scholarly journals The Effect of Intake Valve Timing on Spark-Ignition Engine Performances Fueled by Natural Gas at Low Power

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 398
Author(s):  
Alfredas Rimkus ◽  
Tadas Vipartas ◽  
Donatas Kriaučiūnas ◽  
Jonas Matijošius ◽  
Tadas Ragauskas
Keyword(s):  
Energy Source ◽  
Natural Gas ◽  
Alternative Energy ◽  
Combustion Process ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Valve Closure ◽  
Intake Valve ◽  
Valve Timing ◽  
Spark Timing

To reduce the greenhouse effect, it is important to reduce not only carbon dioxide but also methane emissions. Methane gas can be not only a fossil fuel (natural gas) but also a renewable energy source when it is extracted from biomass. After biogas has been purified, its properties become closer to those of natural gas or methane. Natural gas is an alternative energy source that can be used for spark-ignition engines, but its physicochemical properties are different from those of gasoline, and the spark-ignition engine control parameters need to be adjusted. This article presents the results of a study that considers a spark-ignition engine operating at different speeds (2000 rpm, 2500 rpm, and 3000 rpm) and the regulation of the timing of intake valve closure when the throttle is partially open (15%), allowing the engine to maintain the stoichiometric air–fuel mixture and constant spark timing. Studies have shown a reduction in engine break torque when petrol was replaced by natural gas, but break thermal efficiency has increased and specific emissions of pollutants (NOx, HC, CO2 (g/kWh)) have decreased. The analysis of the combustion process by the AVL BOOST program revealed different results when the engine ran on gasoline as opposed to when it ran on natural gas when the timing of intake valve closure changed. The volumetric efficiency of the engine and the speed of the combustion process, which are significant for engine performance due to the different properties of gasoline and natural gas fuels, can be partially offset by adjusting the spark timing and timing of intake valve closure. The effect of intake valve timing on engine fueled by natural gas more noticeable at lower engine speeds when the engine load is low.

An Experimental Study of the Combustion Process in a Natural-Gas Spark-Ignition Engine

2019 ◽  
Author(s):  
Jinlong Liu ◽  
Cosmin E. Dumitrescu ◽  
Hemanth Bommisetty
Keyword(s):  
Natural Gas ◽  
Equivalence Ratio ◽  
Internal Combustion Engines ◽  
Combustion Process ◽  
Spark Ignition ◽  
High Energy ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Intake Manifold ◽  
Spark Timing

Abstract The conversion of existing internal combustion engines to natural-gas operation can reduce U.S. dependence on petroleum imports and curtail engine-out emissions. In this study, a diesel engine with a 13.3 compression ratio was modified to natural-gas spark-ignited operation by replacing the original diesel injector with a high-energy spark plug and by fumigating fuel inside the intake manifold. The goal of this research was to investigate the combustion process inside the flat-head and bowl-in-piston chamber of such retrofitted engine when operated at different spark timings, mixture equivalence ratios, and engine speeds. The results indicated that advanced spark timing, a lower equivalence ratio, and a higher speed operation increased the ignition lag and made it more difficult to initiate the combustion process. Further, advanced spark timing, a larger equivalence ratio, and a lower speed operation accelerated the flame propagation process inside the piston bowl and advanced the start of the burn inside the squish. However, such conditions increased the burning duration inside the squish due to more fuel being trapped inside the squish volume and the smaller squish height during combustion. As a result, the end of combustion was almost the same despite the change in the operating conditions. In addition, the reliable ignition, stable combustion, and the lack of knocking showed promise for the application of natural-gas lean-burn spark-ignition operation in the heavy-duty transportation.

Simulation of Extended Expansion Lean Burn Spark Ignition Engine

2004 ◽  
Author(s):  
A. Manivannan ◽  
R. Ramprabhu ◽  
P. Tamilporai ◽  
S. Chandrasekaran
Keyword(s):  
Heat Transfer ◽  
Compression Ratio ◽  
Thermal Efficiency ◽  
Numerical Study ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Valve Closure ◽  
Intake Valve ◽  
Lean Burn ◽  
Atkinson Cycle

This paper deals with Numerical Study of 4-stoke, Single cylinder, Spark Ignition, Extended Expansion Lean Burn Engine. Engine processes are simulated using thermodynamic and global modeling techniques. In the simulation study following process are considered compression, combustion, and expansion. Sub-models are used to include effect due to gas exchange process, heat transfer and friction. Wiebe heat release formula was used to predict the cylinder pressure, which was used to find out the indicated work done. The heat transfer from the cylinder, friction and pumping losses also were taken into account to predict the brake mean effective pressure, brake thermal efficiency and brake specific fuel consumption. Extended Expansion Engine operates on Otto-Atkinson cycle. Late Intake Valve Closure (LIVC) technique is used to control the load. The Atkinson cycle has lager expansion ratio than compression ratio. This is achieved by increasing the geometric compression ratio and employing LIVC. Simulation result shows that there is an increase in thermal efficiency up to a certain limit of intake valve closure timing. Optimum performance is attained at 90 deg intake valve closure (IVC) timing further delaying the intake valve closure reduces the engine performance.

Two-Stage Lean-Burn Combustion Inside a Natural-Gas Spark-Ignition Engine With a Bowl-in-Piston Chamber

2019 ◽  
Author(s):  
Jinlong Liu ◽  
Cosmin E. Dumitrescu
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Combustion Process ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Intake Manifold ◽  
Hydrocarbon Emissions ◽  
Fuel Injector ◽  
Unburned Hydrocarbon ◽  
Piston Chamber

Abstract The conversion of existing diesel engines to spark ignition (SI) operation by adding a low-pressure injector in the intake manifold for fuel delivery and replacing the original high-pressure fuel injector with a spark plug to initiate and control the combustion process can reduce U.S. dependence on petroleum imports and increase natural gas (NG) applications in heavy-duty transportation sectors. Since the conventional diesel combustion chamber (i.e., flat-head-and-bowl-in-piston-chamber) creates high turbulence, the converted NG SI engine can operate leaner with stable and repeatable combustion process. However, existing literatures point to a long late-combustion duration and increased unburned hydrocarbon emissions in such retrofitted engines that maintained the original combustion chamber. Consequently, the main objective of this paper was to report recent findings of NG combustion characteristics inside a bowl-in-piston combustion chamber that will add to the general understanding of the phenomena. The new results indicated that the premixed NG burn inside the bowl-in-piston combustion chamber will separate into a bowl-burn and a squish-burn processes in terms of burning location and timing. The slow burning event in the squish region explains the low slope of the burn rate towards the end of combustion in existing studies (hence the longer late-combustion period). In addition, the less-favorable conditions for the combustion in the squish region explained the increased carbon monoxide and unburned hydrocarbon emissions.

Factors influencing the burn rate characteristics of a spark ignition engine with variable valve timing

2008 ◽  
Vol 222 (11) ◽  
pp. 2147-2158 ◽  
Author(s):  
F Bonatesta ◽  
P J Shayler
Keyword(s):  
Mass Fraction ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Variable Valve Timing ◽  
Valve Timing ◽  
Spark Timing ◽  
Piston Speed ◽  
Flame Development ◽  
Variable Valve ◽  
Valve Overlap

The charge burn characteristics of a four-cylinder port-fuel-injected spark ignition engine fitted with a dual independent variable-valve-timing system have been investigated experimentally. The influence of valve timings on the flame development angle and the rapid burn angle is primarily associated with valve overlap values and internal gas recirculation. Conditions examined cover light to medium loads and engine speeds up to 3500r/min. As engine loads and speeds exceeded about 6bar net indicated mean effective pressure and 3000r/min respectively, combustion duration was virtually independent of the valve timing setting. At lower speeds and work output conditions, valve timing influenced burn angles through changes in dilution mass fraction, charge density, and charge temperature. Of these, changes in dilution mass fraction had the greatest influence. Increasing the dilution by increasing the valve overlap produced an increase in both burn angles. The effects of mean piston speed and spark timing have also been examined, and empirical expressions for the flame development and the rapid burn angles are presented.

On the use of artificial neural networks to model the performance and emissions of a heavy-duty natural gas spark ignition engine

2021 ◽  
pp. 146808742110344
Author(s):  
Qiao Huang ◽  
Jinlong Liu ◽  
Christopher Ulishney ◽  
Cosmin E Dumitrescu
Keyword(s):  
Neural Network ◽  
Natural Gas ◽  
Combustion Process ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Heavy Duty ◽  
Network Algorithm ◽  
Performance And Emissions ◽  
Neural Network Algorithm ◽  
Artificial Neural

The use of computational models for internal combustion engine development is ubiquitous. Numerical simulations using simpler to complex physical models can predict engine’s performance and emissions, but they require large computational capabilities. By comparison, statistical methodologies are more economical tools in terms of time and resources. This paper investigated the use of an artificial neural network algorithm to simulate the nonlinear combustion process inside the cylinder. Three engine control variables (i.e. spark timing, mixture equivalence ratio, and engine speed) were set as the model inputs. Outputs included peak cylinder pressure and its location, maximum pressure rise rate, indicated mean effective pressure, ignition lag, combustion phasing, burn duration, exhaust temperature, and engine-out emissions (i.e. nitrogen oxides, carbon monoxide, and unburned hydrocarbons). Eighty percent of the experimental data from a heavy-duty natural gas spark ignition engine were utilized to train the model. The perceptions accurately learned the combustion characteristics and predicted engine responses with acceptable errors, evidenced by close-to-unity coefficient of determination and close-to-zero root-mean-square error. Moreover, the regressors captured the effect of key operating variables on the engine response, suggesting the well-trained models successfully identified the complex relationships and can help assist engine analysis. Overall, the neural network algorithm was appropriate for the application investigated in this study.

Characterizing Two-Stage Combustion Process in a Natural Gas Spark Ignition Engine Based on Multi-Wiebe Function Model

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Jinlong Liu ◽  
Chris Ulishney ◽  
Cosmin Emil Dumitrescu
Keyword(s):  
Natural Gas ◽  
Energy Release ◽  
Combustion Process ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Function Model ◽  
Two Stage ◽  
Long Tail ◽  
Stage Combustion ◽  
Wiebe Function

Abstract The Wiebe function is a simple and cost-effective analytical approach to approximate the burn rates in internal combustion (IC) engines. Previous studies indicated that a double-Wiebe function model can better describe the two-stage combustion process inside diesel engines retrofitted to natural gas (NG) spark ignition (SI) compared with a single-Wiebe function. Specifically, the two Wiebe functions are associated with the bowl burn and the squish burn. However, the long tail in the energy release at the end of combustion produces some differences between experiment and model, which can be attributed to the complexity of the late oxidation process inside the post-flame zone and the incomplete combustion of the unburned mixture flowing out from engine crevices. To improve the matching between the model and experimental data, this paper investigated the effect of adding a third Wiebe function just to describe the long tail in the energy release at the end of combustion. The results indicated that such a methodology greatly improved the fitting accuracy in terms of phasing and magnitude of the heat release rate in each combustion stage.

Numerical and Experimental Characterization of a Natural Gas Engine With Partially Stratified Charge Spark Ignition

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
E. C. Chan ◽  
M. H. Davy ◽  
G. de Simone ◽  
V. Mulone
Keyword(s):  
Natural Gas ◽  
Combustion Process ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Combustion Model ◽  
Turbulence Energy ◽  
Turbulent Fluctuation ◽  
Stratified Charge ◽  
Gas Engine ◽  
Natural Gas Engine

This paper outlines the development of a comprehensive numerical framework for the partially stratified charge (PSC) lean-burn natural gas engine. A 3D model of the engine was implemented to represent fluid motion and combustion. The spark ignition model was based on the works of Herweg and Maly (1992, “A Fundamental Model for Flame Kernel Formation in SI Engines,” SAE Technical Publication, Paper No. 922243) and Tan and Reitz (2006, “An Ignition and Combustion Model Based on the Level-Set Method for Spark Ignition Engine Multidimensional Modeling,” Combust. Flame, 145, pp. 1–15). The EDC model (Ertesvåg and Magnussen, 2000, “The Eddy Dissipation Turbulence Energy Cascade Model,” Combust. Sci. Technol., 159, pp. 213–235) with a two-step mechanism was used to model natural gas turbulent combustion process. An open geometry simulation strategy was adopted to account for intake-exhaust gas and valve movements. Each simulation was executed for multiple cycles to produce a representative residual gas fraction. The numerical results were compared with the experimental data obtained on the Ricardo Hydra single cylinder research engine for both homogeneous and PSC cases and they were found to be in excellent agreement in pressure trace and heat release rate. The detailed investigation of the numerical data showed the development of an ignitable mixture under PSC cases, allowing stable kernel growth well beyond the lean misfire limit of the bulk mixture. Furthermore, limits on successful ignition can be identified using the ignition model, which exhibited self-similar behavior in terms of flame speed and turbulent fluctuation. It can also be shown that, at ultralean air-fuel ratios, the PSC plume helps replicate the ignition conditions that can be found under stoichiometric operation.

scholarly journals Impact of Pyrolysis Oil Addition to Ethanol on Combustion in the Internal Combustion Spark Ignition Engine

2021 ◽  
Vol 3 (2) ◽  
pp. 450-461
Author(s):  
Magdalena Szwaja ◽  
Mariusz Chwist ◽  
Stanislaw Szwaja ◽  
Romualdas Juknelevičius
Keyword(s):  
Combustion Process ◽  
Engine Performance ◽  
Calorific Value ◽  
Internal Combustion ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Spark Ignition Engines ◽  
Pyrolysis Oil ◽  
Indicated Mean Effective Pressure ◽  
Spark Timing

Thermal processing (torrefaction, pyrolysis, and gasification), as a technology can provide environmentally friendly use of plastic waste. However, it faces a problem with respect to its by-products. Pyrolysis oil obtained using this technology is seen as a substance that is extremely harmful for living creatures and that needs to be neutralized. Due to its relatively high calorific value, it can be considered as a potential fuel for internal combustion spark-ignition engines. In order make the combustion process effective, pyrolysis oil is blended with ethanol, which is commonly used as a fuel for flexible fuel cars. This article presents results from combustion tests conducted on a single-cylinder research engine at full load working at 600 rpm at a compression ratio of 9.5:1, and an equivalence ratio of 1. The analysis showed improvements in combustion and engine performance. It was found that, due to the higher calorific value of the blend, the engine possessed a higher indicated mean effective pressure. It was also found that optimal spark timing for this ethanol-pyrolysis oil blend was improved at a crank angle of 2–3° at 600 rpm. In summary, ethanol-pyrolysis oil blends at a volumetric ratio of 3:1 (25% pyrolysis oil) can successfully substitute ethanol in spark-ignition engines, particularly for vehicles with flexible fuel type.

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