Papers by Dimitrios Kouremenos
Experimental investigation of the performance and exhaust emissions of a swirl chamber diesel engine using JP‐8 aviation fuel
International Journal of Energy Research, 1997
An experimental study is conducted to evaluate the use of JP-8 aviation fuel as a full substitute... more An experimental study is conducted to evaluate the use of JP-8 aviation fuel as a full substitute for diesel fuel in a Ricardo E-6 high-speed naturally-aspirated four-stroke experimental engine having a swirl combustion chamber. The study covers a wide range of engine load and speed operating conditions, comprising measurements of cylinder pressure diagrams, high-pressure fuel pipe pressures, exhaust gas temperatures, fuel consumptions, exhaust smokiness and exhaust gas emissions (nitrogen oxides, unburned hydrocarbons and carbon monoxide). Processing of the measurements provides important performance parameters such as maximum combustion pressure, dynamic injection timing, ignition delay, combustion irregularity and knocking tendency. The differences in the measured performance and exhaust emission parameters are determined for engine operation with JP-8 fuel, against baseline engine operation using diesel fuel. The study shows that the exhaust emission levels are not much differen...
Analysis of the performance and emissions characteristics of prechamber diesel engines via a two-zone model in both chambers
Simulation mathématique des pertes de gaz à la segmentation d'un moteur diesel
Le present article decrit un modele d'ecoulement compressible des gaz du cylindre dans et au ... more Le present article decrit un modele d'ecoulement compressible des gaz du cylindre dans et au dehors de regions qui se trouvent entre le piston, les segments et les parois du cylindre, a travers les gorges du piston, pendant le cycle d'un moteur a piston, conduisant ainsi au calcul du debit de blowby. Le mouvement des segments est incorpore dans le modele d'ecoulement, en prenant en compte l'equilibre des forces appliquees. Un modele thermodynamique synthetique des processus de la compression et de la detente est aussi incorpore fournissant la pression et la temperature du cylindre a chaque pas de temps. Les resultats du programme de l'ordinateur sont compares aux valeurs obtenues experimentalement sur un moteur diesel du type Ricardo (compression-detente sans combustion) au laboratoire des auteurs. Les resultats theoriques et experimentaux concernant le debit de blowby pour plusieurs vitesses de rotation, sont compares tres favorablement, eclairant les mecanismes...
Utilisation de propane comme aliment de complément dans un moteur à chambre de turbulence
Entropie, 1988
Phasing cylinder pressure to crank angle in a direct injection diesel engine, by simulation of compression curve and elaboration of measured pressure data
Forschung im Ingenieurwesen, 1991
Page 1. Phasing Cylinder Pressure to Crank Angle in a Direct Injection Diesel Engine, by Simulati... more Page 1. Phasing Cylinder Pressure to Crank Angle in a Direct Injection Diesel Engine, by Simulation of Compression Curve and Elaboration of Measured Pressure Data Dimitrios A. Kouremenos, Constantine D. Rakopoulos and Constantine G. Kotsos*) ...
Description of in-Cylinder Combustion Processes in HCCI Engines Using a Multi-Zone Model
SAE Technical Paper Series, 2005
Abstract: In the present work, a multi-zone model is presented for the simulation of HCCI engines... more Abstract: In the present work, a multi-zone model is presented for the simulation of HCCI engines. This model is an improvement of a previous one developed by the authors. The present model describes the combustion, heat and mass transfer processes for the closed ...
Experimental investigation to specify the effect of oxygenated additive content and type on di diesel engine performance and emissions
SAE Technical Papers, 2004
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Multi-Zone Combustion Modelling for the Prediction of Pollutants Emissions and Performance of DI Diesel Engines
SAE Technical Paper Series, 1997
Diagnosis and condition monitoring of medium-speed marine diesel engines
Tribotest, 1997
ABSTRACT
A FORTRAN program for calculating the evaporation rates in diesel engine fuel sprays
Advances in Engineering Software, 1992
... An experimental investigation has been conducted, at the authors' laboratory, on a singl... more ... An experimental investigation has been conducted, at the authors' laboratory, on a single cylinder, naturally aspirated, four stroke, Ricardo E-6 ... PRRg,DENSL) CALL CPLIQ(TEMPC,CPL~ TEMPC=(TEMP+2.*TDROP)/3.-273.15 CALL PROPAIR(TEMPC,CONDA,VISCA,CPA) 500 ...
Effect of Injection Pressure on the Performance and Emission of Diesel Engine using Blend of Methyl Esters of Karanja Oil and Diesel as Fuel
SAE Technical Paper Series, 2006
Development and Validation of a Diagnosis Method for Diesel Engines
Advanced Energy Systems
Diesel engines are used widely for power production and other applications such as sea vessels, r... more Diesel engines are used widely for power production and other applications such as sea vessels, railways, transportation etc. A serious problem for the service engineer is their maintenance and tuning in order to obtain maximum performance and reliable operation during their operational lifetime. Another serious problem is the detection of faults and their cause especially in the case when the engine does not function properly, i.e. low power output or high exhaust gas temperature. Up to now various techniques have been used for diesel engine monitoring and fault diagnosis that are mainly statistical. These techniques have serious disadvantages since they cannot be applied generally but have to be developed for the specific engine under consideration and fail to provide the actual cause in the case of a fault. To overcome these problems a new method is proposed in the present work for engine monitoring and fault diagnosis. This method allows to know the condition of the engine at ea...
A mathematical simulation of the piston crevice flow and blow-by in internal combustion diesel engines
Entropie; (France), 1993
On the Definition of Entropy and Temperature and on the Energy Interactions
Advanced Energy Systems, 1998
The thermodynamic systems considered here are those that can be described by using only two macro... more The thermodynamic systems considered here are those that can be described by using only two macroscopic variables. For this purpose the specific volume v and the specific internal energy u are used while the pressure function p(u,v) is supposed to be known. It is shown that by a suitable mathematical transformation of variables, the pair (u,v) can be replaced by the pair of functions temperature T(u,v) and entropy s(u,v) that are defined simultaneously by a proposed generic system of differential equations without using the concept of heat. To show the authenticity of these definitons some solutions of this generic system of differential equations are given and in addition to, the special case of the perfect gas is obtained as one of the results. It is proposed to add to the conventional concepts of work and heat a third constitutive component, the throttling. With it the local efficiency η of a differential themodynamic change can be defined. In addition this allows for the deducti...
On the isentropic expansion of steam
Vdi Berichte, 1984
La detente isentropique reelle d'un gaz, decrite par la relation (dp/dv) s =(c p /c v ) (∂p/∂... more La detente isentropique reelle d'un gaz, decrite par la relation (dp/dv) s =(c p /c v ) (∂p/∂v) T , peut etre representee localement de facon approchee par la relation connue pv k =cte, seulement quand k p,v =(1/pv).(c p /c v ).(∂p/∂ρ) T . Les modifications thermodynamiques de la vapeur, le long d'une detente isentropique, ont ete calculees pour differents points initiaux. Dans ce but, un programme d'ordinateur special, ISEXST, a ete developpe. Les donnees thermodynamiques de la vapeur sont obtenues par une modification du sous-programme WASP developpe par la NASA
Forschung im Ingenieurwesen, 1990
This work presents a computer simulation of the exhaust nitric oxide and soot emission histories ... more This work presents a computer simulation of the exhaust nitric oxide and soot emission histories from a four stroke, naturally aspirated, Diesel engine with a swirl prechamber (divided chamber). The simulation is based on a thermodynamic analysis, which was validated successfully concerning the performance of the engine (load, fuel consumption, maximum pressures, etc). The analysis includes the calculation of the heat exchange between gas and walls in both the main chamber and (swirl) prechamber, after computing the relevant characteristic velocities and lengths, while combustion in both the main chamber and the swirl prechamber is attacked by proposing a two-zone combustion model. The concentration of the constituents in the exhaust gases is calculated by incorporating a complete chemical equilibrium scheme for the C-H-0 system of the eleven species considered, together with chemical rate equations for the calculation of nitric oxide (NO). A model for the evaluation of soot formation and oxidation rates is also included, in order to compute the net soot concentration. The contribution of each chamber to the formation of NO and soot is given by presenting time (crank angle) diagrams of the net NO and soot formation inside each chamber (histories of formation). To validate the analysis, an extensive experimental investigation is undertaken at the authors' laboratory on a Diesel engine of this type by evaluating its exhaust emission characteristics in a wide range of operating conditions. The experimental results are found to be in good agreement with the theoretical results obtained from the computer program implementing the analysis, while the detailed NO and soot net formation histories provide insight into the mechanisms involved.
Multi-Zone Combustion Modeling as a Tool for DI Diesel Engine Development – Application for the Effect of Injection Pressure
SAE Technical Paper Series, 2004
During the recent years, extensive research conducted worldwide in the field of Heavy Duty Diesel... more During the recent years, extensive research conducted worldwide in the field of Heavy Duty Diesel engines has resulted to a significant improvement of engine performance and emissions. These efforts have been assisted from simulation models providing good results. Towards this direction a multi-zone model developed by the authors has been used in the past to examine the effect of injection pressure on Dl diesel engine performance and emissions. The attempt was challenging since no experimental data existed when the calculations were conducted, to support the findings. Eventually, experimental data concerning engine performance and emissions became available using slightly different operating conditions and injection pressure data. In the present study an attempt is made to evaluate the prediction ability of the multi zone model by comparing the theoretical results with experimental data and explain any discrepancies between them. The simulation code used is essentially the same while a calibration has been made only for the soot model, to obtain at one operating point (low injection pressure) similar absolute values. It is promising that the simulation manages to predict for all examined cases the effect of injection pressure on engine performance and emissions. It is confirmed that the increase of injection pressure results to fast combustion and a serious reduction of soot especially at part load and high engine speeds but at the same time to a considerable increase of NO emissions. Predictions from the present study using actual injection rate data and operating conditions are qualitatively similar to the ones of the initial investigation while absolute values are closer to the experimental ones. But since the most important role of modeling is not to capture accurately absolute values but trends, its validity as a prediction tool is revealed.
Using Advanced Injection Timing and EGR to Improve DI Diesel Engine Efficiency at Acceptable NO and Soot Levels
SAE Technical Paper Series, 2001
... Kouremenos, DA, Rakopoulos, CD and Hountalas, DT, Thermodynamic analysis of indirect injecti... more ... Kouremenos, DA, Rakopoulos, CD and Hountalas, DT, Thermodynamic analysis of indirect injection diesel engines by two-zone modeling of combustion, Trans. ASME, J. Engng for Gas Turbines and Power, 112, 138-149, 1990. ...
Forschung im Ingenieurwesen, 1991
The Redlich-Kwong-Soave generalized equation of state is transformed into a dimensionless form, w... more The Redlich-Kwong-Soave generalized equation of state is transformed into a dimensionless form, which permits plotting of one compressibility chart for each value of the acentric factor co. Such charts are provided for various values of o~ in the range o~=0-0.6. A systematic evaluation of the Redlich-Kwong-Soave equation is made by comparison with the latest version of the generalized compressibility chart given by Nelson and Obert. It is found that for co=0, the Redlich-Kwong-Soave compressibility chart agrees well with the Nelson-Obert chart, apart from a small region near the critical point: For values of the reduced pressure p, < i, the relative ercompressibility factor z is less than about i%. For reduced pressures and temperatures in the ranges 1 < p, < 8 and i _< T'_ 3.5, respectively, it is found e <_ 1% at the higher values ofT,, e<5% at the intermediate T, and e <_ 10% at the lower 7",. The highest disagreement is observed near the critical point (pr= T,= 1). Moreover, the exact compressibility chart of the real air is developed, based on its exact equation of state, and compared with the Redlich-Kwong-Soave compressibility chart for co=O.
Forschung im Ingenieurwesen, 1986
The present work considers the evaporation process of NH 3 in NH3/H 2 atmosphere, that takes plac... more The present work considers the evaporation process of NH 3 in NH3/H 2 atmosphere, that takes place in neutral gas absorption refrigeration units. The data obtained are used to calculate the "psychrometric problem" and the evaporation process within an insulated tube. The "psychrometric problem" deals with the determination of the mass fraction of the NH3/H 2 gas mixture from known "dry" and "wet bulb" temperatures for Lewis numbers not equal to one. The results are in good agreement with some existing experimental data. The neutral gas absorption refrigeration units use NH 3 as refrigerant and H 2 as pressure equalizing gas. Thus the throttling process of the conventional refrigeration units is being replaced by the diffusion of the evaporated NH 3 through the H 2 atmosphere. To calculate the heat and mass transfer operations taking place in the evaporator and the gas heat exchanger of those units, we need to know the corresponding thermodynamic and transport properties of the mixture involved in. In the following there are presented briefly the main functions required for the solution of the NH3/H 2 "psychrometric problem". By using a "dry" and a "wet bulb" thermocouple, inside the evaporator, we can determine the mass fraction of the mixtures, a measurement that cannot be replaced by gas sampling and analizing due to the stratification and small velocities prevailing in such units. The obtained results are compared to some unpublished experimental data [4-] and give a very good agreement. To exclude the influence of the many parameters affecting the heat transfer on the outside of the evaporator's tube, the special case of the adiabatic evaporation has been selected.
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Papers by Dimitrios Kouremenos