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Determination and calculation of combustion heats of 20 lignite samples
(TAYLOR & FRANCIS INC, 2008) Demirbas, A.; Dincer, K.; Topaloglu, N.
In this study, the proximate analyses, such as volatile materials (VM), fixed carbon (FC), and higher heating value (HHV), were determined for 20 lignite samples from different areas of Turkey. The lignite samples have been tested with particle size of 0-0.05 mm. Combustion heats (higher heating values, HHVs) of 20 lignite samples obtained from different Turkish sources were determined experimentally and calculated from both ultimate and proximate analyses. The HHVs (MJ/kg) of the lignite samples as a function of fixed carbon (FC, wt%) or volatile materials (VM, %) was calculated from the following equations: HHV = 0.2997FC + 11.1170 (1) HHV = -0.3225VM + 42.223 (2) The correlation coefficients for Eqs. (1) and (2) were 0.9820 and 0.9686, respectively. The combustion heats calculated from Eqs. (1) and (2) showed mean differences of +0.4% and +0.4%, respectively.
Experimental examination of the cooling performance of Ranque-Hilsch vortex tube on the cutting tool nose point of the turret lathe through infrared thermography method
(ELSEVIER SCI LTD, 2011) Selek, M.; Tasdemir, S.; Dincer, K.; Baskaya, S.
In the present study, the cooling performance of the Ranque-Hilsch Vortex tube (RHVT) was experimentally investigated by infrared thermography (IRT) method. For this purpose, experiments were conducted on the cutting tool nose point of the lathe at different diameters, cutting speeds and cutting depths for cases in which cooling was not performed and RHTV cooling was performed. The sample material was gray cast iron in the form of round bars with 15 mm and 20 mm diameter respectively and 100 mm length. The inserts were manufactured by Sandvik Inc., with the ISO designation of TNMG 160404 MF (Triangular insert). The inserts were rigidly mounted on three different right hand style tool holders designated by ISO as MTJNR-L2020 K16T. In all instances, the side rake angle and back rake angle are 0 degrees and fixed. The performance of RHVT was determined by using the temperatures obtained from thermal images (TIs). Tls were taken from the FLIR E45 infrared camera at 30 frames per second. When all the experimental results were evaluated together, the maximum performance of RHVT was found to be for a diameter of sample = 15 mm; cutting depth = 3 mm; cutting speed = 800 rpm (P-15,P-3,P-800). (c) 2010 Elsevier Ltd and IIR. All rights reserved.
Experimental Investigation of a Two Dimensional Heat Transfer Performance of Open-Cell Aluminum Foams with the Gis-Based Support Methodology
(GAZI UNIV, 2016) Sertkaya, A. A.; Dincer, K.; Durduran, S. S.
In this study, performances (Delta T= T-x,T-y-T-i) of open cell aluminum foams are investigated experimentally for three different situations with GIS (Geographical Information System) based support methodology. In the 1st situation; the conditions were 10 PPI, u= 1 and 2 m/s, X= 0-200 mm, Y= 0-100 mm. In the 2nd situation; 20 PPI, u= 1 and 2 m/s, X= 0-200 mm, Y= 0-100 mm. As in the 3rd situation; 30 PPI, u= 1 and 2 m/s, X= 0-200 mm, Y= 0-100 mm. When the maximum performances of the three situations were compared, the following sequence appeared: Delta T-10,T-2 < Delta T-10,T-1 < Delta T-20,T-2 < Delta T-20,T-1 < Delta T-30,T-2 < Delta T-30,T-1 and the maximum performance was found at the 3rd situation where the data were (Delta T-30,T-1= 66.95 degrees C; X= 200 mm, Y= 10 mm; Delta T-30,T-2= 40.78 degrees C). The empirical correlation of the capacity of non-dimensional performance for the 3rd situation can be expressed as follows Delta T-30,T-1 (and 2) /(Delta T-30,T-1 and 2)(max) = 6.10(-8) X-4 - 2.10(-5) X-3 + 0.001X(2) - 0.082X + 1.459. Experimental results indicate that the performance depends on porosity density, the magnitude of the air velocity on the test region and the X and Y distances.
Experimental investigation of performance of hot cascade type Ranque-Hilsch vortex tube and exergy analysis
(ELSEVIER SCI LTD, 2011) Dincer, K.; Yilmaz, Y.; Berber, A.; Baskaya, S.
In this study, three Ranque-Hilsch vortex tubes were used, which have 9 mm inside diameter and length/diameter ratio was 15. Their performances were examined as one of the classical RHVT and other was hot cascade type RHVT. Performance analysis was according to temperature difference between the hot outlet and the inlet (Delta T-hot.). The Delta T-hot values of hot cascade type Ranque-Hilsch vortex tubes were greater than the Delta T-hot values of classical RHVT, which were determined experimentally. The total inlet exergy, total outlet exergy, total lost exergy and exergy efficiency of hot stream were investigated by using experimental data. In both the classical RI-PIT and hot cascade type RHVT, it was found that as fraction of cold flow increases the total lost exergy decreases. It was also found that, the hot cascade type RHVT more exergy efficiency of hot outlet than the classical RHVT. Excess Delta T-hot value of hot cascade type Ranque-Hilsch vortex tube causes the excess exergy efficiency of hot outlet. (C) 2011 Elsevier Ltd and IIR. All rights reserved.
Experimental investigation of the effects of length to diameter ratio and nozzle number on the performance of counter flow Ranque-Hilsch vortex tubes
(SPRINGER, 2008) Dincer, K.; Baskaya, S.; Uysal, B. Z.
In this experimental study, performance of counter flow type Ranque-Hilsch vortex tubes (RHVT), with a length to diameter ratio of 10, 15 and 18, were investigated with 2, 4, 6 nozzles. The measure of performance was chosen as the difference between the temperatures of hot output stream and cold output stream. The performances of RHVTs were experimentally tested by making use of velocity and temperature measurements of the input and output streams. It was determined that the difference between the temperatures of these streams, changed between 9 and 56 K. When all the results were assessed, it was concluded that the best performance was obtained when the ratio of vortex tube's length to the diameter was 15 and the nozzle number was at least four, and the inlet pressure was as high as possible. Desired performance could be obtained by controlling the rate of the hot output stream.
Experimental investigation of the performance of a Ranque-Hilsch vortex tube with regard to a plug located at the hot outlet
(ELSEVIER SCI LTD, 2009) Dincer, K.; Baskaya, S.; Uysal, B. Z.; Ucgul, I.
In this study, effects of position, diameter (5, 6, 7, 8 mm) and angle (30 degrees-180 degrees) of a mobile plug, located at the hot outlet side in a Ranque-Hilsch Vortex Tube (RHVT), were determined experimentally for best performance. In addition to plug parameters, effects of supply pressure (200-420 kPa) and number of nozzles (2, 4, 6) were also studied. The internal diameter (D) of the vortex tube used in the experiments was 9 mm; the ratio of the length of the vortex tube to its diameter (L/D) was 15. Four different plug locations were studied. The maximum difference in the temperatures of hot and cold streams was obtained for the plug diameter of 5 mm, tip angles of 30 degrees and 60 degrees, 4 nozzles and by keeping the plug location at the far extreme end. (C) 2008 Elsevier Ltd and IIR. All rights reserved.
Fuzzy Modeling of Performance of Counterflow Ranque-Hilsch Vortex Tubes with Different Geometric Constructions
(TAYLOR & FRANCIS INC, 2008) Dincer, K.; Tasdemir, S.; Baskaya, S.; Ucgul, I.; Uysal, B. Z.
In this article, we present the development of a fuzzy expert system (FES) for fuzzy modeling of the performance of counterflow Ranque-Hilsch vortex tubes for different geometric constructions. Experimental values were obtained from a detailed experimental investigation. With these experimental values, FES models of the Ranque-Hilsch vortex tube behavior were designed using the MATLAB 6.5 fuzzy logic toolbox in Windows XP running on an Intel 3.0-Ghz PC. For this process P, N, , and L/D were chosen as input and Th, Tc, T as output parameters. FES results agree well with experimental data. It was found that the coefficient of multiple determination (R2 value) between the actual and fuzzy predicted data is Th=0.9801, the R2 value for Tc values is 0.9841, and the R2 value for T values is 0.9748.
Geometric parameters and response surface methodology on cooling performance of vortex tubes
(TAYLOR & FRANCIS LTD, 2017) Nouri-Borujerdi, A.; Bovand, M.; Rashidi, S.; Dincer, K.
This research has investigated the effect of certain geometric parameters on cooling performance of three vortex tubes. The influencing parameters include three length/diameter ratios L/D = 10, 25, 40, three nozzle cases and each case with number n = 2, 4, 6 nozzles, three cold orifice/diameter ratios beta = 0.389, 0.5, 0.611 and three inlet pressures P-i = 2, 2.5 and 3 bar. The experiments are conducted based on three factors, two-level and central composite face-centred design with full factorial. The results are analysed according to the principle of response surface methodology. The goodness of fit of the regression model is inspected using the analysis of variance and F-ratio test. The values of R-2 and R-2-adjusted are close to 100% which show a very good correlation between the observed and predicted values. The results show that the effect of number of nozzles on the energy separation depends on the L/D values.
Investigation of optical and dispersion parameters of electrospinning grown activated carbon nanofiber (ACNF) layer
(ELSEVIER SCIENCE SA, 2018) Dincer, K.; Waisi, B.; Onal, G.; Tugluoglu, N.; McCutcheon, J.; Yuksel, O. F.
Activated carbon nanofiber (ACNF) layers are prepared by electrospinning method. We have investigated the optical properties of ACNF layer using UV-vis-NIR spectrophotometer. The optical constants such as refractive index, extinction coefficient and dielectric constants were evaluated using reflectance and transmittance spectra for ACNF layer. The optical energy gap of ACNF layer was determined as 1.07 eV. The refractive index dispersion of ACNF layer was analyzed by using the single oscillator model proposed by Wemple and DiDomenico. The dispersion parameters such as oscillator energy and dispersion energy values of ACNF layer were determined. Several dispersion parameters such as optical dielectric constant at higher frequency, lattice dielectric constant, oscillator average wavelength, oscillator average strength and the ratio of carrier concentration to the effective mass were also determined by analysis of refractive index dispersion. Furthermore, the optical conductivity of ACNF layer was evaluated from the analysis of optical dielectric constants.
Lower emissions from biodiesel combustion
(TAYLOR & FRANCIS INC, 2008) Dincer, K.
Biodiesel has been defined as the monoalkyl esters of long-chain fatty acids derived from renewable feedstocks, such as vegetable oils or animal fats, for use in compression-ignition (diesel) engines. Biodiesel has become more attractive because of its environmental benefits and the fact that it is made from renewable resources. Biodiesel is the first and only alternative fuel to petroleum diesel to have a complete evaluation of emission results. The emission-forming gasses, such as carbon dioxide and carbon monoxide from combustion of biodiesel hydrocarbons, generally are less than diesel fuel. Sulfur emissions are essentially eliminated with pure biodiesel. The exhaust emissions of sulfur oxides and sulfates from biodiesel were essentially eliminated compared to diesel. The smog-forming potential of biodiesel hydrocarbons is less than diesel fuel. The ozone-forming potential of the speciated hydrocarbon emissions was 50% less than that measured for diesel fuel.
Modeling higher heating values of lignites
(TAYLOR & FRANCIS INC, 2008) Demirbas, A.; Dincer, K.
In this work, the elemental analysis results such as carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and sulfur (S) were used for calculated higher heating values (HHVs) of 26 lignite samples from different areas of Turkey. The lignite samples have been tested with particle size of 0-0.05 mm. The HHVs of 26 lignite samples obtained from different Turkish sources were experimentally determined and can be calculated from the equation-based modeling. The HHVs (MJ/kg) of the lignite samples as a function of carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and sulfur (S) was calculated from the following equation: HHV = 31.6(C) + 142.3(H) + 30.8(S) - 15.4(O) - 14.5(N) of which the correlation coefficiens for the equation was 0.9891. HHVs calculated from the equation showed mean deviation of +0.1.
MODELING OF EXERGY EFFICIENCY PERFORMANCES OF COUNTER FLOW RANQUE-HILSCH VORTEX TUBES WITH DIFFERENT GEOMETRIC CONSTRUCTIONS USING ARTIFICIAL NEURAL NETWORKS
(STEF92 TECHNOLOGY LTD, 2012) Berber, A.; Yilmaz, Y.; Dincer, K.; Ozen, D. N.; Baskaya, S.
In this experimental study, the exergy efficiency performances of counter flow type Ranque-Hilsch vortex tubes (RHVT), with a length to diameter ratio of 10-18, were investigated for RHVT made of aluminum, brass, and steel having the internal diameter (D) of 9 mm. Cross section of nozzle was 0.002x0.002 m(2) and the number of nozzles (Nn) was 3. Flow was controlled with a valve on the hot outlet side, and the valve at the hot outlet side was changed from a nearly closed position from its nearly open position. The exergy efficiency of RHVT for various L/D ratios (10-18) and various ksi values (0.1-0.9) were determined under 440 kPa pressurized air. As a new approach, this study proposes determining the exergy efficiency by using artificial neural networks (ANN). As ANN input parameters, L/D, ksi, total outlet exergy and total lost exergy were used, while the exergy efficiency was the output parameter. The actual values and ANN results show that ANN can be successfully used for the exergy efficiency performances of counterflow Ranque-Hilsch vortex tube.
Modeling of the effects of length to diameter ratio and nozzle number on the performance of counterflow Ranque-Hilsch vortex tubes using artificial neural networks
(PERGAMON-ELSEVIER SCIENCE LTD, 2008) Dincer, K.; Tasdemir, S.; Baskaya, S.; Uysal, B. Z.
In this study, the effect of length to diameter ratio and nozzle number on the performance of a counterflow Ranque-Hilsch vortex tube has been modeled with artificial neural networks (ANN), by using experimental data. In the modeling, experimental data, which were obtained from experimental studies in a laboratory environment have been used. ANN has been designed by MATLAB 6.5 NN toolbox software in a computer environment working with Windows XP operating system and Pentium 4 2.4 GHz hardware. In the developed system outlet parameter Delta T has been determined using inlet parameters P, L/D, N and xi. When experimental data and results obtained from ANN are compared by statistical independent t-test in SPSS. it was determined that both groups of data are consistent with each other for P > 0.05 confidence interval, and differences were statistically not significant. Hence, ANN can be used Lis a reliable modeling method for similar Studies. (C) 2008 Elsevier Ltd. All rights reserved.
Modelling of a thermal insulation system based on the coldest temperature conditions by using artificial neural networks to determine performance of building for wall types in Turkey
(ELSEVIER SCI LTD, 2011) Tosun, M.; Dincer, K.
In formation of building external envelope, as two important criteria, climatic data and wall types must be taken into consideration. In the selection of wall type, the thickness of thermal insulation layer (d(i)) must be calculated. As a new approach, this study proposes determining the thermal insulation layer by using artificial neural network (ANN) technique. In this technique five different wall types in four different climatic regions in Turkey have been selected. The ANN was trained and tested by using MATLAB toolbox on a personal computer. As ANN input parameters, U(w), T(e,Met), T(e,TSE), R(wt), and q(TSE) were used, while d(i) was the output parameter. It was found that the maximum mean absolute percentage error (MRE, %) is less than 7.658%. R(2) (%) for the training data were found ranging about from 99.68 to 99.98 and R(2) for the testing data varied between 97.55 and 99.96. These results show that ANN model can be used as a reliable modeling method of d(i) studies. (C) 2010 Elsevier Ltd and IIR. All rights reserved.
Optimization of Parameters for Electrospinning of Polyacrylonitrile Nanofibers by the Taguchi Method
(CARL HANSER VERLAG, 2017) Celep, G. K.; Dincer, K.
This study empirically examined the influences of electrospinning process factors (applied voltage, feed rate of the polymer solution and tip-to-collector distance) and the polymer solution concentration on the diameters of electrospun polyacrylonitrile (PAN) nanofibers. To examine this, the polymer solution concentration, applied voltage, feed rate of the polymer solution and tip-to-collector distance were specified as parameters with four levels. In order to optimize these parameters, Taguchi's L-16 orthogonal design (4 parameters, 4 levels) was applied to the experiential design. In order to describe the optimum production conditions for electrospun PAN nanofibers, the signal-to-noise (S/N) ratio was used, which was calculated from the diameters of electrospun PAN nanofibers using the "smaller-the-better" approach. By using the S/N ratio response results, the most influential parameter determining the nanofiber diameter was identified as the polymer solution concentration. The nanofiber diameter at the optimum conditions was 163.6 nm. In addition, homogeneous nanofibers with no observed beads were obtained by means of the newly designed adjustable rotary plate collector. In conclusion, the Taguchi technique was seen to be an efficient technique to optimise the crucial electrospinning process factors used in nanofiber production.
Rule-based Mamdani-type fuzzy modelling of thermal performance of multi-layer precast concrete panels used in residential buildings in Turkey
(PERGAMON-ELSEVIER SCIENCE LTD, 2011) Tosun, M.; Dincer, K.; Baskaya, S.
Heat insulation applied on outer wall surfaces of buildings for the purpose of conserving energy, can be analyzed experimentally, mathematically and by using simulation modelling. In this study, simulation modelling of insulation layer (d(2)), for residential buildings in 81 cities classified into four climatic regions in Turkey was investigated. This stimulus model is constructed into rule-based Mamdani-type fuzzy modelling (RBMTF), using input parameters (U(w),T(e)) and output parameter d(2), described by RBMTF if-then rules. RBMTF has been designed using the MATLAB 7.04 fuzzy logic toolbox. The d(2) was predicted using two input parameters: U(w) and T(e). The values for U(w) ranged from 0.4 to 0.7. The values for T(e) ranged from -43 degrees C to -3 degrees C. The values for d(2) ranged from 0.07 to 0.21. Seven linguistic terms were considered for each of the input and output variables, namely Very Low (L1), Low (L2), Negative Medium (13), Medium (L4), Positive Medium (L5), High (L6), Very High (L7). R(2) for the testing data were about 97.4%. Overall, RBMTF can be used as a reliable modelling method for thermal performance of multi-layer precast concrete panels used in residential buildings' studies. (C) 2010 Elsevier Ltd. All rights reserved.
Sustainable green diesel: A futuristic view
(TAYLOR & FRANCIS INC, 2008) Demirbas, A.; Dincer, K.
The energy sources have been split into three categories: fossil fuels, renewable sources, and nuclear sources. Energy new and renewable resources will play an important role in the world's future. There are several reasons for biofuels to be considered as relevant technologies by both developing and industrialized countries. They include energy security reasons, environmental concerns, foreign exchange savings, and socioeconomic issues related to the rural sector. The term modern biomass is generally used to describe the traditional biomass use through the efficient and clean combustion technologies and sustained supply of biomass resources, environmentally sound and competitive fuels, heat, and electricity using modern conversion technologies. Modern biomass can be used for the generation of electricity and heat. Biofuels as well as green diesel produced from biomass by Fischer-Tropsch synthesis are the most modern biomass-based transportation fuels. Green diesel is a renewable replacement to petroleum-based diesel. Biomass energy conversion facilities are important for obtaining bio-oil by pyrolysis. Pyrolysis is the most important process among the thermal conversion processes of biomass. There are four different ways of modifying vegetable oils and fats for use as diesel fuel, such as pyrolysis, dilution with hydrocarbons (blending), emulsification, and transesterification.

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