Fresh water is used in a wide variety of applications on ships, and the role of “Fresh water generator (FWG)” that produces fresh water from seawater is significant. Since developing the first FWG in Japan, Sasakura Engineering has continued to remodel the FWG according to changes in the ships, and has supplied more than 17,000 units in total while evolving to the present. In this article, the author has summarized the recently developed X-series FWG and WX-series FWG. We have developed the X-series FWG based on the K-series, which is the conventional FWG. The features of X-series FWG are miniaturization, improved maintainability, and stable operation. Furthermore, we have developed the WX-series FWG based on the X-series FWG. The feature of WX-series FWG is that the amount of heat requirement is halved, that is, energy saving performance. In addition, the operability is the same as the X-series, and retrofit type can be supported as an option. We will continue to improve the FWG to meet the needs of the times.

While IMO (International Marine Organization) regulates CO₂ emissions from ocean going vessels to protect the marine environment, efforts are underway to design and develop various systems to reduce such emissions. As part of these efforts, the author carried out a simulation by applying PAFCs (phosphoric acid fuel cells) that do not release air pollution gases to the electric power system of an ocean going vessel model. At first, the author developed a vessel model in consideration of routes, speed, sailing schedules, diesel engine generator capacity and electric power consumption etc. Then the author designed the electric power system with PAFCs based on the model. Finally, the simulation designed to supply electric power from the diesel engine generator and PAFCs was carry out. From the results of the simulation, the author calculated the degree of reductions in fuel consumption and greenhouse gas emissions and concluded that the use of the PAFCs was an effective method to protect the marine environment.

  The integrity of bolted joints is often checked after a certain period of running time. These checks are designed to examine whether the target bolt has still properly been tightened with prescribed bolt force staying within acceptable ranges. Three types of inspection methods are commonly used for verification, i.e., the release torque method, the re-tightening torque method and the marking method. Depending on the type of the method, inspections are carried out at the site by either measuring loosening torque, re-tightening torque or tightening torque up to the marked position. In this study, aiming at establishing general guidelines for the inspection methods, characteristics of these methods are examined using rigorous equations that represent the relationship between applied torque and generated bolt force. Torque ratios anticipated to be used as a guideline for each inspection method are comprehensively calculated by varying friction coefficients, nominal diameter and thread pitch. Coefficient of friction values, which affect inspection accuracy, are measured by means of tightening equipment which has been developed to measure relevant values, such as torque and bolt force, with high accuracy.

  In this study, the authors investigated particulate matter (PM) collection efficiency of an electrostatic-cyclone precipitator (ESP-cyclone) by conducting bench tests and onboard measurements of PM emissions with three diesel engines. A small sized high-speed 4-Stroke diesel was used for a bench test and two types of low-speed 2-Stroke marine diesels were utilized for another bench test and onboard PM measurements aboard a ship of 2,703 gross-tonnage. In order to study PM collection efficiency of the ESP-cyclone, PM concentrations in exhaust gas were measured upstream and downstream of the ESP-cyclone with a partial flow dilution tunnel system. Experimental results showed that the PM collection efficiency was as high as 60-80% with the ESP-cyclone collecting not only insoluble organic fraction (ISF), but also soluble organic fraction (SOF). The ESP-cyclone realizes stable PM reduction from the diesel engine on the actual ship.

This study is designed to determine the deterioration state of the Li-ion battery by measuring the AC impedance spectrum. To this aim, the possibility of degradation discrimination was examined by changing measured environmental temperature within the practical operating range of the battery, and the following knowledge was obtained. (1) By lowering the ambient temperature below the room temperature, the impedance of the battery increases. The degradation state can be quantified even in the battery with medium and low levels of degradation. (2) Since the cell structure suppresses an increase in the imaginary component of the impedance, it was found that the deterioration progress made it difficult to discriminate the deterioration of the medium and low stage cells. (3) It is possible to distinguish a new battery from a used battery simply by lowering the ambient temperature below 0 degC. (4) It has been found that even in mass-produced batteries, since moisture that is inevitably mixed in during production causes internal condensation, the determination of deterioration at around zero environmental temperature may lead to misdiagnosis. (5) When the ambient temperature is lowered below the room temperature, both the electrolyte resistance and the charge transfer resistance increase, but an increase in the electrolyte resistance is more remarkable. It is appropriate to judge degradation at the ambient temperature around 10 degC where the charge transfer resistance has risen to about twice the case with the normal temperature even in the battery with medium to low levels of degradation.

  As fine cracks occurred in the welded part of a compressor member (JIS-SUS630/ H1075) during the manufacturing phase, a series of test inspections were conducted. As the inspection results suggested that the cracks were most likely to have been caused by hydrogen embrittlement (HE), a bending test was carried out to reproduce these cracks after a small-sized specimen was subjected to TIG welding and post-heat treatment, then charged with hydrogen.

  During the bending test, small cracks occurred in the welded part and HAZ of the specimen, and these cracks were transgranular just like the ones in the compressor member. The fracture surface of the cracks was dominated by brittle fracture, thus it is presumed that the fracture surface was generated by HE. Post-heat treatment is an effective measure to prevent cracking, and it is considered that storage times from welding to post-heat treatment and the thickness of compressor components must have affected the occurrence of cracks.