Band 17, Heft 3 -

Here impact of activation energy in binary chemically reactive flow of third grade fluid is addressed. Flow is discussed by a stretchable rotating disk. Novel characteristics regarding thermophoresis and Brownian movement have been analyzed. Nonlinear thermal radiation is considered. Convergent series solutions to nonlinear problems are computed. Impacts of various physical parameters like Brownian motion parameter, Prandtl number, mixed convection parameter, thermophoresis parameter, radiation parameter, activation energy, chemical reaction and Schmidt number on the velocity, concentration and thermal fields are discussed and analyzed. Velocity, temperature and concentration gradients are computed and discussed through various flow variables. Their obtained results present that velocity, temperature, concentration fields are strongly depends on the flow parameters. Main conclusions are presented.

Comparing with other biological processes, a technological method associated with bio-energy has been developed as the result of the high possibility of fermentative hydrogen productivity; In addition, restricted fossil fuel has been also substituted. The production of fermentative hydrogen is a complicated process influenced by different factors including different kinds of micro-organisms, initial concentration of substrate, inoculum size, initial pH of the medium, concentration of nutrients metals, etc. Thus, the present study is aiming at detecting such different agents to obtain the highest yield of hydrogen and progressing its operation through improving the efficiency of these agents by reliable experimental design. Clostridium saccharoperbutylacetonicum N1-4(ATCC 13564) was applied to produce hydrogen in a batch manner. The highest yield of hydrogen has been resulted in 3.016 mol of hydrogen per mol glucose with production rate of 3.281 mole of hydrogen per hour at 37 °C, 10 % of inoculums size, 10 g/L of an initial glucose concentration, initial pH of medium of 6.5, 30 mg/L of FeSO 4 .7H 2 O. Furthermore, the experimental results were compared to kinetic model of Gompertz. Moreover, it was found out that the experimental issues were compatible with this kinetic model with the regression coefficient values of 0.989.

The experiment of improving Selective Non-Catalytic Reduction (SNCR) denitrification efficiency with gas additives (CH 4 and C 3 H 8 ) was carried out in the 50 kW circulating fluidized bed (CFB) pilot-scale equipment. The results show that the denitrification efficiency can reach 20 % when the reaction temperature is 650 °C, and the optimum mole ratio of C 3 H 8 /NH 3 is 0.5. The denitrification efficiency can exceed 50 % when the mole ratio of C 3 H 8 /NH 3 is 0.4 and the reaction temperature is 720 °C. However, the CH 4 additive does not promote denitrification at this temperature. When the reaction temperature is 760 °C, the optimum denitrification efficiency of CH 4 is 60 %, and the required CH 4 /NH 3 is 0.8. Once the amount of CH 4 exceeds the optimal value, the denitrification efficiency is suppressed. In addition, the concentrations of N 2 O and CO in the gas increase significantly with an increase of gas additives. Due to the incomplete oxidation of C 3 H 8 , a large amount of C 2 H 4 is produced in the low-temperature region (< 750 °C) of SNCR.

Methyl laurate was synthesized from lauric acid and methanol using Brønsted acid ionic liquids as catalysts, by an esterification reaction. The efficiencies of four different catalysts, 1-methylimidazolium hydrogen sulfate ([Hmim]HSO 4 ), 2-pyrrolidonium hydrogen sulfate ([Hnhp]HSO 4 ), 1-(3-sulfonic acid) propyl-2-pyrrolidonium hydrogen sulfate ([C 3 SO 3 Hnhp]HSO 4 ) and H 2 SO 4 were compared. The effect of the methanol/lauric acid molar ratio, reaction temperature, reaction time, and catalyst dosage on the lauric acid conversion was investigated by single-factor experiments. On the basis of single-factor experiments, the esterification of lauric acid and methanol was optimized using response surface methodology (RSM) based on central composite design (CCD). The results showed that the most effective catalyst was the ionic liquid [C 3 SO 3 Hnhp]HSO 4 . The optimal conditions were as follows: [C 3 SO 3 Hnhp]HSO 4 dosage of 10 % (based on the mass of lauric acid), methanol/lauric acid molar ratio of 9:1, reaction time of 1 h and reaction temperature of 70 °C. Under these conditions, the lauric acid conversion reached 95.33 %. The catalytic activity of [C 3 SO 3 Hnhp]HSO 4 still remained high after 5 cycles.

The multigene genetic programming (MGGP) technique based hydrodynamics models were developed to predict the solids holdups of a liquid-solid circulating fluidized bed (LSCFB) riser. Four different particles were considered to investigate the effects of particle size, shape and density on hydrodynamics behavior of the LSCFB riser. In this regard, two spherical shape glass bead particles (500 and 1200 μm), two irregular shape lava rock particles (500 and 920 μm) were employed as solid phase and water as liquid phase. The MGGP models were developed, relating the solids holdup (εs${\varepsilon _s}$, output parameter) with eight input parameters. The developed models were first validated by comparing the model predicted and experimental data of solids holdups. The average solids holdups decreased with the increase of net superficial liquid velocity (Ul−Ut${U_l} - {U_t}$) and normalized superficial liquid velocityUlUt$\left( {\frac{{{U_l}}}{{{U_t}}}} \right)$. Uniform axial solids holdups observed in axial locations (H) except close to the liquid-solid distributor of the riser. The radial non-uniformity of solids holdup observed all radial positions (r/R). In the central region almost flat but increased toward the wall region. The radial profiles of the solid holdup are approximately identical at a fixed average cross-sectional solid holdup for all of the three LSCFB systems of this study. The statistical performance indicators such as the mean absolute percentage error and correlation coefficient are also found to be within acceptable range. All these findings of suggest that the MGGP modeling approach is suitable for predicting effect of particle size and shape on hydrodynamics behavior of the LSCFB system

Fructofuranosidase (EC 3.2.1.26) from Aureobasidium sp. ATCC 20524, recovered from 5 L fermented medium, purified by two simple steps with a yield of 65 % and a purification factor of 16, was immobilized by adsorption onto titanium dioxide (FTIO). The enzyme was also covalently immobilized onto TiO 2 coated with polyethyleneimine (FTIOP) and encapsulated in gellan gum (FTIOPG). FTIO and FTIOP recorded an activity of 903 U g −1 and 9212 U g −1 , respectively. The immobilized enzyme showed high activity and stability at pH levels ranging from 4.0 to 8.0 and there were no changes in the temperature profile for either methodology when compared with free fructofuranosidase. The immobilized biocatalysts were reused 7 times for FOS production without significant activity loss, except FTIO at pH 5.0. Gellan gum was used for FTIOP encapsulation. FOS production was performed in a batch and a continuous reactor using FTIOPG as a biocatalyst. Batch conversion (g FOS /g initial sucrose ) was around 60 % for initial sucrose concentrations of 100, 300 and 600 g L −1 , at a time of maximum conversion. Fixed-bed reactor operational stability was remarkable, providing a constant FOS production in the outlet of the column during 720 h.

The water splitting reaction using aluminum represents one of the best methods for on-demand hydrogen requirements. The present paper describes the hydrogen generation in water splitting reaction using aluminum in presence of potassium hydroxide as an alkaline activator. The effect of concentration of KOH, temperature, and shape of aluminum particles on the hydrogen generation in water splitting reaction was experimentally studied using various concentrations of aqueous KOH viz. 0.25 N, 0.50 N, 0.75 N and 1.0 N, at different temperatures of 30 °C, 40 °C, and 50 °C for Al powder (diameter: 200 mesh) and Al foil (thickness: 11 microns). The complete conversion of Al was recorded for all the experimental runs. The average hydrogen generation rate was found to vary between 3.40 ml/min to 21 ml/min per 0.1 g aluminum under considered concentrations and temperatures. The shrinking core model was applied to the experimental data for predicting the rate controlling mechanism.

Main motivation of the present research article is to investigate impact of Arrhenius activation energy in stagnation point flow of hybrid nanomaterial towards a stretched surface. Hybrid nanomaterial comprises of two or more types of nanomaterials along with continuous phase liquid. In this study two types of nanofluids are used namely titanium dioxide and copper. Nonlinear system is converted to ordinary system through appropriate transformation. For convergence series solutions, the obtained system is solved using homotopy analysis methods. Lorentz force impact is observed. Graphical results for different physical variables on the velocity, concentration, induced magnetic field and temperature for Cu−H2O$Cu - {H_2}O$ and TiO2−Cu/H2O$Ti{O_2} - Cu/{H_2}O$ are discussed. The physical aspects of skin friction and Sherwood and Nusselt numbers are discussed by tabulated values.

During the plasma modification process on activated carbon surface, reactive gas of O 2 in the plasma field dominates the formation of oxygen-containing groups on activated carbon surface, which is a key factor that affects the mercury adsorption. Previous studies showed that change the O 2 concentration would influence the generation of oxygen-containing groups and thus affect the mercury adsorption. It is important to investigate the effects of O 2 concentration in the non-thermal plasma field on the mercury adsorption characteristic of modified activated carbon. This work presents the results of the novel use of non-thermal plasma in Ar-O 2 gas to increase surface oxygen functionality on the surface of a commercially available biomass carbon. The volume fraction of O 2 in the Ar-O 2 mixture was varied from 10 % to 100 %. The surface physical and chemistry properties of modified activated carbon were analyzed by using BET, FT-IR and XPS techniques. Results showed that activated carbon modified by Ar-O 2 non-thermal plasma showed significantly better mercury removal performance compared with the original activated carbon. Moreover, increase O 2 concentration in the plasma field can further increase the mercury removal efficiency of modified activated carbon. Higher O 2 concentration can produce more O radicals during plasma system and facilitated the formation of carbonyl and ester groups on activated carbon surface and thus enhanced the mercury removal. Temperature programmed desorption (TPD) results indicated that mercury reacted with ester groups were prior to carbonyl groups. When O 2 concentration increased to 100 %, the ester groups of modified activated carbon dominated the mercury adsorption process.

The problem discussed in the paper was revealed during experimental and simulation study of the waste fuel utilization (low concentrated CH 4 ) which in coal mines is emitted to the atmosphere as the so-called ventilation air methane (abbreviation: VAM). When an intense heat recovery would be applied to the Reverse-Flow Reactor (RFR) then the reactor becomes susceptible to creation of temperature profiles asymmetry. This may adversely affects the heat recovery efficiency. When a strong asymmetry arises, it can significantly reduce the heat recovery and the system needs immediate counteraction. Commonly used control systems do not always cope with this problem. The paper discusses various RFRs control algorithms from the point of view of the ability to reduce symmetry to the acceptable range. The impact of the loss of reactor symmetry on possible heat recovery efficiency is also briefly discussed. The work is focused on RFRs which operate with significant heat recovery in a heat exchange unit in which heat is retrieved not at the rector outlet, but by cooling the hot gas from the center part of the reactor. Issues discussed in the paper are derived from being carried out in ICE-PAS through many years of simulation research, patent examinations, but primarily from the own experiences on the research & demonstration thermal flow reversal reactor (TFRR) for VAM combustion. Computer control & data recording system process data records of the experiments enabled effectively analyze the problem of creating and preventing thermal asymmetry.