Second Law of Thermodynamics-Based Optimization of Spark-Ignition Engine Operation

2018 ◽  
Author(s):  
Muataz Abotabik ◽  
Richard T. Meyer ◽  
Claudia Fajardo
Keyword(s):  
Second Law Of Thermodynamics ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Second Law ◽  
Engine Operation

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.

Mathematical analysis of spark ignition engine operation via the combination of the first and second laws of thermodynamics

2008 ◽  
Vol 464 (2100) ◽  
pp. 3107-3128 ◽  
Author(s):  
İsmet Sezer ◽  
Atilla Bilgin
Keyword(s):  
Equivalence Ratio ◽  
Engine Speed ◽  
Exergy Analysis ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Second Law ◽  
Operational Parameters ◽  
Engine Operation ◽  
Availability Analysis ◽  
Spark Timing

This study aims at the theoretical exergetic evaluation of spark ignition engine operation. For this purpose, a two-zone quasi-dimensional cycle model was installed, not considering the complex calculation of fluid motions. The cycle simulation consists of compression, combustion and expansion processes. The combustion phase is simulated as a turbulent flame propagation process. Intake and exhaust processes are also computed by a simple approximation method. The results of the model were compared with experimental data to demonstrate the validation of the model. Principles of the second law are applied to the model to perform the exergy (or availability) analysis. In the exergy analysis, the effects of various operational parameters, i.e. fuel–air equivalence ratio, engine speed and spark timing on exergetic terms have been investigated. The results of exergy analysis show that variations of operational parameters examined have considerably affected the exergy transfers, irreversibilities and efficiencies. For instance, an increase in equivalence ratio causes an increase in irreversibilities, while it decreases the first and also the second law efficiencies. The irreversibilities have minimum values for the specified engine speed and optimum spark timing, while the first and second law efficiencies reach a maximum at the same engine speed and optimum spark timing.

scholarly journals EXERGY DESTRUCTION AND CHEMICAL IRREVERSIBILITIES DURING COMBUSTION IN SPARK – IGNITION ENGINE USING OXYGENATED AND HYDROCARBON FUELS

2013 ◽  
pp. 7-11
Author(s):  
MUNAWAR NAWAB KARIMI ◽  
SANDEEP KUMAR KAMBOJ
Keyword(s):  
Combustion Engine ◽  
Second Law Of Thermodynamics ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Second Law ◽  
Exergy Destruction ◽  
Efficient Utilization ◽  
Dead State ◽  
Energy Economy ◽  
Volume Entropy

The growing concern for energy, economy and environment calls for efficient utilization of natural resources in developing useful work. Second law of thermodynamics provides different perspective compared with first law. This paper provides an overview of the quantitative levels of exergy destruction and chemical irreversibilities during the combustion. For the adiabatic combustion at constant volume, entropy generation approach with second law of thermodynamics is applied. The result of this study is based on a spark ignition, single cylinder combustion engine with stoichiometric condition. Iso-octane, methane, methanol and ethanol are the fuels examined. This study shows that exergy destruction during combustion decreases with the increase in reactant temperature and compression ratios, for all the fuels. Exergy destruction during combustion using entropy balance approach for compression ratio range of 7 to 11 found to vary between 16.18 to 21.52%. Chemical irreversibilities calculated at the restricted dead state are found to be in the range of 2.99 to 3.6% for different fuels

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.

Combustion, Knock and Emission Characteristics of a Natural Gas Fuelled Spark Ignition Engine with Particular Reference to Low Intake Temperature Conditions

1975 ◽  
Vol 189 (1) ◽  
pp. 139-147 ◽  
Author(s):  
G. A. Karim ◽  
I. A. Ali
Keyword(s):  
Natural Gas ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Chamber Pressure ◽  
Exhaust Emission ◽  
Emission Characteristics ◽  
Engine Operation ◽  
Temperature Conditions ◽  
Ignition Limits ◽  
Combustion Knock

For various fuel-air mixtures and different compression ratios, the intake temperature was varied over the entire range of ***200°F (366K) down to − 100°F (200K) when employing a single cylinder spark ignited research engine fuelled with natural gas. Performance data such as knock and ignition limits the nature and extent of exhaust emission and chamber pressure cyclic variation were obtained. Means were then suggested for the interpretation of the above mentioned data in terms of engine operation on liquefied natural gas. The experimental work confirmed in general the attractive features of the use of natural gas as a fuel in a spark ignition engine operated under extremely cold intake temperature conditions and that emissions of pollutants were not significantly increased.

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