The effect of using fractal-shaped orifice as flow meters for enhancing flow measuring techniques and their effect on pressure drop and flow mixing properties from point of view of losses saving and future designing of measuring devices with higher accuracy has been investigated. In this frame, a numerical simulation has been used to study a turbulent flow through fractal-shaped orifices in pipes. Different fractal-shaped orifices; namely GEN-1, GEN-2, GEN-3 and GEN-4, have been constructed up to the forth iteration using a commercial CFD package. The studied pipe has a diameter of 0.14 m and a total length of 2.5 m. To validate the numerical simulation results, a direct comparison has been made with recently published experimental results for fractal-shaped orifice to illustrate the effect of the fractal-shaped on the pressure drop. Numerical results showed that the fractal shaped orifice has a significant effect on the flow mixing properties and on the pressure drop downstream a pipe owing to their edge self-similarity shapes.
Cleanrooms are used in a lot of industrial applications, one of which is the field of electronic industries. Manufacturing process tools that equip the cleanroom and are used in this field dissipate a lot of heat in all room areas. This work presents a 3D numerical simulation for a recently published experimental work that proposes an innovative fan dry coil unit (FDCU) return air system. This system consists of ceiling supply fan filter units and ceiling return fan coils. Throughout the research, a comparison of temperature distribution between the FDCU return air system and the traditional wall return air system is presented. Moreover, the effect of changing the FDCU location on the cleanroom ceiling is investigated. To validate the numerical simulation results, a direct comparison is performed with the experiment data, and the numerical model shows good agreement. The results show that FDCU ARR-3 is the best arrangement compared to other models, namely wall-return, ARR-1, and ARR-2. The AVG local air temperature index Θ through the cleanroom was reduced by 77% compared to wall return and 33% compared to ARR-1. Moreover, the AVG local air temperature index Θ above the process tool was reduced by 28% compared to a wall return and 23% compared to ARR-1.
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