Kevser Dincer

Fuzzy Modeling of Performance of Counterflow Ranque-Hilsch Vortex Tubes with Different Geometric Constructions

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, ξ, and L/D were chosen as input and ΔT h , ΔT c , ΔT as output parameters. FES results agree well with experimental data. It was found that the coefficient of multiple determination (R 2 value) between the actual and fuzzy predicted data is ΔT h = 0.9801, the R 2 value for ΔT c values is 0.9841, and the R 2 value for ΔT values is 0.9748.

Development of Cooling Performance of Clinker Cooler Process Based on Energy Audit

In cement plants clinker outlet temperature is directly evaluated by clinker cooler process efficiency. Cooling processes may be evaluated as one of the energy input considering demand of secondary air and carrier gas. In this study the clinker cooler performance development is intended from the viewpoint of capacity increase and energy consumption using cement production plant actual figures. According to this analysis, the standard and actual cooler losses have been calculated as 519.16 kJ/kg.cl and 595.86 kJ/kg.cl, respectively. Considering the standard cooler loss of one state-of-the-art cooler, an amount of 100.48 kJ/kg.cl is savable. Furthermore, approximately 1 kWh/kg.cl of the total power consumption can be achieved. The fluctuations of clinker outlet temperature lead to a variance of 86.61% and 89.22%, respectively, for sieved and un-sieved clinker temperature. This situation demonstrates a significant potential loss of clinker temperature. Regarding the cooler performance development, some suggestions have been made at the end of this study.

HHO HÜCRE PERFORMANSININ BULANIK MANTIK YÖNTEMİ İLE BELİRLENMESİ

Bu calismada, Hidroksi (HHO) hucre performanslari, kural tabanli Mamdani tipi bulanik modelleme teknigi ile gerilim, akim ve sicaklik parametreleri bakimindan modellenmistir. Giris parametreleri plaka sayisi ve zaman (t), cikis parametreleri gerilim (V), akim (A) ve sicaklik (oC); Kural Tabanli Mamdani Tip Bulanik Mantik (KTMTBM) tarafindan tanimlanmistir. Giris ve cikis parametrelerinin sayisal verileri bulaniklastirmistir. Bunlar; cok cok dusuk (L1), cok dusuk (L2), dusuk (L3), negatif orta (L4), orta (L5), pozitif orta (L6), yuksek (L7), cok yuksek (L8) ve cok cok yuksek (L9)’dir. Bu sistem icin 2 giris degeri bulunmakta ve her bir cikis degeri icin 9x9 matrisinden 81 kural olmak uzere toplam 243 kural elde edilmistir. Sistemin girisi ile cikisi arasindaki iliskiyi tanimlayan ve bulanik mantik denetleyicinin davranislarini tespit eden denetim kurallarinin bir sonucu olarak, deneysel calismadan elde edilen her bir deger ayni zamanda bulanik mantik ile belirlenmistir. Bulanik mantik yontemiyle olusturulan modelden elde edilen sonuclar ile deneysel calismada tespit edilen sonuclar determinasyon katsayisi yontemi (R2) kullanilarak karsilastirilmistir. R2 yonteminde, voltaj, akim ve sicaklik icin sirasiyla %98,29; %99,5; %96,47 degerleri tespit edilmistir.Ayrica, deneysel calismada yapilmamis degerler BM modeli sayesinde tahmin edilmistir. Bu calisma, HHO hucresinin performansinin belirlenmesinde, bulanik mantik yonteminin basariyla uygulanabildigini gostermistir.

Modeling of the Effects of Cyclic Voltammetry (CV) Using Fuzzy Logic with Different Membership Functions for Proton Exchange Membrane Fuel Cell (PEM) with Polyvinyl Alcohol/Nano Silver (PVA/Ag)

In this study, the effects of cyclic voltammetry (CV) has been modeled with Rule-based mamdani-type fuzzy (RBMTF), by using experimental data for proton exchange membrane fuel cell with PVA/AG. In the system developed, RBMTF apply input parameters are CV, scan rate and time, output parameters are current density and voltage. 12300 values for experimental study also obtained with RBMTF. Membership functions (MFs) are the building blocks of fuzzy set theory, i.e., fuzziness in a fuzzy set is determined by its MF. Accordingly, the shapes of MFs are important for a particular problem since they effect on a fuzzy inference system. They may have different shapes like triangular, trapezoidal, Gaussian, etc. When the results obtained from RBMTF and statistical analyses of experimental data have been compared, it has been determined that the two groups of data are coherent, and that there is not a significant difference between them. As a result, this study indicates that RBMTF with different membership functions can be safely used for CV.

Investigation of Electrical Conductivity of Polyacrylonitrile (PAN) Nanofibers/Nano Particul (Ag,Cu, CNT and GNR)

In this study 1% Ag (silver), Cu (copper), CNT (carbon nanotube) and graphene nanoribbon (GNR) nanoparticle reinforced PAN fibers were prepared and the effects of nanoparticle reinforcements upon electrical conductivity were investigated. In experimental study, graphene nanoribbon powders were produced from multiwalled carbon nanotube (MWCNT) through using the chemical approach of Hummers method. Fiber layer was dissolved at room temperature in magnetic mixer with Polyacrylonitrile (PAN) and Dimethil Formamide (DMF) which was at the rate of 10 % by mass. Thus, a viscou gel solution was obtained then nanoparticles were added to the PAN/DMF solution and the solution was vigorously stirred for one hour at room temperature. After stirring that solution was continued for 15 m in ultrasonic bath. The polymeric solution was first transferred to a 5 mL syringe, which was connected to a capillary needle with an inside diameter of 0,8 mm. A copper electrode was attached to the needle, a DC power supply produces 25 kV against a grounded collector screen distant 15cm. With the syringe pump set at 2 mL/h, the electric force overcomes the surface tension of the solution at the capillary tip, and a jet emerges. Produced fibers were collected on the rotary collector which spins at 250 rpm. Nanofiber was dried at 60 °C for 12 h in vacuum oven. Eventually, nanofiber of polyacrylonitrile (PAN) reinforced by metallic nanoparticles and graphene nanoribbon (GNR) were prepared by electro spinning process. Electrical conductivity of the obtained nanofiber were studied by measuring the electrical resistance thanks to home-made plate electrodes.

Rule-Based Mamdani-Type Fuzzy Modeling of Heating and Cooling Performances of Counter Flow Ranque-Hilsch Vortex Tubes with Different Geometric Construction for Brass

In this study, thermal performances of counter flow Ranque-Hilsch vortex tubes were experimentally investigated and modeled with a Rule Based Mamdani-Type Fuzzy (RBMTF) modeling technique. The vortex tubes were made of brass. Diameter of vortex tube (D) was 10 mm. Length of vortex tube (L) was 10D, 11D, 12D, 13D, 14D. Input parameters (ξ, L/D) and output parameters (ΔTh, ΔTc) were described by RBMTF if-then rules. 45 experimental data sets were used in the training step. R2 for the ΔTh was found to be 99.42 % and R2 for the ΔTc was 99.66 %. The actual values and RBMTF results demonstrated that RBMTF can be successfully used for the determination of heating and cooling performances of counter flow RHVT with different geometric constructions for brass.

Investigation of Performance of Heating and Cooling of Counter Flow Ranque-Hilsch Tubes with L/D=15, 16, 17, 18 for Brass

In this study, heating and cooling performances of counter flow Ranque-Hilsch vortex tubes (RHVTs) were experimentally investigated for brass. The vortex tubes were made of brass. Diameter of vortex tube (D) was 10 mm. Length of vortex tube (L) was 15D, 16D, 17D and18D. The number of nozzles (Nn) was 5. The conical edges of the plugs have a slope of 30o angle. Working pressure of Ranque-Hilsch was 460 kPa (absolute). According to the experimental results, the maximum heating performance of the RHVT system was found to be 39,5 °C at P17 and the maximum cooling performance of the RHVT in this study was found to be-28,6 °C at P18. An increase in fraction of cold flow (ξ) led to a increase in the heating performance.