Browsing by Author "Lounici, Mohand Said"

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Contribution à la réduction de la pollution urbaine en Algérie par recours à l'utilisation de carburants alternatifs
(2011) Lounici, Mohand Said
La pollution atmosphérique et le réchauffement climatique provoqué par les émissions de gaz à effet de serre sont devenus une préoccupation et un enjeu majeur dans le monde entier. Un grand nombre de travaux de recherche ont été mené dans le but d'identifier des sources d'énergie de substitution plus écologiques que les produits pétroliers conventionnels. Le gaz naturel bénéficie d'un grand intérêt en tant que carburant alternatif propre. Son utilisation dans les moteurs et particulièrement ceux de véhicules est investigué. Relever tous les défis liés à un usage du gaz naturel, digne des avantages qu'il procure, nécessite des stratégies de promotion efficientes qui rallient l'aspect technique à tous les autres aspects inhérents. Dans le but de contribuer à la promotion de ce carburant à l'échelle mondiale en général, et au niveau national en particulier, certains éléments pour des stratégies de promotion sont d'abord proposés sur la lumière d'une revue bibliographique ayant porté sur les différents types de motorisations au gaz naturel. Le fonctionnement dual-fuel est une technique intéressante d'utilisation de ce carburant dans les moteurs, tant sur le plan économique qu'environnemental. Cependant, pour être plus attrayant, quelques aspects doivent être améliorés. La première partie de notre travail est une contribution à la caractérisation et l'amélioration du fonctionnement dual-fuel au gaz naturel. Une investigation expérimentale a été réalisée. Quelques pistes d'amélioration de ce fonctionnement sont explorées. Une stratégie adaptée de contrôle du mode de fonctionnement diesel - dual-fuel est proposée sur la base des résultats obtenus. Le risque de cliquetis aux charges élevées, requiert une attention particulière. Le cliquetis est un phénomène néfaste, voire fatal dans certains cas, pour les moteurs et notamment ceux en fonctionnement dual-fuel. Sa maitrise est d'une importance capitale. Ainsi, nous nous somme intéressés à ce phénomène pour le cas de moteurs dual-fuel au gaz naturel. Sa caractérisation, les moyens de détection de son apparition et les indicateurs utilisés sont investigués. Un nouvel indicateur pertinent est proposé. Une technique de retardement du cliquetis pour ce type de moteur est mise en place. Par ailleurs, le méthane, composant principal du gaz naturel, peut être considéré comme une source d'énergie renouvelable, à travers la production de biogaz issus notamment de la dégradation anaérobique de déchets. La valorisation des biogaz présente un grand intérêt tant sur le plan écologique qu'économique. Cependant, elle est confrontée à des problèmes qui peuvent compromettre leur utilisation industrielle. Les moteurs dual-fuel ont été investigués comme une piste de valorisation de ces gaz et de recherche de solutions à ces problèmes. L'impact de la présence des siloxanes dans ces gaz sur le moteur a été étudié. Une technique innovante de nettoyage des dépôts dus à ces particules dans le moteur a été proposée. La deuxième grande famille de moteurs au gaz naturel est celle à allumage commandé. D'abord, sur la base d'une recherche bibliographique, des pistes d'optimisation de performances et d'émissions sont tirées. Un code de calcul conçu pour servir de banc d'essai numérique pour les moteurs au gaz naturel à allumage commandé, a été développé. Sur la voie de l'optimisation de cet outil, l'évaluation du transfert thermique a été investiguée. Le code de calcul a été validé par des résultats expérimentaux. Cet outil pourra servir comme premier moyen, afin d'étudier différentes techniques d'amélioration de ce type de moteur, en vue du développement de cette catégorie de motorisation au gaz naturel
Corrigendum to “Thermo-hydrodynamic behavior of an innovative solar chimney” [Renew. Energy 145 (2020) 2074–2090]
(Elsevier, 2020) Kebabsa, Hakim; Lounici, Mohand Said; Lebbi, Mohamed; Daimallah, Ahmed
Development of a thermodynamic model for supercharged diesel engine performance and combustion characteristics study
(Taylor and Francis Ltd, 2023) Nezlioui, Ferroudja; Benslimane, Abdelhakim; Hamtache, Brahim; Sahi, Adel; Lounici, Mohand Said; Sadaoui, Djamel
Development of a model that allows performance and combustion characteristics for a supercharged diesel engine was the main objective sought by the present work. Thus, the developed model is used, to examine the impact of start combustion, combustion duration, compression ratio, and heat flux, as well as intake conditions such as pressure and temperature, on the combustion characteristics of the supercharged diesel. For this purpose, a one zone thermodynamic prediction model was adopted with Wiebe function for combustion sub-model. The heat transfer was correlated using Woschni correlation. A numerical simulation is developed considering the crankshaft angle as the independent variable. Validation of the computational code has been favorably evaluated using our experimental data. To give a more general aspect to the developed model, experimental data found in the literature, are also used for this purpose. The results show that the addition of a turbocharger increases low-speed airflow and hence fuel consumption. In addition, an increase in intake pressure contributes to the rise of the heat flux released during combustion, while an increase in intake temperature leads to a strong increase in combustion temperature. Moreover, an increase in the compression ratio leads in a remarkable increase in all parameters simultaneously. However, maximum combustion pressure limits must not be exceeded. This is because the pressure has an effect with the engine mechanical strength.
Development of knock prediction technique in dual fuel engines and its mitigation with direct water injection
(Elsevier, 2024) Sehili, Youcef; Loubar, Khaled; Lounici, Mohand Said; Tarabet, Lyes; Cerdoun, Mahfoudh; Lacroix, Clément
In the face of increasing emission restrictions and the parsimony of conventional fuels, dual fuel engine is presented as a promising solution that is satisfactory for environmental and economic aspects. However, this type of engine is limited by certain problems such as knocking, which negatively influences overall operation. For this reason and for optimal engine operation, prediction of this undesirable auto-ignition is essential. The approach developed in this work for this purpose, is based on dividing the combustion chamber into two zones to follow the thermodynamic properties of the unburnt gases where knock may occur. This thermodynamic modeling is coupled with a model based on Arrhenius equation for the auto-ignition delay as a function of crank angle. In addition, in order to make the model more predictive with the minimum of parameters to be calibrated experimentally, an analysis of variables is used for different engine conditions. The selected parameters undergo a correction before being modeled according to response surfaces methodology. After validation of the model using experimental results, it is coupled with a CFD calculation model to develop a global approach aimed at preventing knocking during dual fuel mode. The model makes it possible to predict knock onset with good precision. Consequently, preventing this phenomenon is possible. Water injection technique is therefore used for this objective. Accurate prediction was useful for knock avoidance via water injection strategy. Our results confirmed the effectiveness of this technique, justified mainly by water injection characteristics. The precision of the instant of knocking predicted by the developed model implied an optimal instant for water injection. Overall, this global model can be considered as a valuable means for knock prediction and prevention in dual fuel mode.
Effect of natural gas enrichment with hydrogen on combustion characteristics of a dual fuel diesel engine
(Elsevier, 2019) Ouchikh, Sarah; Lounici, Mohand Said; Tarabet, Lyes; Loubar, K.; Tazerout, Mohand
Effect of Thermal Collector Height and Radius on Hydrodynamic Flow Control in Small Solar Chimney
(Penerbit Akademia Baru, 2020) Daimallah, Ahmed; Lebbi, Mohamed; Lounici, Mohand Said; Boutina, Lyes
Solar chimney power plant (SCPP) is one of the promising technologies for solar energy utilization. It is an interesting system especially in large isolated desert areas due to its basic techniques and low operating costs. In this study, we investigate numerically the collector geometrical parameters effect on the hydrodynamic flow control in a solar chimney. The finite volume method and the SIMPLE algorithm have been used to solve the turbulent flow equations and energy equation. A standard K-ε model is used. The influence of the collector height (0.05m≤Hc≤0.5m) and the collector radius (2.5m≤Rc≤15m) on the flow behavior has been numerically analyzed. The obtained results indicate that increasing the collector height and collector radius affect considerablythe flow behavior and the SCPP performance. The mass flow rate is enhanced by about 27 %, for Rc=12.5m and Hc = 0.25m.
Eucalyptus biodiesel as an alternative to diesel fuel : preparation and tests on DI diesel engine
(2012) Tarabet, Lyes; Loubar, Khaled; Lounici, Mohand Said; Hanchi, Samir; Tazerout, Mohand
Experimental investigation on NG dual fuel engine improvement by hydrogen enrichment
(Elsevier, 2014) Lounici, Mohand Said; Boussadi, Asma; Loubar, Khaled; Tazerout, Mohand
International conference on advanced mechanics and renewable energies abstracts book
(Belaidi Idir, 2018) Belaidi, Idir; Mechakra, Hamza; Alem, Said; Lounici, Mohand Said
Investigation of natural gas enrichment with high hydrogen participation in dual fuel diesel engine
(Elsevier, 2021) Benbellil, Messaoud Abdelalli; Lounici, Mohand Said; Loubar, Khaled; Tazerout, Mohand
This study explores the impact of natural gas (NG) enrichment with high H2 concentrations (20, 30, 40 and 50 by v %) on combustion characteristics, engine performance, exhaust emissions and knock in a compression ignition engine running in dual fuel (DF) mode. Results indicated that H2 addition to NG contributes to enhance gaseous fuel combustion that corresponds to an increased heat release rate (HRR) during the premixed phase of gaseous fuel that also causes an increase in the pressure peak, particularly at high loads. The maximum pressure peak and HRR correspond to 50% H2 addition. The combustion duration is shortened for all H2 mixtures. Regarding engine performance, an important benefit in terms of brake thermal efficiency is noted for all H2 blends; it increases with increasing enrichment rate and reaches approximately 16% increase for the 50% H2 mixture relative to pure NG case. Moreover, enriching NG with H2 is an effective solution for reducing unburned hydrocarbons and carbon monoxide at moderate to high engine loads. However, for NOx emissions, the addition of H2 to NG is only attractive at low and moderate loads. In addition, over 80% engine load, NG enrichment with H2 generates knock, which rapidly reaches high intensities.
Investigation of natural gas enrichment with high hydrogen participation on knock in dual fuel diesel engine at high loads
(2021) Benbellil, Messaoud Abdelalli; Lounici, Mohand Said; Loubar, Khaled; Tazrout, Mohand
With growing worries about the safety of the environment and the lack of supplies of crude oil, a great deal of effort has been made to use alternative fuels in engines. For internal combustion engines, natural gas (NG) is one of the most attractive available fuels. The dual fuel (DF) concept is an effective way for its use. NG has a slow burning velocity and limited lean-burn ability. Enriching NG with hydrogen is an effective way to mitigate such demerits, since H2 is characterized by a rapid combustion speed, wider combustion limit and low ignition energy. For high engine loads operation, the engine risks to go through a hazardous knocking regime. This study explores experimentally the effect of NG enrichment with high H2 concentrations (20, 30, 40 and 50 by v %) in DF mode on knock at high engine loads of a compression ignition engine. Results indicated that enriching NG with high H2 concentrations in DF mode is an interesting technique for improving dual fuel engine up to 80% load without any knock. However, beyond this load (at 90% of full engine load) the knocking phenomenon appears with high intensities and occurs before achieving the maximum output power of the diesel engine (4.5 kW). In the case of pure NG, the engine reach the maximum output power (100% of full engine load) without knocking. An occurrence of knock with H2 addition might be due to a very low methane number of H2 that means hydrogen is highly prone to generate the knock than NG, which is mainly composed of methane. Knocking combustion causes major engine damage, reduces the efficiency and requires particular attention. Therefore, it is advisable to operate DF engine with H2 enrichment at the safe zone (from 20% to 80% engine load) to prevent knock.
Investigation on heat transfer evaluation for a more efficient two-zone combustion model in the case of natural gas SI engines
(Elsevier, 2011) Lounici, Mohand Said; Loubar, Khaled; Balistrou, Mourad; Tazerout, Mohand
Two-zone model is one of the most interesting engine simulation tools, especially for SI engines. However, the pertinence of the simulation depends on the accuracy of the heat transfer model. In fact, an important part of the fuel energy is transformed to heat loss from the chamber walls. Also, knock appearance is closely related to heat exchange. However, in the previous studies using two-zone models, many choices are made for heat transfer evaluation and no choice influence study has been carried out, in the literature. The current study aims to investigate the effect of the choice of both the heat transfer correlation and burned zone heat transfer area calculation method and provide an optimized choice for a more efficient two-zone thermodynamic model, in the case of natural gas SI engines. For this purpose, a computer simulation is developed. Experimental measurements are carried out for comparison and validation. The effect of correlation choice has been first studied. The most known correlations have been tested and compared. Our experimental pressure results, supported for more general and reliable conclusions, by a literature survey of many other studies, based on measured heat transfer rates for several SI engines, are used for correlation selection. It is found that Hohenberg’s correlation is the best choice. However, the influence of the burned zone heat transfer area calculation method is negligible
Investigationof pilot injection strategy effect on performance and emissions ofdual-fuel engine
(Toronto Metropolitan University, 2023) Ouchikh, Sarah; Lounici, Mohand Said; Loubar, Khaled; Tazerout, Mohand
The dual-fuel combustion is a promising technique for methane utilization in internal combustion. This mode has the potential to reduce emissions of nitrogen oxides and particulate matter. However, this mode presents some deficits at low loads, especially concerning unburned hydrocarbons and carbon monoxide emissions. In the current study, experimental research was conducted to investigate the effect of diesel injection strategy, including single and split injections, on the performance and emissions of a methane/diesel dual-fuel engine.
Knock characterization and development of a new knock indicator for dual-fuel engines
(Elsevier, 2017) Lounici, Mohand Said; Benbellil, Messaoud Abdelalli; Loubar, K.; Niculescu, D.C.; Tazerout, Mohand
Dual-fuel mode is a promising technique for natural gas utilization in internal combustion engines. However, for high loads operation, the engine risks to go through a hazardous knocking regime. Knock phenomenon is an abnormal combustion that can cause some disagreeable effects in engines where it occurs. It can even induce brutal irreparable engine damage under severe knocking conditions. The present paper aims first to highlight and characterize knock in dual-fuel engines fueled with natural gas as main fuel and diesel as pilot fuel. Description of this phenomenon is investigated in this type of engines. Knock behavior in dual-fuel engine is compared to spark ignition engine case. Cyclical variability of this phenomenon is studied. A new knock indicator, based on in-cylinder pressure analysis, is proposed in order to identify and evaluate knock in dual-fuel engines. In addition, knock effects on heat release, cylinder wall temperature and engine performance and emissions are examined. New techniques to delay knock appearance in this type of engines are investigated. It is found that the increase in pilot fuel quantity is an effective technique to delay knock onset in NG dual-fuel engines
Mass flow rate enhancement inside a solar chimney power plant
(Toronto Metropolitan University, 2023) Daimallah, Ahmed; Lebbi, Mohamed; Lounici, Mohand Said
The Solar chimney power plant is a system that converts solar energy to mechanical energy and then to electrical energy. The present work aims to conduct numerical investigation on the influence of the radius ratio Rt* = Rtout/Rtinlet and the height of the tower-chimney, on the flow behavior inside the SCPP of Manzanares. A 2D axi-symetric turbulent model is adopted. The momentum and energy equations are solved using the finite volume method and the simple algorithm. Results show that velocity and mass flow rate inside the SCPP are affected by the radius ratio Rt*, the height of tower-chimney Ht* and intensity radiation Q. We obtain an enhancement of mass flow rate by about 58.23% for the divergence of the tower-chimney.
Numerical investigation of a novel tower solar chimney concept
(elsevier, 2020) Kebabsa, Hakim; Lounici, Mohand Said; Daimallah, Ahmed
Divergent tower solar chimney power plant is an attractive upgrading of the solar chimney system. However, boundary layer separation (BLS) phenomenon can appear when the divergence angle exceeds a specific value, inducing system performance degradation. The present paper proposes a novel solar chimney tower concept, named annular tower solar chimney power plant (ATSCPP), to deal with BLS phenomenon and improve the divergent tower system. Accordingly, the influence of exterior tower radius (ETR) and interior tower radius (ITR) were evaluated, using the Spanish prototype. Simulations were carried out using a 3D model. The results indicate that flow behavior, power output and thermal efficiency shows a strong sensitivity to the change of both ETR and ITR. The best case is obtained when (ETR = 17 m, ITR = 13 m). The new solar chimney tower concept allowed a significant increase in the driving potential. The total improvement in power output reaches 32%. An improved concept which allows a compromise between induced cost and performance gain of the system is also proposed.
Numerical investigation on combustion characteristics of both diesel and dual fuel engine at part load conditions using converge cfd
(2019) Benbellil, Messaoud Abdelalli; Lounici, Mohand Said; Loubar, Khaled; Ouchikh, Sarah
Petroleum resources are nite and, therefore, search for their alternative non-petroleum fuels for internal combustion engines is continuing all over the world. Moreover, gases emitted by petroleum fuel-driven vehicles harm the environment and human health. Dual-fuel engine (diesel/NG) represents one of a possible solution to reduce emissions from a diesel engine. Therefore, this method has been given a lot of attention from many researchers to improve engine performance and reduce diesel consumption, particularly at full loads. However, it is necessary to study the dual-fuel (DF) combustion process with more details at part loads, due to the poor performance at these conditions. This study numerically investigated the e ect of DF (dual fuel) operating mode on combustion characteristics of an existing diesel engine using natural gas as primary fuel and neat diesel as pilot fuel at part loads by adopting a 3D-CFD simulation using the code CONVERGE. A series of numerical simulations were carried out, the purpose of which to gain a better understanding of the combustion behavior in dual-fuel engines. The results are rst validated using experimental data. A comparison with neat diesel fuel operation is achieved.
Numerical investigation on di diesel engine running with eucalyptus biodiesel and its blends
(2012) Tarabet, L.; Loubar, K.; Lounici, Mohand Said; Hanchi, S.; Tazerout, M.
Performance evaluation of the combined solar chimney-photovoltaic system in Algeria
(Elsevier, 2021) Kebabsa, Hakim; Lounici, Mohand Said
The demand for solar energy technologies is increasing due to the growing interest in renewable energy. However, these technologies are affected by atmospheric conditions and low overall efficiency. The present study proposes a combined solar chimney-photovoltaic (SC-PV) system to deal with stand-alone system weaknesses. This work evaluates this self-sustainable system's performance and estimates the electric energy generated under the climatic conditions of Algeria using computational fluid dynamics (CFD). The model is first validated using the Spanish prototype experimental data. The simulations show that the proposed system provides several valuable benefits for improving turbine power, solar cell temperature, and PV efficiency. The results indicate the SC in the combined system performs better turbine generated power than a stand-alone system only for an appropriate PV location and width. Using the heat released from the PV to increase the kinetic energy of airflow beneath the collector, the total improvement in turbine power reaches 8.91%. Similar to the optimal PV widths (10 m), other widths, varying from 20 m to 30 m, increase the overall turbine power without degrading SC performance. Using the SC-PV as a cooling method, the solar cell temperature decreases by 12.12% (6.30 °C) compared with cell temperature in the stand-alone system (52 °C). Accordingly, the PV efficiency increases by 3.23% compared with PV efficiency in the stand-alone system (13.18%). The results also indicate the highly intensive solar radiation region (Adrar) has higher monthly turbine power than other areas. The appropriate areas for building such a system will be in the south of the country, where the solar potential is high. In these regions, the SC-PV could contribute to satisfying the electricity demand
Thermo-hydrodynamic behavior of an innovative solar chimney
(Elsevier, 2020) Kebabsa, Hakim; Lounici, Mohand Said; Lebbi, Mohamed; Daimallah, Ahmed
Production of electricity through solar systems is a viable alternative, especially for deserted regions where access to electricity is difficult. Solar chimney power plant (SCPP) is one of the promising concepts in renewable energy technology that needs performance enhancement. The objective of this research is to investigate a novel concept, which consists of a horizontal solar chimney power plant with an adapted collector entrance, named sloped collector entrance SCPP (SCESCPP). The effect of the collector entrance shape (slope, sloping distance) is investigated. For each sloping distance, eleven values for the slope are examined. Thus, a numerical investigation is carried out using a 2D axisymmetric chimney model. The model was first validated using experimental results. The influence on air thermo-hydrodynamic behavior of this system is comprehensively studied to enhance the understanding and deepen the analysis in order to improve the performance of the SCPP. The results indicate that the new collector entrance design influences the system performance in a significant manner. It is shown that the best performing configuration (sloping distance of 0.8 and slope of 9.1°) produces an available power reaching 16.36% more than that for zero slope collector roof at same conditions. Moreover, it is found that the optimal slope depends on sloping distance and remains almost the same for different Rayleigh numbers