Next-generation energy management

Transcription

1 Next-generation energy management DNV GL, Strategic Research & Innovation George Dimopoulos, PhD - Nikolaos Kakalis, PhD LONDON, 9 APRIL DNV GL 2013 London, 9 April 2014 SAFER, SMARTER, GREENER

2 Motivation Energy efficiency is an inherent and fundamental necessity for ships Through the ages: Speed Endurance Capacity Fuel Emissions 2

3 Current shipping landscape Why in shipping? Complex industry dynamics Complex systems Complex operations Efficiency / losses Cost-effectiveness Emissions footprint

4 Ship Energy Efficiency Energy conversion process Hotel loads Cargo handling Various forms of energy Propulsion Auxiliary machinery Manoeuvring Ship energy system Efficiency = Energy output / Energy input 4

5 Ship energy management Measures: Efficiency improvement Reduction of losses Design Challenges How to reveal the biggest sources of losses? How to prioritise efficiency improvement measures? Operation Procedures How to provide a common way of quantifying efficiency? Hull, hydrodynamics, ballast, propulsors, engines, machinery, networks, operating procedures, awareness, benchmarking, etc. 5

6 Efficiency & Physics 1 st Law of Thermodynamics Energy is always conserved Necessary but not sufficient 2 nd Law of Thermodynamics 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 6

7 Efficiency & the Laws of Thermodynamics T room T room Heat T hot T room Heat from a hot coffee mug dissipates to the environment: 1 st Law Shortcoming: Spontaneous heating of the mug from the environment is not forbidden by 1 st Law! 2 nd Law only excludes the spontaneous heating of the mug 2 nd Law sets the presentence and direction of processes 7

8 Exergy analysis Exergy: The maximum work that a process /component / system can deliver at any given conditions i.e. the max energy we can use Energy cannot be destroyed (energy losses?): Exergy can Every form of energy has an associated exergy definition Same units as energy Formal Consistent Common currency Efficiency definition 8

9 Exergy-based Next generation energy management 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 9

10 Application cases Newly built ships New technologies Ships in operation 10

11 Marine waste heat recovery system for large containerships 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? 11

12 Marine waste heat recovery system Exergy-based results Ranking of components: Top 5 Component Rank Contribution to total exergy losses [%] Combustion block Exhaust Turbocharger Charge air cooler Steam turbine Further optimisation of turbocharger engine matching: Fuel savings: +1% Payback period: - 50% 12

13 Marine fuel cell unit in hybrid propulsion vessels Exergy-based optimisation Design optimisation Space, operability, safety Exergy analysis Full mapping of system losses Losses reduction by 50% 13

14 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 14

15 Main engine of an aframax tanker Energy analysis Exhaust losses Energy efficiency: 51.5% Cooling losses: 26.6% of fuel input Largest contributor! Exhaust losses: 25.1% Two equally important sources of losses identified Cooling losses Prioritise: Cooling: e.g. VFDs, ORC Exhaust: e.g. adv. WHR 15

16 Main engine of an aframax tanker Exergy analysis Exhaust losses 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 Turbocharger losses Cooling losses Combustion losses Prioritise: Combustion tuning (WHR) Turbocharger 16

17 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 efficiencycritical areas Engine tuning and turbocharger more important focus areas for monitoring and improvement than traditionally thought WHR and cooling networks. 17

18 Conclusions Questions Answers How to provide a common way of quantifying efficiency? Using Exergy, a common currency for efficiency and losses How to reveal the biggest sources of losses? Through exergy-based analysis and mapping of losses How to prioritise efficiency improvement measures? By applying the exergy-based energy management methodology Formal, consistent and general-purpose methodology. Suitable for existing ships, new-buildings and new technologies 18

19 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 George Dimopoulos Nikolaos Kakalis SAFER, SMARTER, GREENER 19