Natural Gas Diesel Engine Research Articles

Numerical and optimization modeling of dual-fuel natural gas–diesel engine at the idle load

Numerical and optimization modeling of dual-fuel natural gas–diesel engine at the idle load

Numerical Study on the Combustion and Emission Characteristics of a Partial Premixed Direct Injection Natural Gas-Diesel Engine

ABSTRACT This study investigated the impact of injection strategy on combustion and emission characteristics of a partial premixed direct injection natural gas engine, using the Cummins ISX engine as a numerical model. Specifically, the influence of diesel injection timing and pressure on engine performance was analyzed with a fixed natural gas energy substitution ratio. It is found that advancing the diesel injection timing leads to longer the ignition delay time of diesel since temperature is lower than at top dead center. This resulted in a rapid initial heat release, which further increased the in-cylinder temperature at the beginning of combustion and shortened the combustion duration. Moreover, increasing the pilot diesel injection pressure resulted in longer diesel spray penetration and a higher proportion of natural gas consumption at the beginning of combustion, eventually leading to a faster in-cylinder temperature rise. The findings highlight that optimizing the combustion phasing and combustion temperature by adjusting the diesel injection parameters to avoid too high combustion temperature and negative work at compression end, which can effectively reduce nitrogen oxides emissions while maintaining high indicated mean effective pressure.

Methane slip reduction of conventional dual-fuel natural gas diesel engine using direct fuel injection management and alternative combustion modes

Alternative combustion mode and change of spray geometry show potential for methane slip reduction in a dual fuel diesel-natural gas internal combustion engine. Three combustion regimes are simulated; a conventional diesel methane dual-fuel combustion and two modes of reactivity controlled compression ignition (RCCI) with early (EIRCCI) and late (LIRCCI) injections. Methane is injected as the premixed fuel into the port and diesel as direct-injected fuel in all combustion modes. The start of direct fuel injection (SOI) is used as the combustion management tool, swiping from misfiring to knock limits at part loads.By switching combustion mode from conventional (CDF) to LIRCCI and EIRCCI, methane slip is reduced by 12% and 33%, respectively. SOI is used effectively to manage methane slip in any combustion mode, but the effect is more substantial in the EIRCCI mode.Emission results support methane slip trends’ observations. Nitrogen oxides (NOx) emission is increased in CDF by advancing SOI and decreased in both the LIRCCI and EIRCCI modes. Compared to CDF, late and early injection RCCI modes produce 417% and 67% more soot. Also, results show that high levels of methane slip in CDF can be reduced to some extent without any geometry modification by SOI management.Three diesel spray angles (SAs) of 60, 90, 120° are examined. Minimum methane slip is obtained when the SA is towards the squish area, and maximum methane slip is obtained when the SA is towards the piston bowl. Increasing SA from 60 to 90 and 120° results in a 16.4% and 42.5% reduction of methane slip.

Methane Slip Reduction of Conventional Dual-Fuel Natural Gas Diesel Engine Using Direct Fuel Injection Management and Alternative Combustion Modes

Methane Slip Reduction of Conventional Dual-Fuel Natural Gas Diesel Engine Using Direct Fuel Injection Management and Alternative Combustion Modes

Exergoeconomic Analysis of an Industrial Cogeneration Cooling System Powered By Natural Gas Fueled Diesel Engine

This study presents the exergy and exergoeconomic analysis of a natural gas-powered diesel cogeneration system. The cogeneration system is designed for a sports complex with 1000 m2 closed area in Afyonkarahisar city. Natural gas is used as the fuel in the cogeneration system of the sports complex, which includes a swimming pool and ice rink. The natural gas diesel engine is used as the primary energy source for the cogeneration system. In the system, the electricity required for the cooling cycle is produced from the natural gas diesel engine. At the same time, the engine exhaust gases are used in the process of heat generation for swimming pool water heating. Finally, the waste heat discharged from the system is used to produce electricity in the thermoelectric power unit. The cogeneration system was modeled thermodynamically by the EES program on a computer and then economically analyzed by using the Aspen Plus program. The operation of the cogeneration system is described in detail, and a methodology based on exergoeconomic relations and SPECO method is provided to allocate cost flows through subcomponents of the system. The results were compared by using thermodynamic and exergoeconomic performance parameters. The exergetic efficiency of the cogeneration system is found to be 28.74%, which indicates that 71.26% of the total exergy input to the system, mainly by natural gas, is destroyed. As a result of the economic analysis of the cogeneration system, the investment cost was calculated as 62,000 $. The exergetic cost rate and the specific unit exergetic cost of the power produced in the cogeneration system are calculated to be 0.75 $/h and 10.93 $/GJ (0.039 $/kWh), respectively. The specific unit exergetic cost of the energy produced in the cogeneration system for cooling the ice rink and heating the swimming pool in the sports complex are calculated to be 6.152 $/GJ (0.022 $/kWh) and 4.221 $/GJ (0.0152 $ /kWh), respectively.

Development of a Phenomenological Dual-Fuel Natural Gas Diesel Engine Simulation and Its Use for Analysis of Transient Operations

Development of a Phenomenological Dual-Fuel Natural Gas Diesel Engine Simulation and Its Use for Analysis of Transient Operations

Hybrid-Electric Vehicle with Natural Gas-Diesel Engine

In this paper we demonstrate the potential of combining electric hybridization with a dual-fuel natural gas-Diesel engine. We show that carbon dioxide emissions can be reduced to 43 gram per kilometer with a subcompact car on the New European Driving Cycle (NEDC). The vehicle is operated in charge-sustaining mode, which means that all energy is provided by the fuel. The result is obtained by hardware-in-the-loop experiments where the engine is operated on a test bench while the rest of the powertrain as well as the vehicle are simulated. By static engine measurements we demonstrate that the natural gas-Diesel engine reaches efficiencies of up to 39.5%. The engine is operated lean at low loads with low engine out nitrogen oxide emissions such that no nitrogen oxide aftertreatment is necessary. At medium to high loads the engine is operated stoichiometrically, which enables the use of a cost-efficient three-way catalytic converter. By vehicle emulation of a non-hybrid vehicle on the Worldwide harmonized Light vehicles Test Procedure (WLTP), we demonstrate that transient operation of the natural gas-Diesel engine is also possible, thus enabling a non-hybridized powertrain as well.

Hybrid-Electric Vehicle with Natural Gas-Diesel Engine

In this paper we demonstrate the potential of combining electric hybridization with a dual-fuel natural gas-Diesel engine. We show that carbon dioxide emissions can be reduced to 43 gram per kilometer with a subcompact car on the New European Driving Cycle (NEDC). The vehicle is operated in charge-sustaining mode, which means that all energy is provided by the fuel. The result is obtained by hardware-in-the-loop experiments where the engine is operated on a test bench while the rest of the powertrain as well as the vehicle are simulated. By static engine measurements we demonstrate that the natural gas-Diesel engine reaches efficiencies of up to 39.5%. The engine is operated lean at low loads with low engine out nitrogen oxide emissions such that no nitrogen oxide aftertreatment is necessary. At medium to high loads the engine is operated stoichiometrically, which enables the use of a cost-efficient three-way catalytic converter. By vehicle emulation of a non-hybrid vehicle on the Worldwide harmonized Light vehicles Test Procedure (WLTP), we demonstrate that transient operation of the natural gas-Diesel engine is also possible, thus enabling a non-hybridized powertrain as well.

Combustion and emission characteristics of a natural gas-fueled diesel engine with EGR

The use of natural gas as a partial supplement for liquid diesel fuel is a very promising solution for reducing pollutant emissions, particularly nitrogen oxides (NOx) and particulate matters (PM), from conventional diesel engines. In most applications of this technique, natural gas is inducted or injected in the intake manifold to mix uniformly with air, and the homogenous natural gas–air mixture is then introduced to the cylinder as a result of the engine suction.This type of engines, referred to as dual-fuel engines, suffers from lower thermal efficiency and higher carbon monoxide (CO) and unburned hydrocarbon (HC) emissions; particularly at part load. The use of exhaust gas recirculation (EGR) is expected to partially resolve these problems and to provide further reduction in NOx emission as well.In the present experimental study, a single-cylinder direct injection (DI) diesel engine has been properly modified to run on dual-fuel mode with natural gas as a main fuel and diesel fuel as a pilot, with the ability to employ variable amounts of EGR. Comparative results are given for various operating modes; conventional diesel mode, dual-fuel mode without EGR, and dual-fuel mode with variable amounts of EGR, at different operating conditions; revealing the effect of utilization of EGR on combustion process and exhaust emission characteristics of a pilot ignited natural gas diesel engine.

Theoretical study of the effects of engine parameters on performance and emissions of a pilot ignited natural gas diesel engine☆

With the increasing concern regarding diesel vehicle emissions and the rising cost of the liquid diesel fuel as well, more conventional diesel engines internationally are pursuing the option of converting to use natural gas as a supplement for the conventional diesel fuel (dual fuel natural gas/diesel engines). The most common natural gas/diesel operating mode is referred to as the pilot ignited natural gas diesel engine (PINGDE) where most of the engine power output is provided by the gaseous fuel while a pilot amount of the liquid diesel fuel injected near the end of the compression stroke is used only as an ignition source of the gaseous fuel–air mixture. The specific engine operating mode, in comparison with conventional diesel fuel operation, suffers from low brake engine efficiency and high carbon monoxide (CO) emissions. In order to be examined the effect of increased air inlet temperature combined with increased pilot fuel quantity on performance and exhaust emissions of a PINGD engine, a theoretical investigation has been conducted by applying a comprehensive two-zone phenomenological model on a high-speed, pilot ignited, natural gas diesel engine located at the authors' laboratory. The main objectives of the present work are to record the variation of the relative impact each one of the above mentioned parameters has on performance and exhaust emissions and also to reveal the advantages and disadvantages each one of the proposed method. It becomes more necessary at high engine load conditions where the simultaneous increase of the specific engine parameters may lead to undesirable results with nitric oxide emissions.

Theoretical study of the effects of pilot fuel quantity and its injection timing on the performance and emissions of a dual fuel diesel engine

Various solutions have been proposed for improving the combustion process of conventional diesel engines and reducing the exhaust emissions without making serious modifications on the engine, one of which is the use of natural gas as a supplement for the conventional diesel fuel, the so called dual fuel natural gas diesel engines. The most common type of these is referred to as the pilot ignited natural gas diesel engine (PINGDE). Here, the primary fuel is natural gas that controls the engine power output, while the pilot diesel fuel injected near the end of the compression stroke auto-ignites and creates ignition sources for the surrounding gaseous fuel mixture to be burned. Previous research studies have shown that the main disadvantage of this dual fuel combustion is its negative impact on engine efficiency compared to the normal diesel operation, while carbon monoxide emissions are also increased. The pilot diesel fuel quantity and injection advance influence significantly the combustion mechanism. Then, in order to examine the effect of these two parameters on the performance and emissions, a comprehensive two-zone phenomenological model is employed and applied on a high-speed, pilot ignited, natural gas diesel engine located at the authors’ laboratory. According to the results, the simultaneously increase of the pilot fuel quantity accompanied with an increase of its injection timing results to an improvement of the engine efficiency (increase) and of the emitted CO emissions (decrease) while it has a negative effect (increase) of NO emissions.