Optimization of counter flow Ranque-Hilsch vortex tube performance using Taguchi method

This study discusses the application of Taguchi method in assessing maximum temperature gradient for the Ranque-Hilsch counter flow vortex tube performance. The experiments were planned based on Taguchi's L27 orthogonal array with each trial performed under different conditions of inlet pressure, nozzle number and fluid type. Signal-to-noise ratio (S/N) analysis, analysis of variance (ANOVA) and regression analysis were carried out in order to determine the effects of process parameters and optimal factor settings. Finally, confirmation tests verified that Taguchi method achieved optimization of counter flow Ranque-Hilsch vortex tube performance with sufficient accuracy. © 2009 Elsevier Ltd and IIR

STATISTICAL ASSESSMENT OF COUNTER-FLOW VORTEX TUBE PERFORMANCE FOR DIFFERENT NOZZLE NUMBERS, COLD MASS FRACTIONS, AND INLET PRESSURES VIA TAGUCHI METHOD

In this article, the effect and optimization of process parameters in a counter-flow vortex tube on temperature difference were investigated through the Taguchi method. The experiments were planned as per Taguchi's L27 orthogonal array with each experiment performed under different conditions of inlet pressure, nozzle number, and cold mass fraction. By means of analysis of variance and regression analysis, the effects of factors and their interactions on temperature difference were determined and modeled with a correlation coefficient of 93.5\%. Accordingly, it was observed that temperature difference goes up with the increase in inlet pressure, and the cold mass fraction and decreases with the increase in nozzle number. In addition, the optimum settings of process parameters maximizing the temperature difference are an inlet pressure of 650 kPa, a nozzle number of 2, and a cold mass fraction of 0.7. Finally, confirmation tests verified that the Taguchi method was successful in the assessment of vortex tube parameters for temperature difference

Mathematical calculation and experimental investigation of expanded perlite based heat insulation materials' thermal conductivity values

DURMUS, Gokhan/0000-0002-8827-7041; Agbulut, Umit/0000-0002-6635-6494; KARAAGAC, IBRAHIM/0000-0001-6727-3650WOS: 000437194500003Thermal resistance can be increased by using proper heat insulation materials. Traditional heat insulation materials do not stand all desired properties. Thus, developing new heat insulation materials is very important. In this study, expanded perlite based heat insulation material was developed as an alternative to the traditional insulation materials. The composition of the developed material was designed and prepared using the theoretical thermal conductivity prediction models. The prepared material was molded in a rectangular shape panel. Thermal conductivities of panels were measured experimentally and the results were compared with the calculated results. Also, the results showed that the developed panels can be used for heat insulation applications. On the other hand, the closest model to the experimental results is the parallel model whose average deviation is 4.22% while the farthest model is the Cheng and Vachon model whose average deviation is 12.43%. It is obtained that parallel and series models are generally in good agreement with the experimental results. Nevertheless, it is seen some deviations between experimental and theoretical calculation results. The theoretical prediction models do not include any processing conditions such as molding and curing. It is thought that these deviations have originated because of the missing processing parameters in theoretical prediction models. As a result of experimental studies, the lowest thermal conductivity value of expanded perlite based panels was obtained 43.5 mW/m.K. Consequently, the heat transfer coefficient of the panels containing expanded perlite can be calculated nearly by the parallel method.Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [115M041]; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK)This study was supported by the Scientific and Technological Research Council of Turkey (Project no: 115M041). We are indebted to TUBITAK for its financial support

An important source for cat and house dust mite allergens: Day-care centers [Kedi ve ev tozu akan allerjenleri igin önemli bir kaynak: Anaokullan]

Objective: Exposure to indoor allergens during childhood has been associated with an increased risk of sensitization. There is no data about indoor allergen levels in day-care centers in Turkey. We hypothesized that day-care centers (DC) would be relevant sources of cat and mite allergens. Material and Methods: Fifty-seven dust samples were collected from 19 DCs in Izmir, their gardens, and classrooms of the primary schools where the DCs are located in. A questionnaire about characteristics of DCs was completed. Feld 1, Der p 1 and Der f 1 allergen levels were quantitated by enzyme-linked immunoassay. Results: Feld 1 was detected in all, and mite allergens in 94.7% of the samples. Levels exceeding sensitization threshold level for cat and mite allergens were present in 73.7%, and 21.1% of DCs, respectively. Feld 1 levels exceeding threshold level that might cause asthma exacerbation was detected in 21% of DCs. Feld 1 levels in DCs and their gardens were higher than the classrooms of the same school. Der f 1 levels were identical in DCs, gardens and classrooms. Der p 1 concentration was higher in DCs with air-conditioning, than DCs without a ventilation system. Although there was no difference for Feld 1 levels in DCs with or without carpeted floor, Feld 1 concentrations in DCs with carpet were significantly higher than in classrooms with no carpet. Conclusion: Day-care centers in Izmir are important sources of indoor allergens that could cause sensitization or even allergic symptoms in children and their staff. © 2012 by Türkiye Klinikleri

Mathematical calculation and experimental investigation of expanded perlite based heat insulation materials' thermal conductivity values

Thermal resistance can be increased by using proper heat insulation materials. Traditional heat insulation materials do not stand all desired properties. Thus, developing new heat insulation materials is very important. In this study, expanded perlite based heat insulation material was developed as an alternative to the traditional insulation materials. The composition of the developed material was designed and prepared using the theoretical thermal conductivity prediction models. The prepared material was molded in a rectangular shape panel. Thermal conductivities of panels were measured experimentally and the results were compared with the calculated results. Also, the results showed that the developed panels can be used for heat insulation applications. On the other hand, the closest model to the experimental results is the parallel model whose average deviation is 4.22% while the farthest model is the Cheng and Vachon model whose average deviation is 12.43%. It is obtained that parallel and series models are generally in good agreement with the experimental results. Nevertheless, it is seen some deviations between experimental and theoretical calculation results. The theoretical prediction models do not include any processing conditions such as molding and curing. It is thought that these deviations have originated because of the missing processing parameters in theoretical prediction models. As a result of experimental studies, the lowest thermal conductivity value of expanded perlite based panels was obtained 43.5 mW/m. K. Consequently, the heat transfer coefficient of the panels containing expanded perlite can be calculated nearly by the parallel method. © 2018 Yildiz Technical University

Do cardiac risk factors affect the homocysteine and asymmetric dimethylarginine relationship in patients with coronary artery diseases?

WOS: 000311064200010PubMed ID: 22750146Objectives: Elevated homocysteine (Hcy) concentrations have been shown to be a risk factor for atherosclerotic vascular disease and thrombosis. Increased asymmetric dimethylarginine (ADMA) levels have been implicated in the pathogenesis of numerous conditions affecting the cardiovascular system. In this study, the influence of cardiovascular risk factors and other variables on Hcy and ADMA relationship in patients with coronary artery disease (CAD) was investigated. Design and methods: Seventy-five patients with CAD were divided into three tertiles according to their Hcy levels. The effect of age, gender, blood pressure, lipid profile, renal function, and the presence of diabetes, insulin resistance, heart failure, inflammation, overweight, smoking and severity of coronary atherosclerosis on Hcy and ADMA relationship was evaluated. Results: ADMA concentrations of patients in the middle and highest Hcy tertiles were significantly higher than the patients in the lowest tertile. When ADMA concentrations were adjusted for demographic, clinical and laboratory variables, the significant differences in ADMA concentrations between the tertiles were preserved. ADMA levels positively correlated with Hcy. Homocysteine levels positively correlated with serum creatinine and NT-proBNP concentrations and negatively correlated with glomerular filtration rates. Stepwise multiple regression analysis revealed Hcy as the unique predictor of ADMA levels. Conclusion: Homocysteine concentration has an effect on ADMA levels. There is a strong correlation between Hcy and ADMA. Cardiovascular risk factors do not have an influence on this relationship. (C) 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.Ege University Research Projects, Izmir, TurkeyEge UniversityThis work was supported by the Ege University Research Projects, Izmir, Turkey

Thrombin-activatable fibrinolysis inhibitor and cardiovascular risk factors in polycystic ovary syndrome

WOS: 000255035700001PubMed ID: 18350479Objective: We aimed to assess circulating thrombin activatable fibrinolysis inhibitor (TAFI) levels and carotid intima-media thickness (CIMT) in PCOS patients and control sujects. in this study we aimed to evaluate the relation between the levels of TAFI and homocysteine, high sensitive CRP (hsCRP), fibrinogen and CIMT in PCOS patients carrying a potential risk for developing CVD and diabetes and compared with age- and body mass index-matched controls. Research Design and Methods: We studied 68 PCOS patients and 26 healthy controls. We conducted an observational study examining non-invasive markers of early CV disease in women with PCOS including structural CIMT. Noninvasive markers of early CVD, CIMT were measured in PCOS patients and control subjects. Metabolic parameters included fasting insulin and glucose levels, lipid and androgen levels, TAFI levels, hsCRP. Results: Fasting glucose levels, prolactin, TSH, Total-cholesterol, LDL-cholesterol, triglyceride, estradiol, DHEA-S and age were similar in the two groups, whereas serum insulin, fibrinogen, hs-CRP, 17-OHP, free-testosterone, total testosterone, HCMA-IR, HDL were significantly elevated in PCOS patients in comparison to control subjects (p < 0.05). Plasma TAFI levels were similarly in PCOS patients compared with healthy controls. No difference was observed in the combined IMT among the studied groups. Conclusions: In our study, no significant difference in lipid parameters was determined between patients with PCOS and healthy controls. in our study, we did not observed any difference in CIMT measurements and TAFI levels between patients with PCOS and healthy controls that can be explained by their low ages and short duration of PCOS