Yazar "Zearah, Sajad A." seçeneğine göre listele

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    CFD STUDY OF A DUAL-PASSAGE SOLAR COLLECTOR WITH LONGITUDINAL AND TRANSVERSE BAFFLES FOR ENHANCED THERMAL PERFORMANCE
    (Vinca Inst Nuclear Sci, 2023) Amraoui, Mohammed Amine; Alkhafaji, Mohammed Ayad; Abdullaev, Sherzod; Zearah, Sajad A.; Akgul, Ali; Jarrar, Rabab; Shanak, Hussein
    The focus of this research is to investigate the heat transfer performance of a solar flat plate collector by utilizing CFD simulation. To accomplish this, a 3-D model of the collector with an air inlet was created using ANSYS Workbench, and the grid was generated through ANSYS ICEM, ANSYS FLUENT, and ANSYS CFX were then used to obtain comprehensive results. The primary objective of this study is to enhance the efficiency of the solar collector by introducing two fluid-flow paths and comparing the results with those reported in existing literature. These findings will aid in the development of advanced solar collector designs and promote sustainable use of solar energy. Furthermore, the insights gained from this study may inspire further research in the renewable energy technology field. Overall, this research explores the potential of improving the performance of solar flat plate collectors and sheds light on how the use of CFD simulation can facilitate the development of innovative and sustainable energy solutions.
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    IMPROVEMENT OF THE PERFORMANCE OF SMALL-SIZED CAVITATING VENTURIS BY INSERTING OBSTACLES
    (Vinca Inst Nuclear Sci, 2023) Rostane, Brahim; Aliane, Khaled; Brayyich, Mohammed; Zearah, Sajad A.; Akgul, Ali; Abdullaeva, Barno; Menni, Younes
    Cavitating Venturis are simple apparatus used as a flow meter over a broad range of mass-flow rates. The main objective of this work is to introduce obstacles in small-sized cavitating Venturis in order to increase their capacity by raising the critical pressure, i.e. widens the phase of the cavitating mode. Four configurations have been tested depending on the location of these obstacles. This study focused on investigating the numerical performance of cavitating Venturis with different downstream pressures by employing the k-. SST turbulence model and the Rayleigh-Plesset equation for modeling cavitation. The governing equations were solved using the finite volume method, employing the Rhie and Chow pressure-velocity coupling scheme. The results showed the void fraction and streamlines contours obtained on the symmetry plane. The mass-flow ratio was presented for all configurations and different pressure ratios. The study showed that the cavitating Venturis equipped with obstacles extend the phase of choked mode from 10.71% to 21.42% and that the best configuration correspond to the case where the obstacles are placed in the converging section.
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    NUMERICAL STUDY ON A NATURAL GAS-FUELED ENGINE UNDER LOW TEMPERATURE COMBUSTION MODE
    (Vinca Inst Nuclear Sci, 2023) Kezrane, Cheikh; Naima, Khatir; Alsharari, Abdulrhman M.; Al-Hameed, Mazin Riyadh; Zearah, Sajad A.; Akgul, Ali; Abdullaeva, Barno
    Natural gas, which is also referred to as eco-friendly fuel, is being seen as a potential solution to challenge the decline of crude oil resources and the deteriorating air quality in urban areas. This fuel has been verified to emit less CO, HC, and PM compared to other fuels. A potential approach to reducing NOx and soot emissions while also achieving low fuel consumption is the low temperature combustion process. In this study, internal combustion engines were simulated under various conditions. The objective was to investigate the effect of different operating variables on the low temperature combustion mode. To begin with, a natural gas powered engine was modeled using complex chemical kinetics software. The outcomes of the simulation were then compared to experimental data, demonstrating a high level of agreement. Subsequently, the impacts of key variables, including the air-fuel ratio, compression ratio, and engine speed, were analyzed using a cycle simulation code. Increasing the compression ratio improves engine performance, and the specific fuel consumption decreases. However, it leads to a significant increase in NOx emissions until a certain value. Thereafter, it changes the trend. Engine speed indirectly affects performance by increasing fuel consumption and changing ignition timing. A leaner air fuel ration may be used to produce more power and keep the temperature of combustion below a certain value (low-temperature combustion), ensuring low NOx emissions.