Crosshead Diesel Engine Research Articles

Development of common rail lube oil injector for large two-stroke marine diesel engines

The two-stroke crosshead diesel engines, nowadays moving the majority of merchant vessels, have lubrication systems which significantly contribute to their overall emissions, since they work on total loss basis: a relevant fraction of lubricant enters the exhaust duct, increasing total exhaust emissions. This paper demonstrates that a viable solution to reduce lubrication system related emissions can be found in the application of a new common rail type ( CR) lubrication system. Particularly, in the first part of this study, a common rail injector was simulated and numerically optimized by means of AMESim. The main parameters influencing lube oil injected mass were identified, with the purpose to design a highly time responsive injector. Therefore, a CR injector was realized and experimentally characterized by means of a dedicated test cell, defining the lube oil injection map over the entire engine load range. Finally, full scale engine tests allowed to evaluate oil loss at exhaust, proposing, and applying the Sulfur tracing methodology. A comparison with a pulse jet lubrication system demonstrated a relevant reduction in oil loss: 100% engine load testes demonstrated decreases ranging from 56.2% to 63.3%, while once fixed the lube oil feed rate to 0.8 g/kWh a maximum reduction in oil loss equal to 66.7% was reached. These results allow nominating the common rail lubrication system as a feasible solution to significantly reduce oil loss at exhaust of large two-stroke marine diesel engines.

Определение норм расхода смазочного масла дизелями с учетом инновационной технологии их регенерации на судах

The article considers the current methods of calculating norms of lubricating oil consumption by marine diesels that provide for three causes of oil loss: oil burning, evaporation rate, and replacement expense. According to the manual, the lubricating oil consumption for replacement is considered only in trunk diesel engines; in main crosshead diesel engines with capacity over 3000 kW it is not considered and not performed. The lubricating oil consumption norms are proposed to carry out in terms of burnout and evaporation, according to the methods of determining fuel consumption norms. To determine consumption norms, it is necessary to know the oil consumption characteristic in relation to the load of the diesels and the load distribution in the ship operating mode. In the low speed crosshead diesel engines the circulating oil is only consumed for evaporation, but the trunk diesel engines consume oil for evaporation, burnout and replacement. The diagram of dependence of the relative cylinder oil consumption on the relative load of the diesel engine in the helical characteristic mode is illustrated. A simplified technological scheme of low-tonnage regeneration of the used motor oils is presented. It is proposed to calculate the oil consumption by the lubrication pump according to a nonlinear dependence based on the speed of the crankshaft at a specific mode. The analysis of the evaporation and burnout is recommended to carry out using a linear relationship, subject to oil consumption in the idle mode. The cost of circulating oil replacement is recommended to calculate according to the diesel operating time. Application of the used lubricating oil regeneration by means of a ship small-sized plant allows to achieve the oil consumption reduction by 19-48% depending on the ship operating mo

Design and experimental development of a new electronically controlled cylinder lubrication system for the large two-stroke crosshead diesel engines

Accurate, stable and reliable lubrication for the cylinders is very important to ensure the trouble-free operation of the marine diesel engines. A new electronically controlled cylinder lubrication system has been developed to remedy the defects of the conventional mechanical lubrication system. This new system’s design method, composition and implementation are described. The sensitivity tests are conducted on the test bench and the verification tests are also fulfilled on operating vessels. The main performance data are as follows: oil injection pressure about 3.0 MPa, oil injection timing precision 0.1 ms, oil injection duration 15 °CA or less. The oil injection concentrates onto the piston rings pack to ensure the good lubrication and neutralization, and the oil injection frequency is regulated according to engine load, the sulphur content in fuel, total base number of cylinder oil, cylinder liner running-in condition and so on. This results in the cylinder oil consumption rate falling approximately 25% compared with that of the conventional mechanical lubrication system. As a retrofit on vessels in service, the lubrication system has been fitted more than 120 main engines and has a payback period of less than 2 years.

Adaptive feedforward control of exhaust recirculation in large diesel engines

Environmental concern has led the International Maritime Organization to restrict NOx emissions from marine diesel engines. Exhaust gas recirculation (EGR) systems have been introduced in order to comply to the new standards. Traditional fixed-gain feedback methods are not able to control the EGR system adequately in engine loading transients so alternative methods are needed. This paper presents the design, convergence proofs and experimental validation of an adaptive feedforward controller that significantly improves the performance in loading transients. First the control concept is generalized to a class of first order Hammerstein systems with sensor delay and exponentially converging bounds of the control error are proven analytically. It is then shown how to apply the method to the EGR system of a two-stroke crosshead diesel engine. The controller is validated by closed loop simulation with a mean-value engine model, on an engine test bed and on a vessel operating at sea. A significant reduction of smoke formation during loading transients is observed both visually and with an opacity sensor.

Study Of Wear In Chrome Plated Cylinder Liner In Two Stroke Marine Diesel Engine Lubricated By Hans Jensen Swirl Injection Principle

Over the years, the two-stroke crosshead diesel engine has been the preferred prime mover for large seagoing merchant vessels.The cylinder liner is manufactured from Grey cast iron alloyed with vanadium, titanium and molybdenum. Grey cast iron contains graphite which itself is a decent lubricant and the alloying elements of Grey cast iron help in resisting corrosion and improve its wear resistance at elevated temperatures.And, this cylinder liner, usually, is not chrome plated. Theideaof this work is to study the wearthat occurs inchrome plated cylinder liner and compare it with the non chrome plated cylinder liner when it is lubricatedby Hans Jensen swirl injection principle in the two- stroke marine diesel engine that is available in AMET Majesty cruise ship.Cylinder liner lubrication is one of the major aspects that greatly influences wear in the liner. Consequently, this ventureis also aimed at describing a clear picture of how cylinder liner lubrication is accomplished using Hans Jensen swirl injection principle on two-stroke marine diesel engines.

Control-Oriented Model of Molar Scavenge Oxygen Fraction for Exhaust Recirculation in Large Diesel Engines

Exhaust gas recirculation (EGR) systems have been introduced to large marine engines in order to reduce NOx formation. Adequate modeling for control design is one of the bottlenecks to design EGR control that also meets emission requirements during transient loading conditions. This paper therefore focuses on deriving and validating a mean-value model of a large two-stroke crosshead diesel engine with EGR. The model introduces a number of amendments and extensions to previous, complex models and shows in theory and practice that a simplified nonlinear model captures all essential dynamics that is needed for EGR control. Our approach is to isolate and reduce the gas composition part of the more complex models using nonlinear model reduction techniques. The result is a control-oriented model (COM) of the oxygen fraction in the scavenge manifold with three molar flows being inputs to the COM, and it is shown how these flows are estimated from signals that are commonly available. The COM is validated by first comparing the output to a simulation of the full model, then by comparing with measurement series from two engines. The control-oriented nonlinear model is shown to be able to replicate the behavior of the scavenge oxygen fraction well over the entire envelope of load and blower speed range that are relevant for EGR. The simplicity of the new model makes it suitable for observer and control design, which are essential steps to meet the emission requirements for marine diesel engines that take effect from 2016.

２ストローククロスヘッド型機関用エンジン油の動向

２ストローククロスヘッド型機関用エンジン油の動向

大型クロスヘッドディーゼル機関のシリンダライナの変形―計算値と計測値の比較

An investigation was made into the deformation of a cylinder liner used in a large crosshead diesel engine. This deformation was calculated, but also measured. The results were then compared. They were not perfectly coincidental. The reason for the discrepancy is considered as applying the axis symmetrical model to a cylinder block being a complicated shape, inaccurate temperature distribution and improper modeling of the contact surfaces of the parts.

Secondary Motion of Piston in Large Crosshead Diesel Engines

A secondary motion of the piston in the large crosshead diesel engine was measured. The piston moves in the cylinder to Cam-Exhaust direction, and also to Fore-After direction. The factors affecting on the motion are discussed.

２１世紀の舶用機関システムの展望 Ｉｎｔｅｌｌｉｇｅｎｔ Ｅｎｇｉｎｅの将来性と就航実績

The paper deals with the development of computer controlled low speed crosshead diesel engines and the application prospects for such ‘Intelligent Engines’. The main development goals are enhanced reliability, reduced operational costs and great operational flexibility with regard to output and emissions. The concept is outlined and the paper describes the fuel injection and exhaust valve actuation systems, the electronic control system, the cylinder pressure measuring system and the cylinder lubrication system. Examples of the flexibility of the injection system are given.A full-scale service test of such a system on all cylinders of the 6L60MC main engine of the 37, 500 dwt Norwegian chemical carrier M/T Bow Cecil started in late 2000. The design of the systems is outlined, followed by a description of the experience with those parts of the new system which are already in service. Finally, the first commercial orders for ‘intelligent engine’, four 7S60ME-C engines, is dealt with.

The Analysis of the Lubrication Condition and Friction Losses of a Single Acting Cross Head Guide Shoe of a Low Speed Cross Head Diesel Engine: Part I—An Alogrithm For The Prediction of Oil Film Thickness

The lubrication condition pertaining to the cross head guide shoe of a low speed cross head diesel engine is evaluated in this paper under the principles of hydrodynamic lubrication. The Reynolds differential equation which describes the pressure and oil film thickness distribution of the cross head guide shoe system operating under unsteady load will be solved using a finite difference method. The influence of the width to length ratio of the rectangular cross head guide shoe plate will be considered in terms of variation of the pressure distribution within the bearing and its load carrying capacity.

The Analysis of the Lubrication Condition and Friction Losses of a Single Acting Cross Head Guide Shoe of a Low Speed Cross Head Diesel Engine: Part II — A Practical Model for the Determination of the Oil Film Thickness

The cross head guide shoe plate of a large diesel engine operates under a large normal force which presses it against the rails between which it executes both axial and transverse motion. In order to ensure the safe operation of an unconventional bearing such as the guide shoe system of the cross head engine, an algorithm that can be used to predict accurately the oil film thickness that can be achieved for all the engine's operating regimes, is invaluable. A solution of the three dimensional form of Reynolds differential equation can provide the requisite oil film thickness. However, with even the availability of very fast computers and large computer storage capacity this solution for a large axial bearing such as the guide shoe becomes impractical in terms of computation time and computer core requirements. This paper describes alternative simplified algorithm for accurate prediction of the oil film thickness developed in the guide shoe bearing at different operating regimes of the engine.

The Analysis of the Lubrication Condition and Friction Losses of a Single Acting Cross Head Guide Shoe of a Low Speed Cross Head Diesel Engine: PART III — Friction and Its Minimization

This paper describes a model which can be used to analyze the friction losses in the guide shoe of the cross head bearing of a large two stroke diesel engine. It describes further methods by which the friction losses in this component can be significantly reduced.

オフスペック燃料のディーゼルエンジンへの適用

Mitsui Engineering & Shipping Co., Ltd. has been carrying out research and development for utilizing various kind of off spec. fuels as fuel for diesel engines with the objective of diversifying fuel and sources, and putting inexpensive fuels to practical use. As the fuels deviate from the specifications of marine fuels, they are called off spec. fuel.This paper deals with straight vacuum residue, visbreaker residue, and Orimulsion® of the off spec. fuels investigated by Mitsui until now. The characteristics of the fuels, and performance, exhaust emissions and durability of a diesel engine in the case of using the fuels are described in this paper. All of the three off spec. fuels can be used in 2-stroke cross-head diesel engines, although the same grade of clarification as that for marine fuel oils, using a fuel which has lower viscosity and campatibility with the fuels for changeover at starting and stopping engines, heating up the fuels for controlling their viscosity below 20 mm2/s (20 cSt), etc., are indispensable.

Corrosive wear in crosshead diesel engines

Existing theories describe corrosive wear in crosshead diesel engines in terms of acid condensation, when the temperature in the combustion space drops below the dew point. Here a theory is proposed which stresses the role of alkaline cylinder lubricants in protecting the metal surface. Calculated liner wear rates as a function of fuel sulphur content, feed rate and alkalinity of the oil, and axial position are in satisfactory agreement with experimental data.

THE EFFECT OF USING AN ADDITIVE ON THE COMBUSTION BEHAVIOUR AND SOOT EMISSION OF MARINE FUELS

The ERC company has had an additive tested for its effect on the combustion behaviour and soot (exhaust gas) emission of marine fuels under shipboard conditions in a slow-rotating, 2-stroke crosshead diesel engine 6RTA72. Analysis of the determined combustion processes showed that when additve was used the combustion was completed sooner and the combustion turnover reduced whilst process and exhaust-gas temperatures were lowered at the same time. Moreover, reduced soot (exhaust gas) emission was recorded.