Stroke Marine Diesel Engine Research Articles

舶用４ストロークディーゼル機関用DPFの誘導加熱システムの研究

An induction heating system on a diesel particulate filter (DPF) applied to a 4 -stroke marine diesel engine is studied. The material and structure of the unit filter which comprises the DPF unit are introduced on the basis of the principle of induction heating. Experiments were conducted on a DPF developed for a marine 4 -stroke diesel engine. The PM (Particulate Matter) trapping characteristics were estimated in connection with PM reduction ratio. The DPF regeneration method is mentioned from the point of view of an equivalent electrical circuit of the induction heating load. The effectiveness of the DPF system is verified by experiments.

Impact of sulphuric acid on cylinder lubrication for large 2-stroke marine diesel engines: Contact angle, interfacial tension and chemical interaction

The effect of sulphuric acid on the chemical and physical behaviour of the piston ring lubricant in a marine engine cylinder was investigated. To reveal the basic influence of H2SO4 on the lubricant film, the saturated hydrocarbon Squalane (C30H62) was chosen as a simple model oil. The interfacial tension between aqueous H2SO4 (0–98% w/w) and C30H62 was measured between −3 and 165°C to understand droplet formation in the lubricant. Interfacial tension decreases with increasing acid concentration and is temperature dependent.The wettability of engine parts with corrosive sulphuric acid was characterised by the contact angle. The contact angle of H2SO4 (0–98% w/w) on a grey cast iron cylinder liner material (Wärtsilä, RT84) and a piston ring chrome-ceramic coating (Federal Mogul Goetze, CKS, ø960mm) immersed in C30H62 was measured over a temperature range from 20 to 165°C. In general, larger contact angles were measured under higher temperature conditions and on chrome surfaces.In addition to the physical measurements, chemical reaction between H2SO4 and C30H62 was observed which influenced the interfacial tension, visual appearance, phase separation and formation of solid matter. The reaction time was found to be faster than the neutralisation times of commercially formulated lubricants. The reaction products were analysed using FTIR spectroscopy and EDX to find oxidation and sulphonation.

Physical and Chemical Impact of Sulphuric Acid on Cylinder Lubrication for Large 2-Stroke Marine Diesel Engines

The influence of sulphuric acid, H2SO4, on the physical and chemical behaviour of marine Diesel engine lubricant base oils was investigated. To understand the basic interaction of H2SO4 with the lubricant film, the saturated hydrocarbon squalane, C30H62, was chosen as a simple model oil in addition to a fully formulated lubricant and its corresponding API Group I base oil HVI160B. To understand droplet formation in the lubricant, the interfacial tension between aqueous H2SO4 (0–98 %w/w) and C30H62 measured in a previous study (Sautermeister et al., Tribology International, 38th Leeds-Lyon Symposium on Tribology, 2011) and is compared with three different API Group I base oils. Interfacial tension decreases with increasing acid concentration, but is much lower for the base oil. Both oils were emulsified with a constant volume fraction of aqueous H2SO4. The droplet size was smaller and more distinct for the base oil under the same shearing conditions and the emulsions with base oil were are more stable. The concentration of the dispersed phase had no significant influence on the viscosity of the emulsions compared to the viscosity of the bulk oil alone. In addition to the physical measurements, chemical reaction between H2SO4 and the API Group I base oil HVI160B was observed yielding bituminous matter which appears to be a complex emulsion. The critical acid concentration for the formation of bitumen was found to be 40 %w/w. Between 50 and 80 %w/w, bitumen was formed spontaneously at 85 °C and above 85 %w/w, bitumen was formed spontaneously at room temperature. The observed concentrations for bitumen formation correlate well with the first and second dissociation steps of H2SO4. HSO4− ions are likely to be the driving force for bitumen formation. Finally, the viscosity characteristics of two different bitumen were measured. Both were found to exhibit shear thinning and the one formed with highly concentrated H2SO4 created a solid deposit on the measurement equipment above 120 °C.

Efficiency Improvement of Large Scale 2-Stroke Diesel Engines Through the Recovery of Exhaust Gas Using a Rankine Cycle

Highly increased fuel prices and the need for greenhouse emissions reduction from diesel engines used in marine and stationary applications make diesel engine exhaust gas heat recovery technologies attractive. Such technologies are of special importance for the large two stroke diesel engines due to their large absolute fuel consumption and long operating periods. In this type of engines despite their relatively low exhaust gas temperature there still exists a good potential to recover energy from the exhaust gas. While the use of Rankine cycle is already a well-established technology for energy production with increasing application base, it is still relatively new especially in the marine sector market. This technology offers advantages since it presents relatively high thermodynamic cycle efficiency at both part and full load operation, relatively simple start up procedures, automatic and continuous operation without operator intervention, simple maintenance procedures and long lifecycles. In the present paper, a theoretical study is conducted on a two stroke marine diesel engine equipped with a Rankine cycle to evaluate the potential benefits for fuel consumption. The results with some constraints are also valid for stationary engines used for power generation. A simulation model of the Rankine cycle was developed and employed to estimate the operating parameters of the system. The bottoming cycle considered exploits heat from the exhaust gas stream and the charge air cooler. A comparative evaluation is made for the increase of overall efficiency when using either steam or organic as working medium of Rankine cycle. The analysis reveals that specific fuel consumption is improved for the entire operating range of the installation. Considering the absolute fuel consumption of such engine, it appears to be a promising solution especially if fuel prices remain at the present levels or rise and towards the direction of CO2 emissions reduction.

Predicting Future States With $n$ -Dimensional Markov Chains for Fault Diagnosis

This paper introduces a novel method of predicting future concentrations of elements in lubrication oil, for the aim of identifying possible anomalies in continued operation aboard a large marine vessel. The research carried out is supported by a discussion of previous work in the field of fault detection in tribological mechanisms, although with a focus upon two stroke marine diesel engines. The approach taken implements an n-dimensional Markov chain model with a singular weighted connection between layers. The approach leverages the computational simplicity of the Markov chain and combines this with a weighted decision calculated from the correlational coefficients between variables, with the notable assumption that interconnectivity between elements is not constant. The approach is compared to an established method, which is the Kalman filter, with promising results for future work and extension of the method to include expert knowledge in the decision making process.

Particulate Emissions from a Low-Speed Marine Diesel Engine

This study presents results from tail pipe emissions of particulate matter from a turbocharged common rail 2-stroke marine diesel engine (4RTX-3 from Wartsila) investigated at various operating conditions and using two different fuels. Size distributions were measured with a SMPS (Scanning Mobility Particle Sizer). A thermodesorber (TD) was applied to remove volatile material. In addition, filter samples were taken for gravimetric and chemical analysis. The mean diameters of the particles ranged between 20–40 nm, which is considerably smaller than the diameter of particles known from 4-stroke diesel engines as used in cars. A TD operated at 400°C evaporated the majority of the particles. The particle mass is dominated by volatile organic material, the fraction of which is significantly higher than for engines in cars. A high nucleation mode was found instead of a pronounced accumulation mode as known from 4-stroke diesel engines.

２ストロークディーゼル機関の主軸受におけるジャーナル挙動（第１報 基本解析手法）

Journal movement theoretical analysis method is proposed which can be used to analyze journal movement behavior in main bearing of low speed 2-stroke marine diesel engine for practical usage. For proposing the method, crankshaft is idealized by a set of jointed structures consisting of simple round rods and simple beam blocks of rectangular cross section. The main bearings were idealized by linear spring support. Mobility method of short bearing theorem is used to calculate the journal bearing lubrication as an easy method. In order to solve by combining dynamical crankshaft behavior with journal bearing lubrication, transfer matrix method is applied. Then the journal movement such as journal center locus and journal tilts is calculated. An application example of the method is carried out by a 7-cylinder diesel engine. Journal center loci and journal tilts are also measured with 4 main bearings in an actual 7-cylinder diesel engine. The analyzed results are good correspondence with measured 4 journal results under full loaded condition. The method is also confirmed to be able to simulate faithfully journal movement behavior under several engine loaded condition. Finally, the validity of the method for practical usage is confirmed.

Discrete Speed Controller Design of a Marine Diesel Engine Including Sampling Effects due to Fuel Injection

A linear time invariant (LTI) model of a marine diesel engine is presented. The effect of the discontinuity of the fuel injection into the cylinders and the injection period is considered. The proposed discrete model consists of a sampler and zero-order-hold mechanism, representing the fuel injection process. The design of the discrete controller is based on the pole assignment of the characteristic polynomial of the closed-loop transfer function with the goal of achieving zero steady-state error, and satisfying other design specifications. A numerical example illustrating the characteristic performance of a two stroke marine diesel engine is presented.

燃料潤滑 大型舶用機関の主軸受の挙動解析

For improving the reliability of main bearing in large 2-stroke marine diesel engine, it is indispensable to grasp the journal movement behavior in main bearing with high accuracy. We have studied to disclose the journal movement behavior. Firstly, the journal movements of actual engines were measured. The journal center locus and the journal tilting angle were clarified. Secondly, a theoretical calculation model has been developed in order to simulate the journal movement behavior under uneven alignment between two adjacent main bearings. For confirming the validity of the model, calculated results were compared with measured results. The model was proved effective to simulate the journal movement in high accuracy. At last, by indicating an actual bedplate deflection owing to the loading of a vessel, the calculated journal movement results under the uneven alignment is compared with measured results. As the results, the developed model is able to simulate the journal movement under the uneven alignment. Considering the circumstances mentioned above, the model is proved effective to simulate the journal movement with high accuracy. The developed simulation technique of journal movement behavior has been applied in practical machinery design for high reliability.

Prediction of marine diesel engine performance under fault conditions

The diesel engine, due to its superior efficiency when compared to other thermal engines, is widely used for propulsion of marine vessels. Since in such applications the power concentration is critical, most marine diesel engines are of the turbocharged type. Turbocharging has a serious effect on engine performance due to the interaction between the turbocharger and the engine. This interaction makes the detection of engine faults extremely difficult since a specific fault affects the turbocharger and through it the engine. For this reason various methods have been proposed for the detection of engine faults. The present author has in the past presented a method for marine diesel diagnosis by processing measured engine data using a simulation model. In the present work a completely different approach is followed; an attempt is made to use a simulation model to predict marine diesel engine performance under various fault conditions. The method is applied to a newly built vessel powered by a slow speed two stroke marine diesel engine. Using the engine shop trial data obtained under propeller law the simulation model constants are determined, using an automatic method that has been developed. The comparison of results obtained with the data from the official shop trials confirms the accuracy of the model and its ability to predict almost all operating parameters of the engine. The model is then used to produce results by simulating various engine faults or faults of its subsystems. From this analysis their impact on various measurable engine parameters is determined. It is interesting to see that in the case of turbocharged engines some faults have a different effect when compared to naturally aspirated ones. Also, it is revealed that without the use of modeling in many cases it is relatively difficult to determine the actual cause for an engine malfunction, since the observed effects on engine performance are similar. The proposed method is promising and assists the engineer to understand the actual effect of various faults on engine performance. Also it can be used as a training tool since it is easy to simulate various engine faults, a procedure which is extremely difficult, if not impossible, to perform on the field.

舶用ディーゼル機関の主軸受の挙動

Recent large 2-stroke marine diesel engines have been developed for more powerful, longer strokes, lighter mass and in a more compact size. As for main bearings of the engines, the higher degree specifications have been required.For improving the reliability of the bearing, it has been important to grasp the behavior of the bearing as our first study. Measurement of the bearing behavior was carried out with a 7-cylinder diesel engine under the shop trial test. Measurement bearing was the fourth bearing from the fore side of the engine. The bearing is influenced by continuous combustion of both sides of cylinders, so it is considered that the bearing load during the combustion is severe.Gap sensors, pressure sensors and thermocouples were installed in the measurement bearing. Journal center locus, journal tilting behavior and oil film pressure under the journal tilting behavior were measured on various operating conditions. As the results, the sharp fluctuation of the journal tilting angle was observed during the continuous combustion on 100% propeller law characteristic. Maximum oil film pressure was also appeared at that time. The vertically projected height of the journal in the bearing by maximum tilting angle was almost equal to the half of the bearing clearance. The maximum oil film pressure was sufficiently less than the fatigue limit of white metal of the bearing. On the other hand, the sharp movement of the journal, which was harmful to the bearing, was not detected at starting of the engine.

低速ディーゼルシリンダドレン油分析によるシリンダ潤滑状態の診断

This paper reports the study on monitoring the cylinder lubricating condition of two stroke marine diesel engine by ferrograph analysis.When the number of large/severe or cutting ferrous wear particles is under 300 per 1 ml cylinder drain oil sample, the cylinder lubricating condition might be very good and be satisfied.

Development and application of a fully automatic troubleshooting method for large marine diesel engines

The diesel engine is the main propulsion system for marine vessels except for a small category using gas or steam turbines. This is the result of its high efficiency, power concentration and reliability that have been improved considerably during the current decade. Despite these advantages, the engineer usually has to overcome great difficulties and mainly operational problems arising during the engine's lifetime. In the case of large marine engines it is almost impossible to apply trial and error methods to solve engine operating problems. This is amplified by the fact that almost all large marine diesel engines are turbocharged ones making the problem even more severe because of the interaction between the engine and the exhaust gas turbocharger. For this reason various diagnosis methods have been proposed for diesel engine condition monitoring that are mainly statistical based on known engine operating curves. These systems provide general information only and do not reveal the actual cause for an engine fault or low performance. In the current work an advanced automatic troubleshooting method based mainly on thermodynamics is presented to monitor the engine condition and to detect the actual cause for an engine fault. The method is based on the processing of measured engine data using a simulation model and provides the current engine condition and its tuning. An application of the method on a marine vessel powered by a slow speed two stroke marine diesel engine suffering from high cylinder exhaust gas temperatures and low power output is given in the present work. The method is applied at sea under actual engine operating conditions. From the processing of measured data the diagnosis method provides the current engine condition and the cause for the low power output from which the engine suffered. After conducting the major repair/adjustments proposed by the diagnosis method a substantial improvement in engine behavior was observed providing a validation for the proposed method.

最近の舶用低速ディーゼル機関のシリンダライナ及びピストンリングの摩耗実績

A previous investigation regarding actual circumstances of the wear of low speed, long stroke 2 stroke marine diesel engines clarified their abnormal wear conditions. Since then makers have taken various countermeasures against wear, and in order to confirm the effects, the Japan Ship Owners Association has been collecting wear data. This report describes the results of wear conditions, based on the data of two years (April 1987-March 1989). 1. Statistics of Oil Feed Rate of each type. There are no differences between the actual feed rates converted in catalogue MCO of A type and C type. 2. Analysis of Wear Rate of Linear and Piston Ring. Liner wear characteristics of A type is getting stable comparing with the last investigation. But on the contrary, excessive wear of ring takes place similarly on A type, C type and D type. 3. Analysis of Oil Feed Rate - Wear Rate. It has been clarified that wear rate differs with each diesel maker. 4. Analysis Derating Rate - Wear Rate - Oil Feed Rate. A higher wear rate is found in the higher derating engine, and it is clarified that the oil feed rate on a high derating engine is too small.

Study on the Vibration and Strength of the Long Stroke Diesel Engine Crank Shaftings

Following the previous report which proposed a new calculation model for crank shaftings of the long stroke marine diesel engine and an evaluation method for the stiffness of crank throws, a calculation method for the coupled axial-torsional forced vibration is presented in this report. In the method, conversion of the crank pin force into the equivalent axial force is newly introduced. Moreover, accurate axial-torsional vibration measurements were carried out during both shop and sea trials. Minute analysis on the test results revealed the mechanism of the vibration.Calculation results by the new method show fairly good agreement with the measured ones only except for higher harmonics oscillation at the resonance of 1-node torsional vibration, which is recognized to be caused by non-linearity of the thrust block stiffness.

Laboratory engine testing of marine diesel cylinder lubricants : (A lecture) A. J. S. Baker and R. T. Davies. For a short version see Sci. Lubrication, 15 (1963) 19

The diesel engine is the main propulsion system for marine vessels except for a small category using gas or steam turbines. This is the result of its high efficiency, power concentration and reliability that have been improved considerably during the current decade. Despite these advantages, the engineer usually has to overcome great difficulties and mainly operational problems arising during the engine's lifetime. In the case of large marine engines it is almost impossible to apply trial and error methods to solve engine operating problems. This is amplified by the fact that almost all large marine diesel engines are turbocharged ones making the problem even more severe because of the interaction between the engine and the exhaust gas turbocharger. For this reason various diagnosis methods have been proposed for diesel engine condition monitoring that are mainly statistical based on known engine operating curves. These systems provide general information only and do not reveal the actual cause for an engine fault or low performance. In the current work an advanced automatic troubleshooting method based mainly on thermodynamics is presented to monitor the engine condition and to detect the actual cause for an engine fault. The method is based on the processing of measured engine data using a simulation model and provides the current engine condition and its tuning. An application of the method on a marine vessel powered by a slow speed two stroke marine diesel engine suffering from high cylinder exhaust gas temperatures and low power output is given in the present work. The method is applied at sea under actual engine operating conditions. From the processing of measured data the diagnosis method provides the current engine condition and the cause for the low power output from which the engine suffered. After conducting the major repair/adjustments proposed by the diagnosis method a substantial improvement in engine behavior was observed providing a validation for the proposed method.