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.

Studying the effects of hydrogen addition on the second-law balance of a biogas-fuelled spark ignition engine by use of a quasi-dimensional multi-zone combustion model

2008 ◽  
Vol 222 (11) ◽  
pp. 2249-2268 ◽  
Author(s):  
C D Rakopoulos ◽  
C N Michos ◽  
E G Giakoumis
Keyword(s):  
Combustion Process ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Combustion Model ◽  
Second Law ◽  
Si Engine ◽  
Engine Operation ◽  
Hydrogen Addition ◽  
Cycle Simulation ◽  
Hydrogen Enrichment

Although a first-law analysis can show the improvement that hydrogen addition impacts on the performance of a biogas-fuelled spark-ignition (SI) engine, additional benefits can be revealed when the second law of thermodynamics is brought into perspective. It is theoretically expected that hydrogen enrichment in biogas can increase the second-law efficiency of engine operation by reducing the combustion-generated irreversibilities, because of the fundamental differences in the mechanism of entropy generation between hydrogen and traditional hydrocarbon combustion. In this study, an experimentally validated closed-cycle simulation code, incorporating a quasi-dimensional multi-zone combustion model that is based on the combination of turbulent entrainment theory and flame stretch concepts for the prediction of burning rates, is further extended to include second-law analysis for the purpose of quantifying the respective improvements. The analysis is applied for a single-cylinder homogeneous charge SI engine, fuelled with biogas—hydrogen blends, with up to 15 vol% hydrogen in the fuel mixture, when operated at 1500r/min, wide-open throttle, fuel-to-air equivalence ratio of 0.9, and ignition timing of 20° crank angle before top dead centre. Among the major findings derived from the second-law balance during the closed part of the engine cycle is the increase in the second-law efficiency from 40.85 per cent to 42.41 per cent with hydrogen addition, accompanied by a simultaneous decrease in the combustion irreversibilities from 18.25 per cent to 17.18 per cent of the total availability of the charge at inlet valve closing. It is also illustrated how both the increase in the combustion temperatures and the decrease in the combustion duration with increasing hydrogen content result in a reduction in the combustion irreversibilities. The degree of thermodynamic perfection of the combustion process from the second-law point of view is quantified by using two (differently defined) combustion exergetic efficiencies, whose maximum values during the combustion process increase with hydrogen enrichment from 49.70 per cent to 53.45 per cent and from 86.01 per cent to 87.33 per cent, respectively.

Results From an Engine Cycle Simulation of Compression Ratio and Expansion Ratio Effects on Engine Performance

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Jerald A. Caton
Keyword(s):  
Compression Ratio ◽  
Load Condition ◽  
Engine Performance ◽  
Constant Load ◽  
Expansion Ratio ◽  
Heat Losses ◽  
Spark Ignition Engine ◽  
Maximum Efficiency ◽  
Part Load ◽  
Cycle Simulation

This investigation quantified the effects of compression ratio (CR) and expansion ratio (ER) on performance, efficiency, and second law parameters for an automotive, spark-ignition engine. The well known increase in engine performance for increasing CR and ER is demonstrated. These increases for brake engine performance are modest for CRs greater than about 10 for the conditions studied. The results demonstrated that the increasing friction and heat losses for the higher CRs are of the same order as the thermodynamic gains. Also, the results included the destruction of availability during combustion. For a part load condition, the availability destroyed decreased from about 23% to 21% for CRs of 4 and 10, respectively. In addition, this study examined cases with greater ERs than CRs. The overall cycle for these cases is often called an “Atkinson” cycle. For most cases, the thermal efficiency first increased as ER increased, attained a maximum efficiency, and then decreased. The decrease in efficiency after the maximum value was due to the increased heat losses, increased friction, and ineffective exhaust processes (due to the reduced cylinder pressure at the time of exhaust valve opening). For part load cases, the higher ER provided only modest gains due to the increased pumping losses associated with the constant load requirement. For the wide open throttle cases, however, the higher ERs provided significant gains. For example, for a compression ratio of 10, expansion ratios of 10 and 30 provided brake thermal efficiencies of about 34% and 43%, respectively. Although the net thermodynamic gains are significant, large ERs such as 30 may not be practical in most applications.

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.

An Experimental and Numerical Investigation of Spark Ignition Engine Operation on H2, CO, CH4, and Their Mixtures

2009 ◽  
Vol 132 (3) ◽  
Author(s):  
Hailin Li ◽  
Ghazi A. Karim ◽  
A. Sohrabi
Keyword(s):  
Combustion Process ◽  
Engine Performance ◽  
Spark Ignition ◽  
Combustion Characteristics ◽  
Spark Ignition Engine ◽  
Engine Operation ◽  
Dry Air ◽  
Fuel Mixtures ◽  
Co Addition ◽  
H2 Addition

The knock and combustion characteristics of CO, H2, CH4, and their mixtures were determined experimentally in a variable compression ratio spark ignition (SI) cooperative fuel research (CFR) engine. The significant effects of gaseous fuel mixtures containing H2 in enhancing the combustion and oxidation process of CH4 were examined. The unique combustion characteristics of CO in dry air and its distinct performance in mixtures with H-containing fuels were investigated. The addition of a simulated synthesis gas (2H2+CO) to CH4 was found to enhance the combustion process of the resulting mixture and lowers its knock resistance. The effectiveness of such an addition is slightly weaker than that of a comparable H2 addition but much stronger than that with CO addition only. A predictive model with detailed kinetic chemistry was used successfully to simulate SI engine operation fuelled with CH4, H2, CO, and their mixtures. The predicted engine performance and knock limits of CH4, H2, CO, and their mixtures agree well with experimental data with the exception around pure CO operation in dry air with the presence of small amounts of CH4 or H2. A remedial approach to improve the prediction of the knock limits of fuel mixtures containing mainly CO with a small amount of H-containing fuels such as H2 and CH4 was proposed and discussed.

A Turbocharged, Spark-Ignition Engine: Results From an Engine Cycle Simulation Including the Second Law of Thermodynamics

2009 ◽  
Author(s):  
Vaibhav J. Lawand ◽  
Jerald A. Caton
Keyword(s):  
Combustion Process ◽  
Engine Performance ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Second Law ◽  
Base Case ◽  
Mixing Processes ◽  
Automotive Engine ◽  
Cycle Simulation

The use of turbocharging systems for spark-ignition engines has seen increased interest in recent years due to the importance of fuel efficiency, and in some cases, increased performance. An example of a possible strategy is to use a smaller displacement engine with turbocharging rather than a larger engine without turbocharging. To better understand the tradeoffs and the fundamental aspects of a turbocharged engine, this investigation is aimed at determining the energy and exergy quantities for a range of operating conditions for a spark-ignition engine. A 3.8 liter automotive engine with a turbocharger and intercooler was selected for this study. Various engine performance and other output parameters were determined as functions of engine speed and load. For the base case (2000 rpm and a bmep of 1200 kPa), the bsfc was about 240 g/kW-h. At these conditions, the second law analysis indicated that the original fuel exergy was distributed as follows: 34.7% was delivered as indicated work, 16.9% was moved via heat transfer to the cylinder walls, 23.0% exited with the exhaust gases, 20.6% was destroyed during the combustion process, 2.5% was destroyed due to inlet mixing processes, and 1.9% was destroyed due to the exhaust processes. The turbocharger components including the intercooler were responsible for less than 1.0% of the fuel exergy destruction or transfer.

scholarly journals Numerical Study of Engine Performance and Emissions for Port Injection of Ammonia into a Gasoline\Ethanol Dual-Fuel Spark Ignition Engine

2021 ◽  
Vol 11 (4) ◽  
pp. 1441
Author(s):  
Farhad Salek ◽  
Meisam Babaie ◽  
Amin Shakeri ◽  
Seyed Vahid Hosseini ◽  
Timothy Bodisco ◽  
...  
Keyword(s):  
Numerical Study ◽  
Combustion Process ◽  
Engine Performance ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Combustion Model ◽  
Dual Fuel ◽  
Spark Ignition Engines ◽  
Performance And Emissions ◽  
Hc Emissions

This study aims to investigate the effect of the port injection of ammonia on performance, knock and NOx emission across a range of engine speeds in a gasoline/ethanol dual-fuel engine. An experimentally validated numerical model of a naturally aspirated spark-ignition (SI) engine was developed in AVL BOOST for the purpose of this investigation. The vibe two zone combustion model, which is widely used for the mathematical modeling of spark-ignition engines is employed for the numerical analysis of the combustion process. A significant reduction of ~50% in NOx emissions was observed across the engine speed range. However, the port injection of ammonia imposed some negative impacts on engine equivalent BSFC, CO and HC emissions, increasing these parameters by 3%, 30% and 21%, respectively, at the 10% ammonia injection ratio. Additionally, the minimum octane number of primary fuel required to prevent knock was reduced by up to 3.6% by adding ammonia between 5 and 10%. All in all, the injection of ammonia inside a bio-fueled engine could make it robust and produce less NOx, while having some undesirable effects on BSFC, CO and HC emissions.

scholarly journals Simulation of spark ignition engine performance working on biogas hydrogen mixture

2018 ◽  
Vol 244 ◽  
pp. 03001
Author(s):  
Donatas Kriaučiūnas ◽  
Saugirdas Pukalskas ◽  
Alfredas Rimkus
Keyword(s):  
Carbon Dioxide ◽  
Combustion Process ◽  
Engine Performance ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Simulation Results ◽  
Crankshaft Rotation ◽  
Carbon Dioxide Co2 ◽  
Engine Crankshaft ◽  
Lower Heating

Numerical simulations of Nissan Qashqai HR16DE engine with increased compression ratio from 10,7:1 to 13,5:1 was carried out using AVL BOOST software. Modelled engine work cycles while engine works with biogas (BG) and hydrogen (H2) mixtures. For biogas used mixture of 35 % carbon dioxide (CO2) and 65 % methane (CH4). Three mixtures of biogas with added 5 %, 10 % and 15 % H2 was made. The simulation of engine work cycles was performed at fully opened throttle and changing engine crankshaft rotation speeds: ne1 = 1500, ne2 = 3000, ne3 = 4500, ne4 = 6000 rpm. Simulation results demonstrated what adding hydrogen to biogas increase in-cylinder temperature and nitrogen oxides (NOx) concentration because of higher mixtures lower heating values (LHV) and better combustion process. Other emissions of carbon monoxide (CO) and hydrocarbons (HC) decreased while adding hydrogen due to the fact that hydrogen is carbon-free fuel.

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.

First and Second Law Analyses of a Spark-Ignition Engine Using Either Isooctane or Hydrogen: An Initial Assessment

2006 ◽  
Author(s):  
Jerald A. Caton
Keyword(s):  
Nitric Oxide ◽  
Thermal Efficiency ◽  
Equivalence Ratio ◽  
Performance Metrics ◽  
Combustion Process ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Second Law ◽  
Cycle Simulation ◽  
Nitric Oxide Emissions

The use of either hydrogen or isooctane for a spark-ignition engine was examined using a thermodynamic cycle simulation including the second law of thermodynamics. The engine studied was a 5.7 liter, automotive engine operating from idle to wide open throttle. The hydrogen or isooctane was assumed premixed with the air. Two features of hydrogen combustion that were included in the study were the higher flame speeds (shorter burn durations) and the wider lean flammability limits (lean equivalence ratios). Three cases were considered for the use of hydrogen: (1) standard burn duration and an equivalence ratio of 1.0, (2) a shorter burn duration and an equivalence ratio of 1.0, and (3) a shorter burn duration and variable, lean equivalence ratios. The results included thermal efficiencies, other performance metrics, second law parameters, and nitric oxide emissions. In general, for the cases with an equivalence of 1.0, the brake thermal efficiency was slightly lower for the hydrogen cases due to the higher temperatures and higher heat losses. For the variable, lean equivalence ratio cases, the thermal efficiency was higher for the hydrogen case relative to the isooctane case. Due to the higher temperatures, the hydrogen cases had over 50% higher nitric oxide emissions compared to the isooctane case at the base conditions. In addition, the second law analyses indicated that the destruction of availability during the combustion process was lower for the base hydrogen case (11.2%) relative to the isooctane case (21.1%).

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.

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