Laurie Goldsworthy

Computational Fluid Dynamics Modelling of Residual Fuel Oil Combustion in the Context of Marine Diesel Engines

Abstract A simplified model is presented for vaporization and combustion of heavy residual based fuel oil in high-pressure sprays, in the context of marine diesel engines. The fuel is considered as a mix of residual base and cutter stock. The model accounts for multiple fuel components as well as limited diffusion rates and thermal decomposition rates within droplets by the use of straight-line relationships for the saturation pressure of combustible fuel vapour at the droplet surface as functions of droplet temperature. The energy required for decomposition of heavy molecules is accounted for. Combustion is modelled using a timescale that is the sum of a kinetic timescale based on a single-step reaction and a turbulent timescale based on turbulent mixing rates. The ignition timescale is based on a simple three-equation model. Cellwise ignition is employed. The heavy fuel oil model is applied to two different constant volume chambers that are used to test ignition and combustion quality of marine heavy fuel oil, using the computational fluid dynamics code StarCD version 3.2. Good agreement is shown between trends in measured and computed data including ignition delay, burn rate and spatial distribution of spray and flame parameters. The model is tested for two representative fuels, one with good ignition and combustion properties and one poor. Essentially only two parameters need to be changed to set the fuel quality. These are the ignition delay factor and the activation energy for the high-temperature kinetics. Further tuning of the model to specific fuels is possible by modifying the saturation temperature relationships.

Modelling of ship engine exhaust emissions in ports and extensive coastal waters based on terrestrial AIS data - An Australian case study

A model is developed to calculate and spatially allocate ship engine exhaust emissions in ports and extensive coastal waters using terrestrial Automatic Identification System data for ship movements and operating modes. The model is applied to the Australian region. The large geographical extent and number of included ports and vessels, and anomalies in the AIS data are challenging. Particular attention is paid to filtering of the movement data to remove anomalies and assign correct operating modes. Data gaps are filled by interpolation and extrapolation. Emissions and fuel consumption are calculated for each individual vessel at frequent intervals and categorised by ship type, ship size, operating mode and machinery type. Comparisons of calculated port emissions with conventional inventories and ship visit data are favourable. Estimations of ship emissions from regions within a 300?km radius of major capital cities suggest that a non-negligible percentage of air pollutants may come from ships. Model for estimating regional and in-port ship engine exhaust emissions.Ship movement data from Automatic Identification System.Movement data filtered for anomalies, interpolated and extrapolated.Emissions data categorised and spatially allocated.Comparisons with emissions from non-ship sources.

Vulnerabilities and adaptation of ports to climate change

Climate change is anticipated to have a significant impact on coastal infrastructure, including navigational aids and ports. This paper presents the results of a vulnerability assessment of ports in Australia to climate change. Results reveal variable vulnerability in ports in the short and long term in relation to their exposure to climate change. However, this is offset by inherent adaptive capacity both in current climate change initiatives driven by ports, and in the self-confidence of the industry to be able to adapt. We conclude with a reflection on the implications of these results for future ports analyses.

Phase Averaged Flow Analysis in an Oscillating Water Column Wave Energy Converter

The paper presents the application of phase averaging to experimental data obtained during scale model testing of a forward facing bent duct oscillating water column (OWC). Phase averaging is applied to both wave probe data and a two-dimensional velocity field at the centerline plane of the OWC model obtained using particle imaging velocimetry (PIV). Results are presented for one monochromatic wave condition. The influence of varied wave frequency is briefly discussed.

The mortality effect of ship-related fine particulate matter in the Sydney greater metropolitan region of NSW, Australia.

This study investigates the mortality effect of primary and secondary PM2.5 related to ship exhaust in the Sydney greater metropolitan region of Australia. A detailed inventory of ship exhaust emissions was used to model a) the 2010/11 concentration of ship-related PM2.5 across the region, and b) the reduction in PM2.5 concentration that would occur if ships used distillate fuel with a 0.1% sulfur content at berth or within 300 km of Sydney. The annual loss of life attributable to 2010/11 levels of ship-related PM2.5 and the improvement in survival associated with use of low-sulfur fuel were estimated from the modelled concentrations. In 2010/11, approximately 1.9% of the region-wide annual average population weighted-mean concentration of all natural and human-made PM2.5 was attributable to ship exhaust, and up to 9.4% at suburbs close to ports. An estimated 220 years of life were lost by people who died in 2010/11 as a result of ship exhaust-related exposure (95% CIβ: 140-290, where CIβ is the uncertainty in the concentration-response coefficient only). Use of 0.1% sulfur fuel at berth would reduce the population weighted-mean concentration of PM2.5 related to ship exhaust by 25% and result in a gain of 390 life-years over a twenty year period (95% CIβ: 260-520). Use of 0.1% sulfur fuel within 300 km of Sydney would reduce the concentration by 56% and result in a gain of 920 life-years over twenty years (95% CIβ: 600-1200). Ship exhaust is an important source of human exposure to PM2.5 in the Sydney greater metropolitan region. This assessment supports intervention to reduce ship emissions in the GMR. Local strategies to limit the sulfur content of fuel would reduce exposure and will become increasingly beneficial as the shipping industry expands. A requirement for use of 0.1% sulfur fuel by ships within 300 km of Sydney would provide more than twice the mortality benefit of a requirement for ships to use 0.1% sulfur fuel at berth.

Development of a high pressure chamber for research into diesel spray dynamics

Abstract An optically accessible pressure vessel and ancillary instrumentation for studies of diesel spray dynamics has been designed and built at the Australian Maritime College. The requirement for large observation windows and internal pressures up to 10 MPa necessitated the use of finite element analysis in conjunction with first principles analysis. Strain gauge testing confirmed the calculated maximum stresses in the observation windows. The chamber is a registered pressure vessel conforming to AS1210. A purpose-built injection system capable of fuel pressures up to 120 MPa and injection pulse durations up to 30 ms has been implemented. Laser-based instrumentation is synchronised with individual injection events to measure spray droplet velocities and sizes.

A New Approach for Modeling Coke Particle Emissions from Large Diesel Engines Using Heavy Fuel Oil

In the present study, a new approach for modelling emissions of coke particles or cenospheres from large diesel engines using HFO (Heavy fuel oil) was studied. The model used is based on a multicomponent droplet mass transfer and properties model that uses a continuous thermodynamics approach to model the complex composition of the HFO fuel and the resulting evaporation behavior of the fuel droplets. Cenospheres are modelled as the residue left in the fuel droplets towards the end of the simulation. The mass-transfer and fuel properties models were implemented into a cylinder section model based on the Wartsila W20 engine in the CFD-code Star CD v.4.24. Different submodels and corresponding parameters were tuned to match experimental data of cylinder pressures available from Wartsila for the studied cases. The results obtained from the present model were compared to experimental results found in the literature. The performance of the model was found to be promising although conclusive validation of the model would require more detailed experimental results about cenosphere emissions from the specific case studied here. According to the results obtained from this model the emissions of cenospheres are a function of both operating conditions and fuel properties. While the droplet evaporation and properties models were used in this study to model cenosphere emissions, the approach could also be used to study the combustion behavior of HFO in a broader sense.