Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
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Book Part Citation - Scopus: 4Performance Analysis of Single-Flash Geothermal Power Plants: Gas Removal Systems Point of View(Nova Science Publishers, Inc., 2013) Ozcan,N.Y.; Gokcen,G.Non-condensable gases (NCGs), natural components of geothermal fluids, affect the performance of a geothermal power plant (GPP) significantly. Therefore, the NCGs should be removed from the process to optimise the thermodynamic efficiency of the plant. GPPs require large capacity NCG removal systems that occupy large portion in the total plant cost and auxiliary power consumption. The flashed-steam GPPs, which are commonly used in the World, are a relatively simple way to convert geothermal energy into electricity when the geothermal wells produce a mixture of steam and liquid. The primary aim of this study is to develop a code for simulating flashed-steam GPPs to examine the thermodynamic performance of NCG removal systems, which represent major concerns at planning and basic design stages of GPPs. A single-flash GPP model is developed and simulated to identify the effects of input variables, such as NCG fraction, separator pressure and condenser pressure. Among the variables, NCG fraction is the most significant parameter affecting thermodynamic performance of single-flash GPPs. The net power output and overall exergetic efficiency of single-flash GPP are decreased 0.4% for compressor system (CS), 2.2% for hybrid system (HS), 2.5% for reboiler system (RS), and 2.7% for steam jet ejector system (SJES) by 1% increase in NCG fraction. © 2014 Nova Science Publishers, Inc. All rights reserved.Book Part Control of the Particle Size and Purity of Nano Zinc Oxide(Nova Science Publishers, Inc., 2010) Omurlu,F.O.; Balköse,D.Effects of template, mechanical mixing and/or ultrasound mixing on the size of the ZnO crystals obtained by precipitation at 30 °C from aqueous zinc chloride and potassium hydroxide solutions were investigated by 2k factorial design. Precipitation method is employed to synthesize nano zinc oxide particles. Monodisperse nano ZnO having 29 nm particle size was produced by adding triethyl amine and applying simultaneously mechanical and ultrasound mixing. The surface area and the density of the powder were 21 m2/g and 4.8 g/cm3. It contains 5.2% impurities present as CO3 -2 and bound OH- groups. Volumetric resistivity was found as 1.3 × 107ohm cm. Absorption spectrum of the powder showed absorption peak at 353 nm. The room temperature fluorescence spectrum of the powder revealed a strong and sharp UV emission band at 391 nm due to free exciton or bound exciton of ZnO and a weak and broad violet emission band at 405 nm due to zinc vacancies. © 2014 by Nova Science Publishers, Inc. All rights reserved.Book Part Water Sorption of Polyvinyl Chloride-Luffa Cylindrica Composites(Nova Science Publishers, Inc., 2010) Demir,H.; Balköse,D.Natural Luffa Cylindrica fibers were modified with 0.1M sodium hydroxide (NaOH) for removing lignin and hemicellulose. Natural and modified Luffa fibers were characterized by using IR spectroscopy. Composites were produced with PVC plastisol and natural Luffa fiber. Natural Luffa fiber is a highly hydrophilic substance. This feature increased the water sorption capacity of the composites. Flexible PVC-luffa cylindrica composites had higher liquid water sorption capacity (0.3-0.6%) compared to that of flexible PVC (0.1%). There was no volume change of composites due to liquid water sorption. © 2014 by Nova Science Publishers, Inc. All rights reserved.Book Part An Effect of Climate Change: Increased Health Risks Due To Arsenic in Drinking Water - the Case of İzmir, Turkey(Nova Science Publishers, Inc., 2010) Sofuoglu, S.C.; Sofuoglu, A.Our previous research (Kavcar et al., 2009) has shown that tap water arsenic concentrations in the City of İzmir, Turkey, was of concern as arsenic in 15 of 37 (41%) of the tap water samples (collected in the year 2004) exceeded the Turkish drinking water standard of 10 µg/L (TMH, 2005). The median, mean, and 95th percentile concentrations were 2.9, 12.0, and 42.0 µg/L, respectively. The violations of the standard were in three districts, i.e., Bornova, Çiğli, and Karşıyaka, that were served primarily by groundwater sources. The concentrations in other districts were below the standard. However, concentrations less than the standard may be associated with a carcinogenic risk that is greater than the acceptable risk level of one in ten thousand depending on the level of exposure, mainly, daily drinking water intake rate and body weight. This was the case for the City of İzmir as lifetime carcinogenic risks exceeded the acceptable level for 19 of the 37 participants (51%). As the result of the above cited research, the local government has shut-down a number of groundwater wells as a mitigation measure. In turn, the concentrations were brought down to <15 µg/L in the three districts by increasing the proportion of surface water supplied from Tahtalı Reservoir. However, climate change has been affecting the region. The water volume in the resevoir was dropped below 5% in 2008. As a result, the arsenic contaminated wells were brought back into the service, causing a sharp increase in the arsenic concentrations, this time all around the city, measured by the local health authority. İzmirians who can not afford to buy bottled drinking water are (to be) exposed to arsenic concentrations of 30-40 µg/L until the planned treatment plant is in place. A probablistic risk assessment was conducted to estimate the human health risks for the scenario of no available surface water, in which no treatment and treatment with 90% and 99% efficiencies were assumed for the arsenic contaminated groundwater, based on the concentrations measured by the local health authority. The median carcinogenic risk estimated for the scenario of no treatment for the metropolitan area was approximately eight times the median value estimated when the main source water was Tahtalı Reservoir, a surface water dam. © 2008 Nova Science Publishers, Inc.Book Part Citation - Scopus: 3Performance Analysis of Single-Flash Geothermal Power Plants: Gas Removal Systems Point of View(Nova Science Publishers, Inc., 2012) Yıldırım Özcan, Nurdan; Gökçen, GüldenNon-condensable gases (NCGs), natural components of geothermal fluids, affect the performance of a geothermal power plant (GPP) significantly. Therefore, the NCGs should be removed from the process to optimise the thermodynamic efficiency of the plant. GPPs require large capacity NCG removal systems that occupy large portion in the total plant cost and auxiliary power consumption. The flashed-steam GPPs, which are commonly used in the World, are a relatively simple way to convert geothermal energy into electricity when the geothermal wells produce a mixture of steam and liquid. The primary aim of this study is to develop a code for simulating flashed-steam GPPs to examine the thermodynamic performance of NCG removal systems, which represent major concerns at planning and basic design stages of GPPs. A single-flash GPP model is developed and simulated to identify the effects of input variables, such as NCG fraction, separator pressure and condenser pressure. Among the variables, NCG fraction is the most significant parameter affecting thermodynamic performance of single-flash GPPs. The net power output and overall exergetic efficiency of single-flash GPP are decreased 0.4% for compressor system (CS), 2.2% for hybrid system (HS), 2.5% for reboiler system (RS), and 2.7% for steam jet ejector system (SJES) by 1% increase in NCG fraction.Book Part Citation - Scopus: 1Water Vapour Sorption and Humidity - a Survey on Measuring Methods and Standards(Nova Science Publishers, Inc., 2011) Robens, Erich; Rübner, Katrin; Klobes, Peter; Balköse, DevrimUnder environmental conditions water exists in all three classical states of matter: solid, liquid and gas. The water molecule is non-linear and therefore polar. In comparison with other liq-uids water has anomalous features; about 63 exceptional properties are recorded. This article starts with reviewing properties of water, typical occurrences and definitions such as relative and absolute humidity and moisture content. Water is present everywhere in nature and engineering; it may be helpful or harmful. The survey concerns both: atmospheric hygrometry and usual measuring methods of the mois-ture content of solids and liquids as well as water sorption. The determination of the atmos-pheric humidity is among the more difficult problems in metrology. In contrast, humidity de-termination of materials is simple; however the definition of the dry state is difficult. Because water is bound at and in solids and liquids in many different ways it turns out that the humidi-ty content of materials is difficult to define and to measure accurately. We provide a survey on the measuring methods, describe the most important ones and discuss advantages and ac-curacy. In the search for extraterrestrial water special remote measuring methods have been developed analysing the spectrum of electromagnetic radiation either of natural sources or produced by a probe and reflected. Spacious deposits have been detected photographically. In situ investigations are made using conventional methods. With regard to the problems of measurements, standardisation of measuring methods and procedures is required. There exist many institutions, which are engaged in investigating the use of water and standardising measuring methods. In tabular form, we give a survey on existing standards.Book Part Numerical Modeling of Transport Processes at Hillslope Scale Accounting for Local Physical Features(Nova Science Publishers, Inc., 2011) Tayfur, GökmenHillslope is the basic unit of a watershed. Typical hillslopes may have a size of 1000 m long and 500 m wide. For watershed modeling, it is essential to accurately describe the illslope-scale processes of flow, erosion and sediment transport, and solute transport. Although these processes are usually considered in experimental studies and theoretical subjects, the existing numerical models that are designed to simulate transport processes at hillslope scale rarely take microtopographic variations into account. Instead, those models assume constant slope, roughness, and infiltration rate for a given basic computational unit (i.e., hillslope). As a result, effects of microtopographic features (e.g., rills) on the aforementioned processes cannot be reflected in modeling results. However, the effects could be important because rill and sheet flows exhibit distinctly different dynamics that influence the transport processes. The objective of this chapter is to review the numerical studies for investigating the transport processes at hillslope scale. The chapter focuses particularly on the modeling efforts with the effects of microtopographic features on the dynamics of the transport processes incorporated.