マリンエンジニアリング
Online ISSN : 1884-3778
Print ISSN : 1346-1427
ISSN-L : 1346-1427
50 巻 , 3 号
選択された号の論文の24件中1~24を表示しています
特集 最新の電気電子システム
随想
報告
解説
技術資料
解説
特集 SOx対策技術
随想
解説
技術資料
  • 竹島 茂樹
    2015 年 50 巻 3 号 p. 347-353
    発行日: 2015/05/01
    公開日: 2016/11/22
    ジャーナル フリー

    The International Maritime Organization (IMO) has decided to strengthen regulations on sulphur oxide (SOx) emissions from ships by 2025. This paper consists of two parts. The first part shows the various types of fuels and their combinations which may be used by marine vessels in the next ten years, and presents the influence these fuels may have on engine lubrication. The second part deals with heavy fuel oil (HFO) with scrubbing, and presents the generation of black scum in scrubbers installed on 2-stroke engines. The author proposes a mechanism for scum formation and suggests two countermeasures to prevent its formation. One countermeasure is the use of specifically formulated cylinder lubricants, and the other is the improvement of lubricant demulsibility.

解説
技術資料
  • Mohan Anantharaman, Vikram Garaniya, Faisal Khan, Barrie Lewarn
    2015 年 50 巻 3 号 p. 360-367
    発行日: 2015/05/01
    公開日: 2016/11/22
    ジャーナル フリー

    Commercial shipping industry employs a large number of bulk carriers, crude oil tankers, LNG vessels and mega container vessels. Needless to say these huge vessels would require great magnitude of power to propel them in high seas. More than 85% of these vessels are propelled by large slow speed engines, directly coupled to the propeller. Last decade has observed a considerable development in these large slow speed engines in terms of its design, operational safety, maintenance and fuel efficiency. Major engine builders strive to achieve a high level of efficiency on these engines. From the shipowner’s point of view, commercial shipping has become highly competitive and there is a dire need to reduce operation and maintenance costs to survive under the present market condition. Here comes the economical aspect of running ships which is a very crucial commercial factor. The maritime regulators led by IMO (International Maritime Organisation) ensure that the marine environment is clean and free from pollutants, which in this case would be controlling of various pollutants discharged from the exhaust funnels of these large marine diesel engines. This paper provides a comprehensive review of the various stages of development of large marine slow speed engines over the past four decades, and the factors that have influenced these developments. However, in the present day context and the near future need to closely look at the commercial aspect of merchant shipping, and specifically address the three big factors; economy, efficiency and environment protection. The paper also analyses the methods available that can address these three factors and what is in store for the maritime engineering world in the future.

論文
  • Kim-Bao Nguyen, Tomohisa Dan, Ichiro Asano
    2015 年 50 巻 3 号 p. 368-375
    発行日: 2015/05/01
    公開日: 2016/11/22
    ジャーナル フリー

    The use of bio-fuels has attracted attention as a promising approach to reduce CO2. While many bio-fuels come from food crops, Jatropha which is inedible has been the focus of interest recently. Jatropha oil has, however, high viscosity and low volatility which would influence the emission characteristics and fuel consumption, especially in the low load engine condition. Electrically controlled fuel injection seems to be effective to improve the combustion of such fuels. However, the combustion characteristics of Jatropha fueled diesel engine with a fully electrically controlled fuel injection system which can vary the injection pattern in a wide range have not been investigated. In this study, experimental research has been conducted to investigate the effects of double injections with various injection timings, and amount of after-injection on the combustion, engine performance, and emission characteristics in a high speed, 4-stroke diesel engine fueled with neat Jatropha oil. Retarding main- and after-injection timings significantly reduced the peak combustion pressures and peak heat release rate; slightly reduced ignition delay; and shifted the combustion to the later phase. Retarded double injection timings reduced emissions of NOx, while increasing dust, smoke, CO, CO2, and HC. Large amounts of the fuel in after-injections significantly reduced combustion pressures and rates of heat release at lower and medium loads. In addition, large amounts of the fuel in after-injections reduced thermal efficiency and increased emissions of CO2, CO, smoke, and dust concentration, while reducing HC and NOx emissions.

  • 田島 宏一, 波津久 達也, 清水 悦郎, 大出 剛, 賞雅 寛而
    2015 年 50 巻 3 号 p. 376-381
    発行日: 2015/05/01
    公開日: 2016/11/22
    ジャーナル フリー

      This study was aimed at improving the turning performance of an electric ship with a waterjet propulsion system under low load operation by applying cyclic control of motor output. The required patterns of the cyclic control, including duty ratio and waterjet frequency, for improvement of turning performance were estimated by predicting thrust power of the waterjet during cyclic control. The effectiveness of the cyclic control was also evaluated through turning performance tests using an electric boat “Raicho-S”. By analyzing the average thrust power of the waterjet based on predicted motor revolution during cyclic control, it was confirmed that the contribution of cyclic control was more enhanced at waterjet frequencies ranging from 0.8 to 2.0 s-1 and at duty ratios ranging from 0.33 to 0.6. These estimated patterns of cyclic control were included in the turning performance test conditions of “Raicho-S”. Improvement of turning performance, including increase in turning speed and decrease in turning radius, was confirmed. The increasing and decreasing tendencies of turning speed in relation to the jet frequency and the duty ratio were in qualitative agreement with those of thrust power predicted in the preliminary analysis. The turning performance during cyclic control was confirmed to be optimized at the condition in which the jet frequency and the duty ratio were respectively 1 s-1 and 0.33 in the present test conditions.

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