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  • 1
    Electronic Resource
    Electronic Resource
    Methane steam reforming: II. Diffusional limitations and reactor simulation (1989)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 35 (1989), S. 97-103 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Given the intrinsic kinetics, the tortuosity factor of a Ni/MgAl2O4 catalyst was determined under reaction conditions by minimizing the sum of squares of residuals of the experimental and the simulated conversions. The parallel cross-linked pore model with uncorrelated pore size distribution and orientation was used in the calculation of the effective diffusivities. A modified collocation method was used to obtain the partial pressure profiles of the reacting components in the catalyst pellet. The simulation of the experimental reactor during the optimization of the tortuosity factor also yielded the effectiveness factors of the reactions. The results of the simulation of an industrial steam reformer are also discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690350110
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  • 2
    Electronic Resource
    Electronic Resource
    Thermal cracking of light hydrocarbons and their mixtures (1977)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 23 (1977), S. 93-106 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics and product distributions of the thermal cracking of binary and ternary mixtures of ethane, propane, n- and i-butane were determined in a pilot plant under conditions of residence time, temperature, total pressure, and dilution as close as possible to those prevailing in industrial operation. The kinetics and yields observed with ternary mixtures were compared with those obtained with binary mixtures and with pure components. The experimental selectivities were compared with those which would be obtained from separate cracking and subsequent addition of the product streams. The deviations between the two can be predicted by means of the so-called global kinetics selectivities, which are based upon the selectivities obtained from the pure components cracking and upon the global rates of cracking of the feed components in the mixture.
    Additional Material: 26 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690230114
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  • 3
    Electronic Resource
    Electronic Resource
    Methane steam reforming, methanation and water-gas shift: I. Intrinsic kinetics (1989)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 35 (1989), S. 88-96 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Intrinsic rate equations were derived for the steam reforming of methane, accompanied by water-gas shift on a Ni/MgAl2O4 catalyst. A large number of detailed reaction mechanisms were considered. Thermodynamic analysis helped in reducing the number of possible mechanisms. Twenty one sets of three rate equations were retained and subjected to model discrimination and parameter estimation. The parameter estimates in the best model are statistically significant and thermodynamically consistent.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690350109
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  • 4
    Electronic Resource
    Electronic Resource
    Coupled simulation of heat transfer and reaction in a steam reforming furnaceDedicated to Professor Dr. Hanns Hofmann on the occasion of his 65th birthday (1989)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 12 (1989), S. 20-26 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For design and simulation of chemical process furnaces in accordance with present-day standards, the temperature distributions in the firebox and in the reactors must be generated simultaneously. This calls for coupling of the simulations of the firebox and of the reactor. For the calculation of heat transfer in the firebox, a generalized furnace simulations program, based on the zone method, is applied. Monte Carlo simulation techniques are used to determine the view factors. The location of the burners is explicitly accounted for. Absorption and emission of radiation by the flue gas are calculated by considering band contributions for carbon dioxide and water. For the simulation of the steam reforming reactors, a one-dimensional heterogeneous model, which accounts for the presence of intraparticle partial pressure gradients, is used. The simulated temperature distribution in the furnace is in excellent agreement with industrial results, as is the simulated product distribution.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270120105
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  • 5
    Electronic Resource
    Electronic Resource
    The effect of steric hindrance on physical properties in an amine-cured epoxy (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 35 (1988), S. 1367-1375 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A pair of aliphatic amines were synthesized in order to study the effect steric hindrance has on the physical properties of an amine-cured epoxy resin. The hindered amine (TMSiDA) has NH2 groups that are obstructed by the presence of adjacent methyl groups while the unhindered amine (SiDA) does not contain any NH2 steric hindrance. DGEBA cured with TMSiDA is less dense, absorbs less moisture, and has a higher Tg than does SiDA/DGEBA. Torsional pendulum results show that TMSiDA/DGEBA has a slightly higher rubbery modulus and a secondary transition at a lower temperature than DGEBA cured with SiDA. Activation energies for the secondary transition were determined for TMSiDA/DGEBA and SiDA/DGEBA and are 19 and 14 kcal/mol, respectively.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070350521
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  • 6
    Electronic Resource
    Electronic Resource
    Dielectric and dynamic mechanical measurements of poly(4-methyl pentene-1) (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 3057-3064 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The α-relaxation process of poly(4-methyl pentene-1) was studied by dielectric and dynamic mechanical means. The complex dielectric constant was determined at nine discrete frequencies from 100 to 10,000 Hz and over a temperature range of -50-90°C. The complex dynamic mechanical Young's modulus was determined over the audiofrequency range of 10-22,000 Hz and a temperature range of 21-76°C, from which a master curve was constructed. The relaxation process was studied by comparing the activation energies and width of the dispersion curves. The results of a logarithmic frequency vs. reciprocal temperature plot of the loss peak maxima show that both the dielectric and mechanical curves are roughly linear but have different slopes. From the slopes the activation energies were determined. For the dielectric data an activation energy of 39 kcal/mol was obtained, whereas for the mechanical data a value of 106 kcal/mol was found. The width of the dispersion curves was determined by using a Cole-Cole empirical fit. The width of the dielectric dispersion curve is narrower by as much as a factor of 3 than the mechanical dispersion curve. It is concluded that the energy to cause the large scale molecular motion involved in the α-relaxation is lower when excited by an alternating electric field than by an alternating stress field. Also the number of repeat units involved is smaller in the dielectric case than in the mechanical case.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070291010
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  • 7
    Electronic Resource
    Electronic Resource
    Thermal and dynamic mechanical properties of polyurethaneureas (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 35 (1988), S. 1829-1852 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Measurements were made of the thermal and dynamic mechanical properties of 22 polyurethaneureas of varying diol molecular weight, type of aromatic chain extender, diol molecular weight distribution, and chain extender stoichiometry. The dynamic mechanical data, obtained as a function of temperature and frequency (in the kHz region), were used to construct master curves of shear modulus and loss factor over a wide range of reduced frequencies. Based on these master curves, interpreted in conjunction with the thermal analysis results, it was found that: Soft segment crystallization occurs at the higher diol molecular weights, dynamic mechanical properties are well correlated with the soft segment glass transition, diol molecular weight influences dynamic mechanical properties by affecting the degree of phase separation and hence glass transition temperature, and neither diol molecular weight distribution nor chain extender stoichiometry have a significant effect, in the ranges studied, on transition temperatures or dynamic mechanical properties.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070350710
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of test frequency and cure on glass transition temperature predictions on some epoxy polymers (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 29 (1984), S. 1471-1474 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1984.070290440
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  • 9
    Electronic Resource
    Electronic Resource
    Tensile yield in polypropylene (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 823-828 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Untaxial tension tests to the yield point were performed on polypropylene as a function of temperature from 22 to 143°C at a strain rate of 2 min-1. At 22, 42, and 71°C, measurements were also made at strain rates from 0.02 to 8 min-1. Yield energy was found to be a linear function of temperature extrapolating to zero at the melting point (164°C). The ratio of thermal to mechanical energy to produce yielding is about three times smaller than for glassy polymers. The ratio of yield stress to (initial) Young's modulus is about 0.024 at room temperature and increases to 0.043 at 143°C. Yield stress is a linear function of unstrained volume.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760271109
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  • 10
    Electronic Resource
    Electronic Resource
    Calculation of relaxation time in polyurethanes using additive group contributions (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 1985-1993 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The method of additive properties was used to calculate the dynamic mechanical relaxation time for a series of polyurethanes. Calculations were also made of density and glass transition temperature. Group contributions for nine component groups were determined. With these group values, the densities of the 12 polymers used to determine the groups were calculated and found to agree with measured values within an average of 0.2%. Calculated glass transition temperatures also agreed with measured values within 0.2%. The relaxation time, defined as a parameter in the Havriliak-Negami equation, was shown to be correlated with the glass transition temperature, allowing relaxation time to also be expressed as an additive property. Calculated logarithms of relaxation times agree with measured values to within 7% over a range of relaxation times covering many decades. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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