International marine shipping aims to achieve carbon neutrality by 2050. Marine vessels generate a large amount of waste heat, particularly low-grade waste heat, which remains unutilized. And high -temperature water and steam have been mostly generated by boilers and heaters. In this study, engine room ventilation was assumed as a waste heat source and the performance of a copper high-fin heat exchanger, a highly efficient heat exchanger with excellent corrosion resistance for low-grade waste heat recovery was evaluated, accounting for the presence or absence of condensation on the heat transfer tube surface. Based on measurement data, the heat-transfer rate, outlet temperature, and flow rate of the high-temperature water obtained in the condenser were predicted when using a high-fin heat exchanger as the evaporator of a heat pump and recovering waste heat. Furthermore, CO₂ emission reductions were predicted and compared with the generation of high-temperature water using a heavy oil-fired boiler, demonstrating the potential for environmental impact reduction.

To clarify tribological characteristics of engine components, an analytical method is proposed for investigating how the surface temperature T involves the friction and scuffing using temperature and friction data measured with a rotary-disk typed reciprocative sliding friction tester, which can set the same contact pressure and sliding velocity as those of piston rings in actual engines. The relationship among shear stresses s_i and surface coverage ratios θ_i is determined for four contact areas in a mixed/boundary lubrication model: hydrodynamically lubricated oil film, adsorbed oil molecules film, tribo-chemically reacted oil additives and true metal-metal contact, because a logistic curve is applied to relate the film thickness ratio with the solid contact ratio for rough interfaces as in the previous study. The shear stress and temperature rise of oil-film area and metal contact area are iteratively calculated, where the oil-film thickness depends on conditions of prediction and the shear stress of metal contact follows the change of Vickers hardness with temperature and elastic-plastic contact parameter. The product of shear stress s_ar and surface coverage ratio θ_ar for the tribofilm consisting of adsorbed oil molecules and tribo-chemically reacted oil additives is larger than those for the other areas, so that the tribofilm is a dominant factor in friction. The surface temperature coefficient C_ar is estimated under the exponential relationship between s_ar and T_ar similarly to the Arrhenius equation for chemical reaction rate. The C_ar values become smaller indicating higher involvement of T_ar in reducing s_ar to improve the scuffing resistance.

One of the challenges in implementing shore electric power system for medium sized vessels is the associated cost which requires significant investment from both port authorities and ship owners. Utilizing grid power under a low voltage contract is expected to reduce implementation costs, as high voltage receiving cubicles do not need to be installed on the port side. Furthermore, if a frequency converter can be omitted, the overall expenditure can be further minimized. To address technical concerns about the use of low voltage shore power, this study investigates the influence on onboard equipment operation through long-term observations on general cargo vessels and theoretical analysis.

Results indicate that ballast pump capacity decreases under 50 Hz conditions, leading to extended operating hours for ballast water transfer. Electromagnetic and statistical analyses confirm that transformers do not exhibit abnormal heating. Although the operating hours of air compressors and equipment with electric heaters increase, these changes do not adversely affect onboard systems while the vessel is berthed.