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Öğe Effects of Twisting Ratio, Diagonal Length, and Pitch Ratio of Hexagonal Pin Fins on Thermo-hydraulic Performance of Heat Sink(Toronto Metropolitan University, 2023) Gürdal, M.; Tekir, M.; Algbourie, N.I.; Pazarlioglu, H.K.; Arslan, K.While the effect of the twisting ratio on a heat sink was investigated for the first part of the study, the diagonal length and pitch ratio were observed for following step. The parametric studies were applied under turbulent regime (2658? Re?7138) to monitor thermo-hydraulic performance of novel proposed design. The edge length of the pin fins (Lef) was varied regarding their diagonal length (5? Lef ? 6) while the pitch ratio (P/e) and twisting ratio were varied in the range of 0.75? P/e?1.0 and 50?TR? 200 respectively. By using the turbulent model SST k-? with low-Re correction model on ANSYS Fluent, the computational study has been carried out to discretize RANS equations. Average Nusselt number (Nu) and average Darcy friction factor (f) which define the thermo-hydraulic performance of system were elucidated in detail. As a result, the best thermo-hydraulic performance was achieved as 1.55 by using the lowest twisting ratio (TR=200), pitch ratio (p/e=0.75) and the highest diagonal length (Lef=6) and at Re=2658. © 2023, Toronto Metropolitan University. All rights reserved.Öğe ENERGY, ENTROPY, AND EXERGY ANALYSES OF SUDDEN EXPANSION TUBE WITH CONVEX SURFACE USING FERROFLUID(Begell House Inc., 2024) Gürsoy, E.; Gürdal, M.; Gedik, E.; Arslan, K.Energy, entropy, and exergy analyses have been examined in sudden expansion tube (SET), which used in many thermal applications such as heat exchangers, micro-scale industry application, with both smooth (ST) and convex fin (CFT) surfaces. For the purpose of enhancing the thermal and hydraulic efficiency a ternary approach in which SET, and nanofluid, and convex fin have been employed together. Numerical parametric analyses have been carried out under steady-state, fully developed flow, and constant heat flux conditions with laminar, transitional and turbulent flow regimes (500?Re?10000) using Finite Volume Method (FVM). Two different working fluids as water and ferrofluid (Fe3O4/water) with ?=2.0% volume fraction have used. According to numerical results, the highest increment in the average Nusselt number (Nu) was caused by ferrofluid oc-curred in the laminar flow regime, approximately 7.0%, and its effect on the Darcy friction factor (f) was approximately 4.0%. On the other hand, the average Nu increased nearly twofold under the effect of convex fins at the transitional flow regime. Convex fins severely affected the f, causing an in-crement of nearly 260% in the turbulent flow regime. In the irreversibility analysis, convex fins performed the lowest dimensionless total entropy generation reducing up to 46.0% and increased the second-law efficiency up to 14.0% at Re=2000. Furthermore, the results of first-law efficiency, exergy outlet, exergy loss, and pumping power were investigated in detail and entropy generation results were supported with contours. © 2024, Begell House Inc. All rights reserved.Öğe Forced Heat Convection Analysis and Entropy Production of CoFe2O4/H2O Nanofluid Flow in a Channel with Wavy Tape under Laminar Regime(Toronto Metropolitan University, 2023) Gürdal, M.; Nazli, C.; Özcan, Y.; Kaya, U.The main aim of the study is to investigate the impact of wavy tape geometry and magnetic nanofluid on thermal and hydraulic characteristic under a laminar flow regime. In this direction, it was examined numerically for convection heat transfer and flow behaviors of CoFe2O4/H2O flowing with 1% volume fraction in a circular channel with different wavy tape forms. This work has conducted the analyses for fully developed flow under uniform and constant heat f lux conditions of 2000 W/m2. The analyzes have been implemented with Reynolds numbers ranging from 500 to 2000. All analysis have been carried out using laminar model and single-phase approach. Finally, heat transfer ratio and Darcy friction factor was gained for the tube with wavy tape amplitude of wave ratio (y=h/w) of 4. On the other hand, it was observed that average Nusselt number and Darcy friction factor values are suitable with the literature. The best heat transfer performance value was achieved at Re=2000. Besides, it was obtained that the Darcy friction factor decreased with increasing Reynolds number, while maximum total entropy generation was reached for CoFe2O4/H2O flow having 1% volume fraction in tube with wavy tape. © 2023, Toronto Metropolitan University. All rights reserved.Öğe IMPACT OF TWISTED DUCTS WITH DIFFERENT TWIST RATIOS ON HEAT TRANSFER AND FLUID CHARACTERISTICS OF NIO/WATER NANOFLUID FLOW UNDER MAGNETIC FIELD EFFECT(Begell House Inc., 2022) Pazarlioglu, H.K.; Gürdal, M.; Tekir, M.; Arslan, K.; Gedik, E.Laminar forced convection of NiO/water nanofluid in a twisted square duct has been investigated numerically under the effect of an external magnetic field (B = 0 G, 450 G, and 550 G) in the Reynolds number range of 500 ? Re ? 2000. Four different twist ratios (D/L = 0.0, 1.0, 1.5, and 2.0) of the square duct have also been examined. The nanoparticle volume fractions (NPVF) of NiO/water nanofluid have been selected between 0.6 vol.% and 2.5 vol.%. The effects of the magnitude of the magnetic field (MF), twist ratio, Reynolds number, and nanoparticle volume fraction on thermohydraulic performance have been examined by using the homogeneous model in the numerical analyses. The results of the numerical computations have been reported with average Nusselt number Nu, pressure loss, average Darcy friction factor f, and performance evaluation criterion (PEC). The highest heat transfer increment by 20% has been achieved at D/L = 2.0 with the highest nanoparticle volume fraction, namely, 2.5 vol.% NiO/water nanofluid, compared to the case of distilled water (DW) flowing in a plain duct (PD). In addition, it was determined that the magnetic field effect increases the convective heat transfer in the twisted duct with D/L = 2.0 up to 35% compared to the cases in the absence of a magnetic field at D/L = 2.0. Among all cases, the highest PEC has been obtained with 2.5 vol.% NiO/water nanofluid flowing in the twisted duct with the twist ratio D/L = 2.0. © 2022 by Begell House, Inc.
