Yazar "Coskun, Tuba" seçeneğine göre listele

Listeleniyor 1 - 4 / 4
  • Küçük Resim Yok
    Öğe
    CO2 emission during the combustion of Orhaneli lignite coal
    (Emerald Group Publishing Ltd, 2017) Ozkaymak, Mehmet; Ceylan, Mehmet Ali; Okutan, Hasancan; Atakul, Husnu; Berrin, Engin; Coskun, Tuba; Inanc, Ozgur
    Purpose - In Turkey, dependence on foreign countries for energy is a problem which upsets all economic balances. Turkey's biggest fossil energy source is lignite coal. Therefore, energy conversion of lignite in thermal plants, causing minimum environmental effect is extremely important. The basic problem in terms of the combustion technology is to improve the combustion technology that can burn the low-qualified fuels that do not have standard fuel features (lignite, peat, schist). The most suitable technology today for the efficient and clean combustion of nonstandard low-qualified fuels is the combustion at fluidized-bed technology. In this study, CO2 emission that occurs during the combustion of Orhaneli coal that is one of our native low-qualified lignite, has been investigated according to the experimental study. Design/methodology/approach - For this combustion experiment, laboratory-scaled circulating fluidized-bed (CFB) process that exists at TU BITAK-MAM Energy Institute which has been designed and used before has been used. The effect of excess-air coefficient, combustion type and bed temperature to the greenhouse gas formation and CO2 emission has been investigated experimentally. In terms of flue gas emissions, it has been detected that the decrease of the amount of CO2 that has occurred has no positive effects on combustion efficiency, water vapor, SO2, NOx, CO and other gases which occur during deficient combustion must be thought as a whole and each reaction affects each other similar to complex reactions. Findings - As a consequence of measuring CO2 emissions over 10 minute periods, CO2 emissions are 12.43 percent average, CO2 decreases at different air coefficient values; Often form undesirable side reactions such as CO, NOx with back and forth reactions. Originality/value - The importance of aerodynamic structure of the system, and the losses and leakages forming in the system has been observed experimental and affected parameters are evaluated.
  • Küçük Resim Yok
    Öğe
    Freeze-Drying of Persimmon (Diospyros Kaki) Slices Investigation of Drying Characteristics
    (Gazi Univ, 2023) Dagdeviren, Abdullah; Acar, Bahadir; Alhammadiy, Abdullatif; Roshanaei, Khandan; Coskun, Tuba; Inanc, Ozgur; Ozkaymak, Mehmet
    This study was performed to define the kinetic drying model and to define the effective diffusivity coefficient of the fruit, which is called Diospyros kaki in the literature, from the family of Ebonaceae known as the Persimmon in our country. In the study, blueberries by the weight of 100 g and with a thickness of 5 mm were placed in the drying device, and the data were processed by observing the weight loss every two hours after being subjected to the drying process for 14 hours. 8 different kinetic drying models were applied to the acquired data using the Matlab program. As a result of the application, the estimated standard errors (RMSE), chi-square (X-2), regression coefficients (R-2) were calculated, error analysis was performed, R-2, X-2, and RMSE values were found, as 0.019483, 5.062 x 10(-4) and 0.9558. According to these results, it was determined that the most suitable model is the Page model. Also, the effective diffusivity coefficients for Persimmon (Diospyros Kaki) were calculated as 1.79775 x 10(-10) m(2)/s.
  • Küçük Resim Yok
    Öğe
    Kinetic Model And Effective Diffusivity Of Frozen-Dryed European Blueberry (Vaccinium Myrtillus)
    (Gazi Univ, 2022) Ayriksa, Mutlucan; Acar, Bahadir; Dagdeviren, Abdullah; Roshanaei, Khandan; Coskun, Tuba; Ongun, Goknur K.; Ozkaymak, Mehmet
    In current study, the freeze-drying (FD) method has been investigated. This method is the healthiest drying method that used in recent years by extending the shelf life of the products and preserving the beneficial flavors in its content. Antioxidant, antimicrobial, antidiabetic, anti-inflammatory, antiseptic, etc., are the most emphasized role among the berries. Thus, blueberry is one of the great aspects to be a case for drying. Blueberry (Vaccinium Myrtillus), which is an opulent source of many phenolic compounds with known properties, has been determined. In the study, blueberries by the weight of 100 g and with a thickness of 5 mm were placed in the drying device, and the data were processed by observing the weight loss every two hours after being subjected to the drying process for 14 hours. 8 different kinetic drying models were applied to the acquired data using the Matlab program. As a result of the application, the estimated standard errors (RMSE), chi-square (X-2), regression coefficients (R-2) were calculated, error analysis was performed, R-2, X-2, and RMSE values were found, as 1.4686 x 10(-2), 2.875 x 10(-4) and 9.978 x 10(-1). According to these results, it was determined that the most suitable model is the Page model. Also, the effective diffusivity coefficients for blueberries were calculated as 2.57665 x 10(-12) m(2)/s.
  • Küçük Resim Yok
    Öğe
    Techno-Economic Feasibility Study of the Commercial-Scale Oxy-CFB Carbon Capture System in Turkey
    (Gazi Univ, 2021) Coskun, Tuba; Ozkaymaiv, Mehmet; Okutan, Hasan Can
    Oxy-fuel combustion is a promising technology for the reduction of carbon dioxide emissions, in coal-fired power plants that allow the clean use of fossil fuels. Circulating fluidized bed (CFB) boilers are one of the power generation technologies that can use oxyfuel combustion design successfully. The purpose of this paper is to perform the techno-economic feasibility analysis of the commercial-scale oxy-fuel combustion circulating fluidized bed (oxy-CFB) power plant generating 550 MWe net power with a carbon capture rate of 90%. So far, economic analysis of oxy-PC power plants has been studied by researchers at many reports. Nevertheless, the cost of an oxy-CFB power plant has rarely been studied.This is the first study that has used Turkish lignite (Orhaneli Coal) in an oxy-CFB carbon capture plant economic analysis. The basic economic performance indicators were investigated. The Models are based on cost scaling and Discounted Cash Flow analysis. Three cases were analyzed: In the first case, A base scenario (air-fired CFB plant without CO2 capture) is considered and then based on this baseline scenario the other scenarios are taken into account. The economic viability of transition from the classical air-fired CFB plant system to oxy-CFB with CO2 capture and compression plant is evaluated. The post-combustion monoethanolamine (MEA) based CO2 capture system is investigated as a benchmark study to compare oxy-CFB capture system performances. The main applicability parameters such as cost of electricity (COE), levelized cost of electricity (LCOE) and the cost of CO2 capture for each case are calculated. The obtained results indicated that 54% and 52% increase in terms of total plant cost and COE respectively in the oxy-CFB plant when compared to air fired-CFB without carbon capture. Considering the COE, the designed oxy-CFB power plant is greater than the air-fired SC-PC (without capture) plant by more than 45% (DOE target). The efficiency penalty for oxy-CFB is 10%. Oxy-CFB plant has a net efficiency 2% point higher than amine-based CO2 capture systems. In amine-based CO2 capture system; The capital costs, LCOE, and cost of CO2 captured are higher than the oxy-CFB plant. The results show that the oxy-CFB power plant has a lower cost for carbon capture compared to amine-based capture plant.