Browsing by Author "AZZOUZ Salaheddine (Co-Auteur)"

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    A Novel Micro-Thermophotovoltaic Combustor of Hydrogen–Air to Enable Ultra-Lean Combustion, High Thermal Output and NO Low Emissions
    (International Journal of Energy Research, 2025-01) AZZOUZ Salaheddine (Co-Auteur)
    This study presents a novel micro-combustor (MC) design called micro-trapped vortex combustor (MTVC) for microthermophotovoltaic (MTPV) devices used in small-scale electricity generation. Traditional MC designs struggle to operate efficiently under ultra-lean regimes due to flame quenching, limiting their performance. The proposed MTVC incorporates the trapped vortex concept, inspired by aeronautical applications, to improve thermal performance and stability under ultra-lean conditions. Numerical simulations, using the Navier–Stokes and energy equations for laminar and reactive flow, are conducted to compare the MTVC with conventional micro-backward-step combustors (MBSCs) under hydrogen (H2)–air mixture combustion. The study focuses on key performance parameters such as temperature distribution, heat recirculation, flame shape, flow topology, radiative power and emissions. The results show that the MTVC can operate at an ultra-lean equivalence ratio of Φ=0.5, while the MBSC experiences flame quenching below Φ=0.7. The MTVC design achieves up to 26.51% higher radiative power and a 36% improvement in energy conversion efficiency compared to traditional combustor designs. Additionally, the MTVC produces 43% less nitrogen oxides (NOx) emissions, demonstrating its potential for both higher efficiency and reduced environmental impact in portable power applications.
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    Analytical Modeling of Joule Heating in Electro-Thermal Contacts for Short-Term Industrial Applications
    (International Journal of Heat and Technology, 2024) BENCHADLI Djillali; AZZOUZ Salaheddine (Co-Auteur)
    the thermal transfer at solid-solid interfaces, particularly with heat generation at the interface, is a critical area of study. This research presents a theoretical framework for addressing the direct problem of thermal conduction in electro-thermal contacts, with a focus on short-term scenarios where heat dissipation occurs through the Joule effect. This aspect, not extensively explored in existing literature, is investigated using a semi analytical method. The study also encompasses a simulation-based exploration, aimed at deepening the understanding of physical phenomena at the contact level. Special attention is given to the thermal transfers initiated at the asperity level of the electro-thermal contact. Findings from this investigation underscore the significance of incorporating the thermal diffusivity of materials into the model for achieving convergence. A notable observation is the increasing divergence over time between the temperatures predicted by numerical and analytical solutions, a trend more pronounced in materials with higher thermal diffusivity, such as titanium. This research contributes valuable insights into the modeling of contact parameters essential for simulating various industrial applications, potentially enhancing efficiency and efficacy in thermal engineering practices.
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    Moisture diffusivity of medicinal and aromatic plants during convective drying by hot air: Myrtle leaves
    (Eur. Chem. Bull, 2023) AZZOUZ Salaheddine (Co-Auteur)
    In order to investigate the influence of the drying air characteristics on the drying performance of Tunisian myrtle leaves, drying tests were carried out on a tunnel dryer at the Laboratory of Energetic and Thermal and Mass Transfers LETTM. The sorption isotherm was determined at five temperature levels 40, 45, 50, 55, and 60 °C and at water activity ranging from 0.058 to 0.89, using the static gravimetric method. A non linear regression procedure was used to fit experimental sorption isotherms with the most used empirical mathematical models available in the iterature. The Peleg model was reported to be a suitable fit for the sorption experimental data in the mentioned investigated ranges of water activities and temperature. The myrtle leaves drying experiments were carried out at the five air temperatures in the range of 40-60°C air velocity of 2.0 m/s and performed at a relative humidity of 20%. Results indicated that drying took place in the falling rate period. Moisture transfer from myrtle leaves was described by applying Fick's diffusion model. The drying characteristic curve has been established from experimental convective drying kinetics. The values of the diffusivity coefficients at each condition were obtained using Fick's second law of diffusion. They varied from 1.266∗10−10 to 13.06 ∗ 10−10m²/s in the temperature range of 40-60 °C and the relative humidity of 20%. An Arrhenius relation with an activation energy value of 104.63 kJ/mol was obtained
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    Study of the periodic thermal contact between exhaust valve and its seat in an internal combustion engine
    (Maintenance and Reliability, 2023) AZZOUZ Salaheddine (Co-Auteur); AYAD Amar (Co-Auteur)
    The focus of internal combustion engine development for urban vehicles is shifting towards reducing materials by making them lighter. In order to maintain thermal and flow levels, a model was developed to study the thermal behavior of valve seats during periodic contact, which can also help improve engine performance and fuel efficiency. The model, composed of two cylindrical bars in periodic contact, takes into account the evolution and topography of the contact surface. The model's performance was evaluated through various experimental studies and showed a maximum difference of 5.05% with experimental values, in good agreement with previous literature. The results showed that heat flux increases with increasing contact frequency and thermal diffusivity affects conductive transfer. This model can be used by manufacturers to evaluate cylinder head temperature and by the automotive industry to improve heat transfer in engines.