 C

*Image from www.thermostone.com

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Structural Subsystem

• Internal Frame • Linear Actuator and Spring(s) • Load Isolation

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Internal Frame12

Linear Actuator• Our current design would use a DC linear

actuator (mechanically in series with a spring)

 • Controlling DC actuator would be very

similar to controlling the heater or cooler (won't have to learn/troubleshoot stepper motor controller)

 • Voltage to actuator would be regulated

using feedback from load cell (voltage would ramp down as load cell reading approaches desired load)

 

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www.surpluscenter.com

Springs for Actuator

• Spring would allow the load to be applied over a greater displacement, should result in fine resolution of load application.

 •  Two springs will be in parallel

with each other for a higher spring rate but is still able to deflect a good amount (more compact than one spring).

 • The Linear actuator would

have a 4" stroke to account for different sizes of thermopiles.

 

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Load Cell

 http://www.omega.com/ppt/pptsc.asp?ref=LC302&Nav=pref03  Excitation:                                                 5 - 15  Vdc Output:                                                       1 mV/V Accuracy:                                                     0.5%   Operating Temperature Range:                  -54 to 125 C Safe Overload:                                              150% 

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Load Isolation Model16

Load Isolation- FEA17

Stresses and Deflections Shown on Handout

FOS - 3.01

Vacuum Chamber Subsystem

• Chamber• Chamber Door• Seals• Vacuum Pump • Feed Throughs

oElectrical Feed Through (Sensors)oElectrical Feed Through (Power) oThermocouple Feed ThroughoFluid Feed Through

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Vacuum Chamber Preliminary Designs

Initial

Angle Iron Skeleton

I-Beam Skeleton

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Current Vacuum Chamber Model20

Vacuum Chamber- FEAStresses and Deflections Shown on Handout

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FOS - 4.79

Chamber Door

• 1 in thick clear Plexiglas • Overlaps door cutout by 1.5 in (so cumulative load on door

is distributed more evenly)

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Vacuum Chamber Seals

• Rectangular seal for door• Square seal for base• Two materials considered for

vacuum sealsoVitonoNitrile

• Custom seals available through RSR

  

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www.rubbersheetroll.com

Vacuum Pump (absolute pressures)

• The actual difference between convective losses associated with a medium vacuum pump and an ultra high vacuum pump should be very small. (Even a rough industrial pump capable of 29.8" Hg would remove about 99.6% of the air)

 • Laboratory grade pumps capable of 20-75 microns have

been considered as well as larger industrial vacuum pumps.  (see spreadsheet for various pump specs)

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Vacuum Pump (evacuation time)

• Evacuation times have been estimated for a 3.0 ft^3 chamber assuming a final pressure of about 75 micron.

 • The time in minutes is

plotted against a range of common pump flow rates.

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Suggested Vacuum Pump

JB DV-6E Eliminator

Pressure: 25 Micron

CFM: 6.0 (~3.45 min evacuation time)

 Cost: $275

• Good flow rate and very good vacuum pressure compared to similarly priced pumps.

 • Designed for continual use on AC systems, durable.

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www.jbind.com

Vacuum Feed Throughs

 

*Image from www.pavetechnologyco.com

*Image from www.ancorp.com

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Electrical Subsystem Schematic28

Relay Wiring for Thermopile Impedance Measurment29

Relay Wiring for Linear Actuator Polarity30

Electrical SubsystemSensors

• Axial Loadingo Omega Load Cell LC302-500                     1 mV/V

• Temperatureo Omega Thin Film Thermocouple CO 1K     41 uV/C

• Heat Fluxo Captec Thin Film Heat Flux                         3 mV/W/cm^2

 Other Measurements

• Thermopile Open Circuit Voltage• Load Impedance• Load Voltage• Load Current

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Software & Data Acquisition Subsystem

• LabView• .NET

o Managed Assemblieso C API

• Pros & Cons• Current Hardware Issues

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Data Acquisition Components• NI PXI 1031 4 Slot 3U PXI Chassis

o NI PXI 6251 PXI input card NI SCC 68 Voltage box

o NI PXI 6281 PXI input card NI SCXI 1000  4 Slot SCXI Chassis

NI SCXI 1125 8 channel isolation amplifier NI SCXI 1303  32 channel isothermal terminal block

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Bill of Materials / Budget

See BOM / Detailed Budget Handout 

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Schedule

Detailed Design Review 9/30/2010

Drawing package for fabrication finalized 10/6/10

Finish Fabrication Late October

Submit Testing Data 11/19/2010

Submit Manual Draft 11/30/2010

Final Snapshot 12/3/2010

Final Report and Manual 12/15/2010

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Questions

• Will we receive the power supply in time to incorporate into the design?

 • Is there a preference for set up time for a test (chamber evacuation

time, load application, etc)? • Should we order duplicates of any parts? (Custom seals, specialty

heat flux sensors, heaters, etc?) • Do you know if the power supply can change polarity?

• Is an accuracy of 2.5 lbs acceptable for the load application?  

 

www.home.agilent.com

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