Yazar "Yelmen, Bekir" seçeneğine göre listele

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    A study on microwave assisted drying characteristics of red pepper
    (2011) Yelmen, Bekir; Üstüner, Tamer; Üstüner, Menderes
    The method of drying red pepper by means of a combination of convectional oven plus microwave was investigated in this study. Red pepper was dried using hot air, microwave and a combination of microwave plus hot air. Therefore, some factors such as drying time, ratio of drying, changes in color, drying using microwave power settings above levels of energy consumption, drying by microwave power and hot air drying, only hot air drying, etc. were inspected for red pepper during relevant study. The models of Wang and Singh; Page; Improved Page; Henderson and Pabis; Newton; Logaritmical; Diffusion Approach; Verma; Exponential with Two-Terms; Simplified Fick Diffusion; Midilli; and Kucuk were compared so that moisture content for drying times of products could be determined in a given time by means of a laboratory dryer with microwave feature. The performances of aforesaid models were compared according to the determination coefficient (R2), standard error of estimate (SEE) and residual sum of squares (RSS). It was found that the models of Midilli and Kucuk expressed the drying attitude of products better than the others. © 2011 Academic Journals.
  • Küçük Resim
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    Biomass potential of Turkey and energy production applications
    (TAYLOR & FRANCIS INC, 2016) Yelmen, Bekir; Çakır, M. Tarık
    The fact that fossil-based energy sources will run out requires the efficient use of the existing sources and as well as more effective and widespread use of renewable energy sources. The use of organic waste, which has a significant place among renewable energy resources, gains importance in terms of environment and energy optimization in sustainable development models. One of the renewable energy resources is biogas. In the countries where biogas technology is common, energy is produced by processing all kinds of organic waste in the biogas production facilities. Besides energy production, land, water, and air pollution caused by the waste is reduced to minimum. On the other hand, organic waste from the facilities is used as fertilizer in the vegetable production. In this research, biomass potential, which has an important and different place among renewable energy sources in terms of its existing potential and production technologies, is studied. Animal and vegetable-based waste and the equivalent energy potential of the biogas that can be produced out of these wastes have been identified. In this study, the average amount of dry biomass produced in Turkey in a year and the average heating value of the dry biomass have been calculated. In addition, suggestions have been made for taking advantage of the biomass potential efficiently and extensively. Turkey is rich in biomass and has adequate facilities and environmental conditions in terms of the development of this resource. In order to reduce the dependence of Turkey on foreign energy, transition to energy forestry and energy agriculture, development of obtaining biofuel from them and wastes, and biogas obtained from fertilizers, waste and garbage are required to be given importance.
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    Determining the potential of solar energy and benefiting from this potential using photovoltaic system in Turkey
    (2011) Yelmen, Bekir; Üstüner, Tamer; Üstüner, Menderes
    Today, renewable energy sources which are important substitutes for fossil-based energy sources can be converted into electrical energy using some effective recycle processes. Although Turkey is a country with rather high potential for solar energy, it has yet facilities well below of required practicability levels when it is compared to the instances in the world. In this study, the potential for solar energy in Turkey was identified; it was investigated how that potential was assessed; and the methods and ways to obtain electrical energy from photovoltaic systems using the aforesaid potential in the cities located on referenced latitudes of Turkey. As a conclusion, it was determined that the potential for electrical energy which could be obtained from solar energy was higher in our cities located on Southern latitudes than in other cities. © Sila Science.
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    Estimation of average monthly total solar radiation on horizontal surface for Mediterranean region
    (Taylor & Francis Inc, 2015) Yelmen, Bekir; Çakır, Mutlu Tarık
    In this study, by using long-term measuring data for the Mediterranean Region, total solar radiation intensity, which appears on a horizontal surface, has been calculated by utilizing from equations that are developed from certain patterns presented in the literature and results have been compared. Statistical parameters of these values, which are derived from these functions, have been calculated according to measured values. Although measured solar radiation values show fluctuations within and by years, it is observed that developed equations represent long-term measuring values in the best possible way. Values that arise as a result of modeling are compared with values given for the Mediterranean Region in the literature. It is perceived that those improved patterns can be used for estimating average monthly total solar radiation that appear on horizontal surfaces in provinces involved in the Mediterranean Region.
  • Küçük Resim
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    Estimation of greenhouse heating requirements using artifical neural networks
    (Tarım Makinaları Derneği, 2011) Yelmen, Bekir; Öztekin, Serdar
    In this study by taking into account the latitude, longitude, height, months and mean temperature data of the city and districts of Adana, the heating need for unit base and surface zone is determined. In the model of artificial neural nets the heating need for the green house which is longitude, latitude, height and means temperature data is used as entry layer and the need for heater need is used as exit layer. Of the data belonging to Adana Province and 7 districts; 6 district education data, Adana Seyhan and yüreğir district are- used as test data in artificial neural net model. The data has been tested by using Levenberg-Marquardt algoritm and an estimate (R2) of value from an average of 99% has been found. The average of quadric error square root value is 0.0533 in average and is 0.0021 for education data. The mean absolute error for test data is 0.0485 and 0.0015 for education data. In conclusion, this study focused on the successful estimate of green house heater need by using the model of artificial neural nets. Konu Alanı:
  • Küçük Resim
    Öğe
    Influence of temperature changes in various regions of Turkey on powers of photovoltaic solar panels
    (Taylor and Francis Inc., 2016) Yelmen, Bekir; Çakır, Mutlu Tarık
    Renewable sources of energy, which are significant alternatives for every nonrenewable energy sources, can be converted to electric energy by productive rotations. Although Turkey is the country that has pretty high solar energy potential when compared to samples in the world, it has facilities still remarkably below required structuring. Demand for solar energy applications that is included in renewable sources of energy is increasing gradually. In Turkey, according to results received by the averages of long periods, approximately 2.68% power loss has been substantiated in powers of photovoltaic panel. Here, it is obviously observed that the East Anatolian region is the most convenient district for panel powers of environmental temperature averages. Turkey is involved in between countries that may take advantage from solar energy and annual average sunshine duration is 2,640 hours in the country. A heat factor occurs by the absorption of sun beams, which comes to solar panels and affects the power of the panels. In this study, the influence of losses occurring from temperature differences in various regions of Turkey on power of photovoltaic solar panels has been examined and proposals have been progressed in order to reduce losses down to a minimum in electrical systems to be established for this aim.
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    Red chili pepper drying by farm scale Hothouse
    (Tarım Makinaları Derneği, 2010) Öztekin, Serdar; Yelmen, Bekir
    In this study a farm scale plastic high tunnel hothouse dryer was investigated to dry red chili pepper grown in southeastern Anatolian region. Hothouse dryer was installed in Kahramanmaraş where this crop is intensively cultivated. For drying purpose the green stem was removed manually and then material was split into two pieces. The core of seed was also removed. The fleshes of red chili peppers were placed on the shelf as a thin layer by a density of 2 kg/m2. In this study the lost of moisture from crop and color change were measured. For first and second harvested red chili peppers drying duration varied between 26 and 27 hours. As the control sun-dried chili peppers was placed by 50 cm height from the ground in outside. The moisture loss from solar dried chili peppers was 2 to 4% higher than that of ^sun-dried variant. Although the drying time of solar and sun dried crops was similar, it is expected that the solar dried crops would resulted in higher food quality and safety. Thus the color of solar dried chili was much shining red in compare to sun-dried variant. Hothouse dryers have been already tested for different crops in laboratory scale. However, the implementation of farm scale hothouse dryer by using national and international funds would be a proper strategy to provide more information regarding to marketing advantages and management experiences on this issue.
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    Total for the horizontal surface of the city of Konya solar radiation comparison of predicted and test values
    (2011) Yelmen, Bekir; Chaki, M. Tarık
    In design of solar energy systems, solar radiation data's accuracy is very important. When we survey present studies in literature, because of the expensiveness of system installations that measure solar radiation and sunshine duration, it appears that relations are developed for the area where there will be study by using measured values at the nearest area to chosen area. The most known and commonly used of these formulas is Angstrom formula. Received instantaneous, hourly and daily solar radiation values in the earth surface are measured in some meteorological stations. Furthermore, at some of our areas these measurements still can not be performed. Received instantaneous, hourly and daily solar radiation values in the earth surface can be measured with the help of relations which are developed for solar energy applications at these areas. In this study, total solar radiation change measured by DMI (State Meteorological Services) for the estimation of monthly average daily solar radiation in Konya province has been researched. Based on the measured values, statistical analysis of the calculation methods that are used in monthly average total solar radiation and sunshine duration has been done. Root mean-square error (RMSE), for performance assessment of equation, has been compared by mean bias error (MBE) and t-statistic methods. By comparing measured and obtained values from equations, the right equation has been found.