20/05/2011
School of Engineering and Materials Science
School of Engineering and Materials Science
Content
Nanofuel as a future energy carrier
Dr. Dongsheng Wen
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Introduction: energy and energy carriers
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Metal as an energy carrier
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The Nano-approach: Nanofuels
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Progress so far
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Summary
Reader in Nanotechnology and Energy Engineering
School of Engineering and Materials Science
School of Engineering and Materials Science
The Energy Challenge
Energy carriers
Energy structure 2005
Terawatt challenge
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Efficient uses of fossil fuel
resources
Harness renewable energy
sources
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14 TW (2005)
30 TW (2050)
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Increasing use of renewable energy will
become an integral part of our future energy
supply.
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There is always a dislocation between the
energy supply and demand.
Solar
Biomass
Nuclear (fission/fusion)
Wind / wave …
Sustainable development
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i.e. the places rich in solar energy, wind, wave….
are seldom requires that large amount of energies.
Energy carriers are generally required to
transfer energy from one place to another
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20/05/2011
School of Engineering and Materials Science
School of Engineering and Materials Science
Current energy carriers
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Hydrogen and battery have been long proposed as
energy carriers of the future, but all have their
limitations
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H2: challenges exist in nearly every segments of the
hydrogen economy, from production, delivery, storage
to applications
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Battery technology: low energy density and low life
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Any other options – Metals?
Is metal possible?
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Exothermic reaction with high energy density
4Fe + 3O2 = 2Fe2O3 -824kJ/mol
4 B + 3 O2 = 2 B2O3 -586 kJ/mol
4 Al + 3 O2 = 2 Al2O3 – 835 kJ/mol
2Be + O2 = 2BeO -608.4 kJ/mol
2H2(g) + O2 =2H2O(g)-114.30 kJ/mol
C(s) + O2 =CO2(g)-394.41kJ/mol
1/26C8H18(l)+25/52O2 =9/26H2O(g)+4/13CO2(g)-200.64 kJ/mol
School of Engineering and Materials Science
School of Engineering and Materials Science
Have we ever used metal fuels ?
Is metal possible?
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Metals are abundant
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Metals are recyclable
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The end product of the exothermic reaction is metal
oxide
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Metals are easy to store and transport
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Metals are not so expensive

Energetic particles has been long used as additive to solid
rocket fuels or explosives. The performance increases with
decreasing particle size
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To increase impulse, density and combustion stability.
Particles include iron, aluminium, beryllium, boron, magnesium etc
were tested. The usage of aluminium particles is relatively mature
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Thermite reaction has been used for a variety of
metallurgical applications, combustion synthesis of new
materials and explosives
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Highly exothermic reactions and the products are often
heated above their melting points without requiring additional
energy.

It is a self-propagating high-temperature reactions
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School of Engineering and Materials Science
School of Engineering and Materials Science
Common features of these conventional fuels
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The fuel is a solid-solid mixture
No regeneration
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“There's Plenty of Room at the Bottom”
The oxidized particle went out without capture and
regeneration
Richard P. Feynman 1960
The size of particles is in the order of mm or
micrometer scale.
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The nanotechnological approach
California Institute of Technology
First published in Engineering and Science
magazine, vol. XXIII, no. 5, February 1960.
Incomplete combustion
The ignition and combustion of particles
requires high temperature
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Difficult to control the heat release
School of Engineering and Materials Science
School of Engineering and Materials Science
Nanotechnology approach
Classical engineering and science approach
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Macroscopic
Engineer
Microscopic
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Scientist
Molecular
Nanotechnology can
not be correctly
described by applying
either the microscopic
or molecular method
of analysis
This new, so-called,
in-between field gives
rise to some very
unusual physics
Macroscopic
Microscopic
Nanotechnology
Molecular
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Magic about nano
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The unusual behavior results because the properties
(physical, chemical, electric, optical….) are a strong
function of the size of the substance.
At microscopic or macroscopic sizes, one chunk of
iron (or any substance) has he exact same
properties of another chunk of iron.
At molecular level, an atom of iron has the eat same
properties of another atom of iron.
However at the nanoscale, the properties of any
substance becomes a strong function of particle size
It permits a new way to vary and control properties
of materials by engineering material size, rather than
its composition.
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School of Engineering and Materials Science
Magic about nano
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Increased surface-to-volume ratio
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Size-dependent properties
Chen
Journal
of Heat
Luo (1996)
et al. (2008)
J. Phys.
Chem C,heat
112 (7),
Latent
of2359
fusion
Transfer, 118, 539-545.
Melting
temperature
Aluminium
Specific
heat
Entropy
of fusion
Song P and Wen DS, J. Physical Chemistry, B,
2010, 114 (19), p 8688–8696
Wen DS 2010, Energy and Environmental Science, 3:
391-600
School of Engineering and Materials Science
NanoEnergy Engineering
Nanoenergy engineering
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Utilize the unique properties at nanoscale to enhance energy transportation,
conversion and storage at macroscale
Interfacing nanotechnology and energy engineering
Multi-disciplinary nature: physics, materials, chemistry and engineering
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Nanofuels
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Nanofuels refer to energetic nanoparticles or
nano-structured functional particles in a dry or
wet form (suspended in a liquid/fuel carrier) for
different energy applications.
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The controlled energy release is through
oxidation or combustion of the fuel by tuning
nanoparticle size to appropriate properties.
How can something so small affect something so big?
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At the root of the opportunities provided by nanoscience to enhance our energy
security is the fact that all of the elementary steps of energy conversion (e.g.,
charge transfer, molecular rearrangement, chemical reactions, etc.) take place
on the nanoscale.
At nanometer scale, one could
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Make chemical reaction, energy transportation more efficiently
Create new functional materials
Engineering tailored material properties
Enhance energy conversion efficiency, such as split water using solar energy
Creates an entirely new paradigm for developing new and revolutionary energy
technologies.
Aluminium
Luo et al. (2008) J. Phys. Chem C, 112 (7), 2359
School of Engineering and Materials Science
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Thermal
conductivity
Ignition
temperature
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Oxidisers can be Air, O2, H2O, N2 ….
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20/05/2011
School of Engineering and Materials Science
School of Engineering and Materials Science
Nanofuels as a future energy carrier
Production, primary or
renewable energy
resources are utilized
to manufacture
nanofuels from raw
materials or captured
oxides
Utilization: heat or
indirectly electricity /
work is released
through reaction in a
medium such as air,
nitrogen or water
Major advantages
Recyclable and loop operation
Environment
Raw materials
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Oxidized particle
capture
Nearly zero emission at the level of the engine
Nanofuel
production
Nanofuel
transport /storage
CO2/H2O
Ein (primary or
secondary)
MexOy
Established infrastructure
Nanofuel
Utilization
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Eout
(Heat)
School of Engineering and Materials Science
Technological challenges
The reduction from micro/millimeter size to
nanometer scale poses both promises and
challenges
Key challenges:
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Controlled formulation of nanofuels especially the
passivation layer thickness
Pilot test in a model engine and assess the emission,
wear and lubrication issues
Oxide particle capture and regeneration
Understanding the oxidation, ignition and combustion
characteristics of nanofuels
Life cycle analysis and social/enviromental
considerations
i.e metallurgical industry
Controlled energy release through particle size control, applicable to
different situations
School of Engineering and Materials Science
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zero CO2, zero SOx, zero dioxin or hydrocarbon pollutio), might have
some NOx if air is used as the oxidiser
Easy storage and transportation
N2
Me
Nanofuel
Production
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Nanofuel
application
Air
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solid oxide particles are captured and stored, meaning the only
engine emission would be nitrogen gas (N2) - ideally cold
Our initial studies
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Establish a pilot engine testing system including
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Pilot testing nanofuels in the established system
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A single cylinder engine with variable compression ratios
A controlled delivery system for dilute nanofuels
An exhaust particle capture and sampling system
Controlled formulation of nanofuels
Safely store and handle large scale metallic nanoparticles, and
burn inside the engine
Burned particle capture and characterisation.
Preliminary life-cycle analysis of nanofuels
Fundamental understanding on the oxidation and
ignition behaviour of metal nanoparticles.
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School of Engineering and Materials Science
School of Engineering and Materials Science
Effect of particle concentration on
in-cylinder pressure
Experimental conditions
Engine: 4-stroke, 125 cc, SI engine
Engine speed: from 800 to 2800 rpm
Compression ratio: 5.5 to 10
Ignition timing: from -20 btdc and + 10 atdc
Data measured: engine power, torque, incylinder pressure, exhaust temperature, fuelair ratios, gas and particle emissions, and
particle deposition check.
Average in-cylinder pressure profile (100 cycles)
School of Engineering and Materials Science
200
120
160
CR=8.5, IT=-10
NOx (ppm)
100
80
60
40
Base fuel
20
1w% Al
0
1000
1500
CR=8.5, IT=-20
2000
Gas concentration (ppm)
NOx (ppm)
Gaseous emission
140
Initial life cycle analysis
Base fuel
1w% Al
System boundary
Functional unit
120
Evaluation of
available options
for reducing the
impacts
Goal and scope
definition
80
40
120
NOx
100
80
School of Engineering and Materials Science
CR=8.5, IT=-10, 1w%
NO
NO2
2500
3000
0
1000
1500
Engine speed (rpm)
60
2000
2500
Engine speed (rpm)
3000
Relevant flows
in and out
Inventory
analysis
Interpretation
40
20
0
1000
1500
2000
2500
3000
Engine speed (rpm)
Dilute nanofuel can reduce emission, and is more pronounced for a
longer ignition delay. The main component of NOx is NO
Impact category
and weighing
Impact
assessment
LCA framework in ISO 14040 series
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School of Engineering and Materials Science
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School of Engineering and Materials Science
Life cycle energy analysis for nanometallic fuels by
Utaikar et al., 2007
Production energy of nanoparticles
System boundary
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Fe
Al
20
Life cycle energy balance
GJ/t
0
-20
Metal
production
Nanoparticle
production
Energy yield
Net energy
output
-40
-60
Wen DS (2010) Energy and Environmental Science, 3, 591-600
-80
-100
School of Engineering and Materials Science
School of Engineering and Materials Science
Fundamental understanding of
nanoparticle combustion
25
Tank-to-Wheel
Well-to-Tank
20
According to
Utgikar et al.
MJ/km
15
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Experimental investigation of the
oxidation and ignition of nanoparticle
powders
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Numerical simulation of nanoparticle
properties and interactions, from sizedependent properties to sintering and
reinforced structure.
According to our
data
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5
0
Gasoline ICE
H2 ICE
H2 FC
Nano-Al ICE
Nano-Al ICE
Well-to-Wheel energy use for cars with different powertrains
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School of Engineering and Materials Science
School of Engineering and Materials Science
General trend of size-dependent
oxidation /ignition temperature
Non-isothermal oxidation of Ni powders (d=50nm)
DSC
120
2 K/min
5 K/min
8 K/min
15 K/min
20 K/min
100
Heat flux (mW)
80
60
40
20
0
0
Oxidation of Ni nanoparticles
Wen DS (2010) Energy and Environmental Science, 3, 591-600
100
200
300
400
T(oC )
500
600
700
800
Oxidation of Sn nanoparticles
Song P and Wen DS (2009) Journal of Physical Chemistry. C, 113 (31):13470-13476
School of Engineering and Materials Science
School of Engineering and Materials Science
Activation energies
Kinetic model fitting of NP oxidation
EaallwithFried
2
Kissinger
Starink
ASTM
Boswell
Ozawa
Friedman
Ea is based on the Kinssinger value
changing with 
Ea is based on the Kinssinger value
changing with 
n=3
n=4
n=5
n=6
1-D diffusion
2-D diffusion
Jander
Guintling
15K/min
0.8
15K/min
n=3
n=4
n=5
n=6
1-D diffusion
2-D diffusion
Jander
Guintling
0.7
g( )/g( 0.5)
Ea, eV
1.8
3
0.9
1.7
1.6
0.6
0.5
0.4
0.3
1.5
2
10
g( )/g( 0.5)
1.9
10
1
1
10
0.2
1.4
0.1
1.3
0
0
0.1
0.2
0.3
0.4
0.5
0.6
Conversion rate
0.7
0.8
0.9
1
1) both integral and differential methods was used, and the results among different
methods are similar; 2) Ea is smaller than bulk value (2~3 eV for bulk nickel); 3) a
function of conversion method and 4) similar Ea value with other investigators
Song P and Wen DS (2009) Journal of Physical Chemistry. C, 113 (31):13470-13476
0
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
10
0.5
0.55
0.6
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1


(a) Conversion ratio < 0.5
(b) Conversion ratio > 0.5
Song P, Wen D S et al. (2008), Physical Chemistry Chemical Physics 10(33):5057-65
Wen D S et al. (2010) Journal of Chemical Technology and Biotechnology, 86 (3), 375-380
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20/05/2011
School of Engineering and Materials Science
School of Engineering and Materials Science
Hierarchy of material simulation
1600K
1500K
1200K
g(r)
years
1350K
Atoms
Molecular
conformations
Electrons
Bond formation
900K
750K
600K
Empirical methods:
- Allow large systems
- Rigid connectivity
Time
FEA
MESO
MD
QC
10-15
1050K
Design
Grids
Grains
450K
300K
0
2
4
6
8
10
12
14
16
18
20
r(angstrom)
QC methods:
- Allow reactions
- Expensive, only
small systems
Empirical
force fields
ab initio,
DFT,
HF
Ångstrom
Thermal-mechanical evolution of a Ni-coated Aluminium functional particle
under a heating and cooling cycle (Gray: Nickel and Green: Aluminium)
Kilometres
Distance
- Song P and Wen D S (2010) Journal of Physical Chemistry C 114 (19), p 8688–8696
School of Engineering and Materials Science
School of Engineering and Materials Science
Nanofuel work ongoing
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Continuous experimental run with nanofuels.
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Optical engine header design with high speed
filming of combustion of wet nanofuels
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Oxidised particle regeneration
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Extension of the work to external combustion
system and combustion in different media.
-0.6
-0.8
ball
outl
core
surf
Small cluster
-1
-1.2
log(D)
-1.4
-1.6
-1.8
-2
-2.2
-2.4
-2.6
6.5
7
7.5
8
8.5
1/T
9
9.5
10
10.5
-4
x 10
Sintering and coalescence of two metallic nanoparticles with
unequal size
-Song and Wen (2009-2010). Journal of Nanoscience and Nanotechnology 10, 8010-8017 , Journal of Nanoparticle
Research 12 (3), 823-829.
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School of Engineering and Materials Science
School of Engineering and Materials Science
My other projects
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Nanofluids
Introducing some nanoparticles into a base
fluid to modify its thermo-physical properties to
intensify heat transfer processes
Nanowave
Heating of nanoparticles (esp. Au) by an
external electromagnetic field for biomedical
applications
School of Engineering and Materials Science
Concluding remarks
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Suitable engineered, nanofuels can be a
promising energy carrier
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The reduction in particle size present both
challenges and opportunities, for both
academics and companies
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Cross-disciplinary collaboration is essential
School of Engineering and Materials Science
Acknowledgements
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Research assistants and PhD students
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Dr S. Vafaei, Dr R Yan, Dr K Chee, Mr. P Song, Mr. H. Clarke, Ms D Chen, Mr. F. Noor,
Mr. Balazs Ihracska, Queen Mary University of London
Collaborators:
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Thank you for listening
Profs C. Lawn, R. Crookes and T. Alexander, Queen Mary University of London
Prof. Z X Guo, University College London
Prof M. Micci, University of Pennsylvania
Dr A. C. T. van Duin, Caltech
Prof. A. Vorozhtsov, Tomsk State University
Dr. David Jarvis, European Space Agency
Funding agencies
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Shell Global Solutions
EPSRC/EP 065449/1, EP/F027281/1
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