Global Warming and Impact on ITTC Activities -Energy Saving by Ship Hydro-Aero Dynamics- National Maritime Research Institute Director of Project Teams of Ship Performance Index Noriyuki Sasaki
Contents 1. CO 2 Emission Index - Japanese Proposal - 2. Trend of performance of ships 3. Energy saving devices 4. Simple evaluation method of actual sea performance at initial design phase 5. Conclusions
CO2 Emission from Ships at Operation CO2 emission from all ships in the world corresponds to emission from Germany CO2 emission from ships tends to increase with growing market of world shipping trade 排出量 ( 百万トン ) 0 2,000 4,000 6,000 8,000 アメリカ中国ロシア日本インドドイツ船舶イギリスカナダ韓国イタリアメキシコフランスオーストラリア 出典 )EDMC/ エネルギー 経済統計要覧 2007 年版 MEPC57 agreed that the intersessional working group meeting on GHG in Oslo, Norway, should discuss the development of a CO2 design index for new ships.
CO 2 Emission Index- Japanese Proposal to IMO ANNEX 5 Draft Guidelines on the Method of calculation of the new ship design CO 2 index The attained new ship design CO 2 index is a measure of ships CO 2 efficiency and is: CO2 from main engine CO2 from auxiliary engine New ship design CO 2 index = M f NME C SFC P + Capacity V ref W NAE j FMEi MEi MEi k j= 1 i= 1 k = 1 i= 1 L f f C FAEi SFC AEi P AEi dead weight total volume of cargo tanks gross tonnage design ship speed speed loss actual speed performance
CO 2 Emission Index- Japanese Proposal to IMO 9 f W is a non-dimensional coefficient indicating the decrease of speed in representative sea conditions of wave height, wave frequency and wind speed (e.g., Beaufort Scale 6), and should be determined as follows:. 1 It can be determined by conducting the ship-specific simulation of its performance at representative sea conditions. The simulation methodology shall be prescribed in the Guidelines developed by the Organization and the method and outcome for an individual ship shall be verified by the Administration or an organization recognized by the Administration. 2 In case that the simulation is not conducted, f W value should be taken from the standard f W table/curve. A Standard f W table/curve, which is to be contained in the Guidelines, is given by ship type (the same ship as the baseline below), and expressed in a function of the parameter of Capacity (e.g., DWT). The Standard f W table/curve is to be determined by conservative approach, i.e., based on the data of actual speed reduction of as many existing ships as possible under the representative sea conditions
Similar System to Car FOCR Index Measure Fuel Oil Consumption Rate under metropolitan driving modes
Trend of CO2 Emission from Ships 170 vessels built by Japanese Shipyards Categorized by ship 8 types (Tanker,Container,PCC,BC,etc) Fuel oil consumption per traffic volume (FOC/(Capacity*Vs)) are investigated
300,000 Relation between Loa(m) and DW(ton) 250,000 DW 200,000 150,000 100,000 50,000 0 tanker container 0 100 200 300 Loa bulk car cargo container oil ore ro-ro その他
Relation between DW(ton) and P MCR (kw) 70,000 60,000 MCR(kw) 50,000 40,000 30,000 20,000 10,000 0 bulk car cargo container oil ore ro-ro その他 0 50,000 100,000 150,000 200,000 250,000 300,000 DW
Relation between DW(ton) and P MCR (kw) 70,000 (Container) 60,000 50,000 40,000 P MCR (kw) 30,000 20,000 10,000 0 DW(ton) 0 20,000 40,000 60,000 80,000 100,000 120,000
400 350 Trend of Ship Length (Lpp) 1975-2005 ULCC VLCC 300 250 200 Tanker AFRAMAX PANAMAX 150 100 350 1973 1978 1983 1988 1993 1998 2003 2008 300 250 200 150 Container 100 50 0 1973 1978 1983 1988 1993 1998 2003 2008
17 Trend of Ship Speed (kts) 1975-2005 16.5 16 15.5 15 14.5 Tanker 14 13.5 30 1970 1975 1980 1985 1990 1995 2000 2005 2010 25 20 Container 15 1973 1978 1983 1988 1993 1998 2003 2008
Trend of Design Froude Number 1975-2005 0.2 0.175 Tanker 0.15 0.125 0.350 ULCC 0.1 1970 1975 1980 1985 1990 1995 2000 2005 2010 0.300 0.250 Container 0.200 0.150 1973 1978 1983 1988 1993 1998 2003 2008
Trend of FOC Index of Large Tankers built by Japanese Ship Yards kg / day ton*( m / sec) 0.2 17 16.5 16 0.15 15.5 15 14.5 14 Tanker 13.5 1970 1975 1980 1985 1990 1995 2000 2005 2010 0.1 Correction of Vs + ship length 0.05 turbine Correction of Vs 0 1973 1978 1983 1988 1993 1998 2003 2008
Trend of FOC Index of Large Containers built by Japanese Ship Yards kg / day ton*( m / sec) 30 0.450 25 0.400 20 0.350 Container 15 0.300 1973 1978 1983 1988 1993 1998 2003 2008 0.250 0.200 0.150 0.100 1973 1978 1983 1988 1993 1998 2003 2008
Conclusions 1 Both container ships and tankers, FOC index trend is almost the same except 1995 after The different tendency may be brought by the fact that there are no effective energy saving devices for high speed containerships. It is also obvious that design ship speed of container ship is not so reliable compared with tanker s case.
Energy Loss at Ship Navigation Energy Loss of a conventional ship total loss rudder resistance rotational loss viscous loss momentum loss viscous resistance propulsion loss So complicated! Thrust deduction Recovered by Propeller wind resistance wave resistance
Horizontal Fin in front of a propeller DPF (Sumitomo) 1992 LV-Fin (IHI) 1995 1. Pressure recovery by preventing down flow 2. Induction of bilge vortex to propeller disc
Accelerating duct in front of a propeller SSD (Universal) SILD (Sumitomo ) 1. Pressure recovery by preventing down flow 2. Thrust due to duct 3. Induction of bilge vortex to propeller disc
Scale Effect of energy saving duct 0.03 0.02 SHIP Large Model Lpp=250m 7% (average of 12ships with & 10 ships w/o) Δ(1-t) 0.01 Lpp=8m 4-5% Small Model 0.00 Lpp=2m 1-2% -0.01 0.02 0.04 0.06 Δw Scale effect on SILD Performance Improvement of (1-t) may be originated from reduction of section drag of duct due to Rn effect.
Reduction of Hull/Rudder resistance & Duct Thrust Magnitude of Energy Saving for each device 3 % 4 % 2 % 5 % 6 % Energy saving device in future 7 % 8 % Recovery of Propeller Energy Loss
Conclusions 2 Owing to effective energy saving devices invented by shipyards, FO index of tankers/bulk carriers were much improved in these 20 years. Energy saving device in future will have multifunction such as a duct installed in front of a propeller CFD will be a good tool to investigate mechanism however, it will be another several years to utilize as a design tool. It is very regrettable that there are no effective energy saving devices for containerships which are the most important ships from a global warming view point.
Example of Ship Performance at Actual Sea Speed loss is not the same even if the ships was designed under the same specification 0 0 Calm Sea 2 4 Wave height(m) 2 Due to ship design 4 Speed Loss(Knot ) Shipyard A Shipyard B Shipyard C Shipyard D
ハイブリッド計算手法 Detail of Computation Flow Resistance/Propulsion Test in still water Ship motion in regular wave Resistance in still water Resistance in regular wave spectrum air resistance Resist. in short crest irregular wave Total resistance Effective horse power thrust deduction Tank test Required thrust Calculation Propeller loading Design Index 速力変更 Propeller efficiency relative rotative efficiency Propeller Efficiency Hull efficiency Propulsive Effciency Iterated Process Delivered Power Shaft Power Ship Speed =const M/E performance Fuel Oil Consumption SHP = constant SHP(wave)=SHP Speed Loss) BF Yes Speed Loss
Simplified Method 平水中模型試験 Resistance Test hull Form Empirical Formula Resistance 正面規則波抵抗試験 Test in Regular Wave 波浪中抵抗増加計算 Cal. of Resistance in Waves Linearization 1 1 2 Raw = C * ρgζa BBfcp(1 + C 2 0.8 1 2FnB ) Correction 理論計算の補正 based on Model Test Effect 船体斜行 あて舵計算 of Wind Resistance POWC K T 波浪中自航計算 Propulsive Efficiency Linearization 2 K Q Fuel 主機燃料消費 Oil Consumption Required 波浪中馬力計算 Power in Waves J Design Index of Ship Performance Speed 波浪中船速低下計算 Loss due to Waves Simplified Method can be used at initial design phase where we hardly get the detailed information for the designed vessel.
Simplified Method of Added Resistancein Wave kind of Ship Container Capacity 6500 TEU Lpp 300 m B 40 m D 24 m d 14 m Cb 0.65 Disp 111930 ton Cp 0.658 LCB 0.59 %Lpp Af 1548 m**2 Dp 8.8 m 1-t 0.83 1-w 0.73 Power Curves(calm) Vs 26.0 24.7 23.4 kts EHP 37,735 30,926 26,064 KW BHP 51,786 41,981 35,195 KW Cal of Ship Speed in actual sea Vs 26.0 24.7 23.4 Ro 287790 248268 220864 Cp 0.658 δcp 0.0285 Cpf 0.644 Bfcp2 0.034 Fnb 0.676 0.642 0.608 C1 1.00 C2 31.28 Raw(regular) 37210 35776 34328 Raw 18605 17888 17164 C0 0.60 Raa 28370 27406 26442 To 345403 297970 265080 To+δT 401782 352331 317415 Ct 1.140 1.090 1.080 Ct' 1.326 1.289 1.293 ηo'/ηo 0.975 0.973 0.971 929.8008 BHP' 61762 51004 43388 δvs -1.19 Vs (result) 24.8 δp'/p 19% 21% 23% fw 0.954 Simplified Method by EXCEL Calculation Ship Speed(kts) 16.50 16.00 15.50 15.00 14.50 14.00 13.50 Input items (1) Principal dimensions of ship (2) Power curves (3 points) (3) Self propulsion factors (4) Frontal area of superstructure Voyage Data CAL by Hope Head Wind 1 2 3 4 5 6 7 8 Beaufort Scale
Effect of measurement position on wind velocity
Conclusion Design Index of CO2 emission for individual ship was proposed to IMO and this proposal will be accepted Simulation or prediction tool for CO2 emission at actual sea is very important and the tool should be simple and robust. New idea of energy saving device for high speed ship such as containership is burning issue. Energy saving devices for slow speed vessels such tankers should be deeply investigated. Especially, scale effect and performance in wave are important. Resistance increment due to wind at navigation is not clear and full scale measurement will help us to understand.