Browsing by Author "Doranehgard, MH"

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    Impacts of elasticity and porosity of the channels on the performance features of thermoelectric module mounted system and efficient computations with multi-proper orthogonal decomposition approach
    Selimefendigil, F; Oztop, HF; Doranehgard, MH
    Effects of wall elasticity and porosity of the channel on the performance characteristics of TEG module integrated system are explored numerically with finite element method. A porous layer in the lower channel is introduced with hybrid nanoparticles in the fluid. Effects of different values of elastic modulus of the top and bottom channel walls (5 & times;103 <= E1,& nbsp;E2 & nbsp;<=& nbsp;1010), Darcy number (5 & times;10 & minus;4 & nbsp;<=& nbsp;Da & nbsp;<=& nbsp;5 & times;10 & minus;1), porous layer height (0.2H & nbsp;<=& nbsp;py & nbsp;<=& nbsp;0.8H) and length in flow direction (0.25L & nbsp;<=& nbsp;px & nbsp;<=& nbsp;0.85L), Reynolds number (200 & nbsp;<=& nbsp;Re & nbsp;<=& nbsp;1000) and hybrid nanoparticle volume fraction (0 & nbsp;<=phi <=& nbsp;2%) on the convection and power generation are analyzed. The presence of elastic walls may affect the flow field in local regions but the overall impact on the power variation is slight while 2.8%& nbsp;variation is obtained. The presence of the porous layer altered the power generation features while increasing the permeability and height of the porous layer resulted in higher thermoelectric power generation. The increment amounts are 32%& nbsp;for the highest permeability and 17%& nbsp;for the highest porous layer height. The length of porous layer in the flow direction has slight impact on power generation features while introducing nano-sized particles further enhanced the power by about 15%& nbsp;at the highest & nbsp;phi. The computational cost of generated power is drastically reduced from 2.5 h for full coupled model to two minutes by using a multi-POD approach.& nbsp; (c) 2021 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
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    Phase change dynamics in a cylinder containing hybrid nanofluid and phase change material subjected to a rotating inner disk
    Selimefendigil, F; Öztop, HF; Doranehgard, MH; Karimi, N
    In this numerical study, the phase change dynamics of a 3D cylinder containing hybrid nanofluid and phase change material (PCM) is investigated with a finite element solver. The PCM consists of spherical encapsulated paraffin wax, and the flow is under the forced convection regime. The dynamic features of the phase change process are studied for different values of the Reynolds number (between Re=100 and 300), the rotational Reynolds number of the inner disk (Rew=0 and 300), and the size of the rotating disk (length between 0.1L and 0.55L; height between 0.001H2 and 0.4H2). The flow dynamics and separated flow regions are found to be greatly influenced by the rotational speed and size of the inner disk. As Re is increased, the difference between the transition times at different rotational disk speeds decreases. At Re=100, a 21% reduction in the phase transition time is observed when the inner disk rotates at the highest speed as compared to the motionless case. Up to a 26% variation in the phase transition time occurs when the size of the inner rotating disk is varied. A 5 input-1 output feed-forward artificial neural network is applied to achieve fast and reliable predictions of the phase change dynamics. This study shows that introducing rotational effects can have a profound effect on the phase change dynamics of a hybrid nanofluid system containing phase change material.