Development of Energy-Saving Devices for a 20,000DWT River–Sea Bulk Carrier

A reduction of fuel consumption and an increase in efficiency are currently required for river–sea bulk carriers.Pre-swirl and ducted stators are widely used devices in the industry and efficiency gains can be obtained for single-screw and twin-screw vessels.Based on the hydrodynamic characteristics of the 20,000DWT river–sea bulk carrier,in this study,we proposed,designed,and tested a series of pre-swirl energy-saving devices(ESDs).The experimental results demonstrate that the proposed ESDs improved the propulsive efficiency and reduced the delivered power.The results confirm the success of our ESD for the 20,000DWT river–sea bulk carrier.We validated the role of Reynolds-averaged Navier–Stokes(RANS)computational fluid dynamics(CFD)in the twin-skeg river–sea vessel ESD design and found the circumferential arrangement and number of stators to be important factors in the design process.

Advancement in materials for energy-saving lighting devices

This review provides a comprehensive account of energy efficient lighting devices, their working principles and the advancement of these materials as an underpinning to the development of technology. Particular attention has been given to solid state lighting devices and their applications since they have attracted the most interest and are the most promising. Solid state lighting devices including white light emitting diodes （LEDs）, organic LEDs （OLEDs）, quantum-dot LEDs （QLEDs） and carbon-dot LEDs （CLEDs） are promising energy efficient lighting sources for displays and general lighting. However there is no universal solution that will give better performance and efficiency for all types of applications. LEDs are replacing traditional lamp,; for both general lighting and display applications, whereas OLEDs are finding their own special application,; in various areas. QLEDs and CLEDs have advantages such as high quantum yields, narrow emission spectra, tunable emission spectra and good stability over OLEDs, so applications for these devices are being extended to new types of lighting sources. There is a great dean of research on these materials and their processing technologies and the commercial viability of these technologies appears strong.

A Mathematical Model of a Ship with Wings Propelled by Waves

This paper discusses mathematical modeling of a ship equipped with energy-saving wing devices.Therewith,the ship is mathematically represented by an elongated hull with high-aspect-ratio wings mounted near its bow and stern.Equations,describing ship motions in regular oncoming waves,are written in the spirit of strip theory with account of inertial and damping influence of energy-saving wing elements with the use of linear expansion of wing-related forces with respect to heave and pitch perturbations.This approach readily yields fast numerical solutions for the propulsion of a ship with wings in waves.The latter solutions are then used as an input for calculation of thrust on wing elements on the basis of classical unsteady foil theories corrected for finite aspect ratio.To evaluate speed of the ship in the modes which allow cruising exclusively by wave power,it is hypothetically assumed that in this case,the wave-generated thrust on the wings equals total drag of the ship-plus-wings system,the latter being defined as a sum of its viscous,wave-making,induced(for wing elements)and added-wave components.Excepting the added-wave term and wings’contributions,the total drag is calculated herein by Holtrop method whereas added-wave resistance is evaluated with Beukelman-Gerritsma formula involving kinematic parameters of heaving and pitching motions of the ship calculated both without and with account of the wings.Also discussed in the paper is a decrease of added wave resistance for a ship with wings as compared to that of ship without wings.Finally,the energy efficiency design index(EEDI)introduced by the International Maritime Organization(IMO)is discussed for representative sea conditions as a measure of ship environmental friendliness.