Mechanical Engineering / Makina Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4129
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Article Türkiye' de Rüzgar Enerjisi Uygulamalarının Gelişimi ve Geleceği(TMMOB Makina Mühendisleri Odası, 2003) Özerdem, BarışFosil yakıt kaynaklarının sınırlı oluşu ve hava kirliliği, asit yağmurları ile sera etkisi şeklinde ortaya çıkan çevresel sorunlar nedeniyle, yenilenebilir enerji kaynakları tüm dünyada giderek artan bir ilgi ile karşılanmakta ve enerji gereksiniminin karşılanmasında önemli bir kaynak olarak görülmektedir. Bu bağlamda pek çok ülke 2010 yılında elektrik enerjisi gereksinimlerinin %10'unu rüzgar enerjisinden karşılamayı planlamaktadır. Çünkü; rüzgar, güneş, jeotermal, biyokütle ve dalga gibi yenilenebilir enerji kaynakları arasında elektrik üretimi konusunda en fazla ümit veren yenilenebilir enerji kaynağı, rüzgar enerjisidir. Bu nedenle, pek çok ülke ulusal programlar ve teşvikler uygulayarak rüzgar enerjisi teknolojisini geliştirmeye çalışmaktadırlar. Bu bildiride dünyada ve Türkiye'de rüzgar enerjisi kullanımı mevcut durumu, gelişimi incelenerek, ele alınmıştır. Yaşanan sürece koşut olarak da, ülkemizde rüzgar potansiyelinin en etkin ve yaygın şekilde kullanılması yönünde görüşler aktarılmış, öneriler geliştirilmiştir.Article Citation - Scopus: 1Sizing of Autonomous Wind/Solar Hybrid Energy Conversion Systems for Urla, Turkey(ACTA Press, 2009) Özerdem, Barış; Ekren, OrhanIn this paper, an optimum sizing procedure of autonomous hybrid (wind + solar) energy system is presented which can be used to satisfy the requirements of given load distribution. The main purpose of this study is to find out an appropriate wind-photovoltaic hybrid energy system to satisfy electricity consumption of GSM (Global System for Mobile communication) base station at Izmir Institute of Technology Campus Area, Urla, Izmir, Turkey. To do this, monthly average daily solar radiation and wind speed data are collected. The monthly average wind speeds are measured at 10 m height during 3 years period on Izmir Institute of Technology Campus Area. The monthly average wind speed values are obtained between 5.7 and 7.7 m/s, on the other hand, the monthly average daily value of solar radiations on horizontal surfaces are ranged from 1.4 to 6.9kWh/m2 at Izmir Institute of Technology Campus Area. The hybrid system considered in the present analysis consists of one 5kW nominal power wind energy conversion systems (WECS), 21.82 m2 of photovoltaic (PV) panels (18 mono crystal PV panels each having 75 W power output) together with a battery storage system.Conference Object Cash Flow Forecasting by Using Time Series Methods in Geothermal District Heating Systems: Balcova - Narlidere Case(National Technical University of Athens, 2006) Erdoğmuş, Abdullah Berkan; Özerdem, BarışCash flow forecasting is one of the difficult and important tasks in an economic evaluation of a geothermal investment. Geothermal district heating systems are characterized by a high capital cost. In addition, relatively low operation and maintenance costs occur throughout their life. The aim of this research is to estimate the potential cash flows for Balcova - Narlidere Geothermal District Heating System by using historical data accumulated over a period of time and several forecasting methods: moving average, exponential smoothing, adjusted exponential smoothing and curve fitting functions. Mean absolute percentage deviation (MAPD) which is the most common approach to select the appropriate method to a particular time series is used in the selection of the most suitable model. Alternative methods are compared with each other regarding to their MAPD values. It is found that the models represented by exponential curve fitting functions have smaller MAPD values and give better results in cash flow forecasting of investment investigated.Conference Object Energy Losses From Outdoor Located Air Handling Unit and Connection Duct(Universita degli Studi di Padova, 2007) Erdoğmuş, Abdullah Berkan; Mobedi, Moghtada; Özerdem, BarışIn the present study, energy losses due to heat transmission and air leakage from outdoor located air handling unit and connection duct are investigated based on EN 1886 and NEN-EN 1507 standard. The EN 1886 standard classifies air handling unit according to heat transmission and air leakage, while NEN-EN 1507 standard specify air leakages of rectangular ducts. In this study, air leakage and heat transmission fluxes for three cities in different regions of Turkey are determined and the economical value of energy losses for a building located in the city of Izmir and services 24 hours is calculated. The ambient air temperatures are taken from Turkish State Meteorological Service. The daily average values are considered for ambient temperature. The energy losses are determined for the variable and constant supply temperatures. Tables and charts are provided to show the variation of energy losses due to transmission and air leakage for the whole year. The total amounts of heat transmission and air leakage energy losses for different classes of air handling unit and connection duct are compared and discussed.Article Citation - WoS: 103Citation - Scopus: 132Break-Even Analysis and Size Optimization of a Pv/Wind Hybrid Energy Conversion System With Battery Storage - a Case Study(Elsevier Ltd., 2009) Ekren, Orhan; Yetkin Ekren, Banu; Özerdem, BarışThis paper aims to show an optimum sizing procedure of autonomous PV/wind hybrid energy system with battery storage and a break-even analysis of this system and extension of transmission line. We use net present value (NPV) method for the comparison of autonomous hybrid energy system and extension of transmission line cases. The case study is completed for the satisfaction of the electricity consumption of global system for mobile communication base station (GSM) at Izmir Institute of Technology Campus Area, Urla, Izmir, Turkey. First, we optimize the PV/wind energy system using response surface methodology (RSM) which is a collection of statistical and mathematical methods relying on optimization of response surface with design parameters. As a result of RSM, the optimum PV area, wind turbine rotor swept area, and battery capacity are obtained as 3.95 m2, 29.4 m2, 31.92 kW h, respectively. These results led to $37,033.9 hybrid energy system cost. Second, break-even analysis is done to be able to decide the optimum distance where the hybrid energy system is more economical than the extension of the transmission line. The result shows that, if the distance between national electricity network and the GSM base station location where the hybrid energy system is assumed to be installed is at a distance more than 4817 m, the installation of hybrid energy system is more economical than the electricity network.Article Citation - WoS: 14Citation - Scopus: 19A Numerical Simulation Study for the Human Passive Thermal System(Elsevier Ltd., 2008) Yıldırım, Eda Didem; Özerdem, BarışThe objective of this study is to create a dynamic model representing a transient three-dimensional passive thermal model of the human body. The model is a multi-segmental, multi-layered representation of the human body with spatial subdivisions which simulates the heat transfer phenomena within the body and at its surface. In order to represent the mechanisms of heat transfer within the body, energy balance equations including conduction with adjacent tissue, heat storage, metabolic heat generation, and convective heat transfer due to the blood flow in the capillaries are taken into consideration for each tissue. The present model of the passive system accounts for the geometric and anatomic characteristics of the human body and considers the thermo-physical and the basal physiological properties of tissue materials. It is assumed that the body is exposed to combination of the convection, evaporation and radiation which are taken into account as boundary conditions when solving the passive thermal system equation. The model is capable of predicting human body temperature in any given environmental conditions. Finite difference solution scheme is used to find out the temperature distribution of human body. The results are compared with the experimental data of previous studies present in the literature. Consequently, the numerical results of present model show good agreement with the experimental data.Article Citation - WoS: 18Citation - Scopus: 25Air Leakage Measurement and Analysis in Duct Systems(Elsevier Ltd., 2006) Aydın, Çiğdem; Özerdem, BarışAir ducts and related equipments are used in a large number of buildings having thermal comfort. In this study, energy loss related with air leakage is studied. The leakage measurement setup was produced according to NEN-EN standards and the evaluation of data have been conducted by using power law model. The measurements were made on 300 and 1000 mm diameter single circular ducts, 300 mm × 250 mm and 1000 mm × 500 mm flanged joint rectangular ducts, 300 and 630 mm diameter circular beaded slip joint ducts, 300 mm × 200 mm and 500 mm × 300 mm rectangular flanged and drive slip joint ducts, and an branched air distribution system having different diameters for positive internal pressures. Test results have showed that the most of air leakage is from the joints. The seam contribution to air leakage is relatively lower than the joints. Using sealing gaskets help to improve the air leakage by about 50%.Article Citation - WoS: 11Citation - Scopus: 13Wind Speed Time Series Chacacterization Hy Hilbert Transform(John Wiley and Sons Inc., 2006) Alpay, Selda; Bilir, Levent; Özdemir, Serhan; Özerdem, BarışPredictions 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.Article Citation - WoS: 39Citation - Scopus: 41Economic Assessment of Geothermal District Heating Systems: a Case Study of Balçova-Narlıdere, Turkey(Elsevier Ltd., 2006) Erdoğmuş, Berkan; Toksoy, Macit; Özerdem, Barış; Aksoy, NiyaziGeothermal energy is an important renewable energy resource in Turkey. The aim of this research is to evaluate the Balcova-Narlidere geothermal district heating system from an economic perspective. The system is the largest one in Turkey in terms of heating capacity and located in Izmir. Although there are some assessments regarding energy and exergy analysis for the Balcova-Narlidere geothermal district heating system, an economic assessment was not performed, previously. The profitability of the investment is investigated by using internal rate of return method. Seven hundred and eighty different scenarios are developed in this assessment. In order to estimate the potential cash flows in the remaining project life, operating cost in 2002 is decreased and increased, alternatively, between 5% and 30% by 5% in each step, while monthly energy utilization price is changed between US$ 17 and 72 in those scenarios. The energy utilization prices are suggested according to zero IRR value for all scenarios due to the consideration of social and environmental concerns in this investment. It is found that, the proper monthly energy utilization price for a 100 m2 household would be US$ 55.5 when the operating cost and heating capacity in 2002 were remained constant.Article Citation - WoS: 77Citation - Scopus: 89Feasibility Study of Wind Farms: a Case Study for Izmir, Turkey(Elsevier Ltd., 2006) Özerdem, Barış; Özer, Serra; Tosun, MahirWind is one of the world's fastest growing renewable energy sources. The rapid growth in wind power is a result of improvements accomplished in technology. This paper presents the technical and economical feasibility of wind farms. The method is applied to a potential wind farm site located in Izmir, Turkey. The site is considered on technical and economical parameters for the complete plant and its running costs. For technical consideration wind speed, prevailing wind direction, and temperature measurements are performed. For economical consideration, three different scenarios namely, autoproducer, autoproducer group, and independent power producer (IPP) cases, are investigated and compared with respect to net present value (NPV), internal rate of return (IRR), and pay back period (PBP) criteria. The study indicates the costs of generated energy by wind turbines with different characteristics as a function of the installed capacity. It is concluded that, the larger the installed capacity, the smaller the generating cost per kWh. The generating cost was calculated as low as 2.68 UScent/kWh for the IPP scenario. The profitability analysis also shows that, larger installed capacity with larger rated power wind turbines present higher IRR of the investment. The sensitivity analysis backs up the findings.