CONSTANT TEMPERATURE CONSTANT TEMPERATURE AIR BATHAIR BATH

Team Members:•Mark Campbell•Peter Giles•Andrew Smith•Tom Strapps•Nickolay Suther

Team Supervisor:Dr. Prabir Basu

Presentation OutlinePresentation Outline

•What are we doing?

•What are the options?

•How do thermoelectrics work?

•How are we going to solve the problem?

What is an Air Bath?What is an Air Bath?

•Controlled Environment

•Liquid Baths

•Research and Calibration

http://www.guildline.ca/Datasheet/Guildline503XDatasheet.pdf

Project RequirementsProject Requirements•Temperature Range

+5°C to +25°C

•Temperature Control +/- 0.2°C

•Noise <40 dB

•Minimize Vibration

Design Features ConsideredDesign Features Considered

Design SelectedDesign Selected

•Forced Convection

•Top Loading

•PID Control

•Thermistor Sensing

•Two Thermoelectrics

Air Bath ConstructionAir Bath Construction•Frame

Welded Steel

•InteriorFibreglass (25cm)3

•CaseFolded Sheet Metal

•InsulationStyrofoam™ SM (5cm Thick)

ThermoelectricsThermoelectrics•Pump heat•Small

40mm x 40mm x 4mm

•Efficiency COP Refrigerator ~ 4COP Thermoelectric < 1.5

•Reversible

http://www.electracool.com/

Peltier EffectPeltier Effect

Source:http://jchemed.chem.wisc.edu/Journal/Issues/1996/Oct/abs940.html

PeltierPeltier PerformancePerformance

Heat DissipationHeat Dissipation

•Passive Heat Loadq=kA(T2-T1)/L

q ~ 10W

•Joule HeatP=IVq ~ 70W

Heat Sink AssemblyHeat Sink Assembly

Measurement SystemsMeasurement Systems

•Temperature SensorsRTDThermistorThermocouple

•Overheat ProtectionEmbedded Thermocouple

http://www.veriteq.com/images/thermocouple-thermistor.jpg

Thermocouple ThermistorRTD

System ControlSystem Control•Requires sensing, analysis and power control

On/Off PID

•Lumped Parameter Model

System ModelSystem Model

5

Thermostat

Tout

Temperatures

Relay

Time

Qm

Qf

Qc

Clock

Tm

Tc

Ti

Thermostat1s

Main

Qout

Heat Flow

Ks

Kf

Ks

Kf

1/Cc

1/Ci

Gain1

1/Cm

25

Constant1

Clock1

Clock

1s

Basement

1s

Attic

Add9

Add8

Add7

Add4

Add3

Add2

Add1

Add

Qm

Qm

Tm

Tm

Tm

To

To

To

Tc

Tc

Tc

Tc

Tc

Qf

Qf

Ti

Ti

Ti

Ti

Qi

Thermostat

Thermostat

Qc

Qc

Clock

Time

Lumped Parameter ON/OFF Control Model

0 1 2 3 40

10

20

30T

em

p (

C)

TEMPERATURES

0 1 2 3 40

5

10

15

20

25

Time (hr)

Hea

t Flo

ws

(W)

HEAT FLOWS

CoolerInsulationSetpoint

To Cooler from Insulation

TEC Heat Removal

Simulink ResultsSimulink Results

25 minutes

On/Off Control 1°C Dead band

Mock-up TestingMock-up Testing

The Next Step…The Next Step…•Order necessary parts

•Start construction

•Continue Mock-up Testing

Special Thanks ToSpecial Thanks To

•Greenfield Research

•Greg Jollimore

•Dr. Prabir Basu