Bekir Zühtü Uysal

Fuzzy Modeling of Performance of Counterflow Ranque-Hilsch Vortex Tubes with Different Geometric Constructions

In this article, we present the development of a fuzzy expert system (FES) for fuzzy modeling of the performance of counterflow Ranque-Hilsch vortex tubes for different geometric constructions. Experimental values were obtained from a detailed experimental investigation. With these experimental values, FES models of the Ranque-Hilsch vortex tube behavior were designed using the MATLAB 6.5 fuzzy logic toolbox in Windows XP running on an Intel 3.0-Ghz PC. For this process P, N, ξ, and L/D were chosen as input and ΔT h , ΔT c , ΔT as output parameters. FES results agree well with experimental data. It was found that the coefficient of multiple determination (R 2 value) between the actual and fuzzy predicted data is ΔT h = 0.9801, the R 2 value for ΔT c values is 0.9841, and the R 2 value for ΔT values is 0.9748.

Parametric Investigation of Oil-Shale Extraction with Organic Solvents

Abstract Oil-shale deposits at El-lajjun, a rich oil-shale area south of Jordan, were extracted with organic solvents. The amount of extracted oil depends on the operating conditions and parameters which affect the process. The effects of particle size, extraction time, extraction temperature, mixing rate, solvent-to-oil-shale ratio, and type of solvent were investigated.

Extraction of El-Lajjun Oil Shale

Abstract Extraction of the bitumen fraction of El-Lajjun oil shale was carried out using 17 different solvents, pure and combined. Out of all the solvents used, toluene and chloroform were found to be the most efficient for extraction of the bitumen to perform the major part of the experiments. This selectivity was based on the quality and quantity of the yield and on the quantity of solvent recovered. Extraction was carried out using a Soxhlet extractor. For complete recovery of solvent the extract phase was subjected to two stages of distillation, simple distillation followed by fractional distillation, where different cuts of oil were obtained. It was found that an optimum shale size of 1.0 mm offered better solvent recovery. One hour was the optimum time needed for complete extraction. The yield of oil was determined from the material balance gained from fractional distillation after testing for the existence of any traces of solvent trapped in the different cuts by using a gas chromotography techniqu...

Drying characteristics of oil shale

The tray-drying process for oil shale has been analyzed and modeled. The results for the falling drying-rate domain were correlated with a generalized exponential model that incorporates the effects of dry-bulb temperature and particle size. The results indicate that the drying process is a strong function of the operating dry-bulb temperature. The effect of temperature is more pronounced for particles smaller than 2 mm than for larger particles. The particle size was found not to be important at low temperatures of about 50 °C but was important for particles larger than 4 mm at temperatures greater than 67 °C.

Gas hold-up in a bidimensional two-phase spouted bed

Experimental gas hold-up data in a two-dimensional spouted bed, 22 mm × 220 mm × 1250 mm, at superficial gas velocities between 0.34 and 3.43 m s−1, operating continuously with respect to the gas flow and batchwise with respect to the liquid and using a single-nozzle gas sparger are presented. The effect of the static liquid height, nozzle diameter and superficial gas velocities on gas hold-up were studied. The gas hold-up was measured directly by using the bed expansion technique. The effect of nozzle diameter on the gas hold-up was found to be insignificant. Results were well correlated by the following equation eg = 0. 182 Ug0.584 H−0.288 with an average deviation of less than 1%. The correlation is compared with others available in the literature.

Gas hold-up in a bi-dimensional three-phase spouted bed

Abstract Gas hold-up in a bi-dimensional three-phase spouted bed, operated continuously with respect to the gas flow and batchwise with respect to liquid and solid, was investigated using a bed expansion technique. Experiments were performed in a column of 22 mm × 220 mm × 1250 mm. Sand particles 1.0 mm in diameter, solid fractions 0.05, 0.10, 0.15 and 0.20, five different nozzle sizes (4.0 mm, 5.5 mm, 7.0 mm, 10.0 mm and 12.0 mm), four static bed heights (0.17 m, 0.32 m, 0.58 m and 0.69 m) and superficial gas velocities ranging from 0.34 to 3.43 m s−1 were employed. A correlation for the gas hold-up was developed with an average deviation of 2.5% and maximum deviation not exceeding 9%.

Drying characteristics of oil-shale

Abstract The tray-drying process of oil-shale was analyzed and modeled. The results for the falling drying-rate domain were correlated into a generalized exponential model that incorporates the effects of dry bulb temperature end particle size. The results indicated that the drying process is a strong function of operating dry bulb temperature. The effect of the temperature was more pronounced for particles smaller than 2 mm. Particle size was found to be not very effective at low temperatures about 50°C but was important for particles larger than 4 mm at temperatures greater than 67°C.

A parametric study on coal gasification for the production of syngas

In this parametric study, the effects of coal and oxidiser type, air-to-fuel ratio, steam-to-fuel ratio, reactor temperature, and pressure on H2 and CO amounts at the gasifier output, H2/CO, and higher heating value of the syngas produced have been calculated using a coal gasification model. Model simulations have been performed to identify the optimum values which are assumed to be 100 % for both cold gas efficiency and carbon conversion efficiency in the gasification process. From this study, it may be observed that the moisture content of the coal type is of crucial importance for the air gasification process; the O2 content of similar coals (taking into consideration the moisture and H2 content) is of significant importance for the air gasification process. When compared with air gasification, air-steam gasification becomes a more effective coal gasification method. The optimum working condition for air-steam gasification is to carry out the process at one atmosphere. High gasifier temperatures are not needed for the air-steam gasification of coal.

Combustion Reactivity of Chars

Combustion of chars with special reference to oil shale in fluidized-beds is discussed. The kinetics of char combustion is reviewed. The total time required for carbon burn off is considered for both kinetic controlled combustion and mass transfer controlled combustion. The importance of intraparticle diffusion on the rate of combustion of oilshale particles is explained. The effects of the devolatilization, the decomposition reactions, the carbonate and silicate minerals and the presence of sulphur on char combustion are also described.