Measurement of Particulate Emission from Two-Stroke Marine Diesel Engine
Tatsuro TSUKAMOTO, Kenji OHE, Hiroshi OKADA*
With the increase of the concerns for the global environmental protection, the particulate emission of diesel engines is becoming increasingly serious. In this paper, experimental investigation was conducted with the low speed two-stroke marine diesel engine, to know the present condition and characteristics of particulate emission. The particulate emission from the test engine was measured by partial-flow dilution tunnel system. The effects of engine load, cylinder oil feed rate, temperature of cylinder cooling water and cetane index of the fuel on the particulate emission have been examined. The results show that an increase in engine load promotes both particulate and SOF (soluble organic fraction) emissions and that SOF concentration increases with an increase in cylinder oil feed rate or cooling water temperature. An analysis of SOF by gas chromatography suggests that cylinder lubrication has a significant effect on SOF emission. The effect of cetane index of the fuel is not clearly confirmed within the limits of this experiment.
Key Words: Marine diesel engine, Two-stroke engine, Particulate emission, Soot, SOF
In recent years, the global environmental protection has become of major interest in the world. The further reduction of particulates and NOx emission from diesel engines is a subject of study attracting the interest of many researchers. Concerning marine diesel engines, the regulations for air pollution from ships have been discussed by the International Maritime Organization(IMO)'s Marine Environment Protection Committee (MEPC). The regulation of NOx emission from ships is fixed and applied to engines installed on ships constructed after January 2000. Although there is no regulation on particulate emission from marine diesel engines at present, the information on particulate emission characteristics has become very important. Researches on particulate emission from large-size diesel engine for marine use are seldom found [1-4] and unclear points still remain.
In this report, measurement of particulate concentration in the exhaust gas was conducted with low speed two-stroke cross-head type marine diesel engine using diesel oil and small sized dilution tunnel system. The effects of the engine load, cylinder oil feed rate, temperature of cylinder cooling water and cetane index of the fuel on the particulate emission have been examined.
2. EXPERIMENTAL APPARATUS
The test engine used was a two-stroke, cross-head type, exhaust turbocharged marine diesel engine. The specifications of the test engine are listed in Table 1. Diesel oil was used for the fuel. Properties and constituents of applied fuel are shown in Table 2. In the experiment on the cetane index of the fuel, three kinds of diesel oil, MDO-1 (cetane index: 43.5), MDO-2 (cetane index: 35.5) and mixture of MDO-1 and MDO-2 in the ratio of 5 : 6 (volume) were used.