Performance and Exhaust Emission Characteristics of a Spark Ignition Engine Operated With Gasoline and CNG Blend

2012 ◽  
Author(s):  
Mehrnoosh Dashti ◽  
Ali Asghar Hamidi ◽  
Ali Asghar Mozafari
Keyword(s):  
Experimental Data ◽  
Flame Front ◽  
Octane Number ◽  
Thermodynamic Cycle ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Working Fluid ◽  
Cylinder Wall ◽  
Emission Characteristics ◽  
Cycle Simulation

Using CNG as an additive for gasoline is a proper choice due to higher octane number of CNG enriched gasoline with respect to that of gasoline. As a result, it is possible to use gasoline with lower octane number in the engine. This would also mean the increase of compression ratio in SI engines resulting in higher performance and lower gasoline consumption. Over the years, the use of simulation codes to model the thermodynamic cycle of an internal combustion engine have developed tools for more efficient engine designs and fuel combustion. In this study, a thermodynamic cycle simulation of a conventional four-stroke spark-ignition engine has been developed. The model is used to study the engine performance parameters and emission characteristics of CNG/gasoline blend fuelled engine. A spark ignition engine cycle simulation based on the first law of thermodynamic has been developed by stepwise calculations for compression process, ignition delay time, combustion and expansion processes. The building blocks of the model are mass and energy conservation equations. Newton-Raphson method has been used to solve the equations numerically and there was no need to solve them analytically. In the quasi-dimensional combustion model, the cylinder is divided into two zones separated by a thin flame front. The flame front propagates spherically throughout the combustion chamber to the point that it contacts the cylinder wall and head. The model effectively describes the thermodynamic processes and chemical state of the working fluid via a closed system containing compression, combustion, and expansion processes. The model predicts the trends and tradeoffs the performance characteristics at various engine speeds. The variation of indicated power, ISFC and emissions are predicted by the model. Experimental data are also presented to indicate the validity of the model. The predicted results based on the model have shown reasonable agreement with the corresponding experimental data.

Illustration of the Use of an Instructional Version of a Thermodynamic Cycle Simulation for a Commercial Automotive Spark-Ignition Engine

2002 ◽  
Vol 30 (4) ◽  
pp. 283-297 ◽  
Author(s):  
Jerald A. Caton
Keyword(s):  
Thermodynamic Cycle ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Adjustment Factor ◽  
Cycle Simulation ◽  
Crank Angle ◽  
Overall Performance ◽  
Specific Heat Capacities ◽  
Model Components

The development and use of an instructional version of a thermodynamic engine cycle simulation for classroom use is described. This simulation is based on well-established features, but which are not necessarily the most advanced. The major simplification of this instructional simulation is the use of constant specific heat capacities as opposed to the use of variable composition and properties. The cycle simulation was developed with an elementary set of conventional sub-model components. To account for the unsteady flow dynamics, an empirical adjustment factor was used. With the exception of this empirical adjustment factor, all of the constants associated with the sub-models are used as suggested by the original publications. Students, therefore, are readily able to develop and use this simulation. This paper then demonstrates the usefulness of such a basic simulation in describing the overall performance of a commercial automotive spark-ignition engine for a range of engine speeds and operating conditions. A modern, four-valve per cylinder, two-camshaft engine was selected for this study. Although the cycle simulation was based on elementary conventional features, a number of important engine characteristics were correctly obtained. These included the overall performance for engine speeds up to 7000 rpm, and details such as the time (crank angle) of peak pressure for optimum performance.

A Multiple-Zone Cycle Simulation for Spark-Ignition Engines: Thermodynamic Details

2001 ◽  
Author(s):  
Jerald A. Caton
Keyword(s):  
Combustion Process ◽  
Load Condition ◽  
Engine Performance ◽  
Thermodynamic Cycle ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Engine Operation ◽  
Part Load ◽  
Cycle Simulation ◽  
The Individual

Abstract A thermodynamic cycle simulation was developed for a spark-ignition engine which included the use of multiple zones for the combustion process. This simulation was used to complete analyses for a commercial, spark-ignition V-8 engine operating at a part load condition. Specifically, the engine possessed a compression ratio of 8.1:1, and had a bore and stroke of 101.6 and 88.4 mm, respectively. A part load operating condition at 1400 rpm with an equivalence ratio of 1.0 was examined. Results were obtained for overall engine performance, for detailed in-cylinder events, and for the thermodynamics of the individual processes. In particular, the characteristics of the engine operation with respect to the combustion process were examined. Implications of the multiple zones formulation for the combustion process are described.

Utilizing a Cycle Simulation to Examine the Use of EGR for a Spark-Ignition Engine Including the Second Law of Thermodynamics

2006 ◽  
Author(s):  
Jerald A. Caton
Keyword(s):  
Combustion Process ◽  
Second Law Of Thermodynamics ◽  
Thermodynamic Cycle ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Second Law ◽  
Base Case ◽  
Nitric Oxides ◽  
Automotive Engine ◽  
Cycle Simulation

The use of exhaust gas recirculation (EGR) for a spark-ignition engine was examined using a thermodynamic cycle simulation including the second law of thermodynamics. Both a cooled and an adiabatic EGR configuration were considered. The engine was a 5.7 liter, automotive engine operating from idle to wide open throttle, and up to 6000 rpm. First, the reduction of nitric oxides is quantified for the base case condition (bmep = 325 kPa, 1400 rpm, φ = 1.0 and MBT timing). Over 90% reduction of nitric oxides is obtained with about 18% EGR for the cooled configuration, and with about 26% EGR for the adiabatic configuration. For constant load and speed, the thermal efficiencies increase with increasing EGR for both configurations, and the results show that this increase is mainly due to decreasing pumping losses and decreasing heat losses. In addition, results from the second law of thermodynamics indicated an increase in the destruction of availability (exergy) during the combustion process as EGR levels increase for both configurations. The major reason for this increase in the destruction of availability was the decrease in the combustion temperatures. Complete results for the availability destruction are provided for both configurations.

Thermo-Fluid Dynamic Simulation of a S.I. Single-Cylinder H2 Engine and Comparison With Experimental Data

2006 ◽  
Author(s):  
G. D’Errico ◽  
A. Onorati ◽  
S. Ellgas ◽  
A. Obieglo
Keyword(s):  
Experimental Data ◽  
Low Temperature ◽  
Dynamic Simulation ◽  
Fluid Dynamic ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Working Fluid ◽  
Simulation Code ◽  
Single Cylinder ◽  
Turbulent Flame Speed

This paper deals with the modelling and experimental work carried out on a BMW single cylinder spark ignition hydrogen engine. The authors have enhanced a 1D thermo-fluid dynamic simulation code in order to cope with the different chemical and physical aspects due to the fuelling of a spark ignition engine with hydrogen rather than with conventional gasoline. In particular the combustion module, which is based on a quasi-dimensional approach, has been extended by introducing the possibility of predicting the burning rate of the combustion of a homogeneous mixture of hydrogen and air. A fractal approach was followed for the turbulent flame speed evaluation, while an extend database for laminar burning velocities was created applying a kinetic simulation code for one-dimensional laminar flames. The modelling of the whole intake and exhaust systems coupled to the engine has been addressed, considering port-injection fuel system, in which hydrogen has been injected at very low temperature (cryogenic conditions). The fundamental 1D fluid-dynamic equations are solved by means of second order finite difference schemes; the working fluid is considered as a mixture of ideal gases, with specific heats depending on the gas temperature and the mole fractions of species, whose correlations for each specie (including para-hydrogen) have been extended in the region of low temperature. A first validation of the enhanced model is shown in the paper, comparing the computed results with the experimental data of in-cylinder pressures, intake and exhaust instantaneous pressure histories at different locations and NO emissions discharged by the cylinder.

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