Browsing by Publisher "Serbian Society of Heat Transfer Engineers"
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Item Effects of an adiabatic fin on the mixed convection heat transfer in a square cavity with two ventilation ports(Serbian Society of Heat Transfer Engineers, 2014) Selimefendigil F.; Oztop H.F.In this study, a square cavity with two ventilation ports in the presence of an adiabatic fin of different lengths placed on the walls of the cavity is numerically analyzed for the mixed convection case for a range of Richardson numbers (Ri = 0.1, 1, 10, 100) and at Reynolds number of 300. The effect of the fin height, placement of the fin on each of the four walls of the cavity and Richardson number on the heat transfer and fluid flow characteristics is numerically analyzed. The results are presented in terms of streamlines, isotherm plots, and averaged Nusselt number plots. It is observed that for the convection dominated case, fin length and its position on the one of the four walls of the cavity do not alter the thermal performance whereas when the buoyancy effects become important thermal performance increases for high fin length.Item Numerical analysis of mixed convection in pulsating flow for a horizontal channel with a cavity heated from below(Serbian Society of Heat Transfer Engineers, 2016) Selimefendigil F.In this study, a channel with a cavity heated from below is numerically investigated for the mixed convection case in pulsating flow for a range of Richardson numbers (Ri = 0.1, 1, 10, 100) at Reynolds number of 50 in the laminar flow regime. At the inlet of the channel, pulsating velocity is imposed for Strouhal numbers between 0.1 to 1 and velocity amplitude ratio between 0.3 to 0.9. The effect of the pulsation frequency, amplitude, and Richardson number on the heat transfer enhancement is numerically analyzed. The results are presented in terms of streamlines, isotherm plots, and averaged Nusselt number plots. The fast Fourier transform plots for the Nusselt number response to single sinusoidal velocity forcing at the inlet and non-linearity in the response is also provided.Item Fractional variational iteration method for time-fractional non-linear functional partial differential equation having proportional delays(Serbian Society of Heat Transfer Engineers, 2018) Dogan Durgun D.; Konuralp A.In this paper, time-fractional non-linear partial differential equation with proportional delays are solved by fractional variational iteration method taking into account modified Riemann-Liouville fractional derivative. The numerical solutions which are calculated by using this method are better than those obtained by homotopy perturbation method and differential transform method with same data set and approximation order. On the other hand, to improve the solutions obtained by fractional variational iteration method, residual error function is used. With this additional process, the resulting approximate solutions are getting closer to the exact solutions. The results obtained by taking into account different values of variables in the domain are supported by compared tables and graphics in detail. © 2018 Society of Thermal Engineers of Serbia.Item Packing chromatic number of transformation graphs(Serbian Society of Heat Transfer Engineers, 2019) Durgun D.D.; Ozen Dortok H.B.Graph coloring is an assignment of labels called colors to elements of a graph. The packing coloring was introduced by Goddard et al. [1] in 2008 which is a kind of coloring of a graph. This problem is NP-complete for general graphs. In this paper, we consider some transformation graphs and generalized their packing chromatic numbers. © 2019 Society of Thermal Engineers of Serbia.Item An analytical study on the entropy generation in flow of a generalized Newtonian fluid(Serbian Society of Heat Transfer Engineers, 2019) Aksoy Y.; Gurkan N.; Aksoy A.B.; Dogan Durgun D.D.; Yurddas A.In this study, an analytical investigation on pressure driven flow of Powell-Eyring fluid is conducted to understand the irreversibilities due to heat transfer and viscous heating. The flow between infinitely long parallel plates is considered as fully developed and laminar with constant properties and subjected to symmetrical heat fluxes from solid boundaries. The internal heating due to viscous friction accompanies external heat transfer, that is, viscous dissipation term is to be involved in the energy equation. As a cross-check, accuracy of analytical solutions is confirmed by a predictor-corrector numerical scheme with variable step size. © 2019 Society of Thermal Engineers of Serbia.Item Singular homology algorithm for MA-spaces(Serbian Society of Heat Transfer Engineers, 2019) Unver Demir E.The work on digitizing subspaces of the 2-D Euclidean space with a certain digital approach is an important discipline in both digital geometry and topology. The present work considers Marcus-Wyse topological approach which was established for studying 2-D digital spaces, Z2. We introduce the digital singular homology groups of MA-spaces (M-topological space with an M-adjacency), and we compute singular homology groups of some certain MA-spaces, we give a formula for singular homology groups of 2-D simple closed MA-curves, and an algorithm for determining homology groups of an arbitrary MA-space. © 2019 Society of Thermal Engineers of Serbia.Item Differential representation of the Lorentzian spherical timelike curves by using bishop frame(Serbian Society of Heat Transfer Engineers, 2019) Balki Okullu P.; Kocayigit H.In this study, we will give the differential representation of the Lorentzian spherical timelike curves according to Bishop frame and we obtain a third-order linear differential equation which represents the position vector of a timelike curve lying on a Lorentzian sphere. © 2019 Society of Thermal Engineers of Serbia.Item Naturel mates of equiaffine space curves in affine 3-space(Serbian Society of Heat Transfer Engineers, 2019) Tuncer Y.; Kocayigit H.; Karacan M.K.In this study, we investigated the natural mates of equiaffine curves with constant equiaffine curvatures, associated to equiaffine frame in affine 3-space and we gave the position vectors under some conditions. © 2019 Society of Thermal Engineers of Serbia.Item Some Kannan type fixed point results in rectangular soft metric space and an application of fixed point for thermal science problem(Serbian Society of Heat Transfer Engineers, 2019) Oztunc S.; Mutlu A.; Aslan S.The intention of current study to survey Kannan type mappings for rectangular soft metric space. Some Kannan type results are obtained by using rectangular soft metric and an application for thermal science problem is presented. © 2019 Society of Thermal Engineers of Serbia.Item A computational method for solving differential equations with quadratic non-linearity by using bernoulli polynomials(Serbian Society of Heat Transfer Engineers, 2019) Bicer K.E.; Sezer M.In this paper, a matrix method is developed to solve quadratic non-linear differential equations. It is assumed that the approximate solutions of main problem which we handle primarily, is in terms of Bernoulli polynomials. Both the approximate solution and the main problem are written in matrix form to obtain the solution. The absolute errors are applied to numeric examples to demonstrate efficiency and accuracy of this technique. The obtained tables and figures in the numeric examples show that this method is very sufficient and reliable for solution of non-linear equations. Also, a formula is utilized based on residual functions and mean value theorem to seek error bounds. © 2019 Society of Thermal Engineers of Serbia.Item Numerical solutions of a class of non-linear ordinary differential equations in Hermite series(Serbian Society of Heat Transfer Engineers, 2019) Guler C.; Kaya S.O.; Sezer M.The purpose of this paper is to present a Hermite polynomial approach for solving a high-order ODE with non-linear terms under mixed conditions. The method we used is a matrix method based on collocation points together with truncated Hermite series and reduces the solution of equation to solution of a matrix equation which corresponds to a system of non-linear algebraic equations with unknown Hermite coefficients. In addition, to illustrate the validity and applicability of the method, some numerical examples together with residual error analysis are performed and the obtained results are compared with the existing result in literature. © 2019 Society of Thermal Engineers of Serbia.Item N-bishop darboux vector of the spacelike curve with spacelike binormal(Serbian Society of Heat Transfer Engineers, 2019) Kusak Samanci H.; Kocayigit H.In this article, the N-Bishop frame in Minkowski space is investigated for spacelike curves with a spacelike binormial. Some features of the normal expansion are proven via for the spacelike curve. Then, a new Darboux frame called by the N-Bishop Darboux frame is introduced at first time. Furthermore, some geometrical properties of the N-Bishop Darboux frame are proven. As a result, the N-Bishop Darboux axis and momentum rotation vector are calculated. © 2019 Society of Thermal Engineers of Serbia.Item Some special curves belonging to mannheim curves pair(Serbian Society of Heat Transfer Engineers, 2019) Senyurt S.; Altun Y.; Cevahir C.; Kocayigit H.In this paper, we investigate special Smarandache curves with regard to Sabban frame for Mannheim partner curve spherical indicatrix. We create Sabban frame belonging to this curves. Smarandache curves are explained by taking position vector as Sabban vectors belonging to this curves. Then, we calculate geodesic curvatures of this Smarandache curves. Found results are expressed depending on the Mannheim curve. © 2019 Society of Thermal Engineers of Serbia.Item An explicit characterization of spherical curves according to Bishop frame and an approximately solution(Serbian Society of Heat Transfer Engineers, 2019) Balki Okullu P.; Kocayigit H.; Agirman Aydin T.In this paper, spherical curves are studied by using Bishop frame. First, the differential equation characterizing the spherical curves is given. Then, we exhibit that the position vector of a curve which is lying on a sphere satisfies a third-order linear differential equation. Then we solve this linear differential equation by using Bernstein series solution method. © 2019 Society of Thermal Engineers of Serbia.Item On the Sabban frame belonging to involute-evolute curves(Serbian Society of Heat Transfer Engineers, 2019) Senyurt S.; Altun Y.; Cevahir C.; Kocayigit H.In this paper, we investigate special Smarandache curves with regard to Sabban frame of involute curve. We create Sabban frame belonging to spherical indicatrix of involute curve. Smarandache curves are explained by Sabban vectors belonging to spherical indicatrix. Then, we calculate geodesic curvatures of this Smarandache curves. The results found for each curve is given depending on evolute curve. The example related to the subject is given and their figures are drawn with MAPPLE program. © 2019 Society of Thermal Engineers of Serbia.Item EXPERIMENTAL STUDY ABOUT UTILIZATION OF MWCNT AND GRAPHENE NANOPLATELETS WATER-BASED NANOFLUIDS IN FLAT NON-CONCENTRATING PVT SYSTEMS(Serbian Society of Heat Transfer Engineers, 2021) Alous S.; Kayfeci M.; Uysal A.Although the increment the performance of photovoltaic thermal (PVT) systems by using the nanofluids as working fluids have gained the attention of researchers during the last two decades, there is still, a lack in the literature study associated to this application. This study contributes to the investigations and researches of applying the nanofluids to increase the performance of PVT collectors. A flat non-concentrating PVT collector has been designed, constructed and, outdoor tested in Karabuk University, Turkey. The considered working fluids in this study are multiwall carbon nanotubes (MWCNT), and graphene nanoplatelets dispersed in water as a base fluid with a concentration of 0.5 wt.%. The experiments were run with a volume flow rate of 0.5 L per minute for the aforementioned nanofluids and distilled water (as a reference fluid). The study results have shown and revealed that the MWCNT-water nanofluid presented a better performance in terms of electrical energetic efficiency compared to graphene nanoplatelets-water nanofluid and distilled water, while graphene nanoplatelets-water nanofluid revealed the highest thermal energetic efficiency. Moreover adding thermal unit to photovoltaic module enhanced the total energetic efficiency by 53.4% for distilled water, 57.2% for MWCNT-water, and 63.1% for graphene-water. © 2021. Society of Thermal Engineers of Serbia.Item EXERGETIC PERFORMANCE OF VAPOR-COMPRESSION REFRIGERATION SYSTEM WITH TiO2 NANOADDITIVE IN THE COMPRESSOR OIL(Serbian Society of Heat Transfer Engineers, 2021) Selimefendigil F.; Oztop H.F.Exergy analysis of a vapor-compression refrigeration system with TiO2 nanoadditives in the compressor oil was performed. Two-step method was used for the preparation of nanooil for various solid particle volume fractions between 0% and 1%. Irreversibilities were determined by using the Second law of thermodynamics. It is found that a reduction in total irreversibility is achieved with nano-particle inclusion and it was significant for higher particle volume fraction. © 2021. Society of Thermal Engineers of Serbia.Item A REVIEW ON COMPUTATIONAL FLUID DYNAMICS SIMULATION METHODS FOR DIFFERENT CONVECTIVE DRYING APPLICATIONS(Serbian Society of Heat Transfer Engineers, 2023) Coban S.O.; Selimefendigil F.; Oztop H.F.; Hepbasli A.This paper focuses on the CFD studies on one of the commonly used drying processes for different applications. First, a brief information about drying is given with determining important properties that effect drying characteristics. Next, basic principles of CFD modelling are explained while capabilities of computational processing are presented. A detailed literature survey about CFD studies in convective drying process is then conducted. Finally, some sound concluding remarks are listed. It may be concluded that the CFD is a powerful and flexible tool that can be adopted to many different physical situations including complex scenarios, results of CFD simulations represent good predictions for fluid-flow, heat and mass transfer of various drying methods and those numerical studies can be used for validation and controlling of applicability of new drying systems. © 2023 Society of Thermal Engineers of SerbiaItem NUMERICAL ANALYSIS FOR THE IMPACTS OF USING NANO-ENHANCED PCM ON THE THERMAL MANAGEMENT OF BATTERY MODULE(Serbian Society of Heat Transfer Engineers, 2024) Selimefendigil F.; Cakmak F.A.; Oztop H.F.The temperature and temperature differences in the battery module rise as a result of the high heat output produced by lithium-ion batteries during operation. This can reduce the operating safety of the battery and reduce the battery life. As a result, the temperature of the batteries must be controlled well by thermal management. Thermal control of batteries employs both active and passive techniques. In this study, PCM, which is a passive cooling system, was used. It has been observed that by placing PCM around the battery, it effectively reduces the peak temperature during the end of discharge in the battery cell. The RT-27 and nano-doped RT-27 with suitable melting range were used as PCM. Four different situations were investigated at 0.3C and 0.5C discharge conditions. These are battery models coated with only the battery, RT-27, coated with nano-RT-27, and coated with RT-27 and nano-RT-27, respectively. The peak temperature was found to be higher when the battery module without PCM was compared to the others. The battery module coated on both surfaces with RT-27 and nano-RT-27 performed better than the other modules. At 0.3 C-Rate, the peak temperature reduces by 1.8 K while it is 4.4 K at 0.5C-Rate. © 2024 Society of Thermal Engineers of Serbia.