Nurten Vardar

Performance optimization of a new combined power cycle based on power density analysis of the dual cycle

Abstract In this paper, maximum power density (MPD) analysis of an air standard internal combustion Dual cycle has been performed. Based on the obtained results for MPD analysis of the Dual cycle, a new combined power cycle model (Dual+Joule-Brayton) has been introduced and optimized. Optimal performance and design parameters are obtained analytically under the MPD conditions of the Dual cycle. The obtained results are discussed in terms of thermal efficiency, power and engine sizes. It is shown that for the combined cycle, a design based on the MPD conditions is more advantageous from the point of view of engine sizes and thermal efficiency.

Numerical analysis of the transient turbulent flow in a fuel oil storage tank

Abstract The filling process of a fuel oil storage tank containing a higher temperature fuel oil is numerically analysed. A k–e model, which is developed by some modifications to those existing in the literature, is employed in order to take into account the turbulent effect for low-Re flow phenomena. A transient stream function–vorticity formulation is used for predicting streamlines and temperature distribution. The streamlines, the isotherms and the transient average temperature variations are presented for three different inflow velocities and for three different cases of heating.

Numerical investigation of a water flow in a rib-roughened channel by using Reynolds stress model

In this paper, water flow in a rib-roughened channel is investigated numerically by using Reynolds stress turbulence models (RSM) on a three-dimensional (3-D) domain. Computational results for mean streamwise velocity component and turbulent kinetic energy show good agreements with available experimental data. Five rib pitch-to-height ratios (p/h) of 1, 5, 10, 15 and 20 are analysed for six different Reynolds numbers (Re) of 3000, 7000, 12,000, 20,000, 40,000 and 65,000. Velocity vectors, streamlines and Reynolds stresses are showed for these ratios and Re numbers. Streamlines revealed that Reynolds numbers do not affect flowfield but play an important role in the Reynolds stresses.

The importance of wastewater treatment in shipbuilding industry

There is a huge amount of wastewater outcome during the ship production and repair processes in shipyards. Especially production processes (blasting, welding, painting, machining and metalworking), repair processes (hull washing) and painting processes (paint removal) create a huge amount of wastewater. In addition to these, open area processes of ship repair and maintenance cause stormwater runoff resulting in an increase in wastewater. The flow prevention of these wastewaters to sea or water sources is extremely important. Hazardous waste containing wastewaters should be separated according to waste management principles and discharged accordingly. In this study, the possible wastewater outcome from shipyard production processes is investigated and necessary methods for the wastewater treatment are discussed.

Multimedia Pollutant Sources and Their Effects on the Environment and Waste Management Practice in Turkish Shipyards

Shipbuilding industry is one of the oldest and the heaviest production industries all over the world. There are several production processes which result in hazardous waste and pollutants to the environmental safety and health. Shipyards are often categorized into two basic subdivisions: new shipbuilding division and ship repairing division. The area of the shipyard describes their proficiency; some shipyards build only large ships and also have repair and dry dock facilities while other shipyards have facilities for building small- and medium-sized vessels such as patrol boats, fire and rescue boats, water taxis, ferries, tug boats, fishing boats, and shallow-drafted barges.