Publications Internationales
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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 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, MohandDual-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 enginesItem Performance evaluation of the combined solar chimney-photovoltaic system in Algeria(Elsevier, 2021) Kebabsa, Hakim; Lounici, Mohand SaidThe 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 demandItem 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 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, AhmedItem Thermo-hydrodynamic behavior of an innovative solar chimney(Elsevier, 2020) Kebabsa, Hakim; Lounici, Mohand Said; Lebbi, Mohamed; Daimallah, AhmedProduction 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 numbersItem 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, Mohand