scholarly journals The Need to Amend IMO’s EEDI to Include a Threshold for Performance in Waves (Realistic Sea Conditions) to Achieve the Desired GHG Reductions

2019 ◽  
Vol 11 (13) ◽  
pp. 3668 ◽  
Author(s):  
Elizabeth Lindstad ◽  
Henning Borgen ◽  
Gunnar S. Eskeland ◽  
Christopher Paalson ◽  
Harilaos Psaraftis ◽  
...  
Keyword(s):  
Ghg Emissions ◽  
Operating Conditions ◽  
Testing Methods ◽  
Policy Measure ◽  
Sea Trial ◽  
Adjustment Procedure ◽  
Water Conditions ◽  
Calm Water ◽  
Energy Efficiency Design Index ◽  
Hull Forms

The International Maritime Organization (IMO) has established the Energy Efficiency Design Index (EEDI) as the most important policy measure to reduce greenhouse gas (GHG) emissions from shipping. A vessel’s EEDI is based on sea trials at delivery, and vessels cannot exceed a threshold for emitted CO2 per ton-mile, depending on vessel type and size. From other industries such as cars we have learnt that testing methods must reflect realistic operating conditions to deliver the desired emission reductions. Present sea-trial procedures for EEDI adjust to ‘calm water conditions’ only, as a comparative basis, despite calm sea being the exception at sea. We find that this adjustment procedure excessively rewards full bodied ‘bulky’ hulls which perform well in calm water conditions. In contrast, hull forms optimized with respect to performance in realistic sea-conditions are not rewarded with the current EEDI procedures. Our results indicate that without adjusting the testing cycle requirements to also include a threshold for performance in waves (real sea), the desired reductions will be short on targets and GHG emissions could potentially increase.

Study on Ship Manoeuvering in Adverse Sea State

2017 ◽  
Author(s):  
Bingjie Guo ◽  
Eivind Ruth ◽  
Håvard Austefjord ◽  
Elzbieta M. Bitner-Gregersen ◽  
Odin Gramstad
Keyword(s):  
Time Domain ◽  
Ghg Emissions ◽  
Force Component ◽  
Ship Maneuvering ◽  
Engine Model ◽  
Simulation Speed ◽  
Calm Water ◽  
Force Components ◽  
Energy Efficiency Design Index ◽  
The Time Domain

IMO introduced Energy Efficiency Design Index (EEDI) to regulate the greenhouse gas (GHG) emissions from ships. The cheapest and easiest way to fulfil the EEDI requirement is to reduce installed power for most ships. Therefore, it has raised serious concerns that some ship designers might choose to lower the installed power to achieve EEDI requirements and not consider ship safety in a satisfactory way. This could induce ship manoeuvrability and safety problems in adverse seas, which needs urgent investigations on minimum power to maintain ship manoeuvrability in adverse sea. A time domain code ‘Waqum’ has been developed based on the force superposition of unified theory to study the minimum required power for maintaining ship manoeuvring ability in adverse sea states. The code combines sea-keeping and maneuvering equations, together with an engine model to predict ship responses in waves. The code can help us to study ship responses in transit situation and give us better insight into ship maneuvering ability in adverse sea states. In order to improve the simulation speed, the time domain code does not calculate all the hydrodynamic forces directly. Thus, some precalculations should be done for some force components before launching the simulation for a new ship. Therefore, the methodology and accuracy of each force component will influence the accuracy of the manoeuvring code. The methodology for determining each force component will be discussed, especially the identification of maneuvering derivatives based on CFD simulations. The code has been improved recently, and another rudder model has been implemented. Further, the the code with new rudder model is verified in calm water. The code’s ability to capture ship maneuvering in waves is also demonstrated.

Numerical evaluation of hydrodynamic characteristics of planing hulls by using a hybrid method

2021 ◽  
pp. 147509022199024
Author(s):  
Emre Kahramanoglu ◽  
Silvia Pennino ◽  
Huseyin Yilmaz
Keyword(s):  
Experimental Data ◽  
Hybrid Method ◽  
Design Stage ◽  
Hydrodynamic Characteristics ◽  
Calm Water ◽  
Preliminary Design Stage ◽  
Reduction Function ◽  
Hull Forms ◽  
Good Agreement

The hydrodynamic characteristics of the planing hulls in particular at the planing regime are completely different from the conventional hull forms and the determination of these characteristics is more complicated. In the present study, calm water hydrodynamic characteristics of planing hulls are investigated using a hybrid method. The hybrid method combines the dynamic trim and sinkage from the Zarnick approach with the Savitsky method in order to calculate the total resistance of the planing hull. Since the obtained dynamic trim and sinkage values by using the original Zarnick approach are not in good agreement with experimental data, an improvement is applied to the hybrid method using a reduction function proposed by Garme. The numerical results obtained by the hybrid and improved hybrid method are compared with each other and available experimental data. The results indicate that the improved hybrid method gives better results compared to the hybrid method, especially for the dynamic trim and resistance. Although the results have some discrepancies with experimental data in terms of resistance, trim and sinkage, the improved hybrid method becomes appealing particularly for the preliminary design stage of the planing hulls.

scholarly journals STOCHASTIC CARBON EMISSION ESTIMATION METHOD FOR CONSTRUCTION OPERATION

2016 ◽  
Vol 23 (1) ◽  
pp. 137-149 ◽  
Author(s):  
Chang-Yong YI ◽  
Han-Seong GWAK ◽  
Dong-Eun LEE
Keyword(s):  
Carbon Emission ◽  
Performance Metrics ◽  
Ghg Emissions ◽  
Estimation Method ◽  
Operating Conditions ◽  
Analysis Tool ◽  
Micro Scale ◽  
Work Tasks ◽  
Emission Estimation ◽  
Construction Operation

Low carbon construction is an important operation management goal because greenhouse gas (GHG) reduc­tion has become a global concern. Major construction resources that contribute GHG, such as equipment and labour, are being targeted to achieve this goal. The GHG emissions produced by the resources vary with their operating conditions. It is commendable to provide a statistical GHG emission estimation method that models the transitory nature of resource states at micro-scale of construction operations. This paper proposes a computational method called Stochastic Carbon Emission Estimation (SCE2) that measures the variability of GHG emissions. It creates construction operation models consisting of atomic work tasks, utilizes hourly equipment fuel consumption and hourly labourer respiratory rates that change according to their operating conditions classified into five categories, and identifies an optimal resource combi­nation by trading off eco-economic performance metrics such as the amount of GHG emissions, operation completion time, operation completion cost, and productivity. The study is of value to researchers because SCE2 fill in a gap to eco-economic operation modelling and analysis tool which considers operating conditions at micro-scale of construction operation having many stochastic work tasks. This study is also relevance to practitioners because it allows project man­agers to achieve eco-economic goals while honouring predefined constraints associated with time and cost.

Directional Stability and Control of Ships in Waves

1972 ◽  
Vol 16 (03) ◽  
pp. 205-218
Author(s):  
Haruzo Eda
Keyword(s):  
Automatic Control ◽  
Gain Control ◽  
Small Region ◽  
Wave Crest ◽  
Following Seas ◽  
Directional Stability ◽  
Wave Trough ◽  
Calm Water ◽  
Hull Forms ◽  
And Control

The stability and oscillatory motions of ships (automatically steered and unsteered) in the horizontal plane were examined on a digital computer for the case of regular following seas. Available hydrodynamic data for Series 60 hull forms were used. Analysis of directional stability was made for the case of zero encounter frequency (i.e., the ship runs at high speeds equal to the wave celerity). The ship (which is hydrodynamically stable without automatic control in calm water) is directionally unstable in following seas except for the small region near the ascending node of the waves. Addition of automatic control can give the ship directional stability when it is located on the wave trough, but not when it is located on the wave crest. At relatively high frequency (i.e., at low speeds in following seas), the rudder and control system are almost incapable of reducing oscillatory motion. Violent rudder activity in following seas can be decreased by reducing the yaw-rate-gain control constant and by increasing the rudder-response-time constant.

A Proposal for Performance Criteria for Propulsion Losses Due to Ship Steering

1982 ◽  
Vol 104 (2) ◽  
pp. 158-165 ◽  
Author(s):  
R. E. Reid
Keyword(s):  
High Speed ◽  
Operating Conditions ◽  
Relative Performance ◽  
Performance Criteria ◽  
Ship Steering ◽  
Calm Water ◽  
Simulation Results ◽  
Definition Of ◽  
Hydrodynamic Data

The problem of definition of propulsion loss related to ship steering is addressed. Performance criteria representative of propulsion losses due to steering over a range of operating conditions including operation in calm water and a seaway are considered. Criteria are derived from strict analytical considerations and from empirical assumptions based on experimentally derived hydrodynamic data. The applicability of these various criteria and the implications for both assessment of relative performance of existing ship autopilots and for the design of new steering controllers is discussed in relation to simulation results for a high-speed containership.

A Nonlinear Mathematical Model for Ship Turning Circle Simulation in Waves

2005 ◽  
Vol 49 (02) ◽  
pp. 69-79 ◽  
Author(s):  
Ming-Chung Fang ◽  
Jhih-Hong Luo ◽  
Ming-Ling Lee
Keyword(s):  
Mathematical Model ◽  
Degrees Of Freedom ◽  
Regular Waves ◽  
Nonlinear Mathematical Model ◽  
Ship Maneuvering ◽  
Sea Trial ◽  
Six Degrees Of Freedom ◽  
Strip Theory ◽  
Calm Water ◽  
Maneuvering Motion

In the paper, a simplified six degrees of freedom mathematical model encompassing calm water maneuvering and traditional seakeeping theories is developed to simulate the ship turning circle test in regular waves. A coordinate system called the horizontal body axes system is used to present equations of maneuvering motion in waves. All corresponding hydrodynamic forces and coefficients for seakeeping are time varying and calculated by strip theory. For simplification, the added mass and damping coefficients are calculated using the constant draft but vary with encounter frequency. The nonlinear mathematical model developed here is successful in simulating the turning circle of a containership in sea trial conditions and can be extended to make the further simulation for the ship maneuvering under control in waves. Manuscript received at SNAME headquarters February 19, 2003; revised manuscript received January 27, 2004.

Numerical Modelling of a Planing Craft with a V-Shaped Spray Interceptor Arrangement in Calm Water

2020 ◽  
Author(s):  
Mikloš Lakatoš ◽  
Kristjan Tabri ◽  
Abbas Dashtimanesh ◽  
Henrik Andreasson
Keyword(s):  
Reaction Force ◽  
The Other ◽  
Numerical Comparison ◽  
Total Resistance ◽  
Stagnation Line ◽  
Planing Craft ◽  
Water Conditions ◽  
Calm Water ◽  
Wetted Surface Area ◽  
Novel Concept

V-shaped spray interceptors are a novel concept of spray deflection on planing craft. Conventional spray rails are positioned longitudinally on the bottom of the hull and detach the spray from hull deflecting it towards the sides or slightly down and aftward. The V-shaped spray interceptors, on the other hand, are located in the spray area forward of the stagnation line such that they would deflect the oncoming spray down and aftward, thereby producing a reaction force that reduces the total resistance. An experimental study reported that the V-shaped spray interceptors to reduce the total resistance at low planing speed by up to 4%. This paper features a numerical comparison of two planing craft, one equipped with a conventional setup of longitudinal spray rails and the other with a V-shaped spray interceptor. Both configurations were simulated in calm water conditions and were free to pitch and heave in a speed range of Fr∇ = 1.776 to 3.108. The numerical model was analyzed for grid sensitivity and numerical results were compared with experimental results. The two concepts were compared in terms of total resistance, lift, running position and wetted surface area. Conventional spray rails were shown to account for up to 5.6% of total lift and up to 6.5% of total resistance. The V-shaped spray interceptor was shown to reduce the total resistance by up to 8%. Since the V-shaped spray interceptor was located in the spray area forward of the stagnation line, it deflected the oncoming spray thereby producing a horizontal reaction force (-1.5% of RTM) in the direction of the craft’s motion. The rest of differences in the total resistance of the hulls equipped with the conventional spray rails and the V-shaped spray rails was due to absence of the resistance of the absent spray rails.

scholarly journals Day-Ahead Optimal Battery Operation in Islanded Hybrid Energy Systems and Its Impact on Greenhouse Gas Emissions

2019 ◽  
Vol 9 (23) ◽  
pp. 5221 ◽  
Author(s):  
Lujano-Rojas ◽  
Yusta ◽  
Artal-Sevil ◽  
Domínguez-Navarro
Keyword(s):  
Greenhouse Gas ◽  
Storage System ◽  
Ghg Emissions ◽  
Energy System ◽  
Energy Storage System ◽  
Operating Conditions ◽  
Binary Particle Swarm Optimization ◽  
Peak Shaving ◽  
Hybrid Energy ◽  
Heuristic Techniques

This paper proposes a management strategy for the daily operation of an isolated hybrid energy system (HES) using heuristic techniques. Incorporation of heuristic techniques to the optimal scheduling in day-head basis allows us to consider the complex characteristics of a specific battery energy storage system (BESS) and the associated electronic converter efficiency. The proposed approach can determine the discharging time to perform the load peak-shaving in an appropriate manner. A recently proposed version of binary particle swarm optimization (BPSO), which incorporates a time-varying mirrored S-shaped (TVMS) transfer function, is proposed for day-ahead scheduling determination. Day-ahead operation and greenhouse gas (GHG) emissions are studied through different operating conditions. The complexity of the optimization problem depends on the available wind resource and its relationship with load profile. In this regard, TVMS-BPSO has important capabilities for global exploration and local exploitation, which makes it a powerful technique able to provide a high-quality solution comparable to that obtained from a genetic algorithm.

Numerical Study on the Maneuvering of a Ship in Waves Based on Unified State Space Model

2016 ◽  
Author(s):  
Rameesha Thayale Veedu ◽  
Parameswaran Krishnankutty
Keyword(s):  
State Space ◽  
Numerical Study ◽  
State Space Model ◽  
Container Ship ◽  
Regular Waves ◽  
Ship Maneuvering ◽  
Space Model ◽  
Water Conditions ◽  
Calm Water ◽  
Early Design Stages

Ship maneuvering performance is usually predicted in calm water conditions, which provide valuable information about ship’s turning ability and its directional stability in the early design stages. Investigation of maneuvering simulation in waves is more realistic since the ship usually sails through waves. So it is important to study the effect of waves on the turning ability of a ship. This paper presents the maneuvering simulation for a container ship in presence of regular waves based on unified state space model for ship maneuvering. Standard maneuvers like turning circle and zigzag maneuver are simulated for the head sea condition and the same are compared with calm water maneuvers. The present study shows that wave significantly affects the maneuvering characteristics of the ship and hence cannot be neglected.

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