Yazar "Balbay, Asim" seçeneğine göre listele

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    A fuel cell system using the hydrogen energy obtained from mixture of NaBH4 and H3BO3
    (2012) Balbay, Asim
    This work describes the hydrogen energy obtained from mixture of NaBH4 and H3BO3 and the using it in a Proton Exchange Membrane (PEM) fuel cell (FC) for mini portable applications. The FC system consists of hydrogen separating PEM-FC, a micro pump, a H3BO3 reaction cartridge, NaBH4 cartridge, an oxygen tube and other joint and measurement elements. The integrated performance of the PEM-FC with NaBH4 hydrogen generator was evaluated under various operating conditions (different flow rates (0.02, 0.04, 0.06 and 0.08 mL/min) and different temperatures (20, 30 and 40 °C)). The FC voltage and current can be monitored and recorded through the data acquisition system. The maximum power of the FC system was obtained as 230 mW. © Sila Science.
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    An Investigation of Drying Process of Shelled Pistachios in a Newly Designed Fixed Bed Dryer System by Using Artificial Neural Network
    (Taylor & Francis Inc, 2011) Balbay, Asim; Sahin, Omer; Karabatak, Murat
    In this paper, the drying of Siirt pistachios (SSPs) in a newly designed fixed bed dryer system and the prediction of drying characteristics using artificial neural network (ANN) are presented. Drying characteristics of SSPs with initial moisture content (MC) of 42.3% dry basis (db) were studied at different air temperatures (60, 80, and 100 degrees C) and air velocities (0.065, 0.1, and 0.13 m/s) in a newly designed fixed bed dryer system. Obtained results of experiments were used for ANN modeling and compared with experimental data. Falling rate period was observed during all the drying experiments; constant rate period was not observed. Furthermore, in the presented study, the application of ANN for predicting the drying time (DT) for a good quality product (output parameter for ANN modeling) was investigated. In order to train the ANN, experimental measurements were used as training data and test data. The back propagation learning algorithm with two different variants, so-called Levenberg-Marguardt (LM) and scaled conjugate gradient (SCG), and tangent sigmoid transfer function were used in the network so that the best approach can be determined. The most suitable algorithm and neuron number in the hidden layer are found out as LM with 15 neurons. For this number level, after the training, it is found that Root-mean squared (RMS) value is 0.3692, and absolute fraction of variance (R-2) value is 99.99%. It is concluded that ANNs can be used for prediction of drying SSPs as an accurate method in similar systems.
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    CoB doped acid modified zeolite catalyst for enhanced hydrogen release from sodium borohydride hydrolysis
    (Pergamon-Elsevier Science Ltd, 2020) Saka, Cafer; Eygi, Mustafa Salih; Balbay, Asim
    Cobalt-boron (CoB) catalyst supported on zeolite modified with hydrochloric acid (CoB-zeolite-HCl) and zeolite modified with acetic acid (CoB-zeolite-CH3COOH) is prepared for the hydrogen (H-2) release from sodium borohydride (NaBH4). The supported catalyst samples were characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscope (SEM), Fourier transforms infrared spectroscopy (FTIR), nitrogen adsorption and, inductively coupled plasma optical emission spectroscopy (ICP-OES). The effects of Co metal loading, NaBH4 concentration, NaOH concentration, temperature, and reusability on the catalytic performance of the CoB-zeolite-HCl catalyst were investigated. The completion time of the reaction using the raw zeolite supported CoB catalyst was about 265 min. However, the completion time of the reaction using the CoB-zeolite-HCl catalyst was decreased to about 80 min. BET surface area values showed that there is a 7-fold increase in the specific surface area for the zeolite activated with HCl compared to the BET surface area for the raw zeolite. The activation energy (Ea) of the catalyzed reaction was 42.45 kJ mol(-1). (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Drying behaviours of bittim (Pistacia terebinthus) in a fixed bed drying system
    (2012) Balbay, Asim; Ülker, Hakan; ŞahIn, Ömer
    In this study, drying behaviours of the outer shell peeled Bittim (Pistacia terebinthus) with initial moisture content of 42.2% (dry basis (d.b)) was investigated in a novel fixed bed drying system. The drying experiments were performed at different temperatures (40 °C, 60 °C and 80 °C), ai r velocities (0.5 m/s and 1 m/s) and weights (30 g and 40 g). A constant rate period was not observed in the drying of bittims; all the drying process occurred in falling rate period. Two models in literature were selected to fit the experimental data. The fit quality of models was evaluated using the coefficient of determination (R2), sum square error (SSE) and root mean square error (RMSE). Page model has a good agreement with the experimental data and gave the best results for bittims in a fixed bed system.
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    Drying of black cumin (Nigella sativa) in a microwave assisted drying system and modeling using extreme learning machine
    (Pergamon-Elsevier Science Ltd, 2012) Balbay, Asim; Kaya, Yilmaz; Sahin, Omer
    Drying characteristics of Black cumin seeds (BCs) (Nigella sativa) with initial moisture content 58.14% (d.b) was investigated in microwave assisted drying system. The experiments were carried out in two aspects which were the BCs drying with different temperatures (35, 40 and 50 degrees C) and different microwave power levels (250, 500 and 750 W). The results showed that the drying rates of BCs have high efficiency with drying temperatures at constant microwave power level. Furthermore, in present study, the applications of Extreme Learning Machine (ELM) and Artificial Neural Network (ANN) for predicting the moisture ratio (MR) (output feature for ELM modeling) were investigated. Microwave temperature, microwave power and drying time were input layer features for the modeling. An ELM model by 93 neurons with Sine transfer function in hidden layer was selected. The results revealed that a network with the Sine function made the most accurate prediction for the BCs drying system. For BCs all data set, maximum R-2 and minimum RMSE (root mean square error) were found as 0.9987 and 0.0123, respectively. (C) 2012 Elsevier Ltd. All rights reserved.
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    Effect of acid addition on hydrogen production from potassium borohydride hydrolysis
    (Taylor & Francis Inc, 2017) Balbay, Asim; Sahin, Omer; Saka, Cafer
    This is the first study to produce hydrogen from the potassium borohydride (KBH4) hydrolysis using boric acid (H3BO3). The effect of H3BO3 addition on the hydrogen production via KBH4 hydrolysis was investigated for different H3BO3 and KBH4 molar ratios. In addition, the temperature effect on the hydrolysis reaction was investigated at different temperatures. H3BO3 showed good catalytic activity to produce hydrogen from KBH4 hydrolysis. Activation energy to produce hydrogen from KBH4 hydrolysis was found to be 20.31 kJ/mol. This work also includes kinetic information for the hydrolysis of KBH4. According to the kinetic studies, the reaction between H3BO3 and KBH4 had a reaction order of 0.24 against the H3BO3 concentration, while it had a reaction order of 0.16 against the KBH4 concentration.
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    Effect of phosphoric acid addition on the hydrogen production from hydrolysis of NaBH4 with Cu based catalyst
    (Taylor & Francis Inc, 2018) Balbay, Asim; Saka, Cafer
    Cu based catalysts were synthesized in water and methanol solvents by chemical reduction with sodium borohydride (NaBH4). The obtained catalyst was used to catalyze the NaBH4 hydrolysis reaction with phosphoric acid (H3PO4) including different concentrations. Surface morphology and structural properties of the Cu based catalysts prepared in water and methanol solvents were studied using by X-ray diffraction (XRD), scanning electron microscopy (SEM), surface area measurements and Fourier-transform infrared spectroscopy (FTIR) analyses, respectively. The catalytic activity of the catalysts has been tested by measuring the hydrogen production rate by the acidified hydrolysis of NaBH4. The maximum hydrogen production rates in the hydrolysis reaction including 0.25 M H3PO4 using the Cu based catalyst prepared in water and methanol solvents were 825 and 660 ml g(-1)min(-1), respectively. At the same time, the hydrogen production experiments were carried out from this hydrolysis reaction with only H3PO4 and NaBH4 interactions without using Cu metal catalyst. The activation energy obtained based on the nth order reaction model was found to be 61.16 kJ mol(-1).
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    Effect of phosphoric acid and acetic acid addition on the hydrogen evolution using Ni based catalyst prepared in ethanol, methanol, and water solvents
    (Taylor & Francis Inc, 2018) Balbay, Asim; Saka, Cafer
    Ni-based catalysts were synthesized in water, methanol and ethanol solvents by chemical reduction with sodium borohydride (NaBH4). The obtained catalyst for the first time was used to catalyze the NaBH4 hydrolysis reaction with phosphoric acid and acetic acid including different concentrations. The maximum hydrogen production rates obtained in the hydrolysis reaction including 0.5M phosphoric acid and 0.1M acetic acid of the Ni-based catalyst prepared in ethanol solvent were 5214 and 3650ml g(-1)min(-1), respectively.
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    Effects of environmental temperature and relative humidity on the rehydration of dried pistachios
    (Taylor & Francis Inc, 2019) Balbay, Asim
    In this study, the environmental air temperature and relative humidity effects were investigated through rehydration on the dried and roasted Siirt Pistachios (S_PS) and Antep pistachios (A_PS) with an experimental and computational approach. Therefore, an experimental apparatus was set-up in lab conditions. A series of experiments were conducted to evaluate the water activity and weight change as a function of the relative humidity and temperature of ambient air. The experimental results show that there is a combined effect of relative humidity and temperature on the increase in the weight change and water activity (a(w)). The shell of pistachio is a good hygroscopic material despite its hard texture. The roasted pistachios are less prone to absorb moisture compared to the unroasted pistachios. Beside this experimental study, an intelligent modeling called artificial neural network model was used for prediction of the increase in the weight of different types of pistachios.
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    Effects of plasma treatment, La content and temperature on the La-Ni-Mo-B catalysts for hydrogen production from NaBH4 hydrolysis
    (Taylor & Francis Ltd, 2017) Sahin, Omer; Ekinci, Arzu; Balbay, Asim; Saka, Cafer
    La-Ni-Mo-B catalysts with 0.15, 0.21 and 0.30-mol La molar ratio are prepared by a mixing method followed by a plasma treatment, characterised and investigated for hydrogen production via sodium borohydride hydrolysis. XRD, SEM, Brunauer-Emmett-Teller and FTIR techniques are used for characterising the catalysts. The hydrogen generation rate at 60 degrees C compared to 30 degrees C using La-Ni-Mo-B under the same conditions is significantly different. The effect of temperature, plasma application time and different plasma gases on hydrogen generation from NaBH4 hydrolysis reaction using La-0.21-Ni-Mo-B catalyst is investigated. It was found that the plasma-treated catalysts exhibited low activation energy for zero order (58 kJ mol(-1)).
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    Ethylene glycol as an alternative solvent approach for very efficient hydrogen production from sodium borohydride with phosphoric acid and acetic acid catalysts
    (Pergamon-Elsevier Science Ltd, 2022) Saka, Cafer; Balbay, Asim
    For the first time, phosphoric acid (H3PO4) and acetic acid (CH3COOH) catalysts were used for efficient hydrogen (H-2) production from sodium borohydride (NaBH4) ethylene glycolysis reaction. In this experimental study, the effects of ethylene glycol/water ratio, ethylene glycol/acid ratio, NaBH4 concentration, acid concentration, and temperature were investigated. These ethylene glycol/water ratio experiments showed that the use of water alongside ethylene glycol negatively affects H-2 production. The hydrogen generation rate (HGR) values obtained for this ethylene glycolysis reaction with 1 M H3PO4 and 1 M CH3-COOH catalysts are 5800 and 4542 mLmin(-1), respectively. Also, the completion times of ethylene glycolysis reactions with these acids are 8 and 10 s, respectively. The n value obtained for ethylene glycolysis reactions according to the power-law kinetic model was 0.50. The activation energies obtained with H3PO4 (;)and CH3COOH catalysts were 24.45 kJ mol(-1) and 33.23 kJ mol(-1), respectively. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Experimental computational study on drying of Black Cumin (Nigella sativa) in a fixed bed dryer and in a Thermo-gravimetric analysis system
    (Arabian Gulf University, 2013) Balbay, Asim
    In this study, drying of black cumin seeds (BCs) (Nigella sativa) with initial moisture content (MC) of %56.74 (dry basis (d.b)) was investigated in a novel designed fixed bed drying system (isothermal condition) and in a thermo gravimetric analysis system (non-isothermal condition). In isothermal conditions, the drying experiments were carried out at different temperatures (40, 60, and 80 °C) and air velocities (0.25, 0.5 and 1 m/s) and bed heights (14 mm and 28 mm). Several models in literature were selected to fit the experimental data. The fit quality of models was evaluated using the coefficient of determination (R2), sum square error (SSE) and root mean square error (RMSE). Two term model has a good agreement with the experimental data and gave the best results for BCs. The activation energy was calculated to be as 19.92 kJ/mol and effective diffusivity values were calculated to be between 2.85×10-10 and 6.77×10-10 m2/s depending on air temperatures. Furthermore, drying and decomposition behaviours of BCs in thermo gravimetric analysis system were studied in nitrogen flow of 0.850 ml/s and of constant heating rate of 5 °C/min towards 250 °C by means of non-isothermal methods.
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    Experimental investigation of using ground source heat pump system for snow melting on pavements and bridge decks
    (Academic Journals, 2010) Balbay, Asim; Esen, Mehmet
    Melting snow with a hydronic heating system can eliminate the need for snow removal by chemical or mechanical means and provide greater safety for pedestrians and vehicles. So, a preliminary practical feasibility study of using a ground source heat pump (GSHP) system for snow melting on pavements and bridge decks had been performed for the first time in Turkey on the basis of a university study. The objective of this paper is to investigate the practicability of a GSHP system consisting of the vertical type single U-borehole heat exchangers with different lengths for snow melting on pavements and bridge decks. For this purpose, the vertical drilling of the borehole was performed for three different depths (30, 60, and 90 m) in Elazig, Turkey and U-tube heat exchangers were inserted into the corresponding boreholes. Experiments in winter season of 2006-2007 were carried out for melting snow on surfaces of the prototypes of bridge-slab (BS) and pavement-slab (PS) constructed for the experimental study. The effect of the depth of borehole coupled to heat exchanger on the snow melting system performance was experimentally investigated. This way, the snow accumulation on the surfaces of bridge-slab (BS) and pavement-slab (PS) were efficiently heated and thus melted. Development of the model is described in a companion paper.
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    Fe doped-CoB catalysts with phosphoric acid-activated montmorillonite as support for efficient hydrogen production via NaBH4 hydrolysis
    (Pergamon-Elsevier Science Ltd, 2021) Balbay, Asim; Selvitepe, Nuran; Saka, Cafer
    In this study, montmorillonite (MMT) clay was modified with different acids to be used as support material. The modified MMT clay was used to obtain hydrogen in the hydrolysis reactions of NaBH4 (NaBH4-HR) as a support material for the Co-B and Co-Fe-B catalyst. During the activation of MMT clay, the effects of different acids, phosphoric acid (H3PO4) concentration, and impregnation time with H3PO4 were investigated. During the hydrogen generation from the NaBH4-HR, effects of Co loading, Fe loading, NaBH4 concentration, temperature and, catalyst durability were investigated. The maximum HGRs for MMT-H3PO4-CoB and MMT-H3PO4-CoeFeeB treated with 5 M H3PO4 for 7 days were 1869 and 4536 mL/min/gcatalyst, respectively. The activation energies for MMT-H3PO4-CoB and MMT-H3PO4-Co-Fe-B catalyst samples were 49.5 and 38.90 kJ/mol. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Hydrogen Production by Hydrolysis of NaBH4 with Cr-Ni-W-B Catalyst: Effects of Cold Plasma and Chromium Content
    (Walter De Gruyter Gmbh, 2016) Sahin, Omer; Saka, Cafer; Ekinci, Arzu; Balbay, Asim
    In this study, the hydrogen generation from the hydrolysis of NaBH4 with Cr-0.0125-Ni-W-B catalyst prepared in the presence of cold plasma was investigated based on Cr content, NaBH4 concentration, NaOH concentration, temperature, plasma applying time and plasma gases effects. The results of the activity tests indicate that the choice of Cr and the catalyst composition greatly influenced the activity as well as the selectivity for hydrogen generation from the hydrolysis of NaBH4. The Cr-0.0125-Ni-W-B catalyst was treated with argon, nitrogen and carbon dioxide plasma at different treatment times. The catalysts were characterized using SEM, BET surface area measurement and XRD.
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    Influence of plasma treatment on Ce0.05-Ni-W-B catalyst for hydrogen production by hydrolysis of NaBH4
    (Elsevier Sci Ltd, 2016) Saka, Cafer; Ekinci, Arzu; Sahin, Omer; Balbay, Asim
    The aim of this study was to evaluate the effect of plasma treatment on the surface of Ce-0.05-Ni-W-B catalyst. The Ce-0.05-Ni-W-B catalysts were treated with argon plasma at a different treatment time. Ce was used as a promoter. NaBH4 concentration, NaOH concentration, temperature, plasma applying time and plasma gases was investigated for the hydrogen generation from the hydrolysis of NaBH4 with Ce-0.05-Ni-W-B catalyst. The catalysts were characterized using Fourier Transform Infrared spectrometry (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. The results of the activity tests indicate that the plasma treatment greatly influence the activity. The activation energies for zero-order of the untreated and plasma treated Ce-0.05-Ni-W-B catalysts were found to be 51.87 and 41.18 kJ mol(-1), respectively. (C) 2015 Energy Institute. Published by Elsevier Ltd. All rights reserved.
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    Influence of process parameters on enhanced hydrogen evolution from alcoholysis of sodium borohydride with a boric acid catalyst
    (Pergamon-Elsevier Science Ltd, 2020) Saka, Cafer; Balbay, Asim
    The hydrogen evolution via alcoholysis reaction of sodium borohydride with an H3BO3 catalyst was carried out for the first time. In the process of methanol and NaBH4 (NaBH4-MR), the effects of the H3BO3 and NaBH4 concentration, and temperature parameters were examined and evaluated. The hydrogen yields by the NaBH4-MR, NaBH4 ethanolysis (NaBH4-ER) and NaBH4 hydrolysis reactions (NaBH4-HR) with 0.2 M H3BO3 catalyst are 99, 62, and 88% compared to the theoretical hydrogen yield, respectively. The completion times of the NaBH4-MR using the H3BO3 concentrations of 0.2, 0.4, 0.5, 1 M, and saturated acid solution were about 50, 15, 10, 2 and 1 min, respectively. The hydrogen yields obtained with 50, 15, 10, 2, and 1 min for the same acid concentration values were about 100% compared to the theoretical hydrogen value. By increasing the H3BO3 concentration from 0.2 M to the saturated H3BO3 concentration, the completion time of this NaBH4-MR process was reduced by approximately 50 times, resulting in a significant result. The activation energy (Ea) of the NaBH4-MR with the H3BO3 catalyst was 57.3 kJ/mol. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Metal-free catalyst fabrication by incorporating oxygen groups on the surface of the carbonaceous sample and efficient hydrogen production from NaBH4 methanolysis
    (Pergamon-Elsevier Science Ltd, 2022) Saka, Cafer; Balbay, Asim
    In the present study, metal-free catalysts for efficient H-2 generation from NaBH4 methanolysis was produced for the first time from apricot kernel shells with two-step activation. The first stage of the two-stage activation includes the production of activated carbon with the KOH agent (AKOH), and the second stage includes hydrothermally HNO3 activation with oxygen doping (O doped AKOH + N). The hydrogen production rate (HGR) and the activation energy (Ea) of the reaction with the obtained metal-free catalyst (10 mg) were determined as 14,444 ml min(-1) g(-1) and 7.86 kJ mol(-1), respectively. The structural and physical-chemical properties of these catalysts were characterized by XRD (X-ray diffraction), SEM (scanning electron microscopy), elemental CHNS analysis, FT-IR (Fourier transform infrared spectroscopy), and nitrogen adsorption analysis. Also, the reusability results of this metal-free catalyst for H-2 production are promising. (C) 2021 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.
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    Microwave Drying Kinetics of a Thin-Layer Liquorice Root
    (Taylor & Francis Inc, 2012) Balbay, Asim; Sahin, Omer
    Liquorice root (LR) (Glycyrrize glabra) is known as a sweetener and medicine plant. Drying kinetics of LR with initial moisture content of 49.5% (wet basis (w.b)) were experimentally investigated in a microwave drying system. The drying experiments were carried out at different drying temperatures (40, 45, 50, and 55 degrees C) and microwave power levels (250, 500 and 750 W). Several models from literature were selected to fit the experimental data. The fit quality of models was evaluated using the coefficient of determination (R 2), sum square error (SSE), and root mean square error (RMSE). A new model has been proposed for LR drying in the microwave drying. This new model best describes the experimental data for LRs. The activation energy was calculated to be 46.807 kJ/mol and effective diffusivity ranged from 2.9 x 10(-9) to 5.41 x 10(-9) m(2)/s, depending on drying temperatures at constant microwave power level.
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    MODELING OF CONVECTIVE DRYING KINETICS OF PISTACHIO KERNELS IN A FIXED BED DRYING SYSTEM
    (Vinca Inst Nuclear Sci, 2013) Balbay, Asim; Sahin, Omer; Ulker, Hakan
    Drying kinetics of pistachio kernels with initial moisture content of 32.4% wet basis was investigated as a function of drying conditions in a fixed bed drying system. The drying experiments were carried out at different temperatures of drying air (40, 60 and 80 degrees C) and air velocities (0.05, 0.075, and 0.1 m/s). Several experiments were performed in terms of mass of pistachio kernels (15 g and 30 g) using a constant air velocity of 0.075 m/s. The fit quality of models was evaluated using the determination coefficient, sum square error, and root mean square error. Among the selected models, the Midilli et al model was found to be the best models for describing the drying behavior of pistachio kernels. The activation energies were calculated as 29.2 kj/mol and effective diffusivity values were calculated between 1.38 and 4.94.10(-10) m(2)/s depending on air temperatures.