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POLymer-Actuated Radiator with Independent Surfaces D. Paganini, C. Cacco, F. Cipriani, F. Cocco, R. Dalla Vecchia and M. Zorzan University of Padova - Italy Bexus 18/19 Workshop

Noordwijk – December 4, 2013


OUTLINE • POLARIS EXPERIMENT • BACKGROUND & MOTIVATION • CONCEPTUAL DESCRIPTION • DATA UTILIZATION • DEVELOPMENT PLAN • TEAM & SUPPORT • OUTREACH PROGRAM

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OUTLINE  POLARIS EXPERIMENT • BACKGROUND & MOTIVATION • CONCEPTUAL DESCRIPTION • DATA UTILIZATION • DEVELOPMENT PLAN • TEAM & SUPPORT • OUTREACH PROGRAM

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OBJECTIVES Test a new concept of heat radiator Evaluation of performance in variable environmental conditions

Guarantee thermal steadiness of a dummy payload Mainteinance within a given operational range of temperatures

Compare the thermal numerical model and measured data Model validation to verify the behaviour of this radiator concept

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MAIN FEATURES Radiator with indipendent surfaces Possibility to change the equivalent thermal resistance to modify the heat exchanged with the environment

Electro-Active Polymers (EAP) actuators Cutting edge actuators used to separate and tighten the plates

Dummy payload Simulate the heat wasted by a real payload

Diagnostic and environmental sensors Data acquisition to evaluate boundary conditions and experiment performances

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WORKING PRINCIPLE The radiator is composed by three metallic plates linked together so that EAP actuators can put them in good thermal contact or separate them

SEPARATED PLATES

TIGHTENED PLATES

PLATES NOT IN CONTACT

PLATES IN CONTACT

RADIATIVE LINK BETWEEN THE PLATES

EAP ACTUATION

CONDUCTIVE LINK BETWEEN THE PLATES

HIGHER EQUIVALENT THERMAL RESISTANCE

LOWER EQUIVALENT THERMAL RESISTANCE

MINIMUM HEAT EXCHANGE

MAXIMUM HEAT EXCHANGE

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OUTLINE • POLARIS EXPERIMENT  BACKGROUND & MOTIVATION • CONCEPTUAL DESCRIPTION • DATA UTILIZATION • DEVELOPMENT PLAN • TEAM & SUPPORT • OUTREACH PROGRAM

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HEAT RADIATORS Most of space/planetary missions use passive radiators coupled with devices that allow the thermal control of the system: •

heaters

devices which involve the presence of fluids

devices which involve the presence of mechanical actuators

Our new radiator concept: • • •

STILL PERMITS AN ACTIVE THERMAL CONTROL OF THE SYSTEM

LOW POWER required NO fluids NO typical mechanical actuators

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ELECTRO-ACTIVE POLYMERS (EAPs) Class of polymers that shows a DEFORMATION in response to an ELECTRIC STIMULATION. Among EAPs, DIELECTRIC ELASTOMERS (DE) exhibit the most promising properties.

DE actuators are basically compliant deformable capacitors

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APPLICATIONS Flying Probes / Balloons Earth/planetary atmosphere probes and balloons subjected to random thermal loads coming from the environment

Ground Probes Placed in an extremely variable thermal load environment, with high temperature difference between daylight exposition and night

Active Variable Radiators In general, all applications requiring a variation of the thermal properties regardless environment temperature

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WHY BEXUS? • Earth balloon flight is one of the applications which the radiator is designed for (no attitude control and variable environment) • Realistic interaction with an extremely variable environment, difficult to reproduce in laboratory (random wind, solar radiation, etc.) • It allows a radiator environmental test in different conditions of temperature and pressure, similar to many planetary ones (e.g. Mars, Titan, etc.) Bexus 18/19 Workshop

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OUTLINE • POLARIS EXPERIMENT • BACKGROUND & MOTIVATION  CONCEPTUAL DESCRIPTION • DATA UTILIZATION • DEVELOPMENT PLAN • TEAM & SUPPORT • OUTREACH PROGRAM

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SYSTEM OVERVIEW

Mass Dimension

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5 kg 0.3 x 0.3 x 0.4 m

Power Utilization (peak)

15 W

Total energy consumption

75Wh

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THERMAL MODEL Our preliminary thermal simulation computes:

qpayload

• Tightened and separated plates configuration • Steady state and time-variant systems • Different meshes for finite elements code qsky (rad)

qearth (rad)

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qatm (conv)

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MISSION SIMULATION Ascending phase

System evaluation

Active thermal control Descending phase

qpayload = 10 W

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SENSORS SUBSYSTEM Plates temperature and position RTD to collect temperatures on different spots and position sensors to verify plates separation

Internal status Sensors to measure the effective EAPs actuators deformation and other significant functional data

External environment characterization Absolute pressure sensors and RTD to evaluate the atmosphere properties, radiometer to measure the incoming infrared and visible radiation Sensors data will be acquired by a Pc/104 acquisition board compatible with SBC. A 16 bit ADC is preferred Bexus 18/19 Workshop

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SENSORS SUBSYSTEM

Link budget •

Downlink  22 kbit/s to download sensors data

Uplink

 5 kbit/s to send commands in case of particular environment conditions (optional)

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LINK BUDGET Device

Channels

Sample rate [Hz]

Data Volume [bit]

Data Rate [bit/s]

Radiometer

2

10

16

320

Pt100

25

10

16

400

Vacuometer

2

10

16

320

Eddy current probe

4

10

16

640

Extensymeter

8

10

16

128

System status

4

10

16

640

TOTAL [ bit/s ]*

22000

TOTAL DATA VOLUME [ MByte ]

60

*Safety factor (overhead) ≈ 3

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HV POWER SUPPLY Arc and short-circuit protection • •

Epoxy resin for electric insulation Universal polyurethane foam in order to hold operative range temperature

Low risk for operators •

Fully encapsulated

Plates are not involved in electric circuit

High efficiency* • Performance about 80% • Conversion loss from 1% to 3%

Minimum size and weight •

High operative frequency

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* from example device datasheet

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PRELIMINARY ELECTRICAL DESIGN To induce a pronounced elongation of actuator is required

High Voltage DC Converter

Discharge Circuit

EAPs Actuators

an applied voltage in the kilovolt range.

R1: wiring and electrods resistance R2: DE material C: DE variable capacitance Vamp: Power source Vc: voltage applied to the DE

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OUTLINE • POLARIS EXPERIMENT • BACKGROUND & MOTIVATION • CONCEPTUAL DESCRIPTION  DATA UTILIZATION • DEVELOPMENT PLAN • TEAM & SUPPORT • OUTREACH PROGRAM

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DATA UTILIZATION Overall radiator efficiency check •

Real thermal power dissipation

Thermal numerical model verification •

Incoming radiation (Sky + Sun + Earth)

Radiative external flux

Convective external heat flux

EAP actuators performances verification •

Force applied

Effective deformation

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OUTLINE • POLARIS EXPERIMENT • BACKGROUND & MOTIVATION • CONCEPTUAL DESCRIPTION • DATA UTILIZATION  DEVELOPMENT PLAN • TEAM & SUPPORT • OUTREACH PROGRAM

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GANTT CHART

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COTS • Temperature sensors www.rs-online.com

• Vacuometers www.rs-online.com

• Pressure sensors www.allsensors.com

• Strain gauge www.rs-online.com

• PC/104 www.versalogic.com

• Eddy current probe www.rs-online.com

• Radiometer www.hukseflux.com • HV power supply www.emco-world.com

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FINANCIAL PLAN DIRECT COSTS Raw Materials

1,500 €

Machining

3,500 €

Semi-finished products (Power supply, PC104, ADC, DAC)

5,000 €

Sensors (thermistors, vacuometers, etc.)

5,000 €

Travels (for non-sponsored members)

7,000 €

Total

22,000 €

Funded by: • University of Padova - Department of Industrial Engineering (DII)* • Local SME (Small & Medium Enterprises) involved both in realization and assembling * University full support is also provided regarding personnel involved and facilities utilization

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OUTLINE • POLARIS EXPERIMENT • BACKGROUND & MOTIVATION • CONCEPTUAL DESCRIPTION • DATA UTILIZATION • DEVELOPMENT PLAN  TEAM & SUPPORT • OUTREACH PROGRAM

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TEAM MEMBERS • Davide Paganini (Aerospace Engineering) Team leader, EAP actuators design and testing

• Cristian Cacco (Electric Engineering) High voltage subsystem and electric system

• Federico Cipriani (Aerospace Engineering) Mechanical design and testing, Fund Rising

• Francesco Cocco (Aerospace Engineering) Thermal numerical model

• Riccardo Dalla Vecchia (Aerospace Engineering) Electronics (sensor system), System Engineering

• Matteo Zorzan (Aerospace Engineering) Structural design and testing, Outreach Bexus 18/19 Workshop

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SUPPORT & FACILITIES Supported by • Dr. Alessandro FRANCESCONI, DII/CISAS, Space System • Prof. Pierfrancesco BRUNELLO, DII/CISAS, Thermal Control System • Prof. Giovanni LUCCHETTA, DII, Material Processing Technology • Prof. Mauro ANDRIOLLO, DII, Static Conversion of Electricity • Lorenzo OLIVIERI, CISAS, Member of Bexus Mission SCRAT and ARCADER2 teams • Ing. Francesco BRANZ, CISAS, Member of Bexus Mission ARCADE and ARCADE-R2 teams • Francesco SANSONE, CISAS, Member of Bexus Mission ARCADE and ARCADE-R2 teams

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SUPPORT & FACILITIES

Access to •

University workshop for Manufacturing, Assembly, Integration and Testing

• CISAS "hypervelocity impact facility laboratory" for full system integration and vacuum testing

Further support •

External workshops for critical components

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OUTLINE • POLARIS EXPERIMENT • BACKGROUND & MOTIVATION • CONCEPTUAL DESCRIPTION • DATA UTILIZATION • DEVELOPMENT PLAN • TEAM & SUPPORT  OUTREACH PROGRAM

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OUTREACH PROGRAM WEBSITE Project website linked in: • University of Padova official website • Padova Aerospace Engineering official website www.ias.dii.unipd.it

We will also work with:

UNIVERSITY PRESENTATION

• Local newspapers

At defined milestones in:

• Social networks

• Aerospace Engineering Study Program • PhD School in Science, Technology and Measurements for Space

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'POLARIS Experiment' already exists in several social networks such as Facebook, Twitter, Google+ and LinkedIn Noordwijk – December 4, 2013


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Selection workshop POLARIS  

The experiment presentation exposed to the ESA, DRL, SNSB panel

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