Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

Browse

Filters

2005 - 20105

Settings

Institution Author: search.filters.institutionAuthor.Bilir, Levent

Search Results

Now showing 1 - 5 of 5
  • Article
    Citation - WoS: 15
    Citation - Scopus: 17
    Heat Transfer and Pressure Drop Characteristics of Fin-Tube Heat Exchangers With Different Types of Vortex Generator Configurations
    (Begell House Inc., 2010) Bilir, Levent; Özerdem, Barış; Erek, Aytunç; İlken, Zafer
    A fin-and-tube heat exchanger with three different types of vortex generators is investigated in this study in order to observe the effects of these vortex generators on heat transfer and pressure drop characteristics. The individual as well as the cumulative influences of the vortex generators on the performance of a heat exchanger are examined. The numerical analyses are performed using a computational fluid dynamics (CFD) program named "Fluent". Firstly, each vortex generator type is placed at four different locations on the fin to determine its best location in terms of heat transfer and pressure drop values. After the determination of the best location on the fin for a vortex generator of each type, two different models with all three types of vortex generators are created and analyzed numerically. The investigation of the cumulative effect of three different vortex generators is the novelty of the study. The results of the study show that the use of three different vortex generators together increases heat transfer rate with a moderate increase in pressure drop value. The comparison of the present study results with an experimental and numerical study showed also a good agreement. © 2010 by Begell House, Inc.
  • Article
    Citation - WoS: 11
    Citation - Scopus: 13
    Wind Speed Time Series Chacacterization Hy Hilbert Transform
    (John Wiley and Sons Inc., 2006) Alpay, Selda; Bilir, Levent; Özdemir, Serhan; Özerdem, Barış
    Predictions of wind energy potential in a given region are based on on-location observations. The time series of these observations would later be analysed and modelled either by a probability density function (pdf) such as a Weibull curve to represent the data or recently by soft computing techniques, such as neural networks (NNs). In this paper, discrete Hilbert transform has been applied to characterize the wind sample data measured on Izmir Institute of Technology campus area which is located in Urla, Izmir, Turkey, in March 2001 and 2002. By applying discrete Hilbert transform filter, the instantaneous amplitude, phase and frequency are found, and characterization of wind speed is acomplished. Authors have also tried to estimate the hourly wind data using daily sequence by Hilbert transform technique. Results are varying.
  • Other
    Citation - WoS: 1
    Citation - Scopus: 1
    Erratum To "total Solidification Time of a Liquid Phase Change Material Enclosed in Cylindrical/Spherical Containers" [applied Thermal Engineering 25 (10) (2005) 1488-1502] (doi:10.1016/J.applthermaleng.2004.10.005)
    (Elsevier Ltd., 2007) Bilir, Levent; İlken, Zafer
    Refers To Levent Bilir, Zafer İlken Total solidification time of a liquid phase change material enclosed in cylindrical/spherical containers Applied Thermal Engineering, Volume 25, Issue 10, July 2005, Pages 1488-1502
  • Article
    Citation - WoS: 84
    Citation - Scopus: 96
    Total Solidification Time of a Liquid Phase Change Material Enclosed in Cylindrical/Spherical Containers
    (Elsevier Ltd., 2005) Bilir, Levent; İlken, Zafer
    This study investigates the inward solidification problem of a phase change material (PCM) encapsulated in a cylindrical/spherical container with a third kind of boundary condition. The governing dimensionless equations of the problem and boundary conditions are formulated and solved numerically by using enthalpy method with control volume approach. The problem is solved many times for different values of the affecting parameters and data sets are obtained for dimensionless total solidification time of the PCM. These data sets are then used to derive correlations which express the dimensionless total solidification time of the PCM in terms of Stefan Number, Biot Number and Superheat Parameter.
  • Article
    Citation - WoS: 101
    Citation - Scopus: 132
    Effect of Geometrical Parameters on Heat Transfer and Pressure Drop Characteristics of Plate Fin and Tube Heat Exchangers
    (Elsevier Ltd., 2005) Erek, Aytunç; Özerdem, Barış; Bilir, Levent; İlken, Zafer
    In this study, the influences of the changes in fin geometry on heat transfer and pressure drop of a plate fin and tube heat exchanger are investigated, numerically. A computational fluid dynamics (CFD) program called Fluent is used in the analysis. The segment of one tenth of fin is used in the modeling, due to symmetrical condition. The results of heat transfer, static, and total pressure drop values of ten different fins are tabulated and the normalized values of them are, also, given for the comparison of the models. The distance between fins is found to have a considerable effect on pressure drop. It is observed that placing the fin tube at downstream region affects heat transfer positively. Another important result of the study is that increasing ellipticity of the fin tube increases the heat transfer while it, also, results in an important reduction in pressure drop.