Prediction of Fuel Consumptionof Ships in Actual Seas

National Maritime Research Institute

21, Dec., 2012

Masaru Tsujimoto and Naoto Sogihara

International Research Exchange Meeting on Ship and Ocean Engineering

Contents

1. Backgrounds

2. Calculation of FOC in actual seas

Engine characteristics

3. Validation by onboard measurements

4. Conclusions

2

Backgrounds

The Marine Environment Protection Committee (MEPC) of theInternational Maritime Organization (IMO) has adopted mandatorymeasures to reduce emissions of greenhouse gases.

Reduction of Greenhouse Gas Emissionsfrom International Shipping

IMO

3

Start from 1st, Jan., 2013

Energy Efficiency Design Index (EEDI)Ship Energy Efficient Management Plan (SEEMP)

EEDI is the design index in a calm sea condition.Ship owners/operators fear of performance optimizationin a calm sea condition.They need EEDIweather with fw as complementary index.

Considering the sailing condition....

4 BackgroundsImportance of EEDIweather

fw is non-dimensional coefficientfor decrease of ship speed inrepresentative sea conditions;BF6 of head winds/waves.

fw =Vw / Vref

0 1 2 3 49

10

11

12

13

14

15

16

significant wave height [m]

V [knot] BF3 BF4 BF5 BF6 BF7

fw =0.86

Vw

Vref

At present, methods combined with tank tests are necessary for the accurate evaluation of energy saving technology above water

Evaluation for the technology

to reduce added resistance in waves

Special bow shape

5 Backgrounds

Energy saving device

How to reduce fuel consumption by the operation?

PLAN

Self-evaluation and improvement

ACTION

DO

CHECK

Monitoring

ImplementationPlanning

ship management office

SEEMP is PDCA cycle

Prediction of ship speed/fuel consumption in actualoperational conditions is expected for SEEMP cycle.

weather routeing, optimum trim etc.

6 Backgrounds

Operating Point of M/E(A) No winds and no waves（calm sea）

torque limit

NE

BHP

NE

OLP limit

Another operation limits, Fuel Index limit, is used for fuel saving.

A

winds and waves become more larger

V

BHP

V

winds and waves become larger

in winds and waves

A(D) M/E rev. is decrease due to OLP limit

D

D

(C) M/E rev. is decrease due to torque limit

C

C

(B) M/E power is increased at the same rev. due to governor (FOC increase)

B

B

large V

Calculation of FOC in actual seas7

Calculation of FOC in actual seas

Fuel Index is non-dimensional value of fuel injection

FI : Fuel Index expressed as 100% at MCR

(%)100E

EMCR

MCR NN

MCRBHPFI

: SFCBHP: brake powerNE: M/E revolution

8

Calculation of FOC in actual seas

VcVw10

V [knot]

P [kW]

in a calm sea

in actual seas

Vw2

Different engine characteristics cause different shipspeed/fuel consumption, governor control as well.

P1

P2

9

Constant NE mode

Constant P mode

100110120130140150160170180190200

0 20,000 40,000 60,000 80,000

BHP (kW)

SFC (g/(kWh))

SFC

Container ship of 300m length

Calculation-FOC and ship speed-

Calculation of FOC in actual seas10

0

20

40

60

80

100

120

0 20 40 60 80 100 120NE (rpm)

Fuel Index (%) Fuel Index

(1) constant M/E rev. mode

power curves in actual seas

11 Calculation of FOC in actual seas

different operating points

(2) constant M/E rev. mode with limit of Fuel Index(3)constant M/E power mode

Working Limit of FI

12 Calculation of FOC in actual seas

decrease of ship speed FOC per day

Limit of Fuel Index causes decrease of M/E rev.

90W 120W 150W 180 150E 120E 90E

15N

0

30N

45N

60N

75N

90N

Container ship of length 300m

Route;  Oakland (U.S.A.) to Tokyo (Japan)

Embarkation; March, 2012

13 Validation by onboard measurements

Waves

significant wave height (m)

primary wave direction (deg.)

mean wave period (s)

1        2    3    4        5                6      7          8          9

Day

1                                      2                                       3                                         4    5                                          6                                         7         8                                          9

Day

1                                      2                                       3                                         4    5                                          6                                         7         8                                          9

Day

forecast (JMA)

forecast (JMA)

forecast (JMA)

0 means head waves

14 Validation by onboard measurements

Bering sea

true wind direction (deg.)

true wind speed (m/s)

Winds

1                                      2                                       3                                         4    5                                          6                                         7         8                                          9

Day

1                                      2                                       3                                         4  5                                          6                                         7     8                                          9

Day

forecast (JMA)

forecast (JMA)

0 means head winds

15 Validation by onboard measurements

Bering Sea (H=5.0m Uwind=25m/s)

16 Validation by onboard measurements

Setting of Fuel Index of the container ship

0

20

40

60

80

100

120

0 20 40 60 80 100 120

NE (%)

Fuel Index (%) Limit Line

NE = NE / NE at MCR

17 Validation by onboard measurements

Calculation: constant M/E rev. mode with Fuel IndexWeather: observed data

Comparison between prediction and measured

ship speedM/E rev.

FOC per day FOC per NM

1 2 3 4 5 6 7 8 9Day

VSW (knot) VESTA SIMS

5knot

1 2 3 4 5 6 7 8 9Day

NE (rpm) VESTA SIMS

10rpm

1 2 3 4 5 6 7 8 9Day

FPD (ton/day) VESTA SIMS

10ton/day

1 2 3 4 5 6 7 8 9

Day

FPM (ton/mile) VESTA SIMS

0.1ton/NM

These are generally good agreement.

18 Validation by onboard measurements

Limit of FI

A prediction model of fuel consumption in actual seas is developed for the purpose of evaluation of that in actual seas.

Conclusions19

Effectiveness of the model is validated through onboard measurements by a container ship under the sea conditions are relatively rough.

The model considers the operating characteristics of M/E; especially Fuel Index.

Thank you for your attentions.