IMO adopted a revision of MARPOL Annex VI to establish the Energy Efficiency Design Index (EEDI) for new build ships in July 2011. The target EEDI will be tightened incrementally until 2025. The ship hull roughness is one of the most important factors that affect ship resistance and efficiency. In this study, friction measurements of cylinders painted with antifouling paint were conducted using double rotating cylinder equipment. Some antifouling paints showed lower Rz and higher RSm values, thus resulting in lower Friction Increasing Ratios (FIR) of currently available antifouling paints. Actual ship hull surface roughness is measured using a roughness analyzer that can measure only Rz at a standard length of 50mm. However, the Rz value alone does not provide enough information to predict friction. Therefore, the replicate method was developed in order to analyze the hull roughness parameters. Roughness analysis using both roughness amplitude and wave length parameters is shown to be very useful for predicting more accurately the ships’ friction resistance.
Shipping is recognized as more energy efficient than many forms of transport, but increasing regulation of emissions and increasing fuel prices continue to drive the need for viable means of energy saving and reducing operational costs. One relatively easy way to do this is through the use of low friction fouling control coatings which improve the energy efficiency of ships by reducing hull roughness and frictional drag. The frictional resistance of fouling control technologies is not a new area of interest for International Paint or the marine industry. Over the years International Paint has expended considerable resources to understand the influence of coating frictional resistance on the performance and fuel efficiency of ships. Together with offering class leading products such as Intersleek® and Intersmooth®, International Paint in conjunction with BMT ARGOSS can now deliver clarity on the fuel saving benefits of fouling control coatings in an open and transparent way with the implementation of BMT SMARTSERVICES. This paper will highlight some of the advances made by International Paint and reflect on some of the current and future challenges to the marine coatings industry.
By 2016, under the IMO Tier III rules, NOx emissions from ships sailing in emission control areas (ECA) should decrease by more than 80% relative to IMO Tier I levels. In this study, in order to reduce NOx emissions from marine diesel engines, a low-oxygen and high-humidity system for suction air was connected to the suction line of a high-speed marine diesel engine, and the influence of oxygen density and moisture content in suction air on NOx emission was investigated. The following results were clarified. (1) NOx emission decreases with a decrease in oxygen density for each load factor, and it is necessary to adjust the oxygen density to 17% or less to comply with Tier 3 regulations. (2) NOx emission decreases because oxygen density decreases with an increase in moisture content. The regulations can be complied with by adjusting the humidity of suction air to 16 mol%. (3) NOx emission can be effectively reduced by decreasing both oxygen density and suction air humidity, taking into account the operating conditions of the engine.
Many of the present antifouling agents developed since the ban of organotin compounds have an environmental advantage owing to their high photodegardation rate. However, increased use of these compounds may result in relatively high concentrations of them in the aquatic environment. In addition, their concentration may be changed drastically with solar radiation intensity. Therefore, it is necessary to investigate the effect of solar radiation and other factors that influence the concentration. A numerical model has been developed to predict spatial, seasonal and temporal changes in the concentration of certain photodegradable antifouling agents in a small marina. The model deals with three dimensional unsteady-state water flow and the photodegradation process influenced by various environmental factors. The results showed that the concentration is very sensitive to environmental conditions, which is changed with, season, weather and geographic location. The temporal and spatial concentration distribution makes it difficult to determine meaningful predicted environmental concentration (PEC) for an environmental risk assessment. It also suggests significant uncertainty in environmental samples.
In order to reduce greenhouse gases, it is necessary to develop technologies for improving fuel efficiency. Slow steaming, heat recovery, low friction vessel designs and use of renewable energy are among those being evaluated in the marine engineering field today. Fuel economy lubricants for automobiles have been developed because the frictional loss is significant in automobile engines, and these lubricants contribute to reduced fuel consumption. For marine engines, especially 2-stroke crosshead engines, there has been no study on the improvement of fuel efficiency with lubricants. The authors investigated the influence of the viscosity characteristics of marine diesel lubricants and their additives (friction modifiers, etc.) on fuel efficiency, and showed that marine diesel lubricants with optimized formulations can reduce total friction loss by 20% and improve the fuel efficiency of marine engines by 1.3%.
The elucidation of heat transfer processes is vital for the design of reliable compact heat exchangers used in SMGTs (Super Marine Gas Turbines). To obtain a database for the optimal design of plate-fin recupetators under transient heat transfer conditions, it is very important to study heat transfer process from different-size plates in transient conditions under various gas velocities. In this paper a series of horizontal heaters with different sizes inside a circular tube have been tested for forced convection flow. The heat input was increased with a function of Q =Q0exp(t/τ). The heaters were flat platinum plates with thicknesses of 0.2 mm, 0.1 mm and 0.1mm and widths of 1.5 mm, 4 mm and 6 mm. In the present study, the heat flux, surface temperature, and transient heat transfer coefficient were measured for helium gas flowing over horizontal heaters under wide experimental conditions. It was found that the heat transfer coefficients approach the quasi-steady-state values when the period τ is longer than around 1 second. However, when the period is shorter than 1 second, the heat transfer coefficients become higher as the period decreases. An Empirical correlation for quasi-steady-state heat transfer was obtained based on the experimental data. It was also found that the size of the heater has a great influence on the heat transfer coefficient.