Browsing by Author "Akbari,O.A."

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Citation Count: 2
Entropy and energy analysis of water/silver nanofluid flow in a microchannel by changing the angle of attack of a cam-shaped vortex generator
(Elsevier B.V., 2024) Bayat,M.; Salahshour, Soheıl; Jaafar,M.S.; Dayoub,M.S.; Akbari,O.A.; Marzban,A.; Sarlak,R.
Background: This study simulates the laminar forced flow of water/silver nanofluid in solid nanoparticle volume fractions ranging from 0 % to 6 % in a microchannel with vortex generators. For Reynolds numbers 100 to 800, the angle of attack of the vortex is changed from 0 to -90° Methods: The finite volume method is used for the 2D numerical study. Increasing the angle of attack leads to greater local flow mixing, which diffuses heat towards the upper parts of the flow, resulting in a favorable microchannel temperature distribution. During the movement of the fluid, the temperature difference between the surface and the fluid decreases. In addition to local friction, shear stress is also responsible for the friction factor. If the Reynolds number is high and the angle of attack is -30°, then the Nusselt number becomes significant. After passing the vortex generators, the effective flow area is higher, which is due to the higher effective flow area. Among the studied cases, the highest friction occurs for an angle of attack of -90° Significant findings: For higher volume fractions of nanoparticles (φ), the effect of fluid velocity dissipation and friction factor variations are higher. To limit entropy generation, higher Reynolds numbers and nanoparticle concentrations could be used. Changing the vortex generator angle has a limited influence on the entropy generation. © 2024 The Author(s)
Citation Count: 0
Numerical simulation of the nanofluid flow and heat transfer in porous microchannels with different flow path arrangements using single-phase and two-phase models
(Elsevier B.V., 2024) Salahshour, Soheıl; M․ Ali,A.B.; Jasim,D.J.; Salahshour,S.; Akbari,O.A.; Emami,N.
Background: The fluid flow and nanofluid heat transfer are studied in this research through porous microchannels with different flow path arrangements in single-phase and two-phase modes (Mode I and Mode II). In Mode I, the flow inlet is located in the longitudinal direction of the microchannel (single-way path), while in Mode II, the flow inlet is placed in the transverse direction of the microchannel (two-way path). Methods: The finite volume method was utilized to simulate the flow and heat transfer. The porous medium is supposed homogeneous and isotropic with a porosity coefficient of 0.9 and it is assumed that the local thermal equilibrium is established between the fluid and the solid. The Eulerian-Eulerian mixture model is applied for modeling the two-phase flow. As demonstrated, mode II always has a higher heat transfer rate than mode I. However, in contrast, the pressure drop of mode I is lower than in mode II. Besides, using the two-phase model predicts a higher heat transfer rate than the single-phase model in all cases. Significant Findings: The percent increase of pressure in mode II compared to mode I in Re= 100 and 400 is obtained as 11.5 % and 20.8 %, respectively. At Re= 100 in mode I, the heat transfer percentage increases by 52.6 % from Da=1 compared to a case without the porous foam. Whilst, at Re= 400, the rise is found to be 45.5 %. In mode II, at Re=100, the heat transfer percentage increases by 63.9 % from Da= 1 compared to a case without the porous foam. Whilst, at Re= 400, the rise is found to be 43.3 %. Finally, Mode II microchannel has more heat transfer rate and pressure drop than Mode I. © 2024 The Author(s)