A multi-zone direct-injection (DI) diesel combustion model has been implemented for full cycle simulation of a turbocharged diesel engine. The above combustion model takes into account the following features of the spray dynamics: • the detailed evolution process of fuel sprays; • interaction of sprays with the in-cylinder swirl and the walls of the combustion chamber; The above sub-models were integrated into DIESEL-RK software, which is a full-cycle engine simulation tool, allowing more advanced analysis of PCCI and HCCI diesels.
There is increasing interest in application of various alternative fuels in marine diesel engines, including methanol. One of the challenges in the relevant research is the development of computer codes for simulation of the dual-fuel working process and engineering optimization of engines. In this work the mathematical model is described which simulates a mixture formation and combustion in an engine with a dual-fuel system, in which methanol is used as main fuel and a pilot portion of diesel oil is injected to ignite methanol. The developed combustion model was incorporated into the existing engine full cycle thermodynamic simulation tool, namely DIESEL-RK [1]. The developed combustion model includes the self-ignition delay calculation sub-model based on the detail chemistry simulation of methanol pre-combustion reactions, sub-model of evaporation of methanol droplets, submodels of methanol fuel sprays penetration, spray angle and droplets forming, respectively. The developed computer code allows engineers to account for the arbitrary shape of the combustion chamber. Additionally, each fuel system (for methanol and diesel oil) may include several injectors with arbitrary oriented nozzles with different diameters and central, off-central and side location in the combustion chamber. The fuel sprays evolution model consists of equations with dimensionless parameters to account for fuel properties and in-cylinder conditions. Specifics of injection pressure profiles and interaction of sprays with the air swirl and between themselves are also considered. The model allows engineers to carry out rapid parametric analysis. Results of modelling for a medium speed dual-fuel diesel engine are presented which demonstrate a good agreement between calculated and experimental heat release curves and integral engine data.
Using biodiesel fuel in diesel engines for heavy-duty transport is important to meet the stringent emission regulations. Biodiesel is an oxygenated fuel and its physical and chemical properties are close to diesel fuel, yet there is still a need to analyze and tune the fuel injection parameters to optimize the combustion process and emissions. A four-injections strategy was used: two pilots, one main and one post injection. A highly advanced SOI decreases the NOx and the compression work but makes the combustion process less efficient. The pilot injection fuel mass influences the combustion only at injection close to the top dead center during the compression stroke. The post injection has no influence on the compression work, only on the emissions and the indicated work. An optimal injection strategy was found to be: pilot SOI 19.2 CAD BTDC, pilot injection fuel mass 25.4%; main SOI 3.7 CAD BTDC, main injection fuel mass 67.3% mg; post SOI 2 CAD ATDC, post injection fuel mass 7.3% (the injection fuel mass is given as a percentage of the total fuel mass injected). This allows the indicated work near the base case level to be maintained, the pressure rise rate to decrease by 20% and NOx emissions to decrease by 10%, but leads to a 5% increase in PM emissions.
The article covers analysis of the technical measures, aimed at meeting the requirements on motor vehicles harmful substances emissions. Assessment estimates of expenses for fulfilling of harmful emissions standards from Euro 4 to Euro 6for light commercial vehicle engine with swept volume 2.0 liter with an aftertreatment system. The articles covers diesel, gasoline and natural gas engines.
This article describes a study that aimed to estimate the fuel-saving potential possessed by the hybridization of conventional powertrains intended for heavy-duty vehicles based on diesel and natural gas fueled engines. The tools used for this analysis constitute mathematical models of vehicle dynamics and the powertrain, including its components, i.e., the engine, electric drive, transmission, and energy storage system (ESS). The model of the latter, accompanied by experimental data, allowed for an analysis of employing a supercapacitor regarding the selection of its energy content and the interface between the traction electric drive and the ESS (in light of the wide voltage operating range of supercapacitors). The results revealed the influence of these factors on both the supercapacitor efficiency (during its operation within a powertrain) and the vehicle fuel economy. After implementation of the optimized ESS design within the experimentally validated vehicle model, simulations were conducted in several driving cycles. The results allowed us to compare the fuel economy provided by the hybridization for diesel and gas powertrains in different driving conditions, with different vehicle masses, taking into account the onboard auxiliary power consumption.The complicating aspect of replacing diesel engines with gas engines is the necessity of having an onboard storage for the compressed or liquefied gas, which constitutes a complex system that has its own cost, service, safety, and other issues. Therefore, whether to choose a gas-based vehicle or stay conservative with a diesel-based option becomes a trade-off decision.During the past few years, the National Research Center "NAMI" has been conducting an R&D project in cooperation with one of the country's major producers of heavy-duty vehicles. The project was aimed toward developing a gas-fueled engine family derived from the diesel engine that was newly developed by the aforementioned HD vehicle manufacturer. One can find the details on the project and its results in References [7][8][9]. The main outcomes of the project were the gas-fueled engines (see example in Figure 1) operating with the Otto and Miller thermodynamic cycles. The engines were installed in vehicles intended for long-haul operations (also shown in Figure 1) and tested in road conditions.
Abstract. This work is devoted to the experimental investigation of the possibilities to reduce greenhouse gas emissions and to increase energy efficiency of engines that use natural gas as the main fuel and the analysis of economic efficiency of use of dual fuel engines in vehicles compared to conventional diesel. The results of experimental investigation of a 190 kW dualfuel engine are presented; it is shown that quantitative and qualitative working process control may ensure thermal efficiency at the same level as that of the diesel engine and in certain conditions 5...8% higher. The prospects for reduction of greenhouse gas emissions have been assessed. The technical and economic evaluation of use of dual fuel engines in heavy-duty vehicles has been performed, taking into account the total life cycle. It is shown that it is possible to reduce life cycle costs by two times.
Modern research in the area of internal combustion engines is focused on researching and investigating the technologies that will improve fuel efficiency and decrease emissions. Application of dual-fuel engines is considered as a potential solution to these problems. In the dual-fuel engine, a natural gas-air mixture is ignited by a small amount of the diesel fuel directly injected into a combustion chamber. Pilot fuel injection parameters can strongly effect the combustion process. The aim of this paper is to investigate the effect of such fuel-supply parameters as pilot fuel mass, pilot fuel injection pressure, pilot fuel injection timing and excess air ratio on the combustion process. Investigation is based on the data obtained during bench tests conducted with the use of measurement equipment. The dependences of engine characteristics from the fuel supply parameters under review were obtained based on the results of the experimental study. Optimal values for every investigated fuel-supply parameter were chosen based on the obtained results. Over the course of the investigation, the coefficient for heat release rate according to the Vibe equation was calculated for each operating point.
The paper related to developing of a new gas engines with high energy efficiency and meeting future emission standards. It is necessary to develop complex exhaust gas aftertreatment systems to treat the toxic components efficiently when the engine runs on stoichiometric and lean mixtures. It is proposed to use new combination of three-way catalyst for working on stoichiometric mixtures and a selective catalytic reduction system for NO x aftertreatment on lean mixtures. Experimental studies have shown that efficient (over 90%) conversion of gas engine exhaust components takes place in the range of air excess ratio from 0.99 to 1.01. Theoretical studies have shown that the highest efficiency of nitrogen oxides reduction is achieved in the temperature range of 400...500°C and reaches over 97%.
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