1,720,984 research outputs found
The impact of industrial pollution on solar panel efficiency: the case of Karabük
No full textGünümüzde hızla artan enerji ihtiyacı, fotovoltaik (PV) panel teknolojisinin gelişmesi ve ucuzlaması ile birlikte güneş panellerine olan talebi artırmıştır. Güneş enerjisi santrali (GES) kurulum öncesi sistem tasarımı ve fizibilite çalışmaları bu noktada hayati önem taşımaktadır. Kurulumdan sonra tesisin bakımı ve temizliği panellerin verimini önemli ölçüde etkilemekte olup bulunduğu çevre yapısı ile doğrudan ilgilidir. Tesis kurulmadan önce yapılacak fizibilite çalışmalarında panellerin kirlenmesine neden olabilecek çevre şartlarının da göz önünde bulundurulması gerekmektedir.
Bu çalışmada, Merkez Karabük ili Öğlebeli Sanayi Sitesinde kurulumu yapılmış bir Güneş enerjisi santrali yıllar içerisinde temizlenmeden üzerinde biriken tortunun güneş
paneli verimine etkisi incelenmiştir. Panellerin üzerinden alınan tortunun içerisinde analiz sonuçlarına göre en yoğun kirletici madde %37,37 oranla demir oksit (Fe2O3), daha sonra %29,30 oranla Kalsiyum Oksit (CaO) vardır. Hazırlanan deney düzeneğinde kirlenmiş olan iki adet 250 W polikristal güneş panelinin biri temizlenmiş ve diğeri %75, 60, 45, 30 ve 15 oranlarında kirli bırakılarak deneysel ölçümler yapılmıştır. Güneş panelleri 25° açı ile ve aynı konstrüksiyon üzerinde eşit şartlarda incelenerek endüstriyel kirlenmenin panel verimine etkisi incelenmiştir.
Yapılan deneylerde, görüntü analizi sonucuna göre %75, 60, 45, 30 ve 15 kirli olan bir panelin elektriksel verim kayıpları sırasıyla %45, 39, 38, 35,3 ve 34,8 olarak hesaplanmıştır. Panel arkası sıcaklıkları ise temiz panelde yaklaşık 44-48 °C aralığında sıcaklıklara ulaşırken, %75, 60, 45, 30 ve 15 kirli panellerde ise sırasıyla yaklaşık 45, 42, 42, 43 ve 43,5 °C olarak ölçüşmüştür.In recent years, the rapidly increasing energy demand, along with the advancement and cost reduction in photovoltaic (PV) panel technology, has significantly boosted the demand for solar panels. In this context, system design and feasibility studies for solar power plants (SPPs) before installation are of critical importance. The maintenance and cleaning of the facility after installation significantly affect the efficiency of the panels and are directly related to the environmental conditions. In the feasibility studies to be conducted before the installation of the facility, environmental conditions that may cause pollution on the panels should also be taken into consideration.
This study investigates the impact of the accumulation of residue on solar panel efficiency over the years without cleaning, in a solar power plant installed in the Öğlebeli Industrial Site in the Karabük city centre.
According to the analysis results, the most abundant pollutant found in the residue collected from the panels is iron oxide (Fe2O3) at 37.37%, followed by calcium oxide (CaO) at 29.30%. In the experimental setup prepared, two 250 W polycrystalline solar panels were used—one was cleaned, while the other was left dirty at 75%, 60%, 45%, 30%, and 15% degrees of contamination for experimental measurements. The solar panels were examined under equal conditions on the same construction at a 25° angle to investigate the impact of industrial pollution on panel efficiency.
In the experiments, based on the image analysis results, the electrical efficiency losses for the panels with 75%, 60%, 45%, 30%, and 15% contamination were calculated as 45%, 39%, 38%, 35.3%, and 34.8%, respectively. While the back panel temperatures of the clean panel reached approximately 44-48°C, the temperatures for the panels with 75%, 60%, 45%, 30%, and 15% contamination were measured as approximately 45, 42, 42, 43, and 43.5°C, respectively.Bu tez çalışması, Karabük Üniversitesi Bilimsel Araştırma Projeleri Koordinatörlüğü tarafından KBÜ-BAP-23-YL-118 numaralı tez projesi kapsamında desteklenmiştir
Heat pipe metal hydride hydrogen tank design of charge experimental investigation of the effect of operations
No full textFen Bilimleri Enstitüsü, Enerji Sistemleri Mühendisliği Ana Bilim DalıEnerji kaynaklarının azalması, enerji ihtiyacının ve enerji maliyetlerinin artması, sanayideki rekabetçi koşullar ve çevresel duyarlılık enerji kaynaklarını verimli kullanmayı gerektirmektedir. Bu kapsamda değerlendirilebilecek olan atıklar da çevre sorununun yanı sıra birçok durumda depolanma zorunluluğundan dolayı ilave maliyet getirmektedir. Bu tez çalışmasında, ısı boruları ile donatılmış bir metal hidrür tankı için yeni bir tasarım sunulmaktadır. Bu ısı boruları, metal tabanı boyunca borulamaya ihtiyaç duyulmaksızın hidrojen şarj ve deşarjı için ısı transferini artırmaktadır. Bu çalışma deneysel olarak, depolama ortamı olarak LaNi4,75Al0,25 kullanarak ve ısı borulu ve ısı borusuz tanları karşılaştırarak bir hidrojen depolama tankında ısı transferini iyileştirmek için ısı boruları kullanmasının etkisini göstermektedir. Sonuçlar, ısı borularının hem absorpsiyonda hem de desorpsiyonda (boşaltım)hidrojen depolama oranlarını artırabileceğini göstermektedir. Bu çalışmada LaNi-Al alaşımlarının ısı borulu soğutma sistemi ile ısı borusu kullanılmadan tasarlanan reaktörlerin hidrojen depolama özellikleri deneysel ve teoriksel olarak incelenmiştir.The reduction in energy resources, the increase in energy requirement and energy costs, competitive conditions and environmental consciousness in the industry make the efficient use of energy resources necessary. Waste materials which can be included in this category cause additional cost considering environmental concerns and storage necessity. Therefore, This study presents a novel design for a metal hydride vessel equipped with heat pipes. These heat pipes enhance heat transfer for hydrogen charge and discharge without the need for tubing through the metal bed. This study experimentally demonstrates the effects of using heat pipes to enhance heat transfer in a hydrogen storage tank using LaNi4,75Al0,25 as the storage media and comparing tanks with and without heat pipes. Results show that heat pipes can enhance the hydrogen storage rates in both absorption and desorption. In this study, the new LaNi-Al hydrogen storage properties of reactor designed without the use of heat pipe heat pipe cooling system of the alloy has been investigated experimentally and theoretically
Suspension-type laundry dryer design, prototype and testing
No full textFen Bilimleri Enstitüsü, Enerji Mühendisliği Ana Bilim DalıÇamaşır kurutma işlemlerinde baca tipi, kondenser tipi ve ısı pompalı çamaşır kurutucuları gibi makineler hızlı ve verimli kurutma yapabilmek amacıyla kullanılmaktadır. Bu çalışmada çamaşır kurutma işlemi var olan çamaşır kurutma makinelerinden farklı olarak bir kabin içerisinde giysilerin asılarak kurutulmasını sağlayan askı tipi çamaşır kurutma makinesi tasarımı, prototipi ve testleri yapılmıştır. Makine 1400 dev/dak'da yıkanmış 6 kg'a kadar kurutma işlemlerini yapabilmektedir. Burada 1.255, 2.070, 3.065, 4.085, 5.090 ve 6.005 kg gibi farklı kütlelerde yüklenen kabin içerisinde sıcaklık ve nem miktarının zamana bağlı değişimi ölçülerek, çamaşır kütlesinin kuruma süresine etkisi belirlenmiştir. Deneysel çalışmalarda her kütledeki çamaşırlar aynı nem miktarı ile yüklenerek sonuçlar kaydedilmiştir.Deneysel sonuçlara göre 1,255, 2,070, 3,065, 4,085, 5,090 ve 6,005 kg çamaşır yüklendiğinde kurutma süresi sırasıyla 30, 40, 45, 50, 60 ve 75 dak olarak ölçülmüştür. Çamaşır kütlesi arttıkça toplam nem miktarı ve kabin içerisindeki hava sirkülasyonunun azalmasına bağlı olarak kuruma süresi artmıştır. Kurutma işlemi esnasında enerji tüketimi 1,255 kg çamaşır kütlesi için yaklaşık 0,5 kWh olurken, bu değer 6,005 kg çamaşır için yaklaşık 1,25 kWh olmuştur. Diğer kurutma makineleri ile karşılaştırıldığında ısı pompalı olanlar 1400 devir/dak' da sıkılmış 6 kg çamaşırı 1,62 kWh enerji tüketerek kurutmaktadır. Baca tipi ve kondenser tipi çamaşır kurutma makineleri ise 1400 dev/dak'da sıkılmış 6 kg çamaşırı yaklaşık 3,36 kWh enerji tüketerek kurutmaktadır. Askı tipi çamaşır kurutma makinesinin daha az enerji tüketimi, kurutma süresi ve daha az ütü gerektirmesi gibi avantajlarıyla var olan sistemlere göre üstünlük gösterdiği belirlenmiştir.Laundry drying processes chimney type, and type of heat pump condenser tumble dryers, drying quickly and efficiently in order to make such machines are used. In this study, tumble dryer, washing drying machines, which are in the process of garments hanging in a cabin in a different type of suspension which dry tumble dryer design, prototype and tested. Host 1400 rev / min, drying the washed capable of up to 6 kg. Here, 1255, 2070, 3065, 4085, 5090, and 6005 kg of different masses, such as time-dependent change in the amount of installed measuring the temperature and humidity in the cabin, washing determined the effect of mass of the drying period. Loaded with the same amount of moisture in the laundry experimental studies, the results of each mass were recorded. According to the experimental results 1.255, 2.070, 3.065, 4.085, 5.090, and 6.005 kg of laundry drying time is loaded respectively to 30, 40, 45, 50, 60 and 75 min. As the mass of the total amount of moisture in the washing and drying time is increased due to decreased air circulation in the cabin. During the drying process of about 0.5 kWh of energy consumption, while the mass of 1.255 kg of laundry, this value is approximately 1.25 kWh to 6.005 kg of laundry. Compared with other heat pump dryers first 1400 rev / min at 6 kg of squeezed 1.62 kWh energy consumed to dry laundry. Flue type and tumble dryers condenser type is 1400 rev / min about 3.36 kWh of energy consumed squeezed 6 kg of laundry to dry.Suspension type machine, tumble dryer, less energy consumption, such as drying time and requires less board determined that the benefits of advantages over existing systems
PVT sistemlerinde soğutma akışkanı olarak CDKNT ve grafen su bazlı nano akışkan kullanımının deneysel olarak incelenmesi
No full textFen Bilimleri Enstitüsü, Enerji Sistemleri Mühendisliği Ana Bilim DalıGüneş enerjili ısıl uygulamalarda nano akışkan kullanımı konusunda önemli araştırmalar ve bulgular elde edilmesine rağmen, bu sistemler de nano akışkanların optimum kullanımını etkileyen faktörlerin tam olarak anlaşılması için, detaylı teorik ve deneysel çalışmalar yapılmasına ihtiyaç vardır. Fotovoltaik termal (PVT) sistemlerin performansını arttırmada nano akışkan kullanımı son yirmi yılda yoğun şekilde araştırılmakla birlikte hala literatürde önemli eksiklikler bulunmaktadır. Bu çalışma, PVT kollektör performansını arttırmak için nano-akışkanların kullanımının araştırılmasına ve literatüre katkıda bulunmayı amaçlamaktadır. Bu amaçla bir PVT kollektör tasarlanmış, imal edilmiş ve Karabük/Türkiye'de dış şartlarında test edilmiştir. Çalışmada baz akışkan olarak su bulunan, ağırlıkça %0,5 konsantrasyona sahip çok duvarlı karbon nanotüpler (ÇDKNT) ve grafen nano pelletler kullanılmıştır. Nano akışkan deneylerinden önce PVT kollektörde, optimum kütlesel akış debisini belirlemek amacıyla, saf su kullanılarak 0,5; 1,0 ve 2,0 L/dak debide birçok deney yapılmıştır. Bu deneyler, soğutucu akışkan debisinin elektriksel verimden daha çok ısıl verimi etkilediği sonucunu ortaya koymuştur. Ortalama günlük ısıl verim 0,5 L/dak debide %40; 1,0 L/dak debide %56'ya 2 L/dak debide %67'ye yükselirken; günlük ortalama elektriksel verimlilik 0,5 L/dak'da %14,6; 1,0 L/dak'da %14,8'e ve 2,0 L/dak debide %15,0'e yükselmiştir. Ayrıca sistem için optimum hacimsel debi 0,5 L/dak olarak bulunmuştur. Saf su deneylerinde elde edilen sonuçlar esas alınarak nano akışkan deneyleri de 0,5 L/dak debide gerçekleştirilmiştir. Ağırlıkça %0,25 ve %0,5 nano akışkan konsantrasyonu deneylerine göre, konsantrasyon oranı arttıkça PVT elektriksel veriminin arttığı gözlenmiştir. Ayrıca ÇDKNT-su nano akışkanı daha yüksek elektriksel verim artışı gösterirken, grafen nano pellet-su nano akışkanı ile daha yüksek ısıl verim elde edilmiştir. Soğutucu akışkan olarak; saf su, ağırlıkça %0,5 ÇDKNT-su ve ağırlıkça %0,5 grafen nano pellet-su nano akışkanları enerji ve ekserji verimleri yönünden karşılaştırıldığında, PV panel verimi ortalama %14 iken, PVT-su, PVT-ÇDKNT ve PVT-grafen nano pellet enerji verimleri sırasıyla %53, %57 ve %63, ekserji verimleri ise sırasıyla %11, %12 ve %21 olarak bulunmuştur.Despite considerable researches and significant achievements of using nanofluids in solar thermal applications, more detailed theoretical and experimental studies are needed to enrich the understanding of factors affecting the optimum use of nanofluids in solar thermal systems. Although increasing the performance of photovoltaic thermal (PVT) systems by using the nanofluids as working fluids have gained the attention of researchers in about last two decades, still, there is a lack in the literature associated to this application. This study contributes to the investigations and researches of using the nanofluids to increase the performance of PVT collectors. A PVT collector with serpentine type heat exchanger has been designed, constructed and outdoor tested in Karabuk, Turkey. The considered working fluids in this study are MWCNTs (multi walled carbon nanotubes), and graphene nanoplatelets dispersed in water as a base fluid with a concentrations of 0.25 wt% and 0.5 wt%. Prior to the nanofluids experiments, there were several experiments had been conducted with distilled water at flow rates of 0.5, 1.0 and 2.0 L/min to determine the optimum flow rate for the PVT collector. The results of these experiments revealed that changing the flow rate of the coolant greatly affecting the thermal efficiency more than the electrical efficiency. The average daily thermal efficiency increased from 40% at 0.5 L/min to 56% at 1.0 L/min and to 67% at 2.0 L/min whereas the average daily electrical efficiency increased from 14.6% at 0.5 L/min to 14.8% at 1.0 L/min and 15.0% at 2.0 L/min. Moreover, The working fluid flow rate of 0.5 L/min is the optimum flow rate for the system. Based on the distilled water experiments, all the experiments of the aforementioned nanofluids were run at volume flow rate of 0.5 L/min. According to the results of 0.25 wt% and 0.5 wt% nanofluid concentrations, the higher concentrations of nanofluids the better enhancement in PVT electrical efficiency. Moreover, the MWCNT-water nanofluids showed better electrical efficiency enhancement whereas graphene nanoplatelets-water nanofluids showed higher thermal efficiency. According to energetic and exergetic analytical comparison performed among distilled water, 0.5 wt% MWCNT-water nanofluid and 0.5 wt% graphene nanoplatelets-water nanofluid coolants, the total energetic efficiency for PVT-water, PVT-MWCNT, and PVT- graphene nanoplatelets were 53%, 57% and 63% respectively when the PV module efficiency was 14% in average, while the percentage enhancement in total exergetic efficiency was 11%, 12%, and 21% for PVT-water, PVT-MWCNT nanofluid, and PVT-graphene nanoplatelets nanofluid respectively relative to PV module
Determination of energy saving and optimum insulation thicknesses of the heating piping systems for different insulation materials
No full textLarge amounts of heat losses occur in pipelines of district heating system. If these lines become insulated, a significant energy savings would be obtained. In this study, by using life cycle cost analysis (LCCA) method, the optimum insulation thickness, energy savings, annual costs and payback period were estimated for various pipe diameters and insulation materials of the heating systems in Isparta/Turkey and in the regions with different degree-day values. As a fuel, natural gas was used in the study. In consequence of the calculations, the optimum insulation thickness was found vary between 0.048 and 0.134m, the energy-saving was found vary between 10.84 and 49.78 $/m; and the payback period was found vary between 0.74 and 1.29 years. According to these results, EPS insulation material with a nominal diameter (DN) of 250 mm provides the highest energy savings, while the lowest value was found to be in fiberglass insulation material with DN 50 mm. As a result, heating systems, selection of suitable pipe diameters and insulation materials with optimum thicknesses provide significant economic advantages and savings. (C) 2013 Elsevier B.V. All rights reserved
Effect of Optimum Insulation Thickness on Refrigeration Costs for Different Climate Zones
No full textA large part of energy cost on cooling applications is attributable to heat income through external walls. The best way to save energy is to use the optimum insulation thickness. In this study, the optimum insulation thicknesses, insulation-energy costs, and savings resulting from the use of these insulations is calculated in cities selected from four different climate zones in Turkey for four various insulation materials such as foamboard, extruded polystyrene (XPS), rock wool, and expanded polystyrene (EPS) in cold storage applications. Calculations show that rock wool insulation material yields the highest savings. Optimum insulation thicknesses vary between 0.074 and 0.159 m, energy savings vary between 30.59 and 80.61 $/m(2), and payback periods for investment cost vary between 3.15 and 3.73 years for the cooling. DOI: 10.1061/(ASCE)EY.1943-7897.0000085. (C) 2013 American Society of Civil Engineers
Prediction of thermal conductivity of ethylene glycol-water solutions by using artificial neural networks
No full textThe objective of this study is to develop an artificial neural network (ANN) model to predict the thermal conductivity of ethylene glycol-water solutions based on experimentally measured variables. The thermal conductivity of solutions at different concentrations and various temperatures was measured using the cylindrical cell method that physical properties of the solution are being determined fills the annular space between two concentric cylinders. During the experiment, heat flows in the radial direction outwards through the test liquid filled in the annual gap to cooling water. In the steady state, conduction inside the cell was described by the Fourier equation in cylindrical coordinates, with boundary conditions corresponding to heat transfer between the solution and cooling water. The performance of ANN was evaluated by a regression analysis between the predicted and the experimental values. The ANN predictions yield R2 in the range of 0.9999 and MAPE in the range of 0.7984% for the test data set. The regression analysis indicated that the ANN model can successfully be used for the prediction of the thermal conductivity of ethylene glycol-water solutions with a high degree of accuracy.Thermal conductivity Ethylene glycol-water solutions Artificial neural network
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
COMPARATIVE ANALYSIS OF A SOLAR TRIGENERATION SYSTEM BASED ON PARABOLIC TROUGH COLLECTORS USING GRAPHENE AND FERROFLUID NANOPARTICLES
No full textIn this comparative study, the thermodynamic analysis of a trigeneration system driven by a parabolic through solar collector based on two different types of nanofluid is performed. A standard trigeneration system consists of two subsystems, including an absorption heat pump and the organic Rankine cycle. Two types of nanoparticles (graphene and ferrofluid) that possess excellent and diverse physical properties within a base fluid (Syltherm 800) were selected to be the absorption fluids in the solar cycle. Four organic fluids, namely R123, R401a, R601, and R601a, for the organic Rankine cycle are examined. The results clearly depicted improvement in the system performance. It was found that graphene nanoparticles performed better as compared to the ferrofluid nanoparticles. The largest temperature of the collector outlet was obtained at 257.4 degrees C with Syltherm 800/graphene. The highest net power produced by the system was 134.1 kW and the maximum overall energy and exergy efficiencies of the system were 160.5% and 21.84%, respectively. The highest net power produced by the system was 134.1 kW and the maximum overall energy and exergy efficiencies of the system were 160.5% and 21.84%, respectively. The solar collectors are the main source of the exergy destruction and the highest value was recorded about 683 kW
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