Ahmed Ketata

The adoption of alternative fuels is increasingly regarded as a promising strategy to mitigate emissions from internal combustion engines. However, the influence of biodiesel feedstock choice on engine behavior remains insufficiently explored and warrants further investigation. This study aims to address this gap by examining and comparing the performance and emission responses of a single‐cylinder engine fueled with biodiesel blends derived from different vegetable feedstocks. A combined experimental and numerical approach was employed to assess the impact of four vegetable feedstocks cultivated in Tunisia, which are waste cooking oil, sunflower, almond, and avocado, on engine operation across varying loads (25–75%) and speeds (800–1600 rpm). Four B20 blends were prepared, each containing 20% biodiesel from one feedstock (B20W, B20S, B20AL, and B20AV), along with a fifth blend referred to as 5B20 consisting of equal portions of the four biodiesels (20% for each feedstock) mixed with diesel. The B20AL and B20AV blends exhibited significant reductions in CO, CO ₂ , NOₓ, and HC emissions under diverse engine operating conditions, although this was accompanied by a decline in engine performance compared to B20W, B20S, and 5B20 blends. The results provide valuable insights into feedstock‐dependent biodiesel performance, offering guidance for optimizing fuel selection in next‐generation engine technologies and advancing cleaner, more efficient propulsion systems.

This study investigates the indoor microclimate of a large‐scale soilless greenhouse in northern Tunisia, analyzing its response to daily environmental variations through experimental measurements and numerical simulations. Structural and environmental factors, including glazing, ventilation, vegetation, and concrete ground, were assessed for their influence on the internal climate. The numerical model was validated through a grid independence study and by incorporating appropriate turbulence and thermal radiation models. Simulations with and without crops revealed that soilless cultivation significantly alters temperature patterns, with increases of 1 K above basil crops and 2.2 K above tomato crops. These variations highlight the strong role of crop transpiration in shaping airflow and temperature distribution. Differences between crop types were also evident, as basil and tomato cultivation induced distinct microclimatic effects reflecting their physiological and thermal characteristics. Central indoor temperature variations ranged from a 1.2% decrease between 13 and 16 h to a 2.4% increase between 9 and 13 h, with ground‐level maxima aligned with solar radiation. A predictive correlation was developed to estimate indoor temperature based on external inputs, offering practical tools for climate control. Thermal comfort indicators such as vapor pressure deficit (VPD) were also evaluated to guide crop‐specific climate management. The findings support optimized sensor placement, improved environmental monitoring, and the integration of crop effects into greenhouse thermal modeling. Designed as a representative case study, the experiment provides focused insights on plant‐climate interactions over a single day, serving as a foundation for future research on dynamic greenhouse microclimates.

The use of alternative fuels is widely recognized as an effective way to reduce emissions from internal combustion engines. While biodiesel has been widely studied in naturally aspirated engines, limited research addresses its impact on modern turbocharged configurations. To address this gap, the present study compares the performance and emission characteristics of naturally aspirated and turbocharged engines operating with various biodiesel blends produced from waste oil. Results demonstrate that turbocharging, when combined with a B20 biodiesel blend, substantially reduces emissions while maintaining performance levels comparable to conventional diesel. Turbocharging decreased fuel consumption by up to 20% and enhanced brake torque by as much as 75%, while B20 delivered performance nearly identical to petroleum diesel. Moreover, unburned hydrocarbons were reduced by approximately 6% under boosted conditions. These findings contribute to a deeper understanding of biodiesel utilization in advanced engine technologies and support the development of cleaner, more efficient propulsion systems for diverse applications.

This study presents an experimental investigation into the vibration characteristics of four different Vortex Bladeless Wind Turbine (VBWT) prototypes made with different mast materials - Glass Fiber (GF), Polyurethane (PU), and Polyethylene (PE) - and rod lengths. They were tested in a wind tunnel with different Reynolds number flow regimes using two rod lengths (60 mm and 90 mm) to evaluate their performance under controlled conditions. An acquisition system based on Arduino was constructed to measure the linear acceleration of the vibration of each prototype. The experimental results revealed that the rod length had a significant impact on both the amplitude and frequency of vibration, with longer rods producing greater deflection and lower natural frequencies. The mast diameter was also found to influence the frequency, with larger diameters yielding reduced vibration frequencies. Furthermore, the material of the mast played a crucial role in the dynamic behavior. The PU mast exhibited the highest vibration amplitudes and frequencies due to its lower mass and greater flexibility, compared to the GF and PE configurations. These findings contributed to the advancement of this emerging renewable energy technology of VBWTs.

Biofuel as a sustainable source of energy was investigated in several earlier studies to look for environmentally friendly alternatives to fossil-based fuels. This study aims to investigate a new type of low-cost biofuel based on the palm oil extracted from the palms. The experimental...