Yildirim Özcan, Nurdan
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01.01.09.06. Makine Mühendisliği Bölümü
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2ZERO HUNGER
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3GOOD HEALTH AND WELL-BEING
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4QUALITY EDUCATION
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5GENDER EQUALITY
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6CLEAN WATER AND SANITATION
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9INDUSTRY, INNOVATION AND INFRASTRUCTURE
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10REDUCED INEQUALITIES
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379
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442
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18.95
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| Journal | Count |
|---|---|
| International Journal of Exergy | 3 |
| Energy Conversion and Management | 2 |
| Tesisat Mühendisliği | 2 |
| Energy | 1 |
| Energy and Buildings | 1 |
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Book Part Citation - Scopus: 5Geothermal energy in developing countries–The dilemma between renewable and nonrenewable(Elsevier, 2022) Nurdan H. Yildirim; Emin Selahattin Umdu; Umdu, Emin Selahattin; Yildirim, NurdanGeothermal energy the first application of which was based on heating of hammam and space by the Romans in ancient times is now widely used in 88 countries with total 15950 MWe power and 107727 MWt thermal installed capacity. Geothermal energy which takes its energy from the depths of the earth is not affected much by external meteorological factors and therefore its the most important advantage compared to other renewable energy sources can produce almost uninterrupted energy throughout the year. On the other hand extracting this resource and transferring it to the surface is long difficult and costly. In order for a geothermal resource to be a clean environmentally friendly and sustainable energy source the most important thing to do is to reinject the geothermal fluid used in various applications to underground. Only in this way geothermal energy can be considered sustainable. The usage areas of geothermal energy vary depending on the thermodynamic properties of the geothermal fluid. Combined systems should be expanded to increase the efficiency of geothermal systems. In this chapter firstly basic information about geothermal energy and usage areas are given then current technologies and status are presented. The dilemma: renewable or nonrenewable sustainability and future prospect for developing countries are discussed. In the last part basic approaches in the analyses of geothermal systems are illustrated with a case study. © 2022 Elsevier B.V. All rights reserved.Article Citation - WoS: 92Citation - Scopus: 101Energy and exergy analysis of a milk powder production system(PERGAMON-ELSEVIER SCIENCE LTD, 2017) Nurdan Yildirim; Seda Genc; Yildirim, Nurdan; Genc, SedaMilk has been consumed since time immemorial because of its unique nutritional properties and produced almost 816 million tonnes in the year of 2016. Due to its highly perishable characteristic milk is processed into more stable milk products such as cheese yoghurt and butter and milk powder. Among them milk powder is distinctive for its longer shelf life and can be stored at ambient temperature. The other advantages of milk powder are less volume requirement during its transportation and higher selling price. Therefore it is widely used in many food products such as ice cream bakery products and sausages. According to a recent study on the statistics from Food and Agriculture Organization world production of whole dried milk was 3597015 tonnes in 2014: Oceania 36.5% Americas 36.1% and Europe 24.1% of the World production. Milk powder production is a process that requires high energy especially for evaporation. Recently reducing energy use has been gaining importance by increasing energy and exergy efficiency. Conventional energy analysis is performed based on the First Law of Thermodynamics. Unlike from the First Law the Second Law or exergy analysis (defined as useful work) has appeared in the literature while this analysis not only assesses quantity but also quality of energy. In this study exergy analysis of a milk powder production system mainly includes 3 processes (pasteurization evaporation and spray drying) which will be presented. The aim of the study is to apply a thermodynamic analysis including comprehensive exergy analysis by using different performance parameters such as exergy efficiency improvement potential rate sustainability index relative irreversibility and exergetic factor for the milk powder production system. As a result exergetic efficiencies of the system components were found in the range of 9-83%. The overall energy and exergy efficiencies of the whole milk powder production system were calculated as 85.4 and 57.45% respectively. Additionally it was found that the evaporator and the heater have a higher impact in improvement actions. (C) 2017 Elsevier Ltd. All rights reserved.Article Türkiye’nin Farklı İklim Koşullarında Isıl Konfor Sıcaklıklarına Bağlı Olarak Konutların Enerji Performanslarının Değerlendirilmesi(2021) Nurdan Yildirim; Ebru Hancioglu; Gulden Gokcen Akkurt; Hancioglu, Ebru; Yildirim, Nurdan; Akkurt, Gulden GokcenIsıl konfor insanın yapısı yaşı cinsiyeti gibi kişisel parametrelerin yanı sıra çevresel parametrelere de bağlıdır. Isıtma soğutma ve havalandırma sistemlerinin çalışma şekli ve dış hava sıcaklıkları ısıl konfor içinönemli parametrelerdir. Fanger deneysel çalışmalar sonucu “tahmini ortalama oy (PMV)” olarak adlandırılan bir gösterge oluşturmuş ve PMV=0’ı konfor için en iyi değer olarak belirlemiştir. Bu çalışmada farklıiklim bölgelerinden dört il seçilerek her bir il için ısıl konfor sıcaklıkları belirlenmiş ve bu ısıl konfor sıcaklıklarındaki enerji performansları değerlendirilmiştir. Isıtma ve soğutma sistemi için kişisel kontrole izinverilmeyen tam mekanik kontrollü sistem seçilmiş kesikli ve sürekli rejim için hesaplamalar yapılmıştır.Çalışmada konfor koşullarının PMV=0 olması durumunda enerji tüketimleri incelenerek iller arasındakiısıl konfor memnuniyeti ve enerji tüketiminindeki farklılıklar saptanmaya çalışılmıştır. PMV değerlerininistatistiksel analizinde İzmir ili için kesikli rejimde çalışmanın sürekli rejime göre daha iyi olmasına rağmen İstanbul için sürekli rejimde konfor koşulları açısından daha iyi sonuçlar alınmıştır. Tüm illerde süreklirejim uygulandığında birim enerji tüketiminde artış olduğu belirlenmiştir. Sürekli rejim kesikli rejime göreısıtma enerji tüketiminde % 4 5-6 2 soğutma enerji tüketiminde ise % 9 1-23 2 daha yüksektir.Article Citation - WoS: 1Citation - Scopus: 1SIMULATION OF GEOTHERMAL ENERGY PRODUCTION UTILIZING ABANDONED OIL AND GAS WELLS(STATE OIL CO AZERBAIJAN REPUBLIC OIL GAS SCIENTIFIC RESEARCH PROJECT INST, 2024) A. N. Mukhtarov; G. E. Akkurt; N. H. Yildirim; Mukhtarov, A.N.; Yildirim, N.H.; Akkurt, G.E.Abandoned oil and gas wells (AOGWs) with suitable reservoir temperatures present a promising opportunity to convert subsurface heat into thermal energy or electricity for various applications. This study developed a rigorous thermodynamic model for a single-flash geothermal power plant utilizing a double-pipe direct heat exchanger (DHE) leveraging data from existing literature and modeling via Engineering Equation Solver (EES) software. The model simulates the system using R134a as the working fluid assessing the influence of rock properties geothermal gradient DHE geometry insulation thickness mass flow rate of the working fluid and alternative working fluids on heat extraction efficiency. This innovative approach allows for the efficient utilization of available geothermal heat resources thereby enhancing the potential for sustainable energy generation. Key findings reveal that the power generation potential from AOGWs employing DHEs is significantly affected by the geothermal gradient within the well the length of the heat exchanger and the thermal conductivity of the surrounding rock. Additionally the model projects the system's long-term performance over a 20-year period emphasizing the importance of variable fluid characteristics inside the exchanger. Overall the simulations underscore the necessity of carefully considering these factors to optimize energy extraction from AOGWs. The results highlight the feasibility of harnessing geothermal energy in low-flow-rate conditions ultimately contributing to the sustainability of energy resources and offering insights for future developments in geothermal energy systems. This approach not only addresses environmental concerns associated with AOGWs but also positions them as viable assets for renewable energy generation.Article Citation - WoS: 34Citation - Scopus: 43Thermodynamic assessment of downhole heat exchangers for geothermal power generation(Elsevier Ltd, 2019) Nurdan H. Yildirim; Slamet Parmanto; Gülden Gökçen Akkurt; Parmanto, Slamet; Yildirim, Nurdan; Akkurt, Gulden GokcenDownhole heat exchanger is a device to extract heat from geothermal fluid. While it is widely used for heating purposes its use for power generation has not been reported. The aim of this study is to examine the feasibility of power generation from a 2500 m deep existing geothermal well with high temperature gradient and insufficient flowrate by using a downhole heat exchanger. For this purpose a thermodynamic and an economic evaluation model are developed by the use of Engineering Equation Solver software. Additionally the parametric studies have been carried out to identify the effects of insulation geothermal well conditions geometry of downhole heat exchanger mass flowrate and type of working fluids on the performance of downhole heat exchanger system. Consequently work output of the best alternative is computed as 2511 kWe with 64 kg/s mass flowrate of R-134a for 2500 m-deep downhole heat exchanger having inner pipe diameter of 0.127 m. Electricity generation cost and simple payback time are calculated as 46 $/MWh and 2.25 years respectively. The obtained results showed that the downhole heat exchanger system can be a feasible alternative for wells with very low geothermal flowrate to generate power. © 2019 Elsevier B.V. All rights reserved.Article Citation - WoS: 18Citation - Scopus: 18Modeling and performance analysis of a hybrid system for a residential application(PERGAMON-ELSEVIER SCIENCE LTD, 2018) Levent Bilir; Nurdan Yildirim; Bilir, Levent; Yildirim, NurdanHybrid systems which use more than one renewable energy sources are quite advantageous because they can eliminate or at least vitiate the interrupted characteristics of the renewable sources. In the present study a hybrid system which consists of a small scale wind turbine and photovoltaic panels was focused on. The system supplies the required electricity demand for a detached house with a 117 m(2) area in five different locations (Izmir Madrid Budapest Paris and Helsinki) according to European climate zones. A detailed dynamic hourly electricity generation analysis for the two components of the hybrid system was performed. As a result the coverage ratio of the hybrid system electricity generation for the total electricity demand of the house simple payback time and energy payback time of the system were calculated for each city. The results revealed that yearly electrical energy demand of the house can be entirely met by the evaluated hybrid system for each city. Maximum yearly coverage ratio of 176.6% was observed for Izmir Turkey while minimum coverage ratio was 103.1% for Helsinki Finland. The simple payback time and energy payback time of the hybrid system were determined in the range of 7-25.5 years and 4.6-6.8 years respectively. (C) 2018 Elsevier Ltd. All rights reserved.Article Citation - WoS: 24Citation - Scopus: 30Photovoltaic system assessment for a school building(PERGAMON-ELSEVIER SCIENCE LTD, 2017) Levent Bilir; Nurdan Yildirim; Bilir, Levent; Yildirim, NurdanThe installation of photovoltaic panels (PVs) on the roof of residential and commercial buildings is getting widespread as these areas stand normally idle and can be used for another purpose without losing an inhabited space. Considering the solar potential of Turkey a significant amount of electricity generation is possible using current PV technology. For this reason a two-story detached school building located in Izmir Turkey was taken into consideration and monthly as well as annual coverage ratio of an on-grid PV system for its entire energy requirement (including heating cooling and lighting) was investigated. The PVs were installed on the south face of the school building roof. A heat pump with a typical coefficient of performance (COP) value of 2.5 was used for supplying required cooling and heating. The heating cooling and lighting loads were determined on a monthly basis. The average monthly electrical energy generation of the mounted PVs was calculated using a written code in Energy Equation Solver (EES) software. As a result the monthly as well as yearly electrical energy demand coverage ratio values for the school using the installed PVs were revealed. Since the school building has a large south faced roof the installation of PVs is very suitable to meet the cumulative electrical energy need of the heat pump and the lighting load. For Case 1 180 PVs which supply the entire yearly demand (with a 110% coverage ratio) were taken into consideration while for Case 2 265 PVs which cover 75% of the roof area were evaluated. The results showed that between November and March PV electrical energy generation is not sufficient to meet all energy need of the school for both cases. However significant coverage ratio values were observed for the rest of the year. In a yearly basis the PV generation exceeded the building demand by 62% for the Case 2. This conclusion points out that the school can meet its yearly electricity need with the considered PV system and can even have an additional financial profit by selling its surplus PV electricity to the grid. Economic and environmental payback time values as well as simple payback time value were also computed for both investigated cases. The results pointed out a simple payback time of 7.9 years for Case 1 and 7.6 years for Case 2. Energy payback time was determined as 5 years for both systems. The greenhouse gas payback time of 2.7 years and 5.9 years was encountered for coal based and natural gas based calculations. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Article Energy exergy and economic assessments of wind turbine alternatives(INDERSCIENCE ENTERPRISES LTD, 2024) Nurdan Yildirim; Levent Bilir; Bilir, Levent; Yildirim, NurdanIn this study two wind turbine installation alternatives for a residential district of 20 detached houses in six different European cities are considered. Firstly the installation of an individual residential scale (5 kW) wind turbine for each house is considered. Secondly the installation of a single wind turbine having the same total installed capacity (100 kW) is evaluated. The alternatives are compared according to annual energy production exergy efficiencies and simple payback time. The results pointed that the use of a single wind turbine is better that the use of individual residential scale wind turbines for small communities or districts.Article Citation - WoS: 99Citation - Scopus: 110Evaluation of a hybrid system for a nearly zero energy greenhouse(PERGAMON-ELSEVIER SCIENCE LTD, 2017) Nurdan Yildirim; Levent Bilir; Bilir, Levent; Yildirim, NurdanGreenhouses are widely used in the World especially in the Mediterranean climate to provide suitable environment in cultivation of different agricultural crops. Significant amount of energy is necessary to produce process and distribute these crops. Various systems including steam or hot water radiation system and hot air heater system are being used in greenhouse heating. A ground source heat pump system generally seen as a favorable option since it can provide both heating and cooling energy is considered for a greenhouse in this study. The aim of this study is to evaluate a renewable energy option for the required total energy need of a greenhouse. Grid connected solar photovoltaic panels are selected to assist a ground source heat pump and generate sufficient electrical energy for lighting. In this way a nearly zero energy greenhouse concept is foreseen for three different agricultural products: Monthly and annual heating cooling and lighting energy load of the greenhouse for these agricultural products were computed. The monthly average electricity generation of 66 photovoltaic panels which cover 50% of the southern face part of the asymmetric roof was calculated. Annual photovoltaic electricity generation was found as 21510.4 kWh. It was observed that photovoltaic electricity generation can meet 33.2-67.2% of greenhouse demand in summer operation months. Nevertheless the coverage ratio calculated by dividing the photovoltaic panels electricity generation to the electricity demand of the greenhouse (heating cooling and lighting) for each crop were very high in winter operation months. Yearly coverage ratio values were 95.7% for tomato 86.8% for cucumber and 104.5% for lettuce. These high coverage ratio values justify the nearly zero energy concept for the considered greenhouse. Economic and environmental evaluation of the considered system were also accomplished. A simple payback time of the crop cultivations was computed between 7.0 and 7.4 years. The energy payback time of the system was found to be 4.9 years and the greenhouse gas payback time value of 5.7 years and 2.6 years were calculated based on natural gas and coal based electricity generation respectively. (C) 2017 Elsevier Ltd. All rights reserved.Article Citation - WoS: 33Citation - Scopus: 39Optimization of microalgae panel bioreactor thermal transmission property for building façade applications(Elsevier Ltd, 2018) Emin Selahattin Umdu; Ilker Kahraman; Nurdan H. Yildirim; Levent Bilir; Umdu, Emin Selahattin; Yildirim, Nurdan; Bilir, Levent; Kahraman, İlkerMicroalgae has great potential reducing embedded CO2 emissions of buildings through their entire life cycles by both increasing energy efficiency and actively capturing CO2. The use of closed microalgae photo bioreactors as building components has the added benefits of acting as an effective insulation system. Additionally microalgae can give a dynamic appearance with living dynamic system that also works as an adaptive sunshade. In this study the thermal transmittance (U value) of different photo bioreactors is determined by using experimental design methods for parametric studies. Heat transfer behaviour of the manufactured panel bioreactors at different operational conditions which satisfy both thermal comfort in building and microalgae growth conditions is evaluated. U values between 3.84 and 53.19 W/m2 K are observed in the study. Results show that there is a significant interaction between all main factors (reservoir air layer and reservoir wall thicknesses) and U value. Yet a two-way interaction is observed for only between reservoir and air layer thicknesses. Further air layer thickness has the highest contribution to the U value in the developed model as both a main and synergetic factor. © 2018 Elsevier B.V. All rights reserved.
