An appraisal of advanced engine concepts using second law analysis techniques

Primus, Roy J.; Hoag, Kevin; Flynn, P. F.; Brands, M. C.

doi:10.4271/841287

Cited by 38 publications

(24 citation statements)

References 9 publications

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“…For example, for the 1.5 mm PSZ case, the combustion irreversibilities decrease up to 23.5% compared to the non-insulated configuration, which is indeed a considerable gain. This finding expands on the steady-state results of previous researchers [12][13][14][15][16]. It should be emphasized here that the combustion irreversibilities during transients evolve in a different way compared to the respective steady-state operation (i.e.…”

Section: In-cylinder Calculationssupporting

confidence: 85%

“…Rakopoulos et al [42] concluded that the interest for LHR engines emanates from their potential to do more work by utilizing the exhaust gases in a Rankine bottoming cycle. A higher insulation significantly limits the availability destruction associated with heat transfer from the gas to the cylinder walls [15,16].…”

Section: Background On Steady-state Low Heat Rejection Diesel Enginmentioning

confidence: 99%

“…The reduction of irreversibilities can lead to better engine performance through a more efficient exploitation of fuel [12]. Various steady-state analyses so far have emphasized the importance of cylinder wall insulation on the reduction of combustion irreversibilities [12][13][14][15][16]. It seems therefore very logical to investigate the respective phenomena under transient conditions too.…”

Section: Introductionmentioning

confidence: 99%

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Study of the Transient Operation of Low Heat Rejection Turbocharged Diesel Engine Including Wall Temperature Oscillations

Rakopoulos¹,

Giakoumis²

2007

SAE Technical Paper Series

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During the last decades, a vivid interest in the low heat rejection (LHR) diesel engine has arisen. In a LHR engine, an increased level of temperatures inside the cylinder is achieved resulting from the insulation applied to the combustion chamber walls. The steady-state LHR engine operation has been studied so far by applying either first-or second-law balances. However, very few works have treated this subject during the very important transient operation, with the results limited to the engine speed response. For this purpose, an experimentally validated simulation code of the thermodynamic cycle of the engine during transient conditions is applied. This takes into account the transient operation of the fuel pump, the development of friction torque using a detailed per degree crank angle sub-model, while the equations for each cylinder are solved individually and sequentially. In this work, two common insulators of various thicknesses are considered for the engine in hand, viz. silicon nitride and plasma spray zirconia. The transient response of various engine (e.g. speed, volumetric efficiency, fuel pump rack position, brake mean effective pressure and specific fuel consumption) and turbocharger variables is depicted and analyzed, with the results compared to the non-insulated transientand the insulated steady-state operation. For a more indepth analysis of transient engine heat transfer, the interesting phenomenon of the short-term temperature (cyclic) oscillations in the combustion chamber walls during transients needs to be studied. To this aim, the thermodynamic model of the engine is appropriately coupled to a wall periodic heat conduction model, which uses the gas temperature variation as boundary condition throughout the engine cycle after being treated by Fourier analysis techniques. The evolution of many variables during the transient engine cycles, such as the amplitude of oscillation or gradient of temperature swing is thus illustrated. Moreover, the simulation code is expanded in a way to include the second-law balance, as this may prove an interesting alternative to the firstlaw analysis. It is revealed that after a ramp increase in load, the second-law values unlike the first-law ones are heavily impacted by the insulation scheme applied.Combustion and total engine irreversibilities decrease significantly (up to 24% for the cases examined) with increasing insulation. Unfortunately, this decrease is not transformed into an increase in piston work but rather increases the potential for extra work recovery owing to the higher availability content of the exhaust gas.

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Section: In-cylinder Calculationssupporting

confidence: 85%

Section: Background On Steady-state Low Heat Rejection Diesel Enginmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Study of the Transient Operation of Low Heat Rejection Turbocharged Diesel Engine Including Wall Temperature Oscillations

Rakopoulos¹,

Giakoumis²

2007

SAE Technical Paper Series

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“…The adiabatic flame temperature is assumed as the start of combustion temperature and the mass burning rate is computed from the cosine burn rate equation: In Equation (15), θ st is spark timing and Δθ b is burn duration, which is determined for certain operating parameters by using the following empirical correlations [29]:…”

Section: Governing Equations Of Cycle Modelmentioning

confidence: 99%

“…Another previous study was completed by Patterson in 1962 [14]. Additionally, a series of studies on the application of exergy analysis to ICEs was carried out in the 1980s [15][16][17][18][19] and work on ICEs on the subject of exergy or the second law analysis has continued progressively in recent years [20][21][22][23][24][25]. In the present study, the effects of engine operating parameters such as engine speed and load are investigated via exergy analysis.…”

Section: Introductionmentioning

confidence: 99%

Exergetic Evaluation of Speed and Load Effects in Spark Ignition Engines

Sezer

Bilgin

2012

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Résumé -Évaluation exergétique des effets de la vitesse et de la charge dans les moteurs à allumage par étincelle -Cette étude examine les effets des différentes conditions de fonctionnement de moteurs à allumage commandé via une analyse exergétique. Un modèle de cycle thermodynamique comprenant les processus de compression, combustion et détente a été utilisé. Les processus d'admission et d'échappement sont modélisés à l'aide d'une méthode simple d'approximation. Les principes de la deuxième loi de la thermodynamique ont été appliqués au modèle de cycle pour effectuer l'analyse exergétique. Des variables exergétiques comme les transferts exergétiques de chaleur et de travail, les irréversibilités, l'exergie thermomécanique, l'exergie chimique du carburant et l'exergie totale ont été calculées dans l'analyse exergétique. La variation des paramètres exergétiques et leur distribution dans l'exergie du combustible ont été déterminées pour différentes conditions de fonctionnement, c'est à dire différentes vitesses du moteur et différentes charges. L'efficacité déduite, d'une part, de la première et la deuxième loi de la thermodynamique et, d'autre part, de la consommation spécifique de carburant ont également été calculées pour révéler les conditions optimales de fonctionnement. Les résultats montrent que le transfert exergétique de chaleur diminue et que le transfert exergétique par l'échappement augmente avec la vitesse du moteur. Le régime moteur de 3 000 tr/min donne le transfert d'exergie maximal de travail, les irréversibilités minimales, les meilleurs rendements et la moindre consommation de carburant. Les transferts exergétiques avec la chaleur, le travail et l'échappement et ainsi que les irréversibilités augmentent avec la charge du moteur. En outre, l'efficacité déduite de la première et la seconde loi de la thermodynamique augmente et la consommation de carburant diminue avec la charge du moteur, donc une charge du moteur élevée donne les meilleurs rendements et la moindre consommation de carburant. Oil & Gas Science and Technology -Rev. IFP Energies nouvelles, Vol. 67 (2012) : 10.2516/ogst/2012002 Oil & Gas Science and Technology -Rev. IFP Energies nouvelles, Vol. 67 (2012) The first law efficiency (%) η II The second law efficiency (%) η vol Abstract -Exergetic Evaluation of Speed and Load Effects in Spark Ignition Engines, No. 4, pp. 647-660 Copyright © 2012, IFP Energies nouvelles DOI

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Exergy destruction during the combustion process as functions of operating and design parameters for a spark-ignition engine

Caton

2011

Int. J. Energy Res.

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SUMMARYThe second law of thermodynamics provides different perspectives compared with the first law, and provides the property exergy. Exergy is a measure of the work potential of energy from a given thermodynamic state. Unlike energy, exergy may be destroyed, and for reciprocating engines, the major source of this destruction is during the combustion process. This paper provides an overview of the quantitative levels of exergy destruction during the combustion process as function of engine operating and design parameters, and for eight fuels. The results of this study are based on a spark-ignition, automotive engine. The amount of exergy destroyed during the combustion process has been determined as functions of speed, load, equivalence ratio, start of combustion, combustion duration, combustion rate parameters, exhaust gas recirculation (EGR), inlet oxygen concentration, and compression ratio. In addition, design parameters that were examined included expansion ratio and the use of turbocharging. The fuels examined included isooctane (base), methane, propane, hexane, methanol, ethanol, hydrogen and carbon monoxide. For the part load base case (1400 rpm and a bmep of 325 kPa) using isooctane, the destruction of exergy was 20.8% of the fuel exergy. For many of the engine operating and design parameter changes, this destruction was relatively constant (between about 20 and 23%). The parameters that resulted in the greatest change of the exergy destruction were (1) equivalence ratio, (2) EGR, and (3) inlet oxygen concentration.For the base case conditions, the exergy destruction during the combustion process was different for the different fuels. The lowest destruction (8.1%) was for carbon monoxide and the highest destruction (20.8%) was for isooctane. The differences between the various fuels appear to relate to the complexity of the fuel molecule and the presence (or absence) of an oxygen atom.

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An appraisal of advanced engine concepts using second law analysis techniques

Cited by 38 publications

References 9 publications

Study of the Transient Operation of Low Heat Rejection Turbocharged Diesel Engine Including Wall Temperature Oscillations

Study of the Transient Operation of Low Heat Rejection Turbocharged Diesel Engine Including Wall Temperature Oscillations

Exergetic Evaluation of Speed and Load Effects in Spark Ignition Engines

Exergy destruction during the combustion process as functions of operating and design parameters for a spark-ignition engine

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