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CFD simulation of magnetohydrodynamic flow of a liquid- metal galinstan fluid in circular pipes
(2013) Gedik, E.; Kurt, H.; Recebli, Z.
In this paper, the steady, laminar, incompressible viscous flow of an electrically conducting liquid-metal fluid is investigated numerically in acircular non-conducting pipe. The considered work fluid is Galinstan (GaInSn, i.e. Gallium-Indium-Tin). Such a liquid metal is subjected to a constantpressure gradient along the axial direction and a uniform transverse magnetic field in the spanwise direction. Numerical simulations are performed by means of the Fluent commercial software (used to solve the governing three dimensional fluid dynamics and electromagnetic field partial differential equations iteratively). The magnetic field induction, B, takes values between 0 and 1.5 T with a 0.5 T step size. The fluid velocity is found to decrease with an increase in the intensity of the applied magnetic field. The results, plotted as a function of system parameters, are critically discussed with respect to potential industrial applications.©2013 Tech Science Press.
CFD Simulation of Magnetohydrodynamic Flow of a Liquid-Metal Galinstan Fluid in Circular Pipes
(Tech Science Press, 2013) Gedik, E.; Kurt, H.; Recebli, Z.
In this paper, the steady, laminar, incompressible viscous flow of an electrically conducting liquid-metal fluid is investigated numerically in a circular non-conducting pipe. The considered work fluid is Galinstan (GaInSn, i.e. Gallium-Indium-Tin). Such a liquid metal is subjected to a constant pressure gradient along the axial direction and a uniform transverse magnetic field in the spanwise direction. Numerical simulations are performed by means of the Fluent commercial software (used to solve the governing three dimensional fluid dynamics and electromagnetic field partial differential equations iteratively). The magnetic field induction, B, takes values between 0 and 1.5 T with a 0.5 T step size. The fluid velocity is found to decrease with an increase in the intensity of the applied magnetic field. The results, plotted as a function of system parameters, are critically discussed with respect to potential industrial applications.
Effect to the performance of different type absorber plates on the solar air collectors
(2008) Gedik, E.; Keçebas, A.; Öz, E.S.
In this study, two different types of solar air collectors, zigzagged absorber surface type and flat absorber surface type called Model I and Model II respectively, have been constructed and examined experimentally. Experiments were made between 10.00-17.00 hours of August and September under Karabük conditions and tests were carried out for five days. Energy and exergy performances have been computed using the experimental data. At the end of the study, it showed that energy and exergy performances of the Model II solar air collector were better than Model I solar air collector. While energy and exergy performances of the Model II solar air collector was %46,5 and %1,35, Model I solar air collector performance was %32,72 and %1,35.
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.
Enhancement of PV/T Solar Collector Efficiency Using Alumina Nanoparticles Additives
(International Information and Engineering Technology Association, 2023) Shallal, B.A.; Gedik, E.; Abdul, Wahhab, H.A.; Mahdi, L.A.A.; Chaichan, M.T.
This study explores the performance of the Photovoltaic/Thermal system using nanofluid with a novel collector design. Experiments were carried out on the University of Technology- Iraq campus. An experiment was carried out using two photovoltaic modules, one connected to 120 protrusions arranged eight columns by 15 rows (for comparison) and the other not. Nanofluid was used to cool solar panels with flow rates of 1.5 and 3.5 l/min. The nanofluid contains nano-Al2O3 at 1%, 2%, and 3% concentrations in water. As the flow rate of water used as a cooling fluid increased, the surface temperature of the cell decreased. The cell temperature is reduced by 22.3% when Al2O3/water is added at a volumetric concentration of 3%. An increase in the electrical and thermal efficiency of PV/T systems was also recorded by 12% and 18.4%, respectively, at a concentration of 3%. © 2023 Wit Press. All rights reserved.
Experimental and Numerical Investigation on Laminar Pipe Flow of Magneto-Rheological Fluids under Applied External Magnetic Field
(Isfahan Univ Technology, 2017) Gedik, E.
An experimental and numerical study of Magnetorheological (MR) fluids flow in circular pipes under the influence of uniform magnetic field is considered. In the experiments, an electromagnetic device was manufactured to generate the magnetic field. The experiments were performed using magnetic fields B= 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12 and 0.15 T. Numerical study was performed to show the accuracy of the results obtained from experimental study. In numerical study, Computational Fluid Dynamics (CFD) analysis was used. The ANSYS Fluent 14.0 code based on the finite volume method was used for the CFD analysis. In the experiments, the applied magnetic field decreased the flow rate of the fluids by increasing viscosity. In case of 10 mm pipe diameter, the flow velocity of the A, B and C fluids were obtained as 0.593, 0.749 and 0.938 m/s respectively in situation B= 0 T. When magnetic field was applied as B= 0.15 T, decreases have occurred in the velocity of A, B and C fluids as 95.27%, 90.24% and 85.6% respectively. Similarly, in case of 15 mm pipe diameter, 96.87%, 95.06% and 90.76% decreases have occurred in the flow velocity of A, B and C fluids having 0.301, 0.363 and 0.445 m/s flow velocity respectively. The results were compared for the magnetic field values B= 0, 0.05, 0.10 and 0.15 T. It was found that the differences between experimental and numerical study were found as 6.10% and 1.71% for the B= 0 T and B not equal 0 T situations respectively when the pipe has 10 mm pipe diameter. In case of 15 mm pipe diameter, the differences were found as 2.31% and 0.89%. As a result, it was found that the results obtained from experimental and numerical study were qualitatively and quantitatively in good agreement.
Experimental and numerical investigation on laminar pipe flow of magneto-rheological fluids under applied external magnetic field
(Isfahan University of Technology, 2017) Gedik, E.
An experimental and numerical study of Magnetorheological (MR) fluids flow in circular pipes under the influence of uniform magnetic field is considered. In the experiments, an electromagnetic device was manufactured to generate the magnetic field. The experiments were performed using magnetic fields B= 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12 and 0.15 T. Numerical study was performed to show the accuracy of the results obtained from experimental study. In numerical study, Computational Fluid Dynamics (CFD) analysis was used. The ANSYS Fluent 14.0 code based on the finite volume method was used for the CFD analysis. In the experiments, the applied magnetic field decreased the flow rate of the fluids by increasing viscosity. In case of 10 mm pipe diameter, the flow velocity of the A, B and C fluids were obtained as 0.593, 0.749 and 0.938 m/s respectively in situation B=0 T. When magnetic field was applied as B=0.15 T, decreases have occurred in the velocity of A, B and C fluids as 95.27%, 90.24% and 85.6% respectively. Similarly, in case of 15 mm pipe diameter, 96.87%, 95.06% and 90.76% decreases have occurred in the flow velocity of A, B and C fluids having 0.301, 0.363 and 0.445 m/s flow velocity respectively. The results were compared for the magnetic field values B=0, 0.05, 0.10 and 0.15 T. It was found that the differences between experimental and numerical study were found as 6.10% and 1.71% for the B=0 T and B?0 T situations respectively when the pipe has 10 mm pipe diameter. In case of 15 mm pipe diameter, the differences were found as 2.31% and 0.89%. As a result, it was found that the results obtained from experimental and numerical study were qualitatively and quantitatively in good agreement.
Experimental investigation of collector efficiencies on separated and connected heat pipes
(2008) Acar, B.; Öz, E.S.; Gedik, E.
The aim of study is to determine the effect of heat pipe systems to collector efficiency at solar collectors used in supplying hot water. For this purpose, two different collectors as the connected heat pipe and separated heat pipe have been produced. The experimental studies with the collectors have been conducted in Karabük city environment. The experiments have been completed in six days. The collector efficiencies have been calculated by measuring temperature of water tanks, ambient temperature and solar radiation in both collectors. As a result, while average efficiency of the connected heat pipe collector is 57.6%, average efficiency of the separated heat pipe collector is 48.5%.
FEXPERIMENTAL INVESTIGATION OF PV/T SOLAR COLLECTOR EFFICIENCY WITH SPHERICAL-SHAPED PROTRUSIONS ON THE ABSORBER SURFACE
(Taylor's University, 2023) Ajel, M.G.; Gedik, E.; Wahhab, H.A.A.; Mahdi, L.A.A.; Chaichan, M.T.
The Accumulated heat on the PV panels' upper surface could be dissipated by water circulation in the backside attached collector. This paper presents an experimental study to improve the performance of the PV/T system by modifying the collector design using a spherical bulge on the collector surface. The work was carried out at the University of Technology-Iraq. Two PV solar cells have been used in the experimental investigation. One is cooled by different water flow rates of 1.5, 2, 2.5, and 3.5 l/min; the other is a bare reference unit without any modification. The illustrated bludges are a matrix of spheres with a 25 mm radius arranged in 8 rows by 15 columns. The thermal efficiency of the PV/T increased by 8.08%, and electrical efficiency increased by 8.1% compared with the bare panel. Additionally, the impact of flow rate was discussed and evaluated in this study. Increased water flow rate decreased the PV surface temperature in the new model. With a flow rate of 3.5 l/m, the maximum surface temperature decrease was 15.4%. © School of Engineering, Taylor’s University.
Hydrothermal behavior of hybrid magnetite nanofluid flowing in a pipe under bi-directional magnetic field with different wave types
(Elsevier Ltd, 2022) Tekir, M.; Gedik, E.; Arslan, K.; Kadir, Pazarlioglu, H.; Aksu, B.; Taskesen, E.
This experiment setup has been developed to elucidate the effect of different wave types (sinusoidal, triangle, square) of bi-directional magnetic field on hydrothermal characteristics of hybrid magnetite nanofluid flowing through a tube. The bi-directional magnetic field is not a novel method among active methods of heat transfer enhancements, yet the effects of different wave types have not been researched so far. In this study, the effects of different wave types of alternating magnetic fields with various frequencies (f) (2, 5, and 15 Hz) on flow and heat transfer characteristics of Fe3O4-Cu/Water hybrid magnetic nanofluid flow have been investigated experimentally. The major findings have been discussed for different combinations of hybrid magnetite nanofluid, types of waves, values of Reynolds number (Re), and f. The hydrothermal characteristics and their effects on usability in the industry with high efficiency have been established in terms of average Nusselt number (Nu), average friction factor (f), and Performance Evaluation Criteria (PEC). It is concluded that the use of triangle wave type with f = 15 Hz with 2% Fe3O4/water shows the highest enhancement in f by 500% compared to distilled water (DW) at Re = 994 while the use of square wave type with f = 5 Hz using the same Re and nanofluid presents the highest increase in Nu by 15.3% compared with DW. Above all, the triangular wave type is determined as an optimum wave type for f = 15 Hz while the sinus and square wave types are realized as optimum ones for f = 5 Hz. © 2022 Elsevier Ltd
Impact of Alumina NanoparticlesAdditives onOpen-Flow Flat Collector Performance for PV Panel Thermal Control Application
(Joint Journal of Novel Carbon Resource Sciences and Green Asia Strategy, 2023) Shallal, B.A.; Gedik, E.; Wahhab, H.A.A.; Ajel, M.G.
Photovoltaic Cells are devices made of semiconductor materials that is used to convert solar energy to electrical energy in the form of a constant current. The efficiency of the photovoltaic cell increases with the increase in solar radiation while its generation efficiency decreases with the increase in Photovoltaic Cell temperature above the standard temperature. Therefore, researchers implement methods to decrease overheating. One of these methods is using PV/T. This paper presents an experimental and numerical study on the performance of the Photovoltaic/Thermal (PV/T) system by using Nanofluids with a new design (novelty; sphere fins in open flow flat collector) of the water collector. Experiments were carried out in Iraq/Baghdad/University of Technology. Nanofluids Al2O3/water was used at different volume concentration ratio as 1%, 2%, and 3% for cooling of PV panel. The influence of new design of collector and Nano additives on the PV/T performance at various operational parameters have been simulated and evaluated using ANSYS Fluent software to solved the Navier-Stockes and energy equations. Numerical results noticed a decrease in the surface temperature of the collector by 5.1% when using a Nano liquid with a concentration 1% compared to its temperature when using water only, while it decreases by 6.2% and 7.8% when using concentrations 2% and 3%, respectively at flow rate 3.5 l/min. The evaluation result demonstrates that the performance of PV/T system increased, also the Nanoparticles helped to system enhances. © 2023 Novel Carbon Resource Sciences. All rights reserved.
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.
A Numerical Analysis of Laminar Forced Convection and Entropy Generation of a Diamond-Fe3O4/Water Hybrid Nanofluid in a Rectangular Minichannel
(Isfahan Univ Technology, 2019) Uysal, C.; Gedik, E.; Chamkha, A. J.
The convective heat transfer and entropy generation of diamond-Fe3O4/water hybrid nanofluid through a rectangular minichannel is numerically investigated under laminar flow conditions. Nanoparticle volume fractions for diamond-Fe3O4/water hybrid nanofluid are in the range 0.05-0.20% and Reynolds number varies from 100 to 1000. The finite volume method is used in the numerical computation. The results obtained for diamond-Fe3O4/water hybrid nanofluid are compared with those of diamond/water and Fe3O4/water conventional nanofluids. It is found that 0.2% diamond-Fe3O4 hybrid nanoparticle addition to pure water provides convective heat transfer coefficient enhancement of 29.96%, at Re=1000. The results show that diamond-Fe3O4/water hybrid nanofluid has higher convective heat transfer coefficient and Nusselt number when compared with diamond/water and Fe3O4/water conventional nanofluids. For diamond-Fe3O4/water hybrid nanofluid, until Re=600, the lowest total entropy generation rate values are obtained for 0.20% nanoparticle volume fraction. However, after Re=800, diamond-Fe3O4/water hybrid nanofluid with 0.20% nanoparticle volume fraction has the highest total entropy generation rate compared to other nanoparticle volume fractions. A similar pattern emerges from the comparison with diamond/water and Fe3O4/water conventional nanofluids. For 0.2% nanoparticle volume fraction, diamond-Fe3O4/water hybrid nanofluid and diamond/water nanofluid have their minimum entropy generation rate at Re=500 and at Re=900, respectively. Moreover, this minimum entropy generation rate point changes with nanoparticle volume fraction values of nanofluids.
The prediction of photovoltaic module temperature with artificial neural networks
(Elsevier Ltd, 2014) Ceylan, I.; Erkaymaz, O.; Gedik, E.; Gurel, A.E.
In this study, photovoltaic module temperature has been predicted according to outlet air temperature and solar radiation. For this investigation, photovoltaic module temperatures have been determined in the experimental system for 10, 20, 30, and 40 °C ambient air temperature and different solar radiations. This experimental study was made in open air and solar radiation was measured and then this measured data was used for the training of ANN. Photovoltaic module temperatures have been predicted according to solar radiation and outside air temperature for the Aegean region in Turkey. Electrical efficiency and power was also calculated depending on the predicted module temperature. Kutahya, U§ak and Afyon are the most suitable cities in terms of electrical efficiency and power product in the Aegean region in Turkey.

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