Marine Dual-fuel Engine Research Articles

Size and morphology of soot produced by a dual-fuel marine engine

In recent years, liquefied natural gas (LNG) has become a popular alternative to heavy fuel oils for use in marine engines due to its low cost and increasingly stringent emissions regulations from the International Maritime Organization (IMO). While natural gas (NG) combustion produces substantially less soot than other fossil fuels, its soot emissions are not negligible and have not been morphologically characterized. In this study, transmission electron microscopy (TEM) was used to interpret scanning mobility particle sizer (SMPS) distributions of catalytically-denuded particulate matter (soot) from an NG-powered commercial vessel. The vessel studied was powered by a dual-fuel compression ignition engine which uses a diesel pilot only to ignite the NG. Less than 2% of the engine's power is provided by the diesel pilot for engine loads above 50%. For comparison, tests were also run in diesel-only mode. During NG operation, the SMPS size distributions did not follow a lognormal distribution as expected. Instead, the distribution remained roughly constant from 10 nm to 100 nm. High resolution (HR)-TEM revealed particles as small as 30 nm in diameter were soot. From the TEM images, soot primary particle size and projected-area-equivalent diameter were estimated for individual soot particles. These data were then used to infer the effective density of the particles collected. In general, the primary particle size and correspondingly the estimated effective density of soot from this engine were larger than those from the “universal fit” proposed for soot in previous literature. For both operating conditions the source of the soot was likely the diesel pilot however, there were statistically significant differences between particles produced by the two fuelling modes. With LNG fueling, there were far fewer particles, and mean soot aggregate size decreased, but the primary particle size (for a 100 nm aggregate) increased, relative to diesel. Engine load did not have a statistically significant effect on soot morphology.

Experimental Research on Controllability and Emissions of Jet-Controlled Compression Ignition Engine

Low-temperature combustions (LTCs), such as homogeneous charge compression ignition (HCCI), could achieve high thermal efficiency and low engine emissions by combining the advantages of spark-ignited (SI) engines and compression-ignited (CI) engines. Robust control of the ignition timing, however, still remains a hurdle to practical use. A novel technology of jet-controlled compression ignition (JCCI) was proposed to solve the issue. JCCI combustion phasing was controlled by hot jet formed from pre-chamber spark-ignited combustion. Experiments were done on a modified high-speed marine engine for JCCI characteristics research. The JCCI principle was verified by operating the engine individually in the mode of JCCI and in the mode of no pre-chamber jet under low- and medium-load working conditions. Effects of pre-chamber spark timing and intake charge temperature on JCCI process were tested. It was proven that the combustion phasing of the JCCI engine was closely related to the pre-chamber spark timing. A 20 °C temperature change of intake charge only caused a 2° crank angle change of the start of combustion. Extremely low nitrogen oxides (NOx) emission was achieved by JCCI combustion while keeping high thermal efficiency. The JCCI could be a promising technology for dual-fuel marine engines.

Effect of PCC Channel Angle on Combustion Characteristics of a Marine Dual Fuel Engine

Effect of PCC Channel Angle on Combustion Characteristics of a Marine Dual Fuel Engine

Characterization and Reduction of In-Use CH4 Emissions from a Dual Fuel Marine Engine Using Wavelength Modulation Spectroscopy.

In-use exhaust stream CH4 emissions from two dual fuel marine engines were characterized and strategies for CH4 reduction were identified and evaluated. For this, a low-cost, portable, wavelength modulation spectroscopy (WMS) system was developed. The performance of the developed WMS sensor was assessed using gas standards and demonstrated on a heavy-duty, diesel pilot ignited, direct-injection natural gas research engine through comparison to a flame ionization detector. The WMS sensor was subsequently used to measure the exhaust-stream CH4 concentration from two diesel pilot-ignited, port-injected natural gas engines on a coastal vessel while under normal operation. Using cylinder deactivation to reduce the excess air ratio, λ, and vessel operation changes to minimize operation at lower loads, the total CH4 emission were reduced by up to 33%. The measured, load specific CH4 emissions were subsequently used to identify an improved vessel operation strategy, with an estimated 56-60% reduction in CH4 emissions. These results demonstrate the importance of considering the real-world engine operation profile for accurate estimates of the global warming potential, as well as the utility of a WMS sensor for characterizing and mitigating in-use CH4 emissions.

Influence of intake parameters on combustion and emission performance of dual-fuel Marine diesel engines

We in order to study the influence of intake parameters on the combustion and emission of natural gas-diesel dual-fuel Marine engine, AVL_FIRE simulation software was used to build a high pressure cycle model of combustion chamber based on 4190ZLC-2 Marine medium-speed diesel engine. The accuracy of the model was verified by comparing the simulation data with the cylinder pressure curve obtained from bench test. The influence of intake parameters on combustion and emission performance was studied by model simulation. The results show that the combustion quality can be improved by increasing the intake temperature, and the power performance and economy can be improved by appropriate intake temperature. Increasing the intake pressure has the effect of supercharging, appropriately increasing the intake pressure can obtain better power and emission, and can also avoid the rough operation of dual-fuel diesel engine and reduce the noise

Efficiency Improvement of a Natural Gas Marine Engine Using a Hybrid Turbocharger

The use of a computer simulator, previously developed and validated, applied to a four-stroke marine dual-fuel engine, has allowed the authors to present in this paper a solution to improve the overall efficiency of the engine by adopting a hybrid turbocharger. This component replaces the original one allowing, in addition to maintaining the previous usual functions, the production of electricity to satisfy part of the ship’s electric load. In this study the application of the hybrid turbocharger concerns an engine powered by natural gas in particular. The turbocharger substitution involves a significant variation of the engine load governor operating mode. The improved engine characteristics that the hybrid turbocharger facilitates, compared to the original, are highlighted by the results reported in tabular and graphical form, for different engine loads and speeds.

Development of an Optimized Skeletal Chemical Kinetic Mechanism for Methane Combustion for Marine Engine Applications

The goal of the present study is to develop an optimized skeletal chemical kinetic mechanism for methane combustion, for conditions relevant to dual-fuel marine engines. To this end, a systematic approach is developed, consisting of the following steps: (a) assessment of three widely used detailed mechanisms, by comparing simulation results against three sets of indirect experimental data pertinent to methane combustion, (b) sensitivity analysis, with identification of important reactions (species), (c) selection of one detailed mechanism and production of a skeletal mechanism by means of the simulation error minimization connectivity method, (d) uncertainty analysis of the rate constants of important reactions, and (e) optimization of the skeletal mechanism for the rate constant parameters of the important reactions. The resulting optimized skeletal mechanism, consisting of 28 species and 119 elementary reactions, accurately reproduces experimental data in a wide range of conditions and is an important development for computational fluid dynamics studies in dual-fuel marine engines.

舶用デュアルフューエル機関の開発

舶用デュアルフューエル機関の開発

Characteristic Analysis in Combustion Process of Marine Dual Fuel Engine

Currently, the research of marine dual fuel engine is rare, while the combustion process of marine dual fuel engine is no precise conclusion. This paper built a combustion model of dual fuel engine by AVL FIRE software, and compared experimental data to prove the accuracy of the model, analyzed the characteristics in combustion process of marine dual fuel engines, provided a theoretical basis for the further optimize and design of marine dual fuel engine.

Feedback Control during Mode Transition for a Marine Dual Fuel Engine

Mode transition is an important control challenge for dual fuel engines, particularly for marine applications where fuel quality and composition may vary over a wide range. Feedback control is critical for dealing with fuel uncertainties and assuring robust performance. In this paper, a model-based approach is pursued for dual fuel engine mode switch control. A mean-value control-oriented model for a marine dual fuel engine is constructed in MATLAB™/ Simulink™environment. This model is used to emulate the mode transition process for shipboard generator set applications. Three different control architectures are examined for feedback control based on engine speed regulation during mode transitions. Based on the metric that reflects engine speed tracking error, it is found that a Multiple Input Single Output (MISO) architecture with feedback corrections applied to both gas fuel and diesel is advantageous versus architectures that apply corrections to only one (either diesel or gas) fuel command.

High Operation Capable Marine Dual Fuel Engine with LNG

High Operation Capable Marine Dual Fuel Engine with LNG

The Prospective Analysis of Marine Dual Fuel Engine Application Based on Emission and Energy Efficiency

The new regulations on emissions and energy efficiency in the amendment to MARPOL Annex VI will become effective on January 1, 2013. The old-type marine main engine is difficult to come up to the new standard. Determining how to reduce the NOx, CO2 emissions and improve energy efficiency of ships draws a lot attention. The adaptability of marine dual fuel engine on the new regulations, EEDI and EEOI was studied, and the prospect of dual fuel engine is analyzed in this paper. To some extent, it has guiding meaning in the development of the marine main engine.

Selected aspects of application of dual fuel marine engines

The paper presents examples of application of dual fuel marine engines based on the expertise of the largest marine engine manufacturers. The fueling systems of these engines have been presented as fueled with fuel gases in various combinations with liquid fuels. Examples of the application of dual fuel engines in vessels as well as variants of the powertrains have been shown. The results of own simulation research (Monte Carlo method) have also been presented related to the NOx emission from a variety of vessels operating in the area of the Bay of Gdansk proving that the use of engines fueled with fuel gas may indeed reduce the emission of NOx from marine vessels operating in this area.