2008.11 dsme ship energy saving devices

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045

Printed by DSME 선형연구개발팀 장영훈 2008-11-04 17:03

Energy Saving DevicesEnergy Saving Devices

2008. 11. 06

The House of Wisdom & Innovation ®

Hydrodynamics R&D Team

Prepared by Y. B. Choi

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045


2The House of Wisdom & Innovation ®

ContentsContents

1. Motivations2. Principle of energy saving

• Losses related with resistance components• Losses related with propulsion

3. Energy saving devices• Appendages to reduce stern waves• Special propellers• Fins and other devices in front of the propeller• Stator and other devices behind the propeller

4. DSME’s Pre-Swirl Stator and the others5. Summary

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Motivation – Price of bunker oil

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Motivation - Global warming

CO2 Emission Index

Engine efficiencyShaft Generator

Heat Recovery System

Energy SavingTechnology

Opt. hull form design

Seakeeping perfoamance

MEPC 58/4/35

MEPC 58/4/27∼∼∼∼29

MEPC 58/J(Denmark)

MEPC 58/J(Denmark)

Deadweight

Total volume of cargo capacity

Gross tonnage

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



AnswersAnswers

What’s your choice for the lowest oil burning?

-Dimension of ship

-Main engine

-Low speed operation

-Special devices

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Principles of energy saving

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Principles of energy savingPrinciples of energy saving

1. Energy Saving• to reduce energy losses• to recovery energy losses

2. Energy loss components• Related with resistance• Related with propulsion

3. Means of energy saving• Hull form design• Propeller design• Special Devices

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Losses related resistance componentsLosses related resistance components

Wave breaking 5%5%5%5%

Wave pattern 5%5%5%5%

Form effect on friction 5%5%5%5%

2.50%2.50%2.50%2.50%

10%10%10%10%

15%15%15%15%

30%30%30%30%

10%10%10%10%

WaveWaveWaveWave

resistanceresistanceresistanceresistance

ViscousViscousViscousViscous

resistanceresistanceresistanceresistance

Viscous pressure

Roughness

Flat plate friction 60%60%60%60%

7.50%7.50%7.50%7.50%

10%10%10%10%

40%40%40%40%

Tanker/Bulker Ro-Ro /Containership

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Losses related with propulsionLosses related with propulsion

Containership Tanker/BCLNGC

Propulsion efficiency = 1 – Lx – Lr – Lp – Ld

Lx : axial momentum (20%)Lr : the rotation in the wake (7%)Lp : the profile drag (10%)Ld : the non-optimum loading (3%)

Proper design of propeller and recovery in the rotational loss

CT= T/(0.5ρρρρVa2(ππππD2/4)=8T/(πρVa

2D2)=8KT/(πJ2)

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Example of Energy Saving Devices

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Appendages to reduce stern waves

Reduce wave resistance : 2 ~ 5%

Ducktail with InterceptorWedge

-Afterbody flow modifications :� Flow velocity under the hull decreased./Pressure recovery increased./Transom exit velocity increased.-Wave system modifications :� Localized transom wave system altered./Near field wave heights reduced./Far field wave energy reduced.-Secondary stern flap/ducktail hydrodynamic effects :� Ship length increased./Benificial propulsion interactions./Ship trim modified./Ship sinkage is reduced.

Ducktail

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Air bubble on the bottom

- Reduce a friction resistanceTanker : 15%Bulker : 15%LNGC : 7 ~ 9%Containership : 5 ~ 7%

ACS (DK Group)

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Fins in front of a propeller

- Tanker, B/C : 2%-Tanker : 4% -Container : 2%

-Reduce swirl resistance of the full hull form → Reduce the viscous pressure resistance

L V Fin (IHI Low Viscous Resistance Fin)

Reduce swirl resistance of the full hull form

WA-Fin(Oshima)

-Recovering the bilge vortices rotational energy-Improve the propeller efficiency from the accelerated axial flow-Reduce the pressure pulse

Flow spoiler

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045




-Recovering the bilge vortices rotational energy-Improve the propeller efficiency from the accelerated axial flow

Combination of vane wheel and hydrodynamic fin system

- Tanker, B/C : 1~2%

Reduce swirl resistance of the full hull form → Reduce the viscous pressure resistance

Namura Fin

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Principal of fins in front of a propeller

� Pressure recovery by preventing down flow� Induction of bilge vortex to propeller disc

Cross flow and bilge vortex Flow visualization using a tuft grids

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045




PCTC

3 ~ 7%

-Contra fins pretwist flow to propeller and cancel rotational flow behind flow.-Semi-duct produces thrust with receiving the oblique downward flow due to bilge vortices.-Semi-duct prevent the seperation of flow in front of semiduct with gathering and accelerating flow.

Semi-Duct system with contra Fins (SDS-F)

SSPA : 0 ~ 2%, HSVA : up to 4%

-Duct prevent the seperation of flow in front of semiduct with gathering and accelerating flow.-Duct produces thrust with receiving the oblique downward flow due to bilge vortices.

Wake equalizing duct

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045




-Contra fins pretwist flow to propeller and cancel rotational flow behind flow.-Semi-duct prevent the seperation of flow in front of semiduct with gathering and accelerating flow.

Fin and Duct

PCTC

SSPA : 3%

-Reduce the rotational energy loss - increase hull efficiency

MHI Pre-swirl stator

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Special propellers

Claimed gain : +4~+6%Claimed gain : +6~+12% (in full scale)

- Propeller with blades curved towards the suction side integrating the fin or winlet into the propeller blade.

KAPPEL

-The pitch increases monotonously towards the tip so that the blade tip bears a substantial load.-This is possible thanks to the existance of the tip plate that actuates as a barrier avoiding the communication of water between both sides of the blade.-Tip plate is located on the pressure side of the blade with the aim to obtain a higher overpressure downstream.

CLT (SISTEMAR)(Contracted and Loaded Tip )

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Stators behind the propeller

SSPA : 5~10%HSVA : up to 3%SSPA : 0%Approx. 5% (S/T), 2% (M/T)

- Recovering of kinetic energy due to the rotational flow

MHI Contra-rotating propeller

-Eliminating hub vortex-Recovering the kinetic energy of rotation of rotation flow around the boss-Increase thrust 1% and reduce shaft torque over 3%

PBCF(Propeller Boss Cap Fin)

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Stators behind the propeller

SSPA : 0 ~ 5%HSVA : up to 9%

HSVA : up to 5%SSPA : 0 ~ 3%

Rudder stator fin (MHI)

-Recovering of kinetic energy due to the rotational flow

� IHI Additional Thrust Fin� SURF (NKK Swept-back up-thrusting rudder fin )� HHI Thrust fin� MHI Rudder stator fin

Thrust Fin

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Rudder bulb

Single screw chemical tanker:3~6%Twin screw RoRo : 1~2%

Lips claimed gain : 3 ~ 7%HSVA : up to 6%

HSVA:Twisted rudder(2%)+costa bulb(2%)SSPA:Rudder bulb(0~2%)

-Increased propulsive efficiency-Reduced pressure pulse-Increased manoeuvrability

Rudder bulb hubcap (Rolls-Royce)

- Reduction of the propeller inflow velocity- A more uniform and less contracted slipstream behind the propeller reduces losses in kinetic energy- The hub drag is reduced by avoiding flow separation

Efficiency rudder (Wartsila Lips)

- Reduce the hub vortex- Increased wake fraction- Reduced contraction of the

propeller slipstream- Homogeneous axial slipstream- Reduced pressure pulse induced

by propeller

Twisted rudder with costa bulb

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Rudder bulb

MIPB : 2 ~ 3%HSVA : divergent propeller cap (up to 2%)

- Decrease propeller slip stream contraction- Suppress the contraction of cone vortices from

the propeller boss- Deters flow to the propeller using the displacement

effect- Produce uniform wake distribution and contribute to

reducing vibration

Mitsui Integrated Propeller Boss (MIPB)

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Twisted leading edge of rudder

Twisted leading edge of rudder

�Eliminates rudder cavitation

�Improves propulsive efficiency 1~2%- Regains the rotational energy in the propeller

slipstream- Reduces the drag of the rudder

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



DSME’s own design ofEnergy Saving Divices

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



DSME energy saving devices (I)

Abt. 2~4% reduction in resistance

Abt. 3% gain in propulsion efficiency

Abt. 3~5% gain in propulsion efficiencyEffect

Configuration

Transom Stern Appendage (V-Wedge)

Rudder additional thrusting finPre-Swirl StatorDevice

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



-Abt. 2~3% reduction in required power

- Improve wake distribution

Abt. 1~2% reduction in resistanceEffect

Configuration

Separation Flow Control FinTwisted Full Spade RudderDevice

DSME energy saving devices (II)

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Pre-Swirl Stator(PSS)

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Hydrodynamic aspect Hydrodynamic aspect

Wale field w/o PSSWale field w/o PSSWale field w/o PSSWale field w/o PSS

Asymmetric wake field to propeller provides

proper inflow of propeller

Wake field with PSSWake field with PSSWake field with PSSWake field with PSS

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Arrangement of blades Arrangement of blades

Consideration of propulsion efficiency and cavitati on problem

DSME PSSDamaged propeller (Sept. 2008, LR Technical matters)

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Economic aspect of PSSEconomic aspect of PSS

Not investigatedNot investigatedNot investigatedNot investigated4.8%4.8%4.8%4.8%58m Beam VLCC58m Beam VLCC58m Beam VLCC58m Beam VLCC2005200520052005

1.1%1.1%1.1%1.1%3.5%3.5%3.5%3.5%8,400 TEU8,400 TEU8,400 TEU8,400 TEU2007200720072007

Not investigatedNot investigatedNot investigatedNot investigated3.3%3.3%3.3%3.3%6,300 TEU6,300 TEU6,300 TEU6,300 TEU2007200720072007

0.4%0.4%0.4%0.4%3.3%3.3%3.3%3.3%7,090 TEU7,090 TEU7,090 TEU7,090 TEU2008200820082008


4.7%4.7%4.7%4.7%4.5%4.5%4.5%4.5%14,000 TEU14,000 TEU14,000 TEU14,000 TEU2008200820082008

3.2%3.2%3.2%3.2%4.5%4.5%4.5%4.5%13,050 TEU13,050 TEU13,050 TEU13,050 TEU2008200820082008


Ballast DraughtBallast DraughtBallast DraughtBallast DraughtDesign DraughtDesign DraughtDesign DraughtDesign Draught

Gain in Propulsion PowerGain in Propulsion PowerGain in Propulsion PowerGain in Propulsion Power

Ship TypeShip TypeShip TypeShip TypeYearYearYearYear

The DSME pre-swirl stator could usually achieve 3~5% gains for the vessels whose hull form and propeller designs have already been well optimized.

M/T in HSVA

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045




Not investigatedNot investigatedNot investigatedNot investigated4.0%4.0%4.0%4.0%B58m VLCCB58m VLCCB58m VLCCB58m VLCC2008200820082008

Not investigatedNot investigatedNot investigatedNot investigated1.5%1.5%1.5%1.5%8,000unit PCTC8,000unit PCTC8,000unit PCTC8,000unit PCTC2008200820082008

Not investigatedNot investigatedNot investigatedNot investigated3.2%3.2%3.2%3.2%CLNGCCLNGCCLNGCCLNGC2008200820082008

2.3%2.3%2.3%2.3%3.1%3.1%3.1%3.1%CapesizeCapesizeCapesizeCapesize 180K B/C180K B/C180K B/C180K B/C2008200820082008

2.0%2.0%2.0%2.0%4.5%4.5%4.5%4.5%B60m VLCCB60m VLCCB60m VLCCB60m VLCC2008200820082008

Ballast DraughtBallast DraughtBallast DraughtBallast DraughtDesign DraughtDesign DraughtDesign DraughtDesign Draught

Gain in Propulsion PowerGain in Propulsion PowerGain in Propulsion PowerGain in Propulsion Power

Ship TypeShip TypeShip TypeShip TypeYearYearYearYear

The DSME pre-swirl stator could usually achieve 3~5% gains for the vessels whose hull form and propeller designs have already been well optimized.

M/T in SSPA

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045




* * * * The price of bunker oil is assumed as an average price from the The price of bunker oil is assumed as an average price from the The price of bunker oil is assumed as an average price from the The price of bunker oil is assumed as an average price from the end of 2007 and the first quarter of 2008.end of 2007 and the first quarter of 2008.end of 2007 and the first quarter of 2008.end of 2007 and the first quarter of 2008.

25.325.325.325.3 MilMilMilMil25.725.725.725.7 MilMilMilMil25.725.725.725.7 MilMilMilMil3.23.23.23.2 MilMilMilMil11.311.311.311.3 MilMilMilMil11.311.311.311.3 MilMilMilMil19.019.019.019.0 MilMilMilMil10.910.910.910.9 MilMilMilMil/25 years/25 years/25 years/25 years

1.01.01.01.01 1 1 1 MilMilMilMil1.01.01.01.03 3 3 3 MilMilMilMil1.01.01.01.03 3 3 3 MilMilMilMil0.10.10.10.13 3 3 3 MilMilMilMil0.0.0.0.44445555 MilMilMilMil0.0.0.0.44445555 MilMilMilMil0.0.0.0.76 76 76 76 MilMilMilMil0.40.40.40.44 4 4 4 MilMilMilMil/Year/Year/Year/Year

84,474 84,474 84,474 84,474 85,744 85,744 85,744 85,744 85,744 85,744 85,744 85,744 10,556 10,556 10,556 10,556 37,551 37,551 37,551 37,551 37,551 37,551 37,551 37,551 63,228 63,228 63,228 63,228 36,475 36,475 36,475 36,475 /Month/Month/Month/Month

2,777 2,777 2,777 2,777 2,819 2,819 2,819 2,819 2,819 2,819 2,819 2,819 347 347 347 347 1,235 1,235 1,235 1,235 1,235 1,235 1,235 1,235 2,079 2,079 2,079 2,079 1,199 1,199 1,199 1,199 /Day/Day/Day/Day

Cost savingCost savingCost savingCost saving[USD][USD][USD][USD]

55,092 55,092 55,092 55,092 55,920 55,920 55,920 55,920 55,920 55,920 55,920 55,920 6,884 6,884 6,884 6,884 24,490 24,490 24,490 24,490 24,490 24,490 24,490 24,490 41,236 41,236 41,236 41,236 23,788 23,788 23,788 23,788 /25 years/25 years/25 years/25 years

2,204 2,204 2,204 2,204 2,237 2,237 2,237 2,237 2,237 2,237 2,237 2,237 275 275 275 275 980 980 980 980 980 980 980 980 1,649 1,649 1,649 1,649 952 952 952 952 /Year/Year/Year/Year

184 184 184 184 186 186 186 186 186 186 186 186 23 23 23 23 82 82 82 82 82 82 82 82 137 137 137 137 79 79 79 79 /Month/Month/Month/Month

6.0 6.0 6.0 6.0 6.1 6.1 6.1 6.1 6.1 6.1 6.1 6.1 0.8 0.8 0.8 0.8 2.7 2.7 2.7 2.7 2.7 2.7 2.7 2.7 4.5 4.5 4.5 4.5 2.6 2.6 2.6 2.6 /Day/Day/Day/Day

FuelFuelFuelFuel----IFO380cStIFO380cStIFO380cStIFO380cStsavingsavingsavingsaving

[Metric ton][Metric ton][Metric ton][Metric ton]

180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180 DayDayDayDayNavigation daysNavigation daysNavigation daysNavigation days

3.8 3.8 3.8 3.8 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 1.0 1.0 1.0 1.0 3.3 3.3 3.3 3.3 3.3 3.3 3.3 3.3 3.5 3.5 3.5 3.5 4.8 4.8 4.8 4.8 %%%%Efficiency gainEfficiency gainEfficiency gainEfficiency gain

from M/Tfrom M/Tfrom M/Tfrom M/T

460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 460 USD/MtUSD/MtUSD/MtUSD/MtEstimated pEstimated pEstimated pEstimated pricericericerice ofofofof

IFO380cSt*IFO380cSt*IFO380cSt*IFO380cSt*

177.0 177.0 177.0 177.0 177.0 177.0 177.0 177.0 177.0 177.0 177.0 177.0 177.3 177.3 177.3 177.3 176.7 176.7 176.7 176.7 176.7 176.7 176.7 176.7 177.0 177.0 177.0 177.0 173.7 173.7 173.7 173.7 g/kWhg/kWhg/kWhg/kWhSFOCSFOCSFOCSFOC ofofofof

IFO380cSt at NCRIFO380cSt at NCRIFO380cSt at NCRIFO380cSt at NCR

75,852 75,852 75,852 75,852 65,016 65,016 65,016 65,016 65,016 65,016 65,016 65,016 35,955 35,955 35,955 35,955 38,896 38,896 38,896 38,896 38,896 38,896 38,896 38,896 61,641 61,641 61,641 61,641 26,415 26,415 26,415 26,415 kWkWkWkWNCR powerNCR powerNCR powerNCR power

90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 85 85 85 85 85 85 85 85 90 90 90 90 90 90 90 90 %%%%NCR portionNCR portionNCR portionNCR portion

84,280 84,280 84,280 84,280 72,240 72,240 72,240 72,240 72,240 72,240 72,240 72,240 39,950 39,950 39,950 39,950 45,760 45,760 45,760 45,760 45,760 45,760 45,760 45,760 68,490 68,490 68,490 68,490 29,350 29,350 29,350 29,350 kWkWkWkWMCR powerMCR powerMCR powerMCR power

16,00016,00016,00016,000TEUTEUTEUTEU

13,05013,05013,05013,050TEUTEUTEUTEU

14,00014,00014,00014,000TEUTEUTEUTEU

4,4004,4004,4004,400TEUTEUTEUTEU

7,0907,0907,0907,090TEUTEUTEUTEU

6,3006,3006,3006,300TEUTEUTEUTEU

8,4008,4008,4008,400TEUTEUTEUTEU

58m Beam58m Beam58m Beam58m BeamVLCCVLCCVLCCVLCC

UnitUnitUnitUnitVesselVesselVesselVessel

M/T in HSVA

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Installation of PSSInstallation of PSS

The blades of PSS is directly fitted on the stern frame by the full penetration welding.

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Structural analysis of PSSStructural analysis of PSS

1. Strength analysis

2. Fatigue analysis

3. Vibration analysis

Strength assessment

Fatigue assessment Vibration assessment

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Sea trial resultsSea trial results

The first vessel of DSME PSS , Kristen VLCC is on her voyage after recording of 4.5 % reduction of power than sister vessel in sea trial and waiting for the report from her real operation.

Speed-Power Curve (DSME VLCC)

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



Contract for PSSContract for PSS

PSS to be applied for

• VLCC, LNGC, B/C

• Larger containership

71Grand Total

52CNTship Sub Total

16CNTA.P.MOLLER

18CNTC.P.OFFEN

10CNTHAMBURG-SUD

8CNTCMA-CGM

19VLCC Sub Total

4VLCCKOTC

4VLCCDK MARITIME

2VLCCLYKIARDOPULO

5VLCCTMT

4

No

VLCC

Ship type

KRISTEN

Owner

APCPCWM_4828539:WP_0000045WP_0000045A

PC

PC

WM

_482

8539

:WP

_000

0045

WP

_000

0045



SummarySummary

• To save energy, the first one is optimizing of the dimension and the selection of M/E.

• The reasonable and strong background of the physical phenomenon of the flow around the hull makes the investments of the energy savings effective.

• We would like to listen to feedback from real operation to develop reliable devices.

2008.11 dsme ship energy saving devices

Documents