Publications Internationales
Permanent URI for this collectionhttps://dspace.univ-boumerdes.dz/handle/123456789/13
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Item 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, ClémentIn 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.Item 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, DjamelDevelopment 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.Item 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, MohandThis 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.Item 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, LyesSolar 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.Item Numerical investigation of a novel tower solar chimney concept(elsevier, 2020) Kebabsa, Hakim; Lounici, Mohand Said; Daimallah, AhmedDivergent 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.Item 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, MohandItem Experimental investigation on NG dual fuel engine improvement by hydrogen enrichment(Elsevier, 2014) Lounici, Mohand Said; Boussadi, Asma; Loubar, Khaled; Tazerout, MohandItem Towards improvement of natural gas-diesel dual fuel mode : an experimental investigation on performance and exhaust emissions(Elsevier, 2014) Lounici, Mohand Said; Loubar, Khaled; Tarabet, Lyes; Balistrou, Mourad; Niculescu, Dan-Catalin; Tazerout, MohandItem 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, MohandItem 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, MohandTwo-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