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DNV GL © 2013 London, 9 April 2014 SAFER, SMARTER, GREENER DNV GL © 2013
LONDON, 9 APRIL 2014
George Dimopoulos, PhD - Nikolaos Kakalis, PhD
Next-generation energy management
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DNV GL, Strategic Research & Innovation
DNV GL © 2013 London, 9 April 2014
Motivation
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Energy efficiency is an inherent and fundamental necessity for ships
Through the ages:
Speed
Endurance
Fuel
Capacity
Emissions
DNV GL © 2013 London, 9 April 2014
Current shipping landscape
Why in shipping? Complex industry dynamics
Complex systems
Complex operations
Efficiency / losses
Cost-effectiveness
Emissions footprint
DNV GL © 2013 London, 9 April 2014
Ship Energy Efficiency
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Hotel loads
Propulsion
Auxiliary machinery
Manoeuvring
Cargo handling
Energy conversion process
Ship energy system
Various forms of energy
Efficiency = Energy output / Energy input
DNV GL © 2013 London, 9 April 2014
Ship energy management
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Design
Procedures Operation
Measures:
− Efficiency improvement
− Reduction of losses
Hull, hydrodynamics, ballast, propulsors,
engines, machinery, networks, operating
procedures, awareness, benchmarking, etc.
Challenges
How to reveal the biggest sources
of losses?
How to prioritise efficiency
improvement measures?
How to provide a common way of
quantifying efficiency?
DNV GL © 2013 London, 9 April 2014
Efficiency & Physics
Necessary but not sufficient
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1st Law of Thermodynamics
2nd Law of Thermodynamics
“Energy is always conserved”
“Heat always flows from hot
to cold bodies”
Entropy is never decreased without
an external work input
Entropy: a measure of system’s disorder
Characterise the quality of energy
DNV GL © 2013 London, 9 April 2014
Efficiency & the Laws of Thermodynamics
Heat from a hot coffee mug dissipates to the environment: 1st Law
Shortcoming: Spontaneous heating of the mug from the environment is not forbidden
by 1st Law !
2nd Law only excludes the spontaneous heating of the mug
2nd Law sets the presentence and direction of processes
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Thot
Troom
Troom
Troom
Heat
DNV GL © 2013 London, 9 April 2014
Exergy analysis
Energy cannot be destroyed (energy losses?): Exergy can
Every form of energy has an associated exergy definition
Same units as energy
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Exergy:
The maximum work that a process /component / system
can deliver at any given conditions
i.e. the max energy we can use
Formal Consistent “Common currency”
Efficiency definition
DNV GL © 2013 London, 9 April 2014
Exergy-based Next generation energy management
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1. Identify the ship system to be analysed
2. Create system flowsheet
3. Assess data availability and identify gaps
4. Reconcile data/cover gaps via DNV COSSMOS
5. Perform exergy and energy analyses
6. Component, process and system metrics
7. Map exergy losses & identify improvement areas
DNV GL © 2013 London, 9 April 2014
Application cases
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Newly built ships New
technologies
Ships in
operation
DNV GL © 2013 London, 9 April 2014
Marine waste heat recovery system for large containerships
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Highly complex system
more than 70 components
How to identify and rank the
components that contribute
the most to system’s exergy
losses?
How to further improve the
system design?
DNV GL © 2013 London, 9 April 2014
Marine waste heat recovery system Exergy-based results
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Component Rank
Contribution to total
exergy losses [%]
Combustion block 1 81.78
Exhaust 2 6.11
Turbocharger 3 3.68
Charge air cooler 4 2.20
Steam turbine 5 1.69
Ranking of components: Top 5
Further optimisation of turbocharger –
engine matching:
Fuel savings: +1%
Payback period: - 50%
DNV GL © 2013 London, 9 April 2014
Marine fuel cell unit in hybrid propulsion vessels Exergy-based optimisation
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Design optimisation
Space, operability, safety
Exergy analysis
Full mapping of system
losses
Losses reduction by
50%
DNV GL © 2013 London, 9 April 2014
Main engine of an aframax tanker
Real ship in operation / onboard measurements available
Engine sub-system: Combustion block, turbocharger, charge air cooler, cooling network,
economiser
Perform: Energy & Exergy analyses
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DNV GL © 2013 London, 9 April 2014
Main engine of an aframax tanker Energy analysis
Energy efficiency: 51.5%
Cooling losses: 26.6% of
fuel input
Largest contributor!
Exhaust losses: 25.1%
Two equally important
sources of losses identified
Prioritise:
– Cooling: e.g. VFDs, ORC
– Exhaust: e.g. adv. WHR
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Cooling losses
Exhaust losses
DNV GL © 2013 London, 9 April 2014
Main engine of an aframax tanker Exergy analysis
Exergy efficiency: 44.9%
Losses ranking:
1. Combustion: 33.9% (of
total fuel exergy input)
2. Exhaust: 10.4%
3. Turbocharger: 6.9%
4. Cooling: 4.1%
Significantly different
picture than energy analysis
Prioritise:
– Combustion tuning
– (WHR)
– Turbocharger
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Cooling losses
Turbocharger
losses Combustion
losses
Exhaust losses
DNV GL © 2013 London, 9 April 2014
Main engine of an aframax tanker
Exergy vs. Energy analysis
Different results and findings
Exergy analysis yielded much more sources of losses
Completely different prioritisation of efficiency-
critical areas
Engine tuning and turbocharger more important
focus areas for monitoring and improvement than
traditionally thought WHR and cooling networks.
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DNV GL © 2013 London, 9 April 2014
Conclusions
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Questions
How to provide a common way
of quantifying efficiency?
How to reveal the biggest
sources of losses?
How to prioritise efficiency
improvement measures?
Answers
Using Exergy, a common
currency for efficiency and losses
Through exergy-based analysis
and mapping of losses
By applying the exergy-based
energy management
methodology
Formal, consistent and general-purpose methodology.
Suitable for existing ships, new-buildings and new technologies
DNV GL © 2013 London, 9 April 2014
SAFER, SMARTER, GREENER
www.dnvgl.com
“The real purpose of scientific method is to make sure Nature hasn't misled you into thinking you know something you don't
actually know.” Robert M. Pirsig, Zen and the Art of Motorcycle Maintenance
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George Dimopoulos
Nikolaos Kakalis