Numerical prediction of leakage flow and windage heating for various labyrinth seal geometries

The labyrinth seals are one of the most important components of a gas turbine engine as a sealing element. In this paper, a computational study has been carried out for the various labyrinth seal geometries. One of the aim of the study is to show the effect of the different geometries on the leakage rate. The other object is to show the temperature rise and windage heating for the each geometries. It has been shown that the leakage can be reduced without increase or with a little increase of the windage heating

Present status and future prospects of hydroelectric energy in Turkey

Energy is an essential input for social development and economic growth. Economic growth is arguably the most important driver of energy demand. The energy requirement in Turkey is steadily increasing due to the rapid growth in population and industrialization and is being met by both commercial and renewable energy sources. Among the different forms of renewable energy, hydroelectric energy is one of the major resources in Turkey. Turkey's gross theoretical hydroelectric energy potential is 1% that of the World. The use of hydroelectric energy sources in Turkey is increasing steadily. The hydroelectric power generation sector is the primary consumer of the Turkish energy sector. Turkey will be able to produce only about one fourth of her primary energy demand by her own sources in the near future. Hydropower, being renewable, local, environment friendly, having long operational life and less maintenance cost, seems the most reliable energy source in Turkey, but it is obvious that in order to produce hydroelectric energy, the technically and economically feasible hydroelectric potential of the country should be considered

Pişmiş Brokoli ve Karnabahar İçin Vakum Soğutma Enerji Analizi

Vakumla soğutma, gözenekli ve serbest su içeren herhangi bir ürün için uygulanabilen hızlı buharlaşmalı soğutma tekniği olarak bilinir. Bu teknik, yapraklı sebzelerin ve mantarın, fırın ürünlerinin, balılığın, sosların, pişirilmiş yiyeceklerin ve özel gıdaların ön soğutması için kullanılır. Vakum soğutmanın kısa sürede soğutması, ürün raf ömrünün uzatılması ve ürün kalitesinin ve güvenliğinin geliştirilmesi gibi bazı avantajları vardır. Bu çalışmanın amacı, pişirilmiş brokoli ve karnabaharın soğutulması için vakum soğutma tekniğini uygulamak ve soğutma süresi ve sıcaklık düşüşü üzerindeki basınç etkisini göstermektir. Vakum soğutmanın sonuçları, farklı sıcaklıklar için geleneksel soğutma (buzdolabında soğutma) ile de karşılaştırılmaktadır. Ayrıca, bu çalışmada pişmiş brokoli ve karnabahar için vakum soğutma enerjisi analizi çalışılmıştır. Pişmiş brokoli ve karnabaharın geleneksel soğutma ile karşılaştırıldığında çok daha hızlı ve verimli bir şekilde soğutulabileceği gösterilmiştir

Pişmiş Brokoli ve Karnabahar İçin Vakum Soğutma Enerji Analizi

Vakumla soğutma, gözenekli ve serbest su içeren herhangi bir ürün için uygulanabilen hızlı buharlaşmalı soğutma tekniği olarak bilinir. Bu teknik, yapraklı sebzelerin ve mantarın, fırın ürünlerinin, balılığın, sosların, pişirilmiş yiyeceklerin ve özel gıdaların ön soğutması için kullanılır. Vakum soğutmanın kısa sürede soğutması, ürün raf ömrünün uzatılması ve ürün kalitesinin ve güvenliğinin geliştirilmesi gibi bazı avantajları vardır. Bu çalışmanın amacı, pişirilmiş brokoli ve karnabaharın soğutulması için vakum soğutma tekniğini uygulamak ve soğutma süresi ve sıcaklık düşüşü üzerindeki basınç etkisini göstermektir. Vakum soğutmanın sonuçları, farklı sıcaklıklar için geleneksel soğutma (buzdolabında soğutma) ile de karşılaştırılmaktadır. Ayrıca, bu çalışmada pişmiş brokoli ve karnabahar için vakum soğutma enerjisi analizi çalışılmıştır. Pişmiş brokoli ve karnabaharın geleneksel soğutma ile karşılaştırıldığında çok daha hızlı ve verimli bir şekilde soğutulabileceği gösterilmiştir

Heat transfer and velocity in the squeezing flow between two parallel disks by Gegenbauer Wavelet Collocation Method

In this study, the squeezing flows between parallel disks, which one disk is impermeable and the other is porous, in the presence of magnetic field are investigated byGegenbauerWaveletCollocationMethod (GWCM). Appropriate similarity transformations may be used to convert the governing non-linear partial differential equations into non-linear ordinary differential equations. The resultant non-linear ordinary differential equations are transformed into a sequence of linear differential equations by quasilinearization technique. Velocity and temperature fields of squeezing flows between parallel disks have been obtained by Gegenbauer Wavelet Collocation Method. The effects of squeeze number (S), Hartman number (Ha), Prandtl number (Pr), and Eckert number (Ec) and suction/blowing parameter (A) are analysed through graphs for the velocity and temperature profiles. GWCM is generalized form of the Legendre, Chebyshev and second kind Chebyshev wavelets. The basic advantage of the proposed method (GWCM) is to reduce the computational work. From the numerical results, it is observed that present method is convergent even in the case of a small number of grid points. The obtained results are in good agreement with the results in literature

Forecasting total and industrial sector electricity demand based on genetic algorithm approach: Turkey case study

This study deals with estimation of the total and industrial sector electricity consumption based on genetic algorithm (GA) approach, and then proposes two scenarios to project future consumptions. Total electricity consumption is estimated based on gross national product (GNP), population, import and export figures of Turkey. Industrial sector electricity is calculated based on the GNP, import and export figures. Three forms of the genetic algorithm electricity demand (GAED) models for the total and two forms for the industrial electricity consumption are developed. The best-fit GAED model in terms of total minimum relative average errors between observed and estimated values is selected for future demand estimation. 'High- and low-growth scenarios' are proposed for predicting the future electricity consumption. Results showed that the GAED estimates the electricity demand in comparison with the other electricity demand projections. The GAED model plans electricity demand of Turkey until 2020. Copyright © 2005 John Wiley & Sons, Ltd

Modeling hydraulic and thermal electricity production based on genetic algorithm-time series (GATS)

This study deals with the estimation of electricity production from hydraulic and thermal sources using the Genetic Algorithm (GA) with time series (TS) approach. Two forms of the mathematical models are developed, of which one is exponential and the second is polynomial. The power form of the Genetic Algorithm-Time Series (GATS) model is used for the thermal electricity production. The polynomial form of the GATS is used for the electricity production from the hydraulic sources. The GATS weighting parameters are obtained by minimizing the Sum of Squared Error (SSE) between observed and estimated electricity production from both sources. Therefore, the fitness function adapted is the minimization of the SSE for use in the GA process. The application of the GATS model is correspondingly presented. Some future scenarios are made to increase the electricity production from hydraulic sources. Variations of the electricity production from thermal and hydraulic energy sources are analyzed. Future prospects of electricity production are dealt with in terms of policy changes. The GATS models are used for making scenarios for future electricity planning policy. Results also show if current trend continues, the thermal electricity production amounts to 75% of the total electricity production, which is undesirable for environmental concerns. Results also shows that if new policy is to move from the thermal to hydraulic electricity production, the hydraulic sources will meet the demand until 2020

Turkish sugar production potential and use of waste of sugar beet as energy source

Biomass energy is the most renewable energy resource in the world. Biomass energy is derived from plant and animal material, such as wood from forests, residues from agricultural and forestry processes, and industrial, human or animal wastes. The production of biofuels such as ethanol and biodiesel has the potential to replace significant quantities of fossil fuels in many transport applications, electricity, generate heat and steam, etc. In this study, Turkish sugar sector and sugar capacity, residue quantitiy and its possibility of utilization is examined

Effects of pulsed vacuum osmotic dehydration (PVOD) on drying kinetics of figs (Ficus carica L)

Drying kinetics of non-pretreated (fresh) and pretreated SarIlop (Ficus carica L.) variety figs were compared. In experiments, figs were performed as a whole (unsliced and unpeeled). Pretreatment was pulsed vacuum osmotic dehydration (PVOD). Osmotic dehydration was performed in sucrose solution at 50 °Brix and 50 °C with a solution/fruit mass ratio of 4/1. Vacuum impregnation in osmotic dehydration was applied at 130 mbar for 15 min then the osmotic treatment continued at atmospheric pressure for 165 min, therefore the total pretreatment period lasted for 180 min (15 min (130 mbar) + 165 min (Patm)). Pretreated and non-pretreated figs were dried at 55, 65 and 75 °C in a convective oven. Results showed that increasing of drying temperature shortened the drying time for both non-pretreated and pretreated figs. Drying period of pre-treated figs lasted shorter than non-pretreated figs, thus PVOD shortened the drying period. Non-pretreated (fresh) figs had greater shrinkage than the pretreated figs. Effective moisture diffusivity (Deff) values of pretreated figs are greater than the non-pretreated figs during the drying at all three temperatures. Deff increased with drying temperature for both pretreated and non-pretreated figs. Deff values of non-pretreated and pretreated figs ranged 2.75·10- 10-5.69·10- 10 m2/s and 3.57·10- 10-10.25·10- 10 m2/s, respectively. Activation energy (Ea) of non-pretreated and pretreated figs were obtained 34.68 (kJ/mol) and 50.27 (kJ/mol), respectively. Also, sensory evaluation of color, flavor, odor, texture and overall acceptability of the samples was made. Industrial relevance The use of PVOD technique is relevant for food industry. So that, PVOD treatment shortened the drying period of figs. Thus, this result can cause the economic advantage as reducing the further costs for drying process. Additionally, results of sensory evaluation show that there was no significant difference (p > 0.05) between the pretreated and traditional dried figs except for flavor. Sensory properties of pretreated figs may be improved by changing conditions of pretreatment. © 2016 Elsevier Ltd. All rights reserved

Application of Genetic Algorithm (GA) technique on demand estimation of fossil fuels in Turkey

The main objective of the present study is to investigate Turkey's fossil fuels demand, projection and supplies by giving the structure of the Turkish industry and Turkish economic conditions. This present study develops several scenarios to analyze fossil fuels; such as, coal, oil and natural gas consumption and make future projections based on Genetic Algorithm (GA) notion, and examines the effect of the design parameters on the fossil fuels utilization values. The models developed in the nonlinear form are applied to the coal, oil and natural gas demand of Turkey. Several Genetic Algorithm Demand Estimation Models (GA-DEM) are developed to estimate the future coal, oil and natural gas demand values based on population, Gross National Product (GNP), import, export figures. It may be concluded that the proposed models can be used as an alternative solution and estimation techniques for the future fossil fuel utilization values of any country. Oil is the most important fuel in Turkey, contributing 43% of the Total Primary Energy Supply (TPES), followed by coal (almost 30% of TPES) and natural gas (11.8%). In the study, coil, oil and natural gas consumption of Turkey are projected. Estimation shows that the coal, oil and natural gas consumption values may increase 2.82, 1.73 and 4.83 times from 2000 to 2020. Copyright © 2007 by ASME