The main engine of tugboats is designed for high-power propulsion relative to hull size, but most of its operation is at low loads. In order to improve the performance of such ships, we came to the conclusion that a composite system was needed and developed a hybrid propulsion system. This system consists of an engine and a propulsion system using a motor and lithium ion batteries and it has achieved the fuel consumption and CO2 emissions reduction goal of 20% in comparison with conventional tugboats. The lithium ion batteries can be charged by the power generator, as well as by plugging in to electric power on land (shore power). On March 2013, Japan’s first hybrid tugboat was put into service.
Amid calls for the reduction of greenhouse gases to prevent global warming, the marine industry has been considering strategies and countermeasures. This time, it was decided that an onshore power supply system will be installed for the first time in Japan on a large ferryboat on an exploratory basis, and at the same time the world’s largest-class photovoltaic power generation system for marine use will also be installed on the ship. This article describes this project and its background and provides the project’s technical aspects.
Energy-saving navigation (Eco-Navigation) for domestic vessels is an important subject these days. The Eco-Navigation planning system minimizes fuel consumption by optimal route and speed planning using highly precise weather prediction and ship performance estimation. This system has been demonstrated to reduce FOC statistically by about 4%. Furthermore, a route-only plan achieved similar reductions in the case of the ship I-Maru
The author has promoted and implemented the research and development of the eco-friendly electric propulsion ship “Super Eco-Ship”, weather routing for domestic vessels “Navigation Support System”, and ship allocation problem “Ship scheduling support system” from the viewpoint of operational support of domestic shipping. In other words, the following steps were taken to improve vessel operation efficiency. First, build a highly efficient vessel by adopting the latest technology and having it operated by a great master. Then, optimally allocate vessels to meet the shipper’s requests and perform effective fleet management to achieve environmental and economic benefits. Although there are other tasks such posting crew assignments or vessel maintenance, NMRI takes the viewpoint of operational support technology. This paper introduces the history on Research & Development of operational support technology for fleet-management including the evaluation methodology of transportation fleets. These technologies are expected to find application not only in coastal shipping but also in ocean going shipping.
At low load operation using heavy fuel oil (HFO) and at engine start-up in a 4-stroke cycle marine diesel engine, a significant amount of smoke is generated. This paper presents results of improvement of combustion in a 4-stroke cycle medium speed marine diesel engine using marine diesel oil (MDO) and heavy fuel oil (HFO). The authors investigated the effect of fuel injection control using a novel fuel injection system (HIS: Hybrid Injection System) composed of a common rail system and a cam drive pump. The findings are the following: (1) At engine start-up using MDO, it is possible to reduce smoke by using low pressure pre-injection of a small amount of fuel. (2) In low engine load conditions using HFO, it is possible to reduce CO and smoke by low pressure pre-injection of a small amount of fuel and after-injection of large amount of fuel. (3) By using HFO as main fuel and MDO as sub fuel, it is possible to reduce CO and smoke significantly by low pressure pre-injection of a small amount of fuel and after-injection of large amount of fuel.
In order to investigate heat transfer distributions on riser walls of a circulating fluidized bed (CFB) under rolling motion, a series of visualization experiments which utilized thermo-chromic liquid crystal was performed. Superficial velocity and rolling period were varied in the experiments, while amplitude of the rolling motion was fixed at 15deg. One-dimensional unsteady thermal conduction analysis was also carried out to evaluate followability of liquid crystal coloration to changes in riser wall temperature. The following results were obtained: (1) Thermal conduction analysis shows that the response delay time of liquid crystal coloration to the wall temperature stays within several seconds under the present experimental conditions. (2) In bubbling and turbulent fluidization regimes at the upright attitude, a remarkable change in liquid crystal coloration due to the steep gradient of voidage was observed at the bottom of the riser wall. On the other hand, uniform coloration was observed over the entire area at the middle of the riser wall. Time-averaged heat transfer rate of the present experiment agrees well with previous results. (3) When the CFB undergoes rolling motion, liquid crystal coloration changes periodically at the middle part of the riser wall. The change is induced by heat transfer fluctuation due to the periodic change of the downflow.