CONSIGLIO NAZIONALE DELLE RICERCHE
Romeo Bernini IREA
Il progetto Safuel
(Safer Fuel Systems)
26 e 27 Maggio, 2014
Conferenza
Dipartimento
DIITET
Convegno
del del
Dipartimento
di Ingegneria,
26 ee 27
maggioper
2014
ICT
Tecnologie
l’Energia e i Traporti
Introduction
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Conferenza del Dipartimento
Roma, 26 e 27 maggio 2014
SAFUEL Project
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Rationale
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Objectives
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Conferenza del Dipartimento
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IREA Objectives

Realize a new metal-free fiber optic level sensor with comparable
performances with traditional Jet-Fuel Level sensors.
Main critical requirements






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No sensor degradation from -55°C to +70°C.
Correct operation and no degradation with Vibration 10-2000 Hz 14Grms.
The sensor shall operate correctly and not be damaged when partially or totally exposed to
presence of condensed water on its surface.
The sensor shall operate with an optical power not exceeding 35mW.
The sensor shall measure the height of fuel with following accuracy: ±1.5mm when tank
empty up to ±3mm when tank is full.
No calibration on A/C allowed.
Particular installation constraints on sensor shall be identified (e.g. volume, installation
angle, clearance to structure, bonding to structure…).
The jet fuel, depending on the type and/or the producer, exhibits different refractive index
value that ranges from about 1.432 of Sasol fuel to about 1.455 of conventional fuels,
depending on density.
© Copyright SAFUEL Consortium
Conferenza del Dipartimento
Roma, 26 e 27 maggio 2014
Sensing principle selection

Sensing mechanism that are insensitive to temperature and to the refractive
index (Bragg grating, interferometers, …) and more in general that don’t
require particular compensations in order to increase the fail safety of the
system.
Sensing principles
 Four sensing configuration have been evaluated
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Sensor based on radiation losses
Sensor based on radiation losses TIR
Sensor based on fuel absorption
Sensor based on floating mirror
 Three distributed interrogator have been tested
- Photon-counting Optical Time Domain Reflectometry (PC-OTDR)
- Optical Frequency Domain Reflectometry (OFDR)
- Optical Time Domain Reflectometry (OTDR)
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Conferenza del Dipartimento
Roma, 26 e 27 maggio 2014
TIR Sensors
Fiber optic
input
Fiber optic
output
Conventional TIR sensor are unable to distinguish fuel from water
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Conferenza del Dipartimento
Roma, 26 e 27 maggio 2014
Novel TIR Sensor design
With a suitable choice of the TIR angle the sensor is sensitive to the fuel and insensitive the
water.
Sensor Design parameters:
• Prism angle 60°
• Refractive index n=1.59
• Incident angle 60°
• Air TIR angle 50°
• Water TIR angle 54°
• Fuel TIR angle 65°
© Copyright SAFUEL Consortium
Conferenza del Dipartimento
Roma, 26 e 27 maggio 2014
Novel TIR Sensor design
Refractive Index fuel vs Temperature
1.5
TIR Condition
JP5
JP8, JetA, JetA-1
JP7
JPB-JP4
Refractive Index
1.48
1.46
1.44
1.42
1.4
1.38
-40
-20
0
20
40
T [°C]
60
80
100
The sensor is insensitive to the water but it works with any jet fuel
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Conferenza del Dipartimento
Roma, 26 e 27 maggio 2014
TIR Sensor prototype
Single Sensor
Sensor multiplexing
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Roma, 26 e 27 maggio 2014
TIR OTDR Measurements
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Conferenza del Dipartimento
Roma, 26 e 27 maggio 2014
Optical Power Response vs Liquid Level
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Conferenza del Dipartimento
Roma, 26 e 27 maggio 2014
Optical Power Response vs Liquid Level
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Conferenza del Dipartimento
Roma, 26 e 27 maggio 2014
Jet-Fuel vs Water Detection
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Conferenza del Dipartimento
Roma, 26 e 27 maggio 2014
Prototype under construction
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Conferenza del Dipartimento
Roma, 26 e 27 maggio 2014
Thank you
© Copyright SAFUEL Consortium
Conferenza del Dipartimento
Roma, 26 e 27 maggio 2014