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    Effect of Al2O3-SiO2/Water Hybrid Nanofluid Filled in a Square Enclosure on the Natural Convective Heat Transfer Characteristics: A Numerical Study
    (Amer Scientific Publishers, 2022) Dagdeviren, Abdullah; Gedik, Engin; Kecebas, Ali; Pazarlioglu, Hayati Kadir; Arslan, Kamil; Alsabery, Ammar I.
    In this study, heat transfer enhancement by natural convection Al2O3/water mono and Al2O3-SiO2/water hybrid nanofluid in an enclosure cavity have been performed utilizing the finite element method. For numerical com-putations, the homogeneous nanofluid approach was considered. The cavity was heated from the left vertical wall and cooled from the right vertical wall while the top and bottom walls were taken as adiabatic. The effects of some related factors such as the Rayleigh number (10(3) <= Ra <= 10(6)) and nanoparticles' volume fraction IP: 182.75.148.10 On: Sat, 13 Aug 2022 10:11:41 (0 <= phi <= 0.05) on the heat transfer by natural convction were examined. To discuss fluid characteristics of mono Copyright: American Scientific Publishers and hybrid type nanofluid under natural convecton effect, the obtained results were presented as streamlines Delivered by Ingenta and isotherms. Also, variations of local and average Nusselt numbers were examined in detail. It was obtained that an increase in the nanoparticle volume fraction leads to the enhancement of convective heat transfer for all Rayleigh numbers. It was also indicated that the highest increment in heat transfer by convection occurs in the nanoparticle volume fraction of 2% for Al2O3/water and 4% for Al2O3-SiO2/water. The present study results are also consistent with the literature results.
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    Effect of magnetic field locations on thermo-magnetic convection performance of Fe3O4/H2O ferrofluid flowing in a novel dimpled tube: An experimental study
    (Pergamon-Elsevier Science Ltd, 2023) Gursoy, Emrehan; Gurdal, Mehmet; Pazarlioglu, Hayati Kadir; Dagdeviren, Abdullah; Tekir, Mutlu; Arslan, Kamil; Gedik, Engin
    The aim of this study is to examine the hydrothermal behavior of Fe3O4 Ferrofluid flowing under the effect of uniform magnetic field (0 T <= B <= 0.3 T). In addition, magnetic field locations were changed for each experiment to observe effect of the magnetic field locations (x/D = 20, 40, 60) on the hydrothermal behavior of the proposed system. Fe3O4 Ferrofluid was prepared in phi = 1.0% volume concentration in water and flows under the laminar regime (1131 <= Re <= 2102). Comparisons of the hydrothermal behavior of the novel proposed parameters were performed according to combinations of the different magnetic field locations and magnitudes. It is concluded that the highest Nusselt number was obtained using B = 0.3 T for the magnetic field location of x/D = 20 for both in smooth and dimpled tubes. Compared to B = 0 T, the Nusselt number enhancement was detected by 64.03% for smooth tube for the magnetic field location of x/D = 20 for B = 0.3 T whereas Nusselt number wasaugmented by 45.40% for dimpled tube for the same input parameters. Furthermore, no considerable changes in friction factor was determined under magnetic field effect when the application of magnetic field locations was changed. As a result of these findings, the highest increase in Performance Evaluation Criteria belonging dimpled tube was calculated by 33.54% at Re = 2102 for B = 0.16 T for the magnetic field location of x/D = 20. As a general conclusion, this study can shed light on investigating ferrofluids behavior under magnetic field applied in var-iable magnetic field locations.
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    The effect of MHD flow on hydrothermal characteristics of ferro-nano-fluid in circular pipe
    (Taylor & Francis Inc, 2023) Taskesen, Edip; Tekir, Mutlu; Pazarlioglu, Hayati Kadir; Gurdal, Mehmet; Gedik, Engin; Arslan, Kamil
    In this study, the effect of the constant magnetic field (MF) on the convective heat transfer characteristics of Fe3O4/H2O ferro-nano-fluid with different nano-fluid volumetric concentrations (1.0%, 2.0%, and 5.0%) flowing in a circular pipe has been studied experimentally. Experiments have been conducted under laminar flow regime (1000 <= Re <= 2300). Based on the experimental data, a good agreement has been found with the results and the well-known correlations in the literature. Also, it was obtained that increasing flow rate let to increase in Nusselt number. One of the most important results obtained is that the presence of MF offers up to 8.32% convective heat transfer enhancement compared with the absence of a MF. In addition, the constant MF applied externally to the flow is a key factor to control the convective heat transfer for such kind of geometry, which is widely used in thermal engineering systems.
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    EFFECT OF NANOPARTICLE SHAPE ON NANOFLUID FLOW IN CONICAL HELICAL TUBE
    (Begell House, Inc, 2022) Altunay, Fethi M.; Ali, Majdi A. M.; Gurdal, Mehmet; Pazarlioglu, Hayati Kadir; Arslan, Kamil; Gedik, Engin
    The nanofluid flow in a conical helical tube was numerically investigated. The study has been carried out in three-dimensional laminar flow (85.73 <= De <= 175.55) condition. Al2O3-water nanofluid with different nanoparticle volume fractions (1.0%, 2.0%, 3.0%) has been used as the working fluid in the numerical analyzes. In addition, studies were carried out for blade, platelet, and cylindrical nanoparticle shapes. The average Nusselt numbers and the average Darcy friction factors have been used to estimate the flow and heat transfer performance of nanofluid flow in the conical helical tubes. Numerical results of the study have been presented as the variation of average Nusselt number and average Darcy friction factor with Dean number, nanoparticle shape, and nanoparticle volume fraction. As a result, the highest convective heat transfer performance has been obtained for the cylindrical nanoparticle shape of the %3.0 Al2O3-water nanofluid.
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    Effect of new design of elongated jet hole on thermal efficiency of solar air heater
    (Elsevier, 2022) Pazarlioglu, Hayati Kadir; Tepe, Ahmet Umit; Tekir, Mutlu; Arslan, Kamil
    Effect of new design of elongated jet hole on the thermal efficiency (eta th) of a solar air heater (SAH) has been numerically studied in this paper. Jet impingement technique, which is one of the important active techniques, has been implemented on the absorber plate of the SAH surface to increase the convective heat transfer per-formance. Several designs of elongated jet hole (EJH) technique (gradually increasing, gradually decreasing along the crossflow direction, and equally extended), which is highly effective application to get rid of cross-flow, has been inserted to the jet plate. The main interest of this paper is to investigate the effect of different EJH configurations on convective heat transfer performance and eta th of the SAH. 15 x 7 array of jets have been mounted on the confinement plate. Results have been compared with the conventional SAH, which has the jet impingement Case1. Numerical computations have been conducted using RNG k -epsilon turbulence model. Average Nusselt number (Nu) on the absorber plate surface, eta th of the SAH, and performance evaluation criteria (PEC) have been quantitatively investigated comprehensively. As a result of calculations, the Nu and eta th of SAH can be enhanced by 31.80 % and 2.46 %, respectively, using Case4 instead of Case1 at Re = 25000. Besides, the pressure drop of SAH dramatically rises by 10.26 %, when Case4 and Case1 compared with each other at Re = 25000. Despite increment in pressure drop, the PEC value achieves to 1.28. Finally, it is concluded that the equally extended EJH presents well performance compared to gradually increasing and decreasing EJH.
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    EFFECT OF THE NANOFLUID FLOW AND EXTENDED SURFACES ON AN ABRUPT EXPANSION TUBE REGARDING THERMODYNAMIC IRREVERSIBILITY
    (Begell House Inc, 2024) Pazarlioglu, Hayati Kadir; Ekiciler, Recep
    Numerous scientists have examined circular dimpled surfaces, tubes, and other approaches for enhancing heat transfer. Moreover, the dimples' angle of attack has a substantial effect on the tube's flow and thermal features. This numerical study presents a novel approach to enhancing heat transfer rate in a tube subjected to constant heat flux by incorporating a surface dimpling strategy and evaluates three different tube layouts with elliptical dimpled fins for different working fluids such as DW and Al2O3/DW nanofluid (phi = 0.5-1.0%) by using ANSYS Fluent v2020R2 under laminar flow conditions. Under identical circumstances, the thermal performances of proposed designs are compared to those of a smooth tube, and the influence of the elliptical dimpled fin angle of attack on these parameters is determined for different Reynolds numbers (1000 <= Re <= 2000). When comparing the Nusselt number of a tube with/without elliptical dimpled fins, it is found that EDT 1 performed better. Lower Reynolds numbers are shown to result in a greater friction factor. Besides, elliptical dimpled fins promote flow mixing within the tube and the establishment of a thermal boundary layer. At a 135 degrees attack angle (EDT 1), the 1.0% Al2O3/DW nanofluid is found to be the best-performing nanofluid in the dimpled tube, improving Nu by up to 44.56%. Furthermore, ff presented an increase of 29.18% when comparing ST and EDT 1 flowing 1.0% Al2O3/DW at Re = 2000, while total S-gen is diminished by 37.75% in the same conditions.
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    EFFICIENCY DETERMINATION OF SOLAR CHIMNEY POWER PLANT RETROFITTED WITH NOVEL FINNED COLLECTOR UNDER REAL-TIME SOLAR IRRADIANCE
    (Begell House Inc, 2024) Hasan, Ibrahim Shikh; Pazarlioglu, Hayati Kadir; Arslan, Kamil; Ekiciler, Recep
    This paper discusses the three-dimensional numerical study of a new finned collector integrated into the solar chimney power plant. Manzanares pilot's details, which are tower height 194.6 m, rooftop height 1.85 m, rooftop diameter 244 m, tower diameter 10.16 m, and pilot mean temperature 20 degrees C with air speed 15 m/s, are implemented in this work to check the suitability of the finned collector as a way of improvement. In order to assess the unique idea, a parametric study is done with different number of fins: 46, 33, and 25; different fin widths: 0.5, 0.25, and 0.1 m, and different fin heights: 1.2, 0.925, and 0.6 m. Therefore, optimal outputs could be obtained by the novel rooftop that is proposed in this study, where the efficient case is specified dimensionally by 46 fins, a fin width of 0.1 m, and a fin height of 1.2 m, which gives 1.674% as the station performance, 700.597 kW as the resulted power of the plant, 1790.3 as the Nusselt number, and 1.96E+14 as the Rayleigh number.
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    Energy analysis of magnetite nanofluid flowing in newly designed sudden expansion tube retrofitted with dimpled fin
    (Pergamon-Elsevier Science Ltd, 2022) Guersoy, Emrehan; Pazarlioglu, Hayati Kadir; Dagdeviren, Abdullah; Guerdal, Mehmet; Gedik, Engin; Arslan, Kamil; Kurt, Hueseyin
    Sudden expansion geometry plays an important role in the design of many engineering applications such as heat exchangers to avoid thermal stress on welded joints. While the heat transfer in these geometries is maximized at the reattachment points, it decreases to a minimum in the recirculation regions created by the fluid. To prevent this situation and improve the performance of the expansion tubes, nanofluid, and expanded surfaces can be used. For this purpose, forced convection of magnetite nanofluid flow in various expansion ratios has been investigated numerically in this study. Analyses have been performed on Reynolds ( Re ) numbers ranging from 100 to 2000, constant and uniform heat flux at 600 W/m(2), and volume concentrations (1.0 <=phi <= 2.0 vol.%). The result showed that while the Nu number increases with increasing Re number , the most efficient case is Dimpled Tube ( DT ) 9, and the highest value of performance evaluation criteria (PEC) has been obtained at phi= 2.0 vol.%. Compared with the water, the highest Nu number value has been obtained as 3.34% increased at Re = 20 0 0 and phi= 2.0 vol.%. When compared to the DT9 and Smooth Tube ( ST ) 1 where water was used as the working fluid at Re = 20 0 0 and phi= 2.0 vol.%, the PEC value increased by 8.66% and 110.31%, respectively. In addition, the bottom wall of the DT9 case performs higher convective heat transfer rate than the top wall.(c) 2022 Elsevier Ltd. All rights reserved.
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    Entropy generation of ferronanofluid flow in industrially designed bended dimpled tube
    (Elsevier, 2023) Gürsoy, Emrehan; Pazarlioglu, Hayati Kadir; Gürdal, Mehmet; Gedik, Engin; Arslan, Kamil
    In this study, numerical analyses were conducted on bended tube with different bending radius and pitch ratios of dimpled fin under different Dean numbers from 9.1 to 301.2. The study examined in bended tube containing three dimple pitch ratios (P/d = 6.0-7.5-9.0) carried out under uniform heat flux of 600 W/m2 and different nanofluid volume fractions of Fe3O4/H2O (0.0 <= phi <= 2.0 %). The thermo-hydraulic performance and entropy generation of bended tubes were investigated. The results showed that Case 10 provided the highest Nu using H2O compared to Case 16, this enhancement was realized as 17.56 %. When nanofluid was used, the highest Nu was obtained at phi = 2.0 % volume fraction in Case 7 by 24.47 % in comparison with non-DT at Dn = 245.9. The highest PEC value of Case 7 using phi = 2.0 % was monitored as 1.11 at Dn = 245.9. Compared to the frictional and total EnGs of P/d = 6.0 and 9.0, the frictional and total EnGs of P/d = 6.0 show a decrease of 10.05 % and 9.60 %, respectively.
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    Exergetic, Energetic, and entropy production evaluations of parabolic trough collector retrofitted with elliptical dimpled receiver tube filled with hybrid nanofluid
    (Pergamon-Elsevier Science Ltd, 2023) Pazarlioglu, Hayati Kadir; Ekiciler, Recep; Arslan, Kamil; Mohammed, Noor Adil Mohammed
    In this paper, a numerical study was performed on a parabolic trough collector receiver tube containing elliptical dimpled fins with different elliptical ratios (ER = 0.66-1.66) under turbulent flow regime. The C++ code was developed to perform a non-uniform heat flux on outside of the receiver tube to get approximation real working conditions. Different mono and hybrid nanofluids and their combinations with different nanoparticle volume fractions (2.0 %TiO2/Syltherm800, 2.0 %Al2O3/Syltherm800, 0.5 %TiO2-1.5 %Al2O3/Syltherm800, 1.0 %TiO2-1.0 %Al2O3/Syltherm800, and 1.5 %TiO2-0.5 %Al2O3/Syltherm800) were used as a working fluid. The study provides a detailed analysis of the hydro-thermal characteristics, exergetic, and entropy production of the parabolic trough collector. 1.5 %Al2O3-0.5 %TiO2/Syltherm800 hybrid nanofluid shows the best increase in results obtained in this study using elliptical ratio of a/b = 5/3. The use of the elliptical ratio of a/b = 5/3, the average Nusselt number increases with 38 % compared to the receiver tube without elliptical dimpled fin. Total entropy generation was reduced up to 16.82 % for the elliptical ratio of a/b = 5/3. With the inserting elliptical dimpled fins of a/b = 5/3, the Performance Evaluation Criterion was detected as 1.81 compared to while the thermal efficiency increases from 74 % to 80 % at the lowest Reynolds numbers.
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    Experimental investigation on thermo hydraulic performance of ferronanofluid flow in a dimpled tube under magnetic field effect
    (Taylor & Francis Inc, 2023) Gurdal, Mehmet; Pazarlioglu, Hayati Kadir; Tekir, Mutlu; Arslan, Kamil; Gedik, Engin; Taskesen, Edip
    Active and passive techniques have been utilized together to enhance heat transfer in this study. The ferronanofluid, magnetic field, and dimpled tube have not been utilized together in the literature so far. Regarding this issue, this investigation is the first experimental study to specify the effect of use of these three effects simultaneously. The concept of this study is to determine the thermo-hydraulic performance of Fe3O4/H2O flow inside a dimpled tube under magnetic field effect. Constant and uniform heat flux of 4500 W/m(2) has been applied on the surface of the tube. The work aims to gain data in the range of laminar flow (1131 <= Re <= 2102) in the dimpled tube. Dimple geometry with pitch ratio of P/d = 3.75, magnetic field (B = 0.03 <= T <= 0.16), and nanoparticle volume fraction of 1.0% are the base variables. The results showed that Nusselt number increases with increasing Reynolds number and magnetic field intensity. The highest increase in Nusselt number is obtained as 115.31% compared with the distilled water flow in the smooth tube for the case of magnetic field intensity of 0.3 T. The highest Performance Evaluation Criteria value is also determined as 1.44 for the case of ferronanofluid flow in dimpled tube at Re = 1131 in absence of magnetic field.
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    The first and second law analyses of thermodynamics for CoFe2O4/H2O flow in a sudden expansion tube inserted elliptical dimpled fins
    (Pergamon-Elsevier Science Ltd, 2023) Pazarlioglu, Hayati Kadir; Gursoy, Emrehan; Gurdal, Mehmet; Tekir, Mutlu; Gedik, Engin; Arslan, Kamil; Taskesen, Edip
    In this paper, thermo-hydraulic performance and entropy generation of the sudden expansion tube with elliptical dimpled fins (DFs) at different directions was computationally performed at different Reynolds (Re) numbers ranging between 100 & LE;Re & LE;2000 using cobalt ferrite/H2O (CoFe2O4/H2O) nanofluid (NF) (0.0 & LE;& phi;& LE; 2.0). The novelty of this study is to investigate the effect of the elliptical DF and its arrays in the sudden expansion tube in terms of thermodynamics laws (energy and entropy generations). While the sudden expansion ratio (D2/D1) is 2.5, elliptical dimple width (a) and height (b) show variations between 4 and 8 mm. In addition, the distances among elliptical DFs (P) are taken as P = 10, 15, and 20 mm while the diameter (D1) and length (L1) of the inlet tube are D1=8 mm and L1=375 mm. The diameter (D2) and length (L2) of the tube with the sudden expanding and elliptical DFs are D2=20 mm and L2=1125 mm, respectively. The study comprehensively exhibits results of the thermo-hydraulic performance and entropy generation based on numerical data. The results demonstrated that the highest heat transfer rate is recorded by the case of DT3, and DT3 enhances the convective heat transfer rate by 221%, and increases the pressure drop by 17.38% at Re=2000 compared to smooth tube (ST). It was observed that as the Re increases, the performance evaluation criteria (PEC) gradually increases too, and the highest PEC has been obtained for DT3 as 2.11 at Re=2000. The entropy generation (EnG) was also evaluated in terms of both geometric designs and volumetric concentrations. Moreover, the best total EnG was found around 17% for DT3 at the Re=1000 and & phi;=2.0% compared to ST using H2O. Consequence of the applied analyses, the use of elliptic DFs in a sudden expansion tube enhances the convective heat transfer rate and decreases total EnG.
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    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, Hayati Kadir; Gurdal, Mehmet; Tekir, Mutlu; Arslan, Kamil; Gedik, Engin
    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.
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    Implementation of hybrid nanofluid flowing in dimpled tube subjected to magnetic field
    (Pergamon-Elsevier Science Ltd, 2022) Gurdal, Mehmet; Pazarlioglu, Hayati Kadir; Tekir, Mutlu; Altunay, Fethi Murat; Arslan, Kamil; Gedik, Engin
    To pursue of enhancement convective heat transfer, both active and passive techniques have been elucidated simultaneously in this study. The effect of hybrid nanofluid flow in a dimpled tube implemented constant magnetic field (0 T <= B <= 0.3 T) to determine the convective heat transfer rate has not been investigated comparatively either numerically or experimentally, so far. Therefore, this study is the first study to elucidate the effect of hybrid nanofluid flow under the effect of a magnetic field at the fully developed hydrodynamic and developing thermally flow condition. Hydrothermal behavior of 1.0% vol. Fe3O4/H2O, 1.0% vol. Cu/H2O as mono nanofluid and 0.5% vol. Fe3O4-0.5% vol. Cu/H2O as hybrid nanofluid flow in the dimpled tube has been examined under constant heat flux boundary condition (q = 4357 W/m2) and laminar flow regime (1131 <= Re <= 2102). As a result of experiments and numerical analyses, it is concluded that Nusselt number and friction factor have been enhanced using the magnetic field. Hybrid nanofluid flow in the dimpled tube implemented the magnetic field with the magnitude of 0.3 T causes to increase the Nusselt number and friction factor up to 11.87% and 6.19% for numerical, 174.65%, and 169.4% for experimental compared to the case of absence of a magnetic field, respectively.
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    An innovative approach of alternating magnetic field diversified with different wave types and magnet positions for ferrofluid flow in dimpled tube
    (Elsevier, 2023) Gurdal, Mehmet; Gursoy, Emrehan; Pazarlioglu, Hayati Kadir; Arslan, Kamil; Gedik, Engin
    The purpose of the present experimental study is to investigate the forced magneto-convection of the Fe3O4/H2O ferrofluid flowing along smooth and dimpled tubes implemented with alternating magnetic field (B = 0.16 T and f = 5 Hz). All experiments were carried out for the working fluids pure water and ferrofluid with 1.0% volume fraction in the laminar flow regime (1131 & LE; Re & LE; 2102). Also, an original perspective of this study is to use of changing magnetic field wave types (Sinus, Triangle, and Square) and positions at different axial distances (x/D = 20, x/D = 40, and x/D = 60). Findings shed light on that the highest convective heat transfer ratio was realized at x/D = 20 location and square wave type for all cases. The average Nusselt number of the dimpled tube subjected to square wave type applied at x/D = 20 is increased by 58.13% compared to smooth tube without magnetic field and using H2O as working fluid. Moreover, when the friction factor was compared for the same conditions, the increment rate has been seen by 85.73%. Although Nusselt number is reached to its highest level using square wave type, the highest Performance Evaluation Criteria is detected around 1.45 using dimpled tube subjected to alternating magnetic field with triangle wave type applied at x/D = 20 for Re = 1131.
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    Investigation of magneto-convection characteristics in a sudden expanding channel with convex surface geometry under thermally developing flow conditions
    (Emerald Group Publishing Ltd, 2024) Gursoy, Emrehan; Pazarlioglu, Hayati Kadir; Gurdal, Mehmet; Gedik, Engin; Arslan, Kamil; Dagdeviren, Abdullah
    PurposeThe purpose of this study is to analyse the magnetic field effect on Fe3O4/H2O Ferrofluid flowing in a sudden expansion tube, which has specific behaviour in terms of rheology, with convex dimple fins. Because the investigation of flow separation is a prominent application in performance, the effect of magnetic field and convex dimple on the thermo-hydraulic performance of sudden expansion tube are examined, in detail.Design/methodology/approachDuring the solution of the boundary conditions of the sudden expansion tube, finite volume method was used. Analyses have been conducted considering the single-phase solution, steady-state, incompressible fluid and no-slip condition of the wall under forced convection conditions. In the analyses, it has been assumed that the flow was developing thermally and has been fully developed hydrodynamically.FindingsThe present study focuses on exploring the influence of the magnetic field, nanofluid concentration and convex dimple fins on the thermo-hydraulic performance of sudden expansion tube. The results indicate that the strength of the magnetic field, nanofluid concentration and convex dimple fins have a positive effect on the convective heat transfer in the system.Originality/valueThe authors conducted numerical studies, determining through a literature search that no one had yet investigated enhancing heat transfer on a sudden expansion tube using combinations of magnetic fields, nanofluids and convex dimple fins. The results of the numerical analyses provide valuable information about the improvement of heat transfer and system performance in electronic device cooling and heat exchangers.
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    NUMERICAL ANALYSIS OF EFFECT OF IMPINGING JET ON COOLING OF SOLAR AIR HEATER WITH LONGITUDINAL FINS
    (Begell House Inc, 2021) Pazarlioglu, Hayati Kadir; Ekiciler, Recep; Arslan, Kamil
    In this study, the effect of impinging jet cooling on solar air heater with and without longitudinal fins has been numerically investigated. The absorber plate surface of the solar air heater is modeled as a constant heat flux condition. Numerical analyses have been conducted on turbulent flow conditions (10,000 <= Re <= 50,000). The jet flow velocity has been taken constant. The effect of fin height and mass flow rate of working fluid on the thermal efficiency of the solar air heater has been analyzed in detail. Variation of the convection heat transfer coefficient as a function of Reynolds number has also been determined for finned and unfinned conditions. Temperature and local Nusselt number distributions on the absorber plate have been defined as contour graphs. It is found that the Nusselt number and thermal efficiency enhance by adding impingement jets and increasing the Reynolds number. Also, it is obtained from numerical analyses that the convection heat transfer coefficient increases with increasing the fins height. Finally, it is revealed that using impinging jets and fins enhances the efficiency and convection heat transfer up to 23.35% and 15%, respectively.
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    Numerical investigation on turbulent flow and heat transfer characteristics of ferro-nanofluid flowing in dimpled tube under magnetic field effect
    (Pergamon-Elsevier Science Ltd, 2022) Gurdal, Mehmet; Pazarlioglu, Hayati Kadir; Tekir, Mutlu; Arslan, Kamil; Gedik, Engin
    For the aim of increasing the heat transfer enhancement, a hybrid method in which active and passive heat recovery techniques have been used together. The usage of nanofluid, MHD and dimpled fins tube have not been utilized together so far. Regarding this issue, this study is the first numerical study to determine effect of usage of three effects together comprehensively. In this study, thermo-hydraulic performance of Fe3O4/H2O nanofluid (ferro-nanofluid) flow inside dimpled tube under magnetic field effect has been examined numerically. The main purpose of the study is to obtain numerical data for turbulent flow in the spherical dimpled tubes providing some aid to design a highly efficient thermal energy storage devices. Dimple geometry with nondimensional pitch ratio (P/d = 3.75, 7.50 and 11.25), Hartmann number (Ha = 75, 150, 225) and nanoparticle volume fraction (phi = 0.5, 1.0 and 2.5 vol%) are the parameters investigated in this study. The numerical analyses have been carried out Reynolds number ranging from 10,000 to 50,000 at a constant heat flux at 20 kW/m2. The simulations have been built up by Realizable k-epsilon turbulence model and single-phase approach. Also, MagnetoHydroDynamic (MHD) module has also been activated for defining magnetic field effect. The results showed that Nusselt number increases with increasing Reynolds number and decreasing pitch ratio. The dimple geometry type of P/d = 7.50 has been determined as the most efficient dimple geometry type. In the case of highest magnetic field intensity, the highest Nusselt number increment (72.48%) has been obtained for phi = 2.5 vol% compared to the base fluid of distilled water using as the working fluid for smooth tube. The highest PEC value was also obtained as 1.126 for the case of P/d = 7.5, phi = 2.5 vol% and Ha = 75. In addition, the effect of magnetic field intensity on velocity and temperature distributions has been presented with contour graphs.
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    Numerical simulation of sudden expansion tubes with Ag-MgO nanofluid and innovative fin structure: A thermo-fluidic analysis
    (Elsevier Science Inc, 2024) Pazarlioglu, Hayati Kadir; Gursoy, Emrehan; Gurdal, Mehmet; Said, Zafar; Arslan, Kamil; Gedik, Engin
    This study introduces an innovative approach to employing mono/hybrid nanofluids in tubes with sudden expansion, structured at various expansion angles and equipped with novel capsule -type dimpled fins. Pumping of hybrid nanofluids into sudden expansion tube combined with capsule -type dimpled fins and different expansion angles (ranging from 30 degrees to 90 degrees ) has not been investigated so far in terms of energy, exergy, and entropy analyses. Recognizing the attention currently devoted to the climate effect of a system exposed to high thermal loads, this study sheds light on the literature how a system preferred by engineers and professionals can be cooled down efficiently to increase the performance of the system. The objective is to analyze a detailed 3Estudy (energy, exergy, and entropy production) on water -based mono and hybrid nanofluids, exploring various volume fractions and combinations (including 2.0 % Ag, 2.0 % MgO, and blends of Ag-MgO). The study finds that a 45 degrees expansion angle, combined with capsule -type dimpled fins and 0.5 % Ag-1.5 % MgO nanofluid, offers the most efficient tube design, enhancing the average Nusselt number by 20.0 % . This configuration, also, reduces total entropy generation by approximately 23.0 % and shows exergy output by 26.0 % , though it does lead to a 26.0 % decrease in second law efficiency due to increased pumping power. Interestingly, the first law efficiency remains unchanged mainly across different nanofluid types. These findings provide valuable insights into optimizing heat transfer and fluid dynamics in engineering applications.
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    Parametric analysis of different Al2O3 nanoparticle shapes and expansion angles for sudden expanded tube regarding the first law of thermodynamics
    (Elsevier France-Editions Scientifiques Medicales Elsevier, 2024) Guersoy, Emrehan; Pazarlioglu, Hayati Kadir; Guerdal, Mehmet; Gedik, Engin; Arslan, Kamil
    The thermo-hydraulic performance of Al2O3/H2O nanofluid with different nanoparticle shapes flowing in a sudden expansion tube with variable sudden expansion inclination angles and elliptical dimpled fins with different diameters were numerically investigated. Investigation of variable sudden expansion inclination angles, elliptic dimpled fins, and different nanoparticle shapes together reveals the novelty of this study. The main purpose of this study is to analyse the effect of nanofluid particle shapes, sudden expansion inclination angles, and elliptical dimpled fin on thermo-hydraulic performance for sudden expansion tube. The platelet, cylindrical, and blade nanoparticle shapes of Al2O3 nanoparticle (phi = 1.0 %) were separately mixed into base fluid to obtain working fluid. Numerical studies were carried out under laminar flow regime (500 <= Re <= 2000). Furthermore, the sudden expansion tube was assumed to have inclination angles with alpha = 30 degrees, 45 degrees, 60 degrees, and 90 degrees. The results presented that the highest Performance Evaluation Criterion is obtained for the case of DT6 using Al2O3/H2O with platelet nanoparticle shape at Re = 2000. Besides, the highest Nusselt number and Performance Evaluation Criterion were realized at the inclination angle of 45 degrees. The increment rate of Nusselt number and Performance Evaluation Criterion at alpha = 45 degrees were determined as 8.75 % and 10.52 % compared to alpha = 30 degrees, respectively. Moreover, elliptical dimpled fins with sized as a = 6 mm and b = 12 mm presented the highest thermo-hydraulic performance, and this condition showed an increment of 153.9 % compared to case of a = 2 mm and b = 4 mm.