Entropy

A number of computer programs were established by the research department of the Augsburg works of M. A. N. to provide information on the development of diesel engines. This paper reports on two such programs. One of them aims at determining heat release flow from the indicated pressure diagram, the other at calculating pressure and temperature flow and thermal load from engine dimensions only, assuming a simple heat release diagram. Some results of these calculations are presented.

@article{doi104271650450,
    author = "Woschni, Gerhard",
    title = "Computer Programs to Determine the Relationship Between Pressure Flow, Heat Release, and Thermal Load in Diesel Engines",
    year = "1965",
    journal = "SAE technical papers on CD-ROM/SAE technical paper series",
    abstract = "A number of computer programs were established by the research department of the Augsburg works of M. A. N. to provide information on the development of diesel engines. This paper reports on two such programs. One of them aims at determining heat release flow from the indicated pressure diagram, the other at calculating pressure and temperature flow and thermal load from engine dimensions only, assuming a simple heat release diagram. Some results of these calculations are presented.",
    url = "https://doi.org/10.4271/650450",
    doi = "10.4271/650450",
    openalex = "W2301964542"
}

By using as sources supersonic jets of hydrogen or helium containing small concentrations of heavier molecules we have been able to obtain molecular beams with kinetic energies of the heavy molecules well into the range above I electron volt. A variety of molecules have been successfully accelerated. Intensities of 10(16) to 10(17) heavy molecules per steradian-second have been achieved at these high energies.

@article{doi101126science1553765997,
    author = "Abuaf, N. and Anderson, James B. and Andres, R. P. and Fenn, John B. and Marsden, D. G. H.",
    title = "Molecular Beams with Energies above One Electron Volt",
    year = "1967",
    journal = "Science",
    abstract = "By using as sources supersonic jets of hydrogen or helium containing small concentrations of heavier molecules we have been able to obtain molecular beams with kinetic energies of the heavy molecules well into the range above I electron volt. A variety of molecules have been successfully accelerated. Intensities of 10(16) to 10(17) heavy molecules per steradian-second have been achieved at these high energies.",
    url = "https://doi.org/10.1126/science.155.3765.997",
    doi = "10.1126/science.155.3765.997",
    openalex = "W2092118067"
}

Basic heat release data have been obtained by analysis of cylinder pressure diagrams from a variety of engines, two-stroke and four-stroke, small (3·4-in bore) to medium size (12-in bore) over ranges of power, speed, and air supply conditions. The paper gives an account of early attempts to obtain a simple formula for heat release suitable for performance calculations by computer, using the simple and widely used single-zone model for conditions in the cylinder. The conclusion is reached that although it is possible to obtain useful calculations in this way, more sophisticated models are necessary for better understanding of conditions in the engine.

@article{doi101243pimeconf196918431502,
    author = "Whitehouse, N. D. and Way, R. J. B.",
    title = "Rate of Heat Release in Diesel Engines and Its Correlation with Fuel Injection Data",
    year = "1969",
    journal = "Proceedings of the Institution of Mechanical Engineers Conference Proceedings",
    abstract = "Basic heat release data have been obtained by analysis of cylinder pressure diagrams from a variety of engines, two-stroke and four-stroke, small (3·4-in bore) to medium size (12-in bore) over ranges of power, speed, and air supply conditions. The paper gives an account of early attempts to obtain a simple formula for heat release suitable for performance calculations by computer, using the simple and widely used single-zone model for conditions in the cylinder. The conclusion is reached that although it is possible to obtain useful calculations in this way, more sophisticated models are necessary for better understanding of conditions in the engine.",
    url = "https://doi.org/10.1243/pime\_conf\_1969\_184\_315\_02",
    doi = "10.1243/pime\_conf\_1969\_184\_315\_02",
    openalex = "W2066988244"
}

This paper proposes a new equation for calculating instantaneous heat transfer in internal combustion engines. The equation constitutes expressions of heat transfer due to convection, and gas and flame radiation. In the term for convective heat transfer three sets of parameters appear: operating parameters (pressure in the combustion chamber, mean piston speed, gas temperature), an engine parameter (equivalent diameter of the cylinder), and a constant that takes swirl velocities (at the time when combustion starts) into account. Consideration of gas radiation and data obtained on flame radiation make the equation broadly complete, scientifically sound, and universally applicable.

@article{doi104271720027,
    author = "Sitkei, György and Ramanaiah, G.",
    title = "A Rational Approach for Calculation of Heat Transfer in Diesel Engines",
    year = "1972",
    journal = "SAE technical papers on CD-ROM/SAE technical paper series",
    abstract = "This paper proposes a new equation for calculating instantaneous heat transfer in internal combustion engines. The equation constitutes expressions of heat transfer due to convection, and gas and flame radiation. In the term for convective heat transfer three sets of parameters appear: operating parameters (pressure in the combustion chamber, mean piston speed, gas temperature), an engine parameter (equivalent diameter of the cylinder), and a constant that takes swirl velocities (at the time when combustion starts) into account. Consideration of gas radiation and data obtained on flame radiation make the equation broadly complete, scientifically sound, and universally applicable.",
    url = "https://doi.org/10.4271/720027",
    doi = "10.4271/720027",
    openalex = "W2228179997"
}

A model for describing turbulent flame propagation in internal combustion engines is presented. The model is based upon the assumption that eddies having a characteristic radius ℓ e are entrained by the flame front at a turbulent entrainment velocity u e and subsequently burn in a characteristic time τ = ℓ e /u ℓ, where u ℓ is the laminar flame speed for the fuel-air mixture. An approximate analytic method for determining the equilibrium state of the burned gases is also presented. To verify the predictions of the model, experiments were carried out in a single-cylinder research engine at speeds from 1000-3200 rpm, spark advances from 30-110 deg btc and fuel-air equivalence ratios from 0.7-1.5. Simultaneous measurements of the cylinder pressure and the position of the flame front as a function of crank angle were made, and good agreement with the predictions of the model was obtained for all operating conditions. Correlations were developed that permit both the entrainment speed u e and the eddy radius ℓ e to be calculated from a knowledge of the engine geometry, fuel type, and operating conditions. It is anticipated that the model will be useful for design studies directed toward improving the efficiency and pollution characteristics of internal combustion engines.

@article{doi104271740191,
    author = "Blizard, Norman C. and Keck, James C.",
    title = "Experimental and Theoretical Investigation of Turbulent Burning Model for Internal Combustion Engines",
    year = "1974",
    journal = "SAE technical papers on CD-ROM/SAE technical paper series",
    abstract = "A model for describing turbulent flame propagation in internal combustion engines is presented. The model is based upon the assumption that eddies having a characteristic radius ℓ e are entrained by the flame front at a turbulent entrainment velocity u e and subsequently burn in a characteristic time τ = ℓ e /u ℓ, where u ℓ is the laminar flame speed for the fuel-air mixture. An approximate analytic method for determining the equilibrium state of the burned gases is also presented. To verify the predictions of the model, experiments were carried out in a single-cylinder research engine at speeds from 1000-3200 rpm, spark advances from 30-110 deg btc and fuel-air equivalence ratios from 0.7-1.5. Simultaneous measurements of the cylinder pressure and the position of the flame front as a function of crank angle were made, and good agreement with the predictions of the model was obtained for all operating conditions. Correlations were developed that permit both the entrainment speed u e and the eddy radius ℓ e to be calculated from a knowledge of the engine geometry, fuel type, and operating conditions. It is anticipated that the model will be useful for design studies directed toward improving the efficiency and pollution characteristics of internal combustion engines.",
    url = "https://doi.org/10.4271/740191",
    doi = "10.4271/740191",
    openalex = "W1491647851"
}

@misc{fenn1982engines1,
    author = "Fenn, J. B",
    title = "Engines, Energy, and Entropy",
    year = "1982",
    howpublished = "New York, W.H. Freeman, 293 p",
    note = "talkorigins\_source = {true}; raw\_reference = {Fenn, J. B., 1982, Engines, Energy, and Entropy: New York, W.H. Freeman, 293 p.}"
}

@article{bent1983engines,
    author = "Bent, Henry A.",
    title = "Engines, energy and entropy: A thermodynamics primer",
    year = "1983",
    journal = "Journal of Chemical Education",
    url = "https://doi.org/10.1021/ed060pa25.2",
    doi = "10.1021/ed060pa25.2",
    number = "1",
    openalex = "W2025485767",
    pages = "A25",
    volume = "60"
}

@article{doi101021ed060pa252,
    author = "Bent, Henry A.",
    title = "Engines, energy and entropy: A thermodynamics primer",
    year = "1983",
    journal = "Journal of Chemical Education",
    url = "https://doi.org/10.1021/ed060pa25.2",
    doi = "10.1021/ed060pa25.2",
    openalex = "W2025485767"
}

List of Symbols Thermodynamics Concepts and Laws Definitions Closed Systems Open Systems The Momentum Theorem Useful Steps in Problem Solving The Temperature-Energy Interaction Diagram, and the Entropy Interaction-Energy Interaction Diagram Problems Entropy Generation and Exergy Destruction The Gouy-Stodola Theorem Systems Communicating with More than One Heat Reservoir Adiabatic Systems Exergy Analysis of Steady Flow Processes Exergy Analysis of Non-Flow Processes Characteristic Features of Irreversible Systems and Processes Problems Entropy Generation in Fluid Flow Relationship between Entropy Generation and Viscous Dissipation Laminar Flow Turbulent Flow The Transition Buckling Theory of Turbulent Flow Entropy Generation in Isothermal Turbulent Flow The Bernoulli Equation Entropy Generation in Heat Transfer The Local Rate of Entropy Generation in Convective Heat Transfer Fluid Friction vs. Heat Transfer Irreversibility Internal Flows External Flows Conduction Heat Transfer Convective Mass Transfer General Heat Exchanger Passage Heat Transfer Augmentation Techniques Problems Heat Exchangers Counterflow Heat Exchangers Heat Exchangers with Negligible Pressure Drop Irreversibility The Three-Part Structure of Heat Exchanger Irreversibility Two-Phase-Flow Heat Exchangers Other Heat Exchanger Entropy Generation Studies Distribution of Heat Exchanger Area on the Absolute Temperature Scale Distribution of Heat Transfer Area in Counterflow Heat Exchangers Problems Insulation Systems Power Plants and Refrigeration Plants as Insulation Systems The Generation of Entropy in an Insulation with Fixed Geometry Optimum Continuous Cooling Regime Counterflow Heat Exchangers as One-Dimensional Insulations Parallel Insulations Intermediate Cooling or Heating of Insulation Systems for Power and Refrigeration Plants Problems Storage Systems Sensible Heat Storage Optimum Heating and Cooling Processes Subject to Time Constraint Hot Storage vs. Cold Storage Latent Heat Storage Power Generation Model with Bypass Heat Leak and Two Finite-Size Heat Exchangers Power Plant Viewed as an Insulation Between Heat Source and Ambient Combined-Cycle Power Plant Optimal Combustion Chamber Temperature Other Power Plant Optimization Studies Why Maximum Power Means Minimum Entropy Generation Rate Maximum Power from Fluid Flow Problems Solar-Thermal Power Generation Models with Collector Heat Loss to the Ambient Collector-Ambient Heat Loss and Collector-Engine Heat Exchanger Collector-Ambient Heat Loss and Engine-Ambient Heat Exchanger Storage by Melting Extraterrestrial Solar Power Plant Nonisothermal Collectors Time-Varying Conditions Other Areas of Solar Power Conversion Study Problems Refrigeration Refrigeration Plant Model with Heat Transfer Irreversibilities Model with Heat Leak in Parallel with Reversible Compartment Model with Cold End Heat Exchanger and Room Temperature Heat Exchanger Minimization of the Heat-Leak Entropy Generation Problems Time-Dependent Operation Defrosting Refrigerators Cleaning the Heat Exchanger of a Power Plant Power Plants Driven by Heating from a Bed of Hot Dry Rock Maximum Rate of Ice Production Problems Appendices Local Entropy Generation Rate Variational Calculus Author Index Subject Index

@article{doi105860choice333933,
    title = "Entropy generation minimization: the method of thermodynamic optimization of finite-size systems and finite-time processes",
    year = "1996",
    journal = "Choice Reviews Online",
    abstract = "List of Symbols Thermodynamics Concepts and Laws Definitions Closed Systems Open Systems The Momentum Theorem Useful Steps in Problem Solving The Temperature-Energy Interaction Diagram, and the Entropy Interaction-Energy Interaction Diagram Problems Entropy Generation and Exergy Destruction The Gouy-Stodola Theorem Systems Communicating with More than One Heat Reservoir Adiabatic Systems Exergy Analysis of Steady Flow Processes Exergy Analysis of Non-Flow Processes Characteristic Features of Irreversible Systems and Processes Problems Entropy Generation in Fluid Flow Relationship between Entropy Generation and Viscous Dissipation Laminar Flow Turbulent Flow The Transition Buckling Theory of Turbulent Flow Entropy Generation in Isothermal Turbulent Flow The Bernoulli Equation Entropy Generation in Heat Transfer The Local Rate of Entropy Generation in Convective Heat Transfer Fluid Friction vs. Heat Transfer Irreversibility Internal Flows External Flows Conduction Heat Transfer Convective Mass Transfer General Heat Exchanger Passage Heat Transfer Augmentation Techniques Problems Heat Exchangers Counterflow Heat Exchangers Heat Exchangers with Negligible Pressure Drop Irreversibility The Three-Part Structure of Heat Exchanger Irreversibility Two-Phase-Flow Heat Exchangers Other Heat Exchanger Entropy Generation Studies Distribution of Heat Exchanger Area on the Absolute Temperature Scale Distribution of Heat Transfer Area in Counterflow Heat Exchangers Problems Insulation Systems Power Plants and Refrigeration Plants as Insulation Systems The Generation of Entropy in an Insulation with Fixed Geometry Optimum Continuous Cooling Regime Counterflow Heat Exchangers as One-Dimensional Insulations Parallel Insulations Intermediate Cooling or Heating of Insulation Systems for Power and Refrigeration Plants Problems Storage Systems Sensible Heat Storage Optimum Heating and Cooling Processes Subject to Time Constraint Hot Storage vs. Cold Storage Latent Heat Storage Power Generation Model with Bypass Heat Leak and Two Finite-Size Heat Exchangers Power Plant Viewed as an Insulation Between Heat Source and Ambient Combined-Cycle Power Plant Optimal Combustion Chamber Temperature Other Power Plant Optimization Studies Why Maximum Power Means Minimum Entropy Generation Rate Maximum Power from Fluid Flow Problems Solar-Thermal Power Generation Models with Collector Heat Loss to the Ambient Collector-Ambient Heat Loss and Collector-Engine Heat Exchanger Collector-Ambient Heat Loss and Engine-Ambient Heat Exchanger Storage by Melting Extraterrestrial Solar Power Plant Nonisothermal Collectors Time-Varying Conditions Other Areas of Solar Power Conversion Study Problems Refrigeration Refrigeration Plant Model with Heat Transfer Irreversibilities Model with Heat Leak in Parallel with Reversible Compartment Model with Cold End Heat Exchanger and Room Temperature Heat Exchanger Minimization of the Heat-Leak Entropy Generation Problems Time-Dependent Operation Defrosting Refrigerators Cleaning the Heat Exchanger of a Power Plant Power Plants Driven by Heating from a Bed of Hot Dry Rock Maximum Rate of Ice Production Problems Appendices Local Entropy Generation Rate Variational Calculus Author Index Subject Index",
    url = "https://doi.org/10.5860/choice.33-3933",
    doi = "10.5860/choice.33-3933",
    openalex = "W586644502"
}

Part I. Design of Engines for a New 600-Seat Aircraft: 1. The new large aircraft - requirements and background 2. The aerodynamics of the aircraft 3. The creation of thrust in a jet engine 4. The gas turbine cycle 5. The principle and layout of jet engines 6. Elementary fluid mechanics of compressible gases 7. Selection of bypass ratio 8. Dynamic scaling and dimensional analysis 9. Turbomachinery: compressors and turbines 10. Overview of the civil engine design Part II. Engine Component Characteristics and Engine Matching: 11. Component characteristics 12. Engine matching off-design Part III. The Design of the Engines for a New Fighter Aircraft: 13. A new fighter aircraft 14. Lift, drag and the effects of manoeuvring 15. Engines for combat aircraft 16. Design point for a combat aircraft 17. Combat engines off-design 18. Turbomachinery for combat aircraft Part IV. A Return to the Civil Engine: 19. A return to the civil transport engine 20. Conclusion.

@book{openalexw1727565109,
    author = "Cumpsty, N. A.",
    title = "Jet Propulsion: A Simple Guide to the Aerodynamic and Thermodynamic Design and Performance of Jet Engines",
    year = "1997",
    journal = "Medical Entomology and Zoology",
    abstract = "Part I. Design of Engines for a New 600-Seat Aircraft: 1. The new large aircraft - requirements and background 2. The aerodynamics of the aircraft 3. The creation of thrust in a jet engine 4. The gas turbine cycle 5. The principle and layout of jet engines 6. Elementary fluid mechanics of compressible gases 7. Selection of bypass ratio 8. Dynamic scaling and dimensional analysis 9. Turbomachinery: compressors and turbines 10. Overview of the civil engine design Part II. Engine Component Characteristics and Engine Matching: 11. Component characteristics 12. Engine matching off-design Part III. The Design of the Engines for a New Fighter Aircraft: 13. A new fighter aircraft 14. Lift, drag and the effects of manoeuvring 15. Engines for combat aircraft 16. Design point for a combat aircraft 17. Combat engines off-design 18. Turbomachinery for combat aircraft Part IV. A Return to the Civil Engine: 19. A return to the civil transport engine 20. Conclusion.",
    openalex = "W1727565109"
}

@article{doi101016s0360128597000348,
    author = "Graboski, Michael S. and McCormick, Robert L.",
    title = "Combustion of fat and vegetable oil derived fuels in diesel engines",
    year = "1998",
    journal = "Progress in Energy and Combustion Science",
    url = "https://doi.org/10.1016/s0360-1285(97)00034-8",
    doi = "10.1016/s0360-1285(97)00034-8",
    openalex = "W2017658150"
}

This paper addresses issues associated with the accurate determination of gross heat release energy. The magnitude of analysis and measurement errors has been quantified using simulated and measured gasoline engine pressure data. This has revealed that calculated gross heat release is very sensitive to the assumed ratio of specific heats, charge to wall heat transfer and pressure data errors. Two improved heat release models have been proposed and further investigated and shown to generally give good performance for specific applications although further work is required to fully quantify their accuracy.

@article{doi104271981052,
    author = "Brunt, Michael F. J. and Rai, Harjit and Emtage, Andrew L.",
    title = "The Calculation of Heat Release Energy from Engine Cylinder Pressure Data",
    year = "1998",
    journal = "SAE technical papers on CD-ROM/SAE technical paper series",
    abstract = "This paper addresses issues associated with the accurate determination of gross heat release energy. The magnitude of analysis and measurement errors has been quantified using simulated and measured gasoline engine pressure data. This has revealed that calculated gross heat release is very sensitive to the assumed ratio of specific heats, charge to wall heat transfer and pressure data errors. Two improved heat release models have been proposed and further investigated and shown to generally give good performance for specific applications although further work is required to fully quantify their accuracy.",
    url = "https://doi.org/10.4271/981052",
    doi = "10.4271/981052",
    openalex = "W1526513898",
    references = "doi104271841359"
}

I Historical Roots: From Heat Engines to Cosmology 1 Basic Concepts and the Law of Gases 2 The First Law of Thermodynamics 3 The Second Law of Thermodynamics and the Arrow of Time 4 Entropy in the Realm of Chemical Reactions II Equilibrium Thermodynamics 5 Extremum Principles and General Thermodynamics Relations 6 Basic Thermodynamics of Gases, Liquids and Solids 7 Thermodynamics of Phase Change 8 Thermodynamics of Solutions 9 Thermodynamics of Chemical Transformations 10 Fields and Internal Degrees of Freedom 11 Thermodynamics of Radiation III Fluctuations and Stability 12 The Gibbs Stability Theory 13 Critical Phenomena and Configurational Heat Capacity 14 Entropy Productions, Fluctuations and Small Systems IV Linear Nonequilibrium Thermodynamics 15 Nonequilibrium Thermodynamics: The Foundations 16 Nonequilibrium Thermodynamics: The Linear Regime 17 Nonequilibrium Stationary State and Their Stability: Linear Regime V Order Through Fluctuations 18 Nonlinear Thermodynamics 19 Dissipative Structures 20 Elements of Statistical Thermodynamics 21 Self-Organization and Dissipative Structures in Nature

@article{doi105860choice364495,
    title = "Modern thermodynamics: from heat engines to dissipative structures",
    year = "1999",
    journal = "Choice Reviews Online",
    abstract = "I Historical Roots: From Heat Engines to Cosmology 1 Basic Concepts and the Law of Gases 2 The First Law of Thermodynamics 3 The Second Law of Thermodynamics and the Arrow of Time 4 Entropy in the Realm of Chemical Reactions II Equilibrium Thermodynamics 5 Extremum Principles and General Thermodynamics Relations 6 Basic Thermodynamics of Gases, Liquids and Solids 7 Thermodynamics of Phase Change 8 Thermodynamics of Solutions 9 Thermodynamics of Chemical Transformations 10 Fields and Internal Degrees of Freedom 11 Thermodynamics of Radiation III Fluctuations and Stability 12 The Gibbs Stability Theory 13 Critical Phenomena and Configurational Heat Capacity 14 Entropy Productions, Fluctuations and Small Systems IV Linear Nonequilibrium Thermodynamics 15 Nonequilibrium Thermodynamics: The Foundations 16 Nonequilibrium Thermodynamics: The Linear Regime 17 Nonequilibrium Stationary State and Their Stability: Linear Regime V Order Through Fluctuations 18 Nonlinear Thermodynamics 19 Dissipative Structures 20 Elements of Statistical Thermodynamics 21 Self-Organization and Dissipative Structures in Nature",
    url = "https://doi.org/10.5860/choice.36-4495",
    doi = "10.5860/choice.36-4495",
    openalex = "W1590304060"
}

This investigation was concerned with the rate of heat transfer from the working gases to the combustion chamber walls of the internal combustion engines. The numerical formula for estimating the heat transfer to the combustion chamber wall was derived from the theoretical analysis and the experiment, which were used the constant volume combustion chamber and the actual gasoline engine. As a result, mean heat transfer in the internal combustion engine becomes possible to estimate with measuring the cylinder pressure. In addition, the derived numerical formula forms with quite simple variables. Therefore it is very useful for engine design.

@article{doi1042712000010300,
    author = "Suzuki, Takashi and Oguri, Y. and Yoshida, Masatake",
    title = "Heat Transfer in the Internal Combustion Engines",
    year = "2000",
    journal = "SAE technical papers on CD-ROM/SAE technical paper series",
    abstract = "This investigation was concerned with the rate of heat transfer from the working gases to the combustion chamber walls of the internal combustion engines. The numerical formula for estimating the heat transfer to the combustion chamber wall was derived from the theoretical analysis and the experiment, which were used the constant volume combustion chamber and the actual gasoline engine. As a result, mean heat transfer in the internal combustion engine becomes possible to estimate with measuring the cylinder pressure. In addition, the derived numerical formula forms with quite simple variables. Therefore it is very useful for engine design.",
    url = "https://doi.org/10.4271/2000-01-0300",
    doi = "10.4271/2000-01-0300",
    openalex = "W1542611850"
}

In a recent letter (J. Phys. Chem. A, 2001, 105,1), we argued that, although all major thermochemical tables recommend a value of (OH) based on a spectroscopic approach, the correct value is 0.5 kcal/mol lower as determined from an ion cycle. In this paper, we expand upon and augment both the experimental and theoretical arguments presented in the letter. In particular, three separate experiments (mass-selected photoionization measurements, pulsed-field-ionization photoelectron spectroscopy measurements, and photoelectron-photoion coincidence measurements) utilizing the positive ion cycle to derive the O−H bond energy are shown to converge to a consensus value of the appearance energy AE0(OH+/H2O) = 146117 ± 24 cm-1 (18.1162 ± 0.0030 eV). With the most accurate currently available zero kinetic energy photoionization value for the ionization energy IE(OH) = 104989 ± 2 cm-1, corroborated by a number of photoelectron measurements, this leads to D0(H−OH) = 41128 ± 24 cm-1 = 117.59 ± 0.07 kcal/mol. This corresponds to ΔHf0(OH) = 8.85 ± 0.07 kcal/mol and implies D0(OH) = 35593 ± 24 cm-1 = 101.76 ± 0.07 kcal/mol. These results are completely supported by the most sophisticated theoretical calculations ever performed on the HxO system, CCSD(T)/aug-cc-pVnZ, n = Q, 5, 6, and 7, extrapolated to the CBS limit and including corrections for core-valence effects, scalar relativistic effects, incomplete correlation recovery, and diagonal Born−Oppenheimer corrections. These calculations have an estimated theoretical error of ≤0.2 kcal/mol based on basis set convergence properties. They reproduce the experimental results for dissociation energies, atomization energies, and ionization energies for the HxO system to within 0.0−0.2 kcal/mol. In contrast, the previously accepted values of the two successive bond dissociation energies of water differ from the current values by 0.5 kcal/mol. These values were derived from the spectroscopic determinations of D0(OH) using a very short Birge−Sponer extrapolation on OH/OD A1Σ+. However, on the basis of a calculation of the A state potential energy curve (with a multireference single and double excitation wave function and an aug-cc-pV5Z basis set) and an exhaustive reanalyzis of the original measured data on both the A and B states of OH, the Birge−Sponer extrapolation can be demonstrated to significantly underestimate the bond dissociation energy, although only the last vibrational level was not observed experimentally. The recommended values of this paper affect a large number of other thermochemical quantities which directly or indirectly rely on or refer to D0(H−OH), D0(OH), or. This is illustrated by an analysis of several reaction enthalpies, deprotonation enthalpies, and proton affinities.

@article{doi101021jp013909s,
    author = "Ruščić, Branko and Wagner, Albert F. and Harding, Lawrence B. and Asher, Robert L. and Feller, David and Dixon, David A. and Peterson, Kirk A. and Song, Yang and Qian, Ximei and Ng, C. Y. and Liu, Jianbo and Chen, Wenwu and Schwenke, David W.",
    title = "On the Enthalpy of Formation of Hydroxyl Radical and Gas-Phase Bond Dissociation Energies of Water and Hydroxyl",
    year = "2002",
    journal = "The Journal of Physical Chemistry A",
    abstract = "In a recent letter (J. Phys. Chem. A, 2001, 105,1), we argued that, although all major thermochemical tables recommend a value of (OH) based on a spectroscopic approach, the correct value is 0.5 kcal/mol lower as determined from an ion cycle. In this paper, we expand upon and augment both the experimental and theoretical arguments presented in the letter. In particular, three separate experiments (mass-selected photoionization measurements, pulsed-field-ionization photoelectron spectroscopy measurements, and photoelectron-photoion coincidence measurements) utilizing the positive ion cycle to derive the O−H bond energy are shown to converge to a consensus value of the appearance energy AE0(OH+/H2O) = 146117 ± 24 cm-1 (18.1162 ± 0.0030 eV). With the most accurate currently available zero kinetic energy photoionization value for the ionization energy IE(OH) = 104989 ± 2 cm-1, corroborated by a number of photoelectron measurements, this leads to D0(H−OH) = 41128 ± 24 cm-1 = 117.59 ± 0.07 kcal/mol. This corresponds to ΔHf0(OH) = 8.85 ± 0.07 kcal/mol and implies D0(OH) = 35593 ± 24 cm-1 = 101.76 ± 0.07 kcal/mol. These results are completely supported by the most sophisticated theoretical calculations ever performed on the HxO system, CCSD(T)/aug-cc-pVnZ, n = Q, 5, 6, and 7, extrapolated to the CBS limit and including corrections for core-valence effects, scalar relativistic effects, incomplete correlation recovery, and diagonal Born−Oppenheimer corrections. These calculations have an estimated theoretical error of ≤0.2 kcal/mol based on basis set convergence properties. They reproduce the experimental results for dissociation energies, atomization energies, and ionization energies for the HxO system to within 0.0−0.2 kcal/mol. In contrast, the previously accepted values of the two successive bond dissociation energies of water differ from the current values by 0.5 kcal/mol. These values were derived from the spectroscopic determinations of D0(OH) using a very short Birge−Sponer extrapolation on OH/OD A1Σ+. However, on the basis of a calculation of the A state potential energy curve (with a multireference single and double excitation wave function and an aug-cc-pV5Z basis set) and an exhaustive reanalyzis of the original measured data on both the A and B states of OH, the Birge−Sponer extrapolation can be demonstrated to significantly underestimate the bond dissociation energy, although only the last vibrational level was not observed experimentally. The recommended values of this paper affect a large number of other thermochemical quantities which directly or indirectly rely on or refer to D0(H−OH), D0(OH), or. This is illustrated by an analysis of several reaction enthalpies, deprotonation enthalpies, and proton affinities.",
    url = "https://doi.org/10.1021/jp013909s",
    doi = "10.1021/jp013909s",
    openalex = "W2163746642"
}

@article{doi101016jpecs200510001,
    author = "Rakopoulos, C.D. and Giakoumis, Evangelos G.",
    title = "Second-law analyses applied to internal combustion engines operation",
    year = "2006",
    journal = "Progress in Energy and Combustion Science",
    url = "https://doi.org/10.1016/j.pecs.2005.10.001",
    doi = "10.1016/j.pecs.2005.10.001",
    openalex = "W1995951980",
    references = "doi104271670931"
}

Abstract A thermodynamic theory for the voltage or free energy generated by a quantum solar energy converter which has recently been proposed, is developed here in a more direct and simpler way. We consider separately the luminescence and conversion of a single photon of the incident radiation. The energy/entropy balance for the conversion process yields an expression for the voltage in a form familiar from the classical thermodynamics of the work carried out by the heat engine. A similar balance for the absorption and emission of light gives an expression for the irreversible entropy generation which reduces the open circuit voltage generated by the solar cell. Detailed expressions for losses due to individual mechanisms, including non‐radiative recombination, are obtained with the use of an approximation where photons in the incident and emitted beams are modelled as an ideal two‐dimensional gas. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

@article{doi101002pssa200880460,
    author = "Markvart, Tom",
    title = "Solar cell as a heat engine: energy–entropy analysis of photovoltaic conversion",
    year = "2008",
    journal = "physica status solidi (a)",
    abstract = "Abstract A thermodynamic theory for the voltage or free energy generated by a quantum solar energy converter which has recently been proposed, is developed here in a more direct and simpler way. We consider separately the luminescence and conversion of a single photon of the incident radiation. The energy/entropy balance for the conversion process yields an expression for the voltage in a form familiar from the classical thermodynamics of the work carried out by the heat engine. A similar balance for the absorption and emission of light gives an expression for the irreversible entropy generation which reduces the open circuit voltage generated by the solar cell. Detailed expressions for losses due to individual mechanisms, including non‐radiative recombination, are obtained with the use of an approximation where photons in the incident and emitted beams are modelled as an ideal two‐dimensional gas. (© 2008 WILEY‐VCH Verlag GmbH \& Co. KGaA, Weinheim)",
    url = "https://doi.org/10.1002/pssa.200880460",
    doi = "10.1002/pssa.200880460",
    openalex = "W2117902597",
    references = "doi101016092702489390098n, doi101016b9780444508867x50000, doi101016jtsf200612105, doi101016s0079672700000033, doi101016s0079672798000123, doi10106311736034, doi10106312766857, doi101088146442581001015008, doi101103physrevb76085303, doi10111911934738"
}

@article{doi101016jrser200808003,
    author = "Sahoo, Bibhuti B. and Sahoo, Niranjan and Saha, Ujjwal K.",
    title = "Effect of engine parameters and type of gaseous fuel on the performance of dual-fuel gas diesel engines—A critical review",
    year = "2008",
    journal = "Renewable and Sustainable Energy Reviews",
    url = "https://doi.org/10.1016/j.rser.2008.08.003",
    doi = "10.1016/j.rser.2008.08.003",
    openalex = "W1967903134"
}

@article{doi101016jpecs200908001,
    author = "Verhelst, Sebastian and Wallner, Thomas",
    title = "Hydrogen-fueled internal combustion engines",
    year = "2009",
    journal = "Progress in Energy and Combustion Science",
    url = "https://doi.org/10.1016/j.pecs.2009.08.001",
    doi = "10.1016/j.pecs.2009.08.001",
    openalex = "W3103675312",
    references = "doi104271670931"
}

@article{doi101016jpecs201302001,
    author = "Kuravi, Sarada and Trahan, Jamie and Goswami, D. Yogi and Rahman, Muhammad M. and Stefanakos, Elias",
    title = "Thermal energy storage technologies and systems for concentrating solar power plants",
    year = "2013",
    journal = "Progress in Energy and Combustion Science",
    url = "https://doi.org/10.1016/j.pecs.2013.02.001",
    doi = "10.1016/j.pecs.2013.02.001",
    openalex = "W1986823125",
    references = "doi105860choice333933"
}

@article{doi101016jpecs201305002,
    author = "Saxena, Samveg and Bedoya, Iván D.",
    title = "Fundamental phenomena affecting low temperature combustion and HCCI engines, high load limits and strategies for extending these limits",
    year = "2013",
    journal = "Progress in Energy and Combustion Science",
    url = "https://doi.org/10.1016/j.pecs.2013.05.002",
    doi = "10.1016/j.pecs.2013.05.002",
    openalex = "W2063807605",
    references = "doi104271670931"
}

@article{doi101016japenergy201509016,
    author = "Xu, Ben and Li, Peiwen and Chan, Cholik",
    title = "Application of phase change materials for thermal energy storage in concentrated solar thermal power plants: A review to recent developments",
    year = "2015",
    journal = "Applied Energy",
    url = "https://doi.org/10.1016/j.apenergy.2015.09.016",
    doi = "10.1016/j.apenergy.2015.09.016",
    openalex = "W1803690640",
    references = "doi105860choice333933"
}

@misc{chandra2016energy,
    author = "Chandra, Sanjeev",
    title = "Energy, Entropy and Engines",
    year = "2016",
    url = "https://doi.org/10.1002/9781119013167",
    doi = "10.1002/9781119013167",
    openalex = "W4229868863"
}

HPC Data Center's performance and growth are now being limited by both cost and power. A cost-efficient data center and an energy-efficient data center are all too often mutually exclusive, but they do not have to be. Liquid cooling is one area that, when done right, can improve both costs and energy efficiency. The design for liquid cooling systems generally begins with the ASHRAE liquid cooling datacenter classes. These provide guidance to both datacenter facility cooling system designers and electronic equipment manufacturers by providing a common baseline and understanding of the interface conditions between the cooling and the IT equipment. Further, the liquid cooling classes also suggest possible cooling equipment for a given datacenter class. Due to the aforementioned cooling equipment prescription, perception exists that moving from W1/W2 class environments to W3 or W4 classes represent increased energy efficiency during IT equipment operation. In this paper we show this not to be the case universally and explore a more detailed, technical approach to optimizing both cost and energy efficiency. The range of parameters includes geographical and climate conditions, state of the existing data center cooling infrastructure (greenfield, retrofit, cluster change-out, expansion), and IT level liquid cooling architecture. Through this analysis we show that for energy efficient operation of the IT equipment there exists an optimum liquid operating temperature that can also provide the lowest TCO. This temperature can drive the right capital investment as well as reduce facility operational expense and IT operational expense. We also explore the impact on reliability, the controls architecture, use of efficiency metrics, cluster compute performance, and opportunities for energy re-use.

@article{doi101109itherm20167517615,
    author = "Patterson, Michael K. and Krishnan, Shankar and Walters, John M.",
    title = "On energy efficiency of liquid cooled HPC datacenters",
    year = "2016",
    abstract = "HPC Data Center's performance and growth are now being limited by both cost and power. A cost-efficient data center and an energy-efficient data center are all too often mutually exclusive, but they do not have to be. Liquid cooling is one area that, when done right, can improve both costs and energy efficiency. The design for liquid cooling systems generally begins with the ASHRAE liquid cooling datacenter classes. These provide guidance to both datacenter facility cooling system designers and electronic equipment manufacturers by providing a common baseline and understanding of the interface conditions between the cooling and the IT equipment. Further, the liquid cooling classes also suggest possible cooling equipment for a given datacenter class. Due to the aforementioned cooling equipment prescription, perception exists that moving from W1/W2 class environments to W3 or W4 classes represent increased energy efficiency during IT equipment operation. In this paper we show this not to be the case universally and explore a more detailed, technical approach to optimizing both cost and energy efficiency. The range of parameters includes geographical and climate conditions, state of the existing data center cooling infrastructure (greenfield, retrofit, cluster change-out, expansion), and IT level liquid cooling architecture. Through this analysis we show that for energy efficient operation of the IT equipment there exists an optimum liquid operating temperature that can also provide the lowest TCO. This temperature can drive the right capital investment as well as reduce facility operational expense and IT operational expense. We also explore the impact on reliability, the controls architecture, use of efficiency metrics, cluster compute performance, and opportunities for energy re-use.",
    url = "https://doi.org/10.1109/itherm.2016.7517615",
    doi = "10.1109/itherm.2016.7517615",
    openalex = "W2494849112"
}

This study investigates energy and entropy analyses of an experimental turbojet engine build in Anadolu University Faculty of Aeronautics and Astronautics Test-Cell Laboratory. Law of motions and Brayton thermodynamic cycle model are used for this purpose. The processes (that is, compression, combustion, and expansion) are simulated in P-v, T-s and h-s diagrams. Furthermore, the second law of thermodynamics is applied to the cycle model to perform the entropy analysis. A distribution of the wasted and thrust power, the overall (energy-based the first law efficiency), and the specific fuel consumption and specific thrust of the engine were calculated during the analyses as well. The results of the study also show the entropy changing value in engine components due to irreversibilities and inefficiencies. As a conclusion, it is expected that this study is useful to study future design and research work similar aircraft turbojets, auxiliary power units and target drone power systems.

@article{doi1018038aubtda279861,
    author = "Turan, Önder",
    title = "ENERGY AND ENTROPY ANALYSES OF AN EXPERIMENTAL TURBOJET ENGINE FOR TARGET DRONE APPLICATION",
    year = "2016",
    journal = "Anadolu University Journal of Science and Technology-A Applied Sciences and Engineering",
    abstract = "This study investigates energy and entropy analyses of an experimental turbojet engine build in Anadolu University Faculty of Aeronautics and Astronautics Test-Cell Laboratory. Law of motions and Brayton thermodynamic cycle model are used for this purpose. The processes (that is, compression, combustion, and expansion) are simulated in P-v, T-s and h-s diagrams. Furthermore, the second law of thermodynamics is applied to the cycle model to perform the entropy analysis. A distribution of the wasted and thrust power, the overall (energy-based the first law efficiency), and the specific fuel consumption and specific thrust of the engine were calculated during the analyses as well. The results of the study also show the entropy changing value in engine components due to irreversibilities and inefficiencies. As a conclusion, it is expected that this study is useful to study future design and research work similar aircraft turbojets, auxiliary power units and target drone power systems.",
    url = "https://doi.org/10.18038/aubtda.279861",
    doi = "10.18038/aubtda.279861",
    openalex = "W2582725715",
    references = "doi101016jenergy201203030, doi101016jenergy201305064, doi101016jenergy201407029, doi101016jenergy201504025, doi101016jenergy201504026, doi101504ijex2012049738, doi101515tjj20150030, openalexw1727565109, openalexw2169574411"
}

@article{doi101016jenconman201707024,
    author = "Li, Deyou and Wang, Hongjie and Qin, Yonglin and Han, Lei and Wei, Xianzhu and Qin, Daqing",
    title = "Entropy production analysis of hysteresis characteristic of a pump-turbine model",
    year = "2017",
    journal = "Energy Conversion and Management",
    url = "https://doi.org/10.1016/j.enconman.2017.07.024",
    doi = "10.1016/j.enconman.2017.07.024",
    openalex = "W2734691667",
    references = "doi105860choice333933"
}

@article{doi101016jrser201701001,
    author = "Mahmudul, H.M. and Hagos, Ftwi Yohaness and Mamat, Rizalman and Adam, A. Abdul and Ishak, Wan Faizal Wan and Alenezi, R.",
    title = "Production, characterization and performance of biodiesel as an alternative fuel in diesel engines – A review",
    year = "2017",
    journal = "Renewable and Sustainable Energy Reviews",
    url = "https://doi.org/10.1016/j.rser.2017.01.001",
    doi = "10.1016/j.rser.2017.01.001",
    openalex = "W2579178478",
    references = "doi101016japenergy201009029, doi101016jfuel201112063"
}

Abstract Entropy generation and energy efficiency of turbofan engines become greater concern in recent years caused by rises fuel costs and as well as environmental impact of aviation emissions. This study describes calculation of entropy generation for a two-spool CFM56-7B high-bypass turbofan widely used on short to medium range, narrow body aircrafts. Entropy generation and power analyses are performed for five main engine components obtaining temperature-entropy, entropy-enthalpy, pressure-volume diagrams at ≈121 kN take-off thrust force. In the study, maximum entropy production is determined to be 0.8504 kJ/kg K at the combustor, while minimum entropy generation is observed at the low pressure compressor component with the value of 0.0025 kJ/kg K. Besides, overall efficiency of the turbofan is determined to be 14 %, while propulsive and thermal efficiencies of the engine are 35 % and 40 %, respectively. As a conclusion, this study aims to show increase of entropy due to irreversibilities and produced power dimension in engine components for commercial turbofans and aero-derivative cogeneration power plants.

@article{doi101515tjj20170053,
    author = "Cilgin, Mehmet Emin and Turan, Önder",
    title = "Entropy Generation Calculation of a Turbofan Engine: A Case of CFM56-7B",
    year = "2017",
    journal = "International Journal of Turbo and Jet Engines",
    abstract = "Abstract Entropy generation and energy efficiency of turbofan engines become greater concern in recent years caused by rises fuel costs and as well as environmental impact of aviation emissions. This study describes calculation of entropy generation for a two-spool CFM56-7B high-bypass turbofan widely used on short to medium range, narrow body aircrafts. Entropy generation and power analyses are performed for five main engine components obtaining temperature-entropy, entropy-enthalpy, pressure-volume diagrams at ≈121 kN take-off thrust force. In the study, maximum entropy production is determined to be 0.8504 kJ/kg K at the combustor, while minimum entropy generation is observed at the low pressure compressor component with the value of 0.0025 kJ/kg K. Besides, overall efficiency of the turbofan is determined to be 14 \%, while propulsive and thermal efficiencies of the engine are 35 \% and 40 \%, respectively. As a conclusion, this study aims to show increase of entropy due to irreversibilities and produced power dimension in engine components for commercial turbofans and aero-derivative cogeneration power plants.",
    url = "https://doi.org/10.1515/tjj-2017-0053",
    doi = "10.1515/tjj-2017-0053",
    openalex = "W2773129121",
    references = "doi1018038aubtda279861"
}

@article{doi101016japenergy201809022,
    author = "Hoang, Anh Tuan",
    title = "Waste heat recovery from diesel engines based on Organic Rankine Cycle",
    year = "2018",
    journal = "Applied Energy",
    url = "https://doi.org/10.1016/j.apenergy.2018.09.022",
    doi = "10.1016/j.apenergy.2018.09.022",
    openalex = "W2891833385",
    references = "doi101016jrser201204013"
}

@article{doi101016jpecs201810001,
    author = "Verhelst, Sebastian and Turner, James and Sileghem, Louis and Vancoillie, Jeroen",
    title = "Methanol as a fuel for internal combustion engines",
    year = "2018",
    journal = "Progress in Energy and Combustion Science",
    url = "https://doi.org/10.1016/j.pecs.2018.10.001",
    doi = "10.1016/j.pecs.2018.10.001",
    openalex = "W2898011573",
    references = "doi101002kin20218"
}

@article{doi101016jenergy201907103,
    author = "Metin, Ece Yurdusevimli and Aygün, Hakan",
    title = "Energy and power aspects of an experimental target drone engine at non-linear controller loads",
    year = "2019",
    journal = "Energy",
    url = "https://doi.org/10.1016/j.energy.2019.07.103",
    doi = "10.1016/j.energy.2019.07.103",
    openalex = "W2961684566",
    references = "doi1018038aubtda279861"
}

@article{doi101016jenergy2020118261,
    author = "Aygün, Hakan and Cilgin, Mehmet Emin and Ekmekçi, İsmail and Turan, Önder",
    title = "Energy and performance optimization of an adaptive cycle engine for next generation combat aircraft",
    year = "2020",
    journal = "Energy",
    url = "https://doi.org/10.1016/j.energy.2020.118261",
    doi = "10.1016/j.energy.2020.118261",
    openalex = "W3044351583",
    references = "doi1018038aubtda279861"
}

This paper redraws and shows the pressure volume Pv - diagram and the T-S diagram of the Carnot cycle, Otto engine, and turbocharged Zhou Engine. It imitates the thermodynamic analysis of steam or gas turbines, takes into account the transport-work, and rederives the ideal thermal efficiency formula of Otto engines, which is much different from the current one. It is found that the current thermodynamics of internal combustion (IC) engines neglected the transport-work and the entropy increase in the exhaust pipe, overvalued the ideal thermal efficiency, and is a wrong line in the temperature entropy (T-S) diagram. In particular, the entropy increase in the exhaust pipe hides and wastes a lot of mechanical energy, which the turbocharged Zhou Engine can recycle.

@article{doi1042712021015098,
    author = "Zhou, Jing Yuan",
    title = "Four Common Deficiencies in the Current Thermodynamics of Internal Combustion Engines",
    year = "2021",
    journal = "SAE technical papers on CD-ROM/SAE technical paper series",
    abstract = "This paper redraws and shows the pressure volume Pv - diagram and the T-S diagram of the Carnot cycle, Otto engine, and turbocharged Zhou Engine. It imitates the thermodynamic analysis of steam or gas turbines, takes into account the transport-work, and rederives the ideal thermal efficiency formula of Otto engines, which is much different from the current one. It is found that the current thermodynamics of internal combustion (IC) engines neglected the transport-work and the entropy increase in the exhaust pipe, overvalued the ideal thermal efficiency, and is a wrong line in the temperature entropy (T-S) diagram. In particular, the entropy increase in the exhaust pipe hides and wastes a lot of mechanical energy, which the turbocharged Zhou Engine can recycle.",
    url = "https://doi.org/10.4271/2021-01-5098",
    doi = "10.4271/2021-01-5098",
    openalex = "W3209897923",
    references = "chandra2016energy"
}

Internal combustion engines face increased market, societal, and governmental pressures to improve performance, requiring researchers to utilize modeling tools capable of a thorough analysis of engine performance. Heat release is a critical aspect of internal combustion engine diagnostic analysis, but is prone to variability in modeling validity, particularly as engine operation is pushed further from conventional combustion regimes. To that end, this effort presents a comprehensive open-source, zero-dimensional equilibrium heat release model. This heat release analysis is based on a combined mass, energy, entropy, and exergy formulation that improves upon well-established efforts constructed around the ratio of specific heats. Furthermore, it incorporates combustion using an established chemical kinetics mechanism to endeavor to predict the global chemical species in the cylinder. Future efforts can augment and improve the chemical kinetics reactions for specific combustion conditions based on the radical pyrolysis of the fuel. In addition, the incorporation of theoretical calculations of energy and exergy based on the change in chemical species allows for cross-checking of combustion model validity.

@article{depcik2023opensource,
    author = "Depcik, Christopher and Mattson, Jonathan and Alam, Shah Saud",
    title = "Open-Source Energy, Entropy, and Exergy 0D Heat Release Model for Internal Combustion Engines",
    year = "2023",
    journal = "Energies",
    abstract = "Internal combustion engines face increased market, societal, and governmental pressures to improve performance, requiring researchers to utilize modeling tools capable of a thorough analysis of engine performance. Heat release is a critical aspect of internal combustion engine diagnostic analysis, but is prone to variability in modeling validity, particularly as engine operation is pushed further from conventional combustion regimes. To that end, this effort presents a comprehensive open-source, zero-dimensional equilibrium heat release model. This heat release analysis is based on a combined mass, energy, entropy, and exergy formulation that improves upon well-established efforts constructed around the ratio of specific heats. Furthermore, it incorporates combustion using an established chemical kinetics mechanism to endeavor to predict the global chemical species in the cylinder. Future efforts can augment and improve the chemical kinetics reactions for specific combustion conditions based on the radical pyrolysis of the fuel. In addition, the incorporation of theoretical calculations of energy and exergy based on the change in chemical species allows for cross-checking of combustion model validity.",
    url = "https://doi.org/10.3390/en16062514",
    doi = "10.3390/en16062514",
    number = "6",
    openalex = "W4323365088",
    pages = "2514",
    volume = "16",
    references = "depcik2023opensource, doi101002kin20218, doi101002kin20603, doi101016jfuel201112063, doi101016jproci201405129, doi101016jrser201204013, doi103390en16062514, doi104271670931, doi104271790825, doi104271841359, doi104271890269, doi104271920808"
}

Optimizing the cooling system plays a central role for capping the data center power consumption. However, the performance of traditional cooling management strategies is not satisfactory due to the complexity of thermodynamic process. Recently, several works leveraged Reinforcement Learning (RL) to improve the energy efficiency of data center cooling system. While they demonstrated that it is possible to reduce the cooling power consumption via RL, there are still some key challenges that have to be addressed before field deployment, such as safe operation guarantee and sample complexity, etc. In this paper, we propose SafeCool, an actor-critic Model-Based Reinforcement Learning (MBRL) algorithm for data center cooling management. SafeCool incorporates two system models, i.e., a transition model to predict the future system state and a risk model to estimate the negative effect of executing an action. The safety of proposed algorithm is ensured by Model Predictive Control (MPC) and risk-guided exploration. In addition, by employing the MBRL framework, SafeCool achieves higher sample efficiency and accelerated convergence. Simulations using real-world workload trace reveal that SafeCool saves up to 13.18% cooling power compared with state-of-the-art MBRL data center cooling solutions.

@article{doi101109tetci20233234545,
    author = "Wan, Jianxiong and Duan, Yanduo and Gui, Xiang and Liu, Chuyi and Li, Leixiao and Ma, Zhiqiang",
    title = "SafeCool: Safe and Energy-Efficient Cooling Management in Data Centers With Model-Based Reinforcement Learning",
    year = "2023",
    journal = "IEEE Transactions on Emerging Topics in Computational Intelligence",
    abstract = "Optimizing the cooling system plays a central role for capping the data center power consumption. However, the performance of traditional cooling management strategies is not satisfactory due to the complexity of thermodynamic process. Recently, several works leveraged Reinforcement Learning (RL) to improve the energy efficiency of data center cooling system. While they demonstrated that it is possible to reduce the cooling power consumption via RL, there are still some key challenges that have to be addressed before field deployment, such as safe operation guarantee and sample complexity, etc. In this paper, we propose SafeCool, an actor-critic Model-Based Reinforcement Learning (MBRL) algorithm for data center cooling management. SafeCool incorporates two system models, i.e., a transition model to predict the future system state and a risk model to estimate the negative effect of executing an action. The safety of proposed algorithm is ensured by Model Predictive Control (MPC) and risk-guided exploration. In addition, by employing the MBRL framework, SafeCool achieves higher sample efficiency and accelerated convergence. Simulations using real-world workload trace reveal that SafeCool saves up to 13.18\% cooling power compared with state-of-the-art MBRL data center cooling solutions.",
    url = "https://doi.org/10.1109/tetci.2023.3234545",
    doi = "10.1109/tetci.2023.3234545",
    openalex = "W4317384992",
    references = "doi101109icjece20203011357"
}

In this study, parametric cycle analysis of a conceptual turbojet engine with an afterburner (TJEAB) was conducted at sea level conditions-zero Mach. Based on this analysis, exergetic sustainability parameters of TJEAB were scrutinized for military mode (MM) and afterburner mode (ABM). Constitutively, several design parameters of TJEAB were chosen so as to optimize performance and exergetic parameters which consist of specific fuel consumption (SFC), overall efficiency, exergy efficiency, environmental effect factor (EEF) and exergetic sustainability index (ESI). In this context, compressor pressure ratio (CPR), turbine inlet temperature (TIT) were preferred due to high effect of these variables on engine performance. CPR ranges from 4 to 11 whereas TIT varies from 1150 K to 1550 K. According to optimization of performance parameters, minimum SFC was achieved as 28.59 g/kN.s at MM and 43.95 g/kN.s at ABM. On the other hand, maximum overall efficiency is determined as to be 13.07 % at MM and to be 8.5 % at ABM. As for exergetic parameters, exergy efficiency was calculated as maximum with 30.85 % at MM and 23.2 %at ABM. Finally, maximum exergetic sustainability index of TJEAB was computed as 0.446 at MM and 0.269 at ABM. It is thought that energetic and exergetic parameters analyzed in this analysis could guide in designing turbojet engines in terms of lower fuel consumption thereby environmental-benign.

@article{doi1018186thermal1242919,
    author = "Aygün, Hakan",
    title = "Optimization of energy and exergy parameters for a conceptual after burning turbojet engine",
    year = "2023",
    journal = "Journal of Thermal Engineering",
    abstract = "In this study, parametric cycle analysis of a conceptual turbojet engine with an afterburner (TJEAB) was conducted at sea level conditions-zero Mach. Based on this analysis, exergetic sustainability parameters of TJEAB were scrutinized for military mode (MM) and afterburner mode (ABM). Constitutively, several design parameters of TJEAB were chosen so as to optimize performance and exergetic parameters which consist of specific fuel consumption (SFC), overall efficiency, exergy efficiency, environmental effect factor (EEF) and exergetic sustainability index (ESI). In this context, compressor pressure ratio (CPR), turbine inlet temperature (TIT) were preferred due to high effect of these variables on engine performance. CPR ranges from 4 to 11 whereas TIT varies from 1150 K to 1550 K. According to optimization of performance parameters, minimum SFC was achieved as 28.59 g/kN.s at MM and 43.95 g/kN.s at ABM. On the other hand, maximum overall efficiency is determined as to be 13.07 \% at MM and to be 8.5 \% at ABM. As for exergetic parameters, exergy efficiency was calculated as maximum with 30.85 \% at MM and 23.2 \%at ABM. Finally, maximum exergetic sustainability index of TJEAB was computed as 0.446 at MM and 0.269 at ABM. It is thought that energetic and exergetic parameters analyzed in this analysis could guide in designing turbojet engines in terms of lower fuel consumption thereby environmental-benign.",
    url = "https://doi.org/10.18186/thermal.1242919",
    doi = "10.18186/thermal.1242919",
    openalex = "W4318068999",
    references = "doi1018038aubtda279861"
}

Internal combustion engines face increased market, societal, and governmental pressures to improve performance, requiring researchers to utilize modeling tools capable of a thorough analysis of engine performance. Heat release is a critical aspect of internal combustion engine diagnostic analysis, but is prone to variability in modeling validity, particularly as engine operation is pushed further from conventional combustion regimes. To that end, this effort presents a comprehensive open-source, zero-dimensional equilibrium heat release model. This heat release analysis is based on a combined mass, energy, entropy, and exergy formulation that improves upon well-established efforts constructed around the ratio of specific heats. Furthermore, it incorporates combustion using an established chemical kinetics mechanism to endeavor to predict the global chemical species in the cylinder. Future efforts can augment and improve the chemical kinetics reactions for specific combustion conditions based on the radical pyrolysis of the fuel. In addition, the incorporation of theoretical calculations of energy and exergy based on the change in chemical species allows for cross-checking of combustion model validity.

@article{doi103390en16062514,
    author = "Depcik, Christopher and Mattson, Jonathan and Alam, Shah Saud",
    title = "Open-Source Energy, Entropy, and Exergy 0D Heat Release Model for Internal Combustion Engines",
    year = "2023",
    journal = "Energies",
    abstract = "Internal combustion engines face increased market, societal, and governmental pressures to improve performance, requiring researchers to utilize modeling tools capable of a thorough analysis of engine performance. Heat release is a critical aspect of internal combustion engine diagnostic analysis, but is prone to variability in modeling validity, particularly as engine operation is pushed further from conventional combustion regimes. To that end, this effort presents a comprehensive open-source, zero-dimensional equilibrium heat release model. This heat release analysis is based on a combined mass, energy, entropy, and exergy formulation that improves upon well-established efforts constructed around the ratio of specific heats. Furthermore, it incorporates combustion using an established chemical kinetics mechanism to endeavor to predict the global chemical species in the cylinder. Future efforts can augment and improve the chemical kinetics reactions for specific combustion conditions based on the radical pyrolysis of the fuel. In addition, the incorporation of theoretical calculations of energy and exergy based on the change in chemical species allows for cross-checking of combustion model validity.",
    url = "https://doi.org/10.3390/en16062514",
    doi = "10.3390/en16062514",
    openalex = "W4323365088",
    references = "doi101002kin20218, doi101002kin20603, doi101016jfuel201112063, doi101016jproci201405129, doi101016jrser201204013, doi104271670931, doi104271790825, doi104271841359, doi104271890269, doi104271920808"
}

The study involves using thermal cracking techniques and enhancing fuel quality by incorporating di-ethyl ether, referred to as blended stock solution (BSS). In this work, an investigation was conducted on the Entropy, Energy, Emission Factors, Sustainability Index (SI) analyses, Exergy of BSS-diesel blends and the correlation between BSS-diesel blends and pure diesel. A single cylinder diesel engine running at speed of 1500 rpm was used for this experiment. The engine was tested with various blend ratios, including BSS20, BSS40, BSS60, BSS100, and pure diesel. The findings indicate that BSS60 has the best levels of exergy efficiency and energy, with a value of 30.35 % and 28.50 % respectively, surpassing other blends and pure diesel. The research findings suggest that BSS60 exhibited the lowest level of entropy formation compared to other fuel blends and pure diesel. The BSS60 exhibits the highest level of sustainability index. Emission factors of carbon monoxide (CO), demonstrate lower emission index (EI) and specific emissions (SE) as compared to both pure diesel and its blends. The emissions of NOx have shown a notable increase of 3.37 % in both the EI and SE when compared to pure diesel. The conclusions suggest the BSS60 exhibits superior performance and is suitable for use in direct-injection diesel engines.

@article{doi101016jasej2024103190,
    author = "Saravanan, R. and Navaneethakrishnan, P. and Rengasamy, M. and Manieniyan, V.",
    title = "Energy, Exergy, Entropy, Emission Factors (4E’s) and Sustainability Index analyses of thermal splintering waste paraffin Oil, di-ethyl ether − diesel blends",
    year = "2024",
    journal = "Ain Shams Engineering Journal",
    abstract = "The study involves using thermal cracking techniques and enhancing fuel quality by incorporating di-ethyl ether, referred to as blended stock solution (BSS). In this work, an investigation was conducted on the Entropy, Energy, Emission Factors, Sustainability Index (SI) analyses, Exergy of BSS-diesel blends and the correlation between BSS-diesel blends and pure diesel. A single cylinder diesel engine running at speed of 1500 rpm was used for this experiment. The engine was tested with various blend ratios, including BSS20, BSS40, BSS60, BSS100, and pure diesel. The findings indicate that BSS60 has the best levels of exergy efficiency and energy, with a value of 30.35 \% and 28.50 \% respectively, surpassing other blends and pure diesel. The research findings suggest that BSS60 exhibited the lowest level of entropy formation compared to other fuel blends and pure diesel. The BSS60 exhibits the highest level of sustainability index. Emission factors of carbon monoxide (CO), demonstrate lower emission index (EI) and specific emissions (SE) as compared to both pure diesel and its blends. The emissions of NOx have shown a notable increase of 3.37 \% in both the EI and SE when compared to pure diesel. The conclusions suggest the BSS60 exhibits superior performance and is suitable for use in direct-injection diesel engines.",
    url = "https://doi.org/10.1016/j.asej.2024.103190",
    doi = "10.1016/j.asej.2024.103190",
    openalex = "W4405095794",
    references = "depcik2023opensource, doi103390en16062514"
}

@article{doi101016jenergy2024133870,
    author = "Антонов, Д.В. and Черкасов, Р. В. and Gneusheva, V.V. and Mikulich, M.E. and Стрижак, П. А. and Yanovskiy, L. S.",
    title = "Comprehensive approach to static firing tests of micro gas turbine engines powered by liquid fuels",
    year = "2024",
    journal = "Energy",
    url = "https://doi.org/10.1016/j.energy.2024.133870",
    doi = "10.1016/j.energy.2024.133870",
    openalex = "W4404459677",
    references = "doi1018038aubtda279861"
}

Abstract The combustion process in spark ignition (SI) and compression ignition (CI) engines plays a significant role in ascertaining engine performance, efficiency, and emissions. As the automotive industry faces challenges related to energy conservation and environmental impacts, understanding and optimizing SI and CI engine combustion become paramount. This study uses a zero-dimensional (0D) internal combustion engine (ICE) model utilizing the Wiebe function to predict mass fraction burned profiles in port fuel injection (PFI) engines. The model incorporates chemical reactions of air–fuel mixtures under lean and rich combustion conditions, accounting for residual and exhaust gas recirculation (EGR). Pressure-based equilibrium constants are applied for rich combustion reactions. Further implementation of the combustion reaction model requires an accurate estimate of the combustion duration. As a result, an exploration of analogous efforts in the literature was accomplished, subsequently drawing insights. This resulted in the development of an empirical model that predicts combustion duration for various fuels such as gasoline, natural gas, propane, methanol, ethanol, hydrogen, and methane–hydrogen blends under different conditions. This includes a unique feature of spark timing variation with run-time conditions. Flame speed data, notably a maximum adiabatic flame speed at an equivalence ratio of 1.1, serve as normalization parameters. The model shows a relative fit to experimental data (R2-values: 0.729–0.972) and is explored through parametric studies, thus demonstrating its utility in simulating fuels under various engine runtime operating conditions.

@article{doi10111514067403,
    author = "Feyijimi, Clement and Depcik, Christopher",
    title = "Predictive Zero-Dimensional Combustion Modeling in Internal Combustion Engines With Residual Fraction and Exhaust Gas Recirculation",
    year = "2024",
    journal = "Journal of Engineering for Gas Turbines and Power",
    abstract = "Abstract The combustion process in spark ignition (SI) and compression ignition (CI) engines plays a significant role in ascertaining engine performance, efficiency, and emissions. As the automotive industry faces challenges related to energy conservation and environmental impacts, understanding and optimizing SI and CI engine combustion become paramount. This study uses a zero-dimensional (0D) internal combustion engine (ICE) model utilizing the Wiebe function to predict mass fraction burned profiles in port fuel injection (PFI) engines. The model incorporates chemical reactions of air–fuel mixtures under lean and rich combustion conditions, accounting for residual and exhaust gas recirculation (EGR). Pressure-based equilibrium constants are applied for rich combustion reactions. Further implementation of the combustion reaction model requires an accurate estimate of the combustion duration. As a result, an exploration of analogous efforts in the literature was accomplished, subsequently drawing insights. This resulted in the development of an empirical model that predicts combustion duration for various fuels such as gasoline, natural gas, propane, methanol, ethanol, hydrogen, and methane–hydrogen blends under different conditions. This includes a unique feature of spark timing variation with run-time conditions. Flame speed data, notably a maximum adiabatic flame speed at an equivalence ratio of 1.1, serve as normalization parameters. The model shows a relative fit to experimental data (R2-values: 0.729–0.972) and is explored through parametric studies, thus demonstrating its utility in simulating fuels under various engine runtime operating conditions.",
    url = "https://doi.org/10.1115/1.4067403",
    doi = "10.1115/1.4067403",
    openalex = "W4405371217",
    references = "depcik2023opensource, doi103390en16062514"
}

The increasing influence of machine learning in engine emission prediction is on rising trend. The present study of thermodynamic analysis of ternary fuel with advanced Machine learning model provides valuable insights and adds significant outcomes to existing analysis. The current work deals with performance and sustainability of binary (diesel-biodiesel) and ternary (diesel-biodiesel-ethanol) fuel blends in a single-cylinder engine. Engine experiments were conducted using a structured design of experiments (DOE) approach, followed by thermodynamic analyses to evaluate key performance parameters, including exergy efficiency, brake thermal efficiency (BTE), and sustainability index. To optimize fuel parameters, the Desirability Function Approach (DFA) integrated with Response Surface Methodology (RSM) was employed. Additionally, advanced machine learning (ML) techniques were utilized to predict these performance characteristics. Notably, the binary blend demonstrated superior performance, achieving a 3.76% higher BTE, 5.62% higher exergy efficiency, and a 1.56% increase in the sustainability index compared to conventional fuel. However, the inclusion of ethanol in the ternary blend (45% Diesel–45% Biodiesel–10% Ethanol) resulted in a slight reduction in the sustainability index, which reached a peak value of 1.28 under full-load conditions. Interestingly, both sustainability index and exergy efficiency exhibited a consistent increase with rising engine load. At 5.2 kW, the blend BDE50 exhibits lower thermal efficiency than D100 and BDE10 by about 14.06% and 7.36%. Also, BDE50 blend exhibits lower exergy efficiency than D100 and BDE10 by about17.01% and 11.66% respectively. At full load, BDE50 blend possess 2.684 kW thermal loss and 18.583 kW exergy destruction, while BDE10 possess 2.331 kW thermal loss and 14.817 kW exergy destruction respectively. When comparing predictive models, the ML model demonstrated superior accuracy over RSM, as evidenced by higher R 2 values. Furthermore, desirability analysis confirmed the blends' strong performance and emission characteristics, achieving an optimal desirability rating of 0.777. Among the advanced ML models evaluated, XGBoost outperformed all others across multiple performance metrics, indicating its robustness in predicting fuel blend efficiency and sustainability. • Drop in thermal efficiency and exergy efficiency is observed for BDE blends with the increasing concentration of ethanol. • Surge in exergy destruction and thermal energy losses for BDE blends is observed and increase in higher with higher concentration of ethanol in BDE blends • Maximum value of sustainable index analysis is reported for B40 blends and in positive range, while ternary blends of BDE have negative range (which is of course, suitable for good fuel). • Optimized engine characteristics were found with the RSM-ML approach. • The desirability analysis validated the blend's high performance and emissions features, achieving a good desirability rating of 0.777. • The statistical assessment findings indicate that the XGBoost model beat the other advance ML model in all metrics tested

@article{doi101016jcsite2025106516,
    author = "Venu, Harish and Raju, V. Dhana and Nair, Jayashri N. and Algburi, Sameer and Anqi, Ali E. and Rajhi, Ali A. and Kareemullah, Mohammed",
    title = "Exergy and energy-based sustainability evaluation of diesel-biodiesel-ethanol blends with emission forecasting using advanced machine learning models",
    year = "2025",
    journal = "Case Studies in Thermal Engineering",
    abstract = "The increasing influence of machine learning in engine emission prediction is on rising trend. The present study of thermodynamic analysis of ternary fuel with advanced Machine learning model provides valuable insights and adds significant outcomes to existing analysis. The current work deals with performance and sustainability of binary (diesel-biodiesel) and ternary (diesel-biodiesel-ethanol) fuel blends in a single-cylinder engine. Engine experiments were conducted using a structured design of experiments (DOE) approach, followed by thermodynamic analyses to evaluate key performance parameters, including exergy efficiency, brake thermal efficiency (BTE), and sustainability index. To optimize fuel parameters, the Desirability Function Approach (DFA) integrated with Response Surface Methodology (RSM) was employed. Additionally, advanced machine learning (ML) techniques were utilized to predict these performance characteristics. Notably, the binary blend demonstrated superior performance, achieving a 3.76\% higher BTE, 5.62\% higher exergy efficiency, and a 1.56\% increase in the sustainability index compared to conventional fuel. However, the inclusion of ethanol in the ternary blend (45\% Diesel–45\% Biodiesel–10\% Ethanol) resulted in a slight reduction in the sustainability index, which reached a peak value of 1.28 under full-load conditions. Interestingly, both sustainability index and exergy efficiency exhibited a consistent increase with rising engine load. At 5.2 kW, the blend BDE50 exhibits lower thermal efficiency than D100 and BDE10 by about 14.06\% and 7.36\%. Also, BDE50 blend exhibits lower exergy efficiency than D100 and BDE10 by about17.01\% and 11.66\% respectively. At full load, BDE50 blend possess 2.684 kW thermal loss and 18.583 kW exergy destruction, while BDE10 possess 2.331 kW thermal loss and 14.817 kW exergy destruction respectively. When comparing predictive models, the ML model demonstrated superior accuracy over RSM, as evidenced by higher R 2 values. Furthermore, desirability analysis confirmed the blends' strong performance and emission characteristics, achieving an optimal desirability rating of 0.777. Among the advanced ML models evaluated, XGBoost outperformed all others across multiple performance metrics, indicating its robustness in predicting fuel blend efficiency and sustainability. • Drop in thermal efficiency and exergy efficiency is observed for BDE blends with the increasing concentration of ethanol. • Surge in exergy destruction and thermal energy losses for BDE blends is observed and increase in higher with higher concentration of ethanol in BDE blends • Maximum value of sustainable index analysis is reported for B40 blends and in positive range, while ternary blends of BDE have negative range (which is of course, suitable for good fuel). • Optimized engine characteristics were found with the RSM-ML approach. • The desirability analysis validated the blend's high performance and emissions features, achieving a good desirability rating of 0.777. • The statistical assessment findings indicate that the XGBoost model beat the other advance ML model in all metrics tested",
    url = "https://doi.org/10.1016/j.csite.2025.106516",
    doi = "10.1016/j.csite.2025.106516",
    openalex = "W4411373376",
    references = "depcik2023opensource, doi103390en16062514"
}

This article discusses the potential of using the double-Wiebe function to model combustion in a compression-ignition engine fueled by diesel fuel or its substitutes, such as hydrotreated vegetable oil (HVO) and rapeseed methyl ester (RME), and hydrogen injected into the engine intake manifold. The hydrogen amount ranged from 0 to 35% of the total energy content of the fuels burned. It was found that co-combustion of liquid fuel with hydrogen is characterized by two distinct combustion phases: premixed and diffusion combustion. The premixed phase, occurring just after ignition, is characterized by a rapid combustion rate, which increases with an increase in hydrogen injected. The novelty in this work is the modified formula for a double-Wiebe function and the proposed parameters of this function depending on the amount of hydrogen added for co-combustion with liquid fuel. To model this combustion process, the modified double-Wiebe function was proposed, which can model two phases with different combustion rates. For this purpose, a normalized HRR was calculated, and based on this curve, coefficients for the double-Wiebe function were proposed. Satisfactory consistency with the experiment was achieved at a level determined by the coefficient of determination (R-squared) of above 0.98. It was concluded that the presented double-Wiebe function can be used to model combustion in 0-D and 1-D models for fuels: RME and HVO with hydrogen addition.

@article{doi103390en18215622,
    author = "Szwaja, Stanisław and Pukalskas, Saugirdas and Juknelevičius, Romualdas and Rimkus, Alfredas",
    title = "Modeling Hydrogen-Assisted Combustion of Liquid Fuels in Compression-Ignition Engines Using a Double-Wiebe Function",
    year = "2025",
    journal = "Energies",
    abstract = "This article discusses the potential of using the double-Wiebe function to model combustion in a compression-ignition engine fueled by diesel fuel or its substitutes, such as hydrotreated vegetable oil (HVO) and rapeseed methyl ester (RME), and hydrogen injected into the engine intake manifold. The hydrogen amount ranged from 0 to 35\% of the total energy content of the fuels burned. It was found that co-combustion of liquid fuel with hydrogen is characterized by two distinct combustion phases: premixed and diffusion combustion. The premixed phase, occurring just after ignition, is characterized by a rapid combustion rate, which increases with an increase in hydrogen injected. The novelty in this work is the modified formula for a double-Wiebe function and the proposed parameters of this function depending on the amount of hydrogen added for co-combustion with liquid fuel. To model this combustion process, the modified double-Wiebe function was proposed, which can model two phases with different combustion rates. For this purpose, a normalized HRR was calculated, and based on this curve, coefficients for the double-Wiebe function were proposed. Satisfactory consistency with the experiment was achieved at a level determined by the coefficient of determination (R-squared) of above 0.98. It was concluded that the presented double-Wiebe function can be used to model combustion in 0-D and 1-D models for fuels: RME and HVO with hydrogen addition.",
    url = "https://doi.org/10.3390/en18215622",
    doi = "10.3390/en18215622",
    openalex = "W4415650072",
    references = "depcik2023opensource, doi103390en16062514"
}