Mete AVCI
@erdogan.edu.tr
Department of Mechanical Engineering
Recep Tayyip Erdogan University
RESEARCH INTERESTS
thermal energy storage, thermal management, vortex tubes, microfluidics
Scopus Publications
Scopus Publications
Ayse Nur Altunkaya, Orhan Aydin, and Mete Avci
Elsevier BV
Ayse Nur Altunkaya, Orhan Aydin, and Mete Avci
Wiley
AbstractIn the present study, laminar pulsating power‐law momentum and heat transfer in a uniformly heated plane duct is studied analytically. Assuming that fully developed conditions exist both hydrodynamically and thermally, a perturbation series method is utilized to derive analytical solutions for the momentum and energy balance equations, and the amplitude is prescribed as the perturbation parameter. For varying values of the power‐law index (), representing pseudoplastic, Newtonian, and dilatant fluids, effects of dimensionless amplitude () and frequency () on periodic and period‐averaged friction factor and Nusselt number are obtained. The results obtained for Newtonian fluid are shown to be in good harmony with the corresponding findings in the open literature.
Mustafa Yusuf Yazici, Mete Avci, Orhan Aydin, Adeel Arshad, and Mark Jabbal
Elsevier BV
Ayse Nur Altunkaya, Orhan Aydin, and Mete Avci
Vilnius University Press
In this study, the pulsating flow of a non-Newtonian fluid and heat transfer in a pipe with uniform heat flux at its wall is examined analytically. The flow is assumed to be both hydrodynamically and thermally fully developed. The perturbation method based on the series expansion is used in the analysis. The periodic change and period-averaged values of the friction factor and Nusselt number as well as velocity and temperature profiles are obtained at varying values of dimensionless frequency and amplitude for shear-thinning, Newtonian and shear-thickening fluids. It is shown that the frequency is effective on the friction factor for a specific range of the dimensionless frequency. For some specific cases, excellent agreements are obtained with the literature. It is disclosed that the dimensionless frequency, the amplitude and the power-law index are interactively effective on the friction and heat transfer.
Burak Markal, Beyzanur Kul, Mete Avci, and Ramazan Varol
Elsevier BV
Yunus Emre Cetin, Mete Avci, and Orhan Aydin
Informa UK Limited
Abstract In this study, effect of air change rate (air change per hour – ACH) on indoor particle dispersion and deposition in a ventilated room is investigated. A reduced-scale model is designed to conduct experiments. Numerical predictions are performed by using the commercial software ANSYS Fluent 16.0. Four different values of the air change rate (1.73, 2.88, 5.76 and 7.68) and five different values of the particle diameter (0.181, 2.188, 4.42, 8.89 and 17.8 μm) are considered. Constant particle flow rate and proportional particle flow rate with inlet velocity cases are examined comparatively. Results show that, except from some inconsistencies for the largest particle diameter due to the accumulation and outlet opening location, the contaminant level decreases with increasing air change rate for a constant value of the particle flow rate while an opposite trend is observed for the proportional particle flow rate case.
Burak Markal, Ayse Candan Candere, Mete Avci, and Orhan Aydin
Elsevier BV
Burak Markal, Ayse Candere, Mete Avci, and Orhan Aydin
Elsevier BV
M.Y. Yazici, M. Saglam, O. Aydin, and M. Avci
Elsevier BV
Burak Markal, Mete Avci, and Orhan Aydin
Springer Science and Business Media LLC
Fatih Atci, Yunus Emre Cetin, Mete Avci, and Orhan Aydin
Informa UK Limited
In-duct ultraviolet germicidal irradiation systems are effective systems that are used in disinfection of pathogenic particles transported by air that moving through the ventilation systems. Proper design of these systems is quite important for energy consumption and disinfection performance. In this study, effect of four different lamp arrays within a square cross-section ventilation duct on the average UV dose, UV dose distribution and disinfection rate are examined by using computational fluid dynamics. The standard k-ε turbulence model and the discrete phase modeling are used to analyze airflow and particle distribution within the duct, respectively. Also, Discrete Ordinates (DO) radiation model is employed to obtain the irradiation field formed by each UV lamp. It is disclosed that UV lamp arrangement within duct significantly affects UV dose distribution.
Aleyna Agirman, Yunus Emre Cetin, Mete Avci, and Orhan Aydin
Springer Science and Business Media LLC
Yunus Emre Cetin, Mete Avci, and Orhan Aydin
Informa UK Limited
The aim of this study is to investigate dispersion and deposition characteristics of different particle diameters (0.5–5–10 μm) for a displacement ventilated and floor heated environment, experimentally and numerically. The experiments are performed in a reduced scale model with the operating parameters determined regarding to the similarity. Results are used to validate simulation outputs obtained via Eulerian-Lagrangian method. Three different outlet opening configurations and particle source heights are considered. Results are compared in terms of air change efficiency (ACE), average concentration of the room and the breathing height, contaminant removal effectiveness (CRE) and deposition fraction. It is disclosed that contaminant distribution is highly related with the outlet opening configuration and particle source position. Moreover, it is figured out that for the best ventilation strategy with the operating parameters to be determined, related performance indices and area of concern to be protected from particles must be well defined.
Yunus Emre Cetin, Mete Avci, and Orhan Aydin
Informa UK Limited
In this study, effect of inlet/outlet configurations on the dispersion and removal of fine particles are examined experimentally and numerically. Ten different inlet/outlet configurations are tested for three different contaminant release cases as by incoming air, from breathing level and close to the outlet. Air velocity and contaminant distributions, air change efficiency, contaminant removal effectiveness and particle decay are investigated for each case. Results revealed that both inlet and outlet opening positions have a strong impact on the performance of the ventilation system. The highest air change efficiency is achieved for the inlet/outlet positioned on the same vertical wall. In terms of particle removal, ventilation performance changes up to the particle source position and the area of interest. The most proper inlet/outlet positions should be decided by considering the source position and the main region of concern of the ventilation system. Moreover, close relation of particle source and outlet opening is found most likely to remove the contaminants effectively.
Burak Markal, Ayse Candan, Orhan Aydin, and Mete Avci
Informa UK Limited
Abstract The present study mainly concentrates on the prediction of two-phase heat transfer coefficient for saturated flow boiling conditions in minichannels. The experimental database has been generated through systematic experiments on the basis of the effect of aspect ratio. In the experiments, deionized water is used as the working fluid and five single rectangular minichannels with different aspect ratios but with the same hydraulic diameter of 1.2 mm have been tested. The database (120 data points) contains mass fluxes of 70 − 310 kg m−2s−1, wall heat fluxes of 216.2 − 1,117.6 kWm−2, vapor qualities of 0.012 − 0.788, liquid Reynolds numbers of 59.6 − 1,201.7, and aspect ratios of 0.25 − 4.00. The data obtained has been used to evaluate the previous correlations proposed for different scales (macro − mini − micro), and, then, a new empirical correlation has been developed. This new correlation presents clearly a good performance with an overall mean absolute error of 9.2%, and all the predictions fall within ±30% error band.
Aleyna Agirman, Yunus Emre Cetin, Mete Avci, and Orhan Aydin
Informa UK Limited
Operating room ventilation is quite important to protect patients from infection risk inside a surgical field. The laminar flow units (LAF) used in these applications contribute to removal of pathogen particles from the operation area by creating a protection zone on the surgical field. In this study, effect of LAF diffuse size on airflow and particle distribution in an operating room is investigated using computational fluid dynamics (CFD). Three different diffuser sizes (1.8 m x 2.4 m, 2.4 m x 2.4 m, 3.2 m x 3.2 m) and three different particle diameters (5 µm, 10 µm, 20 µm) are examined. In the modeling of airflow and particle motion, the Realizable k-ε turbulence model and Lagrangian approach are used, respectively. The distributions of airflow and particles originated from the surgical team are analysed. Also, the air change efficiency is predicted as for the entire operating room and for the breathing zone. The results reveal that the LAF diffuser size has a decisive role in air velocity and contaminant distribution in the operating room. It is seen that the amount of particles deposited on the operating table could be reduced up to 73% by increasing the diffuser size.
Y E Cetin, M Avci, and O Aydin
IOP Publishing
Abstract Similarity between a model and a prototype is important for scale model experimental studies. Proper scaling by considering similarity parameters can lead to valuable results. The objective of this study is to investigate dispersion of fine particles under different air change rates by experimental and numerical techniques. Experimental studies are performed on a 1:5 reduced scale model. Similarity parameters are considered for kinematic and particle dispersion similarities. The RNG k – ε turbulence model is used in the numerical predictions. It is shown that the average room and outlet concentrations get similar values with the removal of accumulation as the air velocity increases. Moreover, it is disclosed that the advantages of the increasing air change rates may have limits in reducing contaminant level.
A Agirman, Y E Cetin, M Avci, and O Aydin
IOP Publishing
Abstract This study investigates the effect of exhaust outlet location on airflow and particle distribution in an operating room with laminar ventilation system via computational fluid dynamics (CFD). Four different exhaust opening locations and three different particle diameters (5, 10 and 20μm) are taken into consideration for the same air change rate (30 ACH). It is found that the total number of particles deposited on the operating table decreased by 64 % for the smallest particle diameter (5 μm) and 26 % for the largest particle diameter (20 μm) when ceiling and floor level outlets are used together.
Yunus Emre Cetin, Mete Avci, and Orhan Aydin
EDP Sciences
In this study, particle decay in a cleanroom is investigated numerically. A commercial CFD package, FLUENT, is used in the analysis. The governing equations are solved by using the k-å turbulence model. For particle dispersion, the discrete phase model (DPM) is applied. Four different air change rates (3-10-25-43 ACH) with three particle diameters (0,5-5-10 ìm) are considered. It is shown that 10 ACH satisfies the needs in terms of recovery time.
Aleyna Agirman, Yunus Emre Cetin, Mete Avci, and Orhan Aydin
EDP Sciences
Bacteria-carrying particles released by surgical staff are the main factors leading to surgical site infections (SSI). Operating rooms must be designed to reduce risks of such infections. In this numerical study, the effect of different ceiling heights on particle dispersion and deposition are studied for an operating room with laminar airflow (LAF) system. Two different particle diameters (12 and 20 ìm) are tested under three different ceiling heights (2.43–2.8–3.0 m) at a constant air change rate (ACH=20). Numerical predictions are performed by using the commercial software ANSYS Fluent 16.0. The results reveal that decreasing of the ceiling height reduces the amount of particle deposited on the surgical table.
Mustafa Yusuf Yazici, Mete Avci, and Orhan Aydin
Elsevier BV
O. Kaan Yagci, Mete Avci, and Orhan Aydin
Elsevier BV
Burak Markal, Orhan Aydin, and Mete Avci
Springer Science and Business Media LLC
Burak Markal, Orhan Aydin, and Mete Avci
Informa UK Limited
ABSTRACT In this study, two new correlations are developed to predict pressure drop for the flow boiling in micro systems with low mass flux. The correlations developed rely on extensive experimental results. Experiments are conducted for flow boiling in nine different silicon multichannel heat sinks with deionized water. In the experiments, mass fluxes of 51–324 kg⋅m−2⋅s−1, wall heat fluxes of 36–121.8 kW⋅m−2, exit vapor qualities of 0.04–0.81, liquid-only Reynolds number of 20.3–89.4, aspect ratios of 0.37–5.00 and hydraulic diameters of 100–250 µm are tested. At first, validation tests for the single phase have been conducted. Then, some of the well-known existing correlations developed for the prediction of two phase pressure drop are used for comparison of the experimental results obtained. Finally, two new empirical correlations are developed for low mass flux conditions. The first one is for frictional pressure drop component, which is obtained by following a general procedure. The second one is for the prediction of total pressure drop (a dimensionless pressure drop correlation). The latter has been shown to predict better with an overall mean absolute error of 14.5% and, 87.8%, 94.8% and 96.5% of the predictions falling within ±30, ±40 and ±50% error bands, respectively.
A. Candan, B. Markal, O. Aydin, and M. Avci
Informa UK Limited
ABSTRACT In this study, saturated flow boiling characteristics of deionized water in single rectangular minichannels are investigated experimentally. A special attention is paid to the effect of aspect ratio (channel width to depth, Wch/Hch) on the heat transfer and total pressure drop. Experiments are conducted for various values of the mass flux and the wall heat flux. Flow visualization is used as a complementary technique for a deeper physical understanding of flow phenomena. The results show that the channel aspect ratio has a significant effect on both the local two-phase heat transfer coefficient and the total pressure drop. In general manner, the aspect ratio of 1 presents the highest heat transfer coefficients, while the aspect ratio of 0.25 demonstrates the lowest ones. On the other hand, the lowest values of the pressure drop are obtained at the extreme values of the aspect ratio (0.25 and 4).