Applying detailed chemistry for the dual-fuel engine combustion process simulation using CFD approach

Modern research in the area of internal combustion engines is focused on searching and investigating the technologies that will improve fuel efficiency and decrease emissions. The application of dual-fuel engines is considered a potential solution to these problems. In the dual-fuel engine, the natural gas-air mixture is ignited by a small amount of diesel fuel directly injected into a combustion chamber. This paper aims to develop a detailed chemistry mechanism for 3D simulation of the combustion process of a dual-fuel engine, providing sufficient convergence with the experimental data. It should be noted that sufficient convergence must also be provided in terms of such parameters as pilot fuel ignition delay and premixed air-fuel mixture flame propagation speed. In the course of the research, the analysis of the most commonly used detailed chemistry mechanisms for calculation of the combustion process and mechanisms’ disadvantages was performed. The results obtained with the use of the detailed mechanisms were compared with the results obtained without using detailed chemistry and with the experimental data as well.

Thermophysical characteristics of gas-power dual-fuel engines w12v50 df for liquefied gas shipping vessels

Maritime transport plays important role in the economic development of society – 90% of goods are transported by ships. At the same time, maritime transport requires a significant amount of fuel resources. Production of liquefied natural gas (LNG) is becoming the fastest growing industry in the modern global energy sector. Today, LNG accounts for 40% of the physical volume of world gas trade, and its share will increase up to 60% by 2040. Currently, natural gas is used on ships in the form of liquefied petroleum gas, compressed natural gas, and liquefied natural gas (LNG). The article deals with the urgent problem of operation of dual-fuel diesel-electric installations of ships. The need to study the heat-engineering parameters of two-fuel diesel generators of the Wartsila company has been substantiated. The authors present the dependencies of main heat-engineering parameters on the load of Wartsila W12V50DF dual-fuel engines used as a generator drive in the main electric propulsion engines on LNG tankers. A comparative assessment of the dependencies of exhaust gas temperature, turbocharger rotation speed, boost pressure and gas pressure on the load of diesel generators on two LNG tankers has been carried out. The article analyzes the presented dependencies. The authors substantiate the need for further improvement of their design and workflow.

Effects of Gasoline-Diesel Ratio on Combustion and Emission Characteristics of a Dual-Fuel CI Engine: A CFD Simulation

Recently, considerable efforts are made by the engine researches all over the world, focusing primarily on achieving ultra-low emissions of NOx (nitrogen oxides) and soot without any compromise to high thermal efficiency from dual-fuel engine. In this study, combustion performance and engine-out emission of a single cylinder gasoline-diesel dual-fuel engine are numerically investigated by employing a commercial computation fluid dynamics (CFD) software, especially developed for internal combustion engines modeling. Here, gasoline-diesel relative ratio has been varied to find its impacts on performance of a dual-fuel engine. The results show that, in-cylinder pressure, in-cylinder temperature and rate of heat release (ROHR) are increased with gradual increment in diesel relative to gasoline. Injecting higher amount of diesel directly inside the combustion chamber as pilot fuel might have facilitated the auto-ignition process by reducing the ignition delay and accelerated the premixed gasoline-air flame propagation. These led to shorter main combustion duration which is quite desirable to suppress the knock in dual-fuel engines. In addition, NOx emission is found to decrease with relatively higher percentage of diesel. On the other hand, with increasing gasoline ratio relative to diesel, combustion duration is prolonged significantly and led to incomplete combustion, thereby increasing unburned hydrocarbon (UHC) and carbon monoxide (CO).

A Review of Low-CO2 Emission Fuels for a Dual-Fuel RCCI Engine

This article discusses the problems of exhaust gas emissions in the context of the possibility of their reduction through the use of fuels with hydrogen as an additive or hydrotreatment. These fuels, thanks to their properties, may be a suitable response to more and more demanding restrictions on exhaust emissions. The use of such fuels in reactivity controlled dual fuel engines (RCCI) is currently the most effective way of using them in internal combustion (IC) engines. Low-temperature combustion in this type of engine allows the use of all modern fuels intended for combustion engines with high thermal efficiency. Thermal efficiency higher than in classic engines allows for additional reduction of CO2 emissions. In this work, the research on this subject was compiled, and conclusions were drawn as to further possibilities of popularizing the use of these fuels in a wide spectrum of applications and the prospect of using them on a mass scale.

Assessment of technical and environmental performance of Marine Alternative fuels for Container Ships

Environmental issues, for example, the expanded air pollutant emissions from ships are progressively affecting the operation of ships. Therefore, International Maritime Organization (IMO) has adopted many goals to decarbonizing the shipping industry by at least 40% by 2030. Marine fuels play a major role in these goals because of the emissions resulting from the combustion process. Therefore, the present research proposes to convert the conventional engine operated by marine diesel oil (MDO) to a dual-fuel engine operated by either natural gas (NG) or methanol. As a case study, A15-class container ship is investigated. The results showed that the dual-fuel engine operated with (98.5% NG and 1.5% MDO) will reduce CO2, SOx, and NOx emissions by 28%, 98% and 85%, respectively when compared with their values for conventional diesel engine. On the other hand, the reduction percentages reach to 7%, 95% and 80% when using a dual-fuel engine operated with (95% Methanol and 5% MDO), respectively. The proposed dual-fuel engines operated by either NG and methanol will improve the ship energy efficiency index by 26% and 7%, respectively.

CFD Study and Experimental Validation of a Dual Fuel Engine: Effect of Engine Speed

Dual fuel engines induce benefits in terms of pollutant emissions of PM and NOx together with carbon dioxide reduction and being powered by natural gas (mainly methane) characterized by a low C/H ratio. Therefore, using natural gas (NG) in diesel engines can be a viable solution to reevaluate this type of engine and to prevent its disappearance from the automotive market, as it is a well-established technology in both energy and transportation fields. It is characterized by high performance and reliability. Nevertheless, further improvements are needed in terms of the optimization of combustion development, a more efficient oxidation, and a more efficient exploitation of gaseous fuel energy. To this aim, in this work, a CFD numerical methodology is described to simulate the processes that characterize combustion in a light-duty diesel engine in dual fuel mode by analyzing the effects of the changes in engine speed on the interaction between fluid-dynamics and chemistry as well as when the diesel/natural gas ratio changes at constant injected diesel amount. With the aid of experimental data obtained at the engine test bench on an optically accessible research engine, models of a 3D code, i.e., KIVA-3V, were validated. The ability to view images of OH distribution inside the cylinder allowed us to better model the complex combustion phenomenon of two fuels with very different burning characteristics. The numerical results also defined the importance of this free radical that characterizes the areas with the greatest combustion activity.