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  • 1
    Electronic Resource
    Electronic Resource
    The polymerisation of ethylene with high activity magnesium reduced titanium trichloride catalysts in the absence of hydrogen (1974)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 175 (1974), S. 3461-3473 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polymerisation von Äthylen unter Verwendung eines mit Magnesium reduzierten Titantrichlorid-Katalysators, zusammen mit gewöhnlichen Aluminiumalkyl-Aktivatoren, wird beschrieben. Die bereits berichtete hohe Aktivität dieses Katalysatortyps wird bestätigt. Bei 50°C und 1 Atm. (1,01325 bar) Druck wird ein Wert für die Aktivitätskonstante von 3,4.106 g dm3 (mol TiCl3)-1 h-1 erhalten. Dieser Wert ist ungefähr 102 mal höher als derjenige eines auf übliche Weise mit Aluminium reduzierten Titantrichlorids. Die Viskosotäts-Molekulargewichts-Zeit (oder Umsatz)-Beziehungen sind nicht sehr verschieden von denen, die mit den üblichen Katalysatoren erhalten werden. Die Analyse der Resultate weist darauf hin, daß ein großer Teil (z. B. 50%) der Titan-Atome im Titantrichlorid, das mit Magnesium reduziert wurde, als aktive Zentren fungieren.
    Notes: The polymerisation of ethylene using magnesium reduced titanium trichloride catalysts, together with the usual aluminium alkyl activators is described. The previously reported high activity of this type of catalyst was confirmed. At 50°C and 1 atm. (1,01325 bar) pressure a value of 3,4.106 g dm3 (mol TiCl3)-1h-1 was obtained for the activity constant, a value about 102 times larger than for a conventional aluminium reduced TiCl3. On the other hand the viscosity-molecular weight-time (or conversion) relations are not very different from those given by conventional catalysts. Analysis of the results suggests that a high proportion (e.g. 50%) of the titanium atoms in the magnesium reduced TiCl3 functions as active sites.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1974.021751212
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  • 2
    Electronic Resource
    Electronic Resource
    Transport characteristics of suspensions: Part IV. Friction loss of concentrated-flocculated suspensions in turbulent flow (1962)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 8 (1962), S. 266-271 
    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: Turbulent flow friction factors were determined for flocculated suspensions of thoria, kaolin, and titania in tubes 1/8- to 1-in. diameter. The non-Newtonian laminar flow data were arbitrarily fitted with the Bingham plastic model. With this model the range of yield stress values was 0.018 to 1.39 lb.f/sq. ft., with a maximum ratio of coefficient of rigidity to viscosity of suspending medium of 11.1. The volume fraction solids were varied from 0.042 to 0.23.Two types of behavior were observed depending on the value of the yield stress. For yield values less than 0.5 lb.f/sq. ft. the turbulent friction factors were always less than those for Newtonian fluids but tended to approach the Newtonian values as the Reynolds number was increased. For yield values greater than 0.5 lb.f/sq. ft. the friction factors were again less than those for New-tonian fluids but tended to diverge from the Newtonian values as the Reynolds number was increased. Both sets of data were correlated with the Blasius relation with the coefficient and exponent given in terms of the laminar flow properties und the volume fraction solids.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690080227
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  • 3
    Electronic Resource
    Electronic Resource
    Transport characteristics of suspensions: Part VI. Minimum transport velocity for large particle size suspensions in round horizontal pipes (1962)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 8 (1962), S. 373-378 
    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 minimum transport velocity (defined as the mean-stream velocity required to prevent the accumulation of a layer of stationary or sliding particles on the bottom of a horizontal conduit) vas determined in a 1-in. pipe for an aqueous suspension of glass beads using glass beads having mean diameters of 78 and 310 μ.The results of the present study were combined with prior pneumatic- and hydraulic-transport data for air and water suspensions to give a unique minimum-transport relation, valid for particles larger than the thickness of the laminar sublayer, that is for particles which are immersed in the buffer layer or which extend into the turbulent core when resting on the pipe wall. The correlation showed that the ratio of particle settling velocity to friction velocity at the minimum transport condition was a function of particle Reynolds number, pipe Reynolds number, and the relative density ratio of particle to fluid. The results of the correlation suggest that a single mechanism is responsible for the initiation of particle transport throughout the range of conditions covered. This mechanism may be identified with Bernoulli forces due to instantaneous velocity differences accompanying turbulent fluctuations and largely confined to the buffer layer.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690080323
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  • 4
    Electronic Resource
    Electronic Resource
    Turbulent disruption of flocs in small particle size suspensions (1964)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 10 (1964), S. 517-523 
    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: In the absence of turbulent fluctuations the main effect of a velocity gradient on the floc properties is a rearrangement of particles within the floc producing a more dense floc structure. When the suspension is sufficiently dilute that floc-floc collisions are negligible, the limits on the floc diameter are (1 + α)5/3 〈 (Df/Dp) ≤ (1 + α)2, where α is the ratio of the volume of fluid immobilized in the floc structure to volume of solids in the floc structure as determined from hindred-settling measurements. These results set an upper limit on the floc size.Under turbulent flow conditions the principle mechanism leading to floc rupture is pressure differences on opposite sides of the floc which cause bulgy deformation and rupture. The breakup of the floc is resisted by the yield stress τy and is promoted by an increase in the energy dissipation per unit mass of fluid ∊. Because the energy dissipation per unit mass is at a maximum near the pipe wall, the floc size is at a minimum in this same region.By application of the concepts of local isotropy, the floc size is found to be proportional to (τy9/∊5)1/2once the turbulent intensity is sufficient to overcome the yield stress. In the wall region the floc diameter is proportional to (du/dr)3 (τy9/∊8)1/2.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690100420
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  • 5
    Electronic Resource
    Electronic Resource
    Transport characteristics of suspensions: Part IX. Representation of periodic phenomena on a flow regime diagram for dilute suspension transport (1964)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 10 (1964), S. 303-308 
    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: Four different flow regimes may be identified during transport of dilute suspensions of solid particles through horizontal pipes by liquids in turbulent flow as the velocity is varied. The regimes may be characterized by the distribution of solids in the channel. In two of the regimes the bulk of the material is immediately adjacent to the bottom of the channel and is clumped up either into transverse waves (dunes or islands) with a reproducible periodicity or into longitudinal waves (long stria). The definition of the other two regimes is somewhat more arbitrary but may qualitatively be described as heterogeneous or homogeneous flow. Extensive studies of the conditions under which transverse and longitudinal waves occurred, when combined with results of previous studies, showed that all four of these flow regimes may be conveniently represented on a single diagram in which the terminal-settling velocity divided by the friction velocity and the Reynolds number on particle diameter and friction velocity are the coordinates. Because the particle Reynolds number based on the terminal-settling velocity can be uniquely defined as an additional parametre on such a diagram the particular flow behavior for any given combination of system and particle characteristics can be readily determined.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690100307
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  • 6
    Electronic Resource
    Electronic Resource
    Dropwise and filmwise condensation of water vapor on gold (1973)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 19 (1973), S. 119-123 
    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: A pure gold tube was found to give filmwise condensation in the absense of organic contamination in a flow sitution simulating that found in seawater conversion plants. A sensitive test for the presence of organic contamination has been developed. The gold tube, promoted by paraffinic thio-silane or mercaptan, gave 100% excellent dropwise condensation. Overall heat transfer coefficients are reported for filmwise and dropwise condensation. The steamside heat transfer coefficient with dropwise condensation was estimated to be over 0.2 MW/m2-°C (35,000 B.t.u./hr-ft2-°F) at the 95% confidence level.Gold plated tubesSupplied by P. Tomalin and S. Mulford of the Office of Saline Water, USDI. gave 95% filmwise condensation after one week of operation in a clean, once-through system.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690190117
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  • 7
    Electronic Resource
    Electronic Resource
    Transport characteristics of suspensions: II. Minimum transport velocity for flocculated suspensions in horizontal pipes (1961)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 7 (1961), S. 423-430 
    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 minimum transport velocity (defined as the mean stream velocity required to prevent the accumulation of a layer of stationary or sliding particles on the bottom of a horizontal conduit) has been determined for flocculated thorium oxide and kaolin suspensions flowing in glass pipes. The pipes ranged from 1 to 4 in. in diameter, and the concentration was varied from 0.01 to 0.17 volume fraction solids.Two flow regimes were observed depending on the concentration of the suspension. In the first the suspension was sufficiently concentrated to be in the compaction zone and hence had an extremely low settling rate. The second regime was observed with more dilute suspensions which were in the hindered-settling zone and settled ten to one-hundred times faster than slurries which were in compaction. The concentration for transition from one regime to the other was dependent on both the tube diameter and the degree of flocculation. The suspension particles were smaller than the thickness of the laminar sublayer, and they settled according to Stokes' law for the particular conditions of this study. Under these circumstances the relation developed for dilute suspensions is consistent with particle transfer in the radial direction owing to Bernoulli forces on the particle and the action of turbulent fluctuations which penetrate the laminar sublayer. For concentrated suspension in compaction the minimum transport velocity was given by a characteristic critical Reynolds number.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690070316
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  • 8
    Electronic Resource
    Electronic Resource
    Transport characteristics of suspensions VII. Relation of hindered-settling floc characteristics to rheological parameters (1963)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 9 (1963), S. 310-316 
    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: Both the rheological and the hindered-settling characteristics of small particle size suspensions (0.1 to 50 μ) are primarily determined by the degree of flocculation and the concentration of the suspension. Previous studies have shown that when the laminar shear diagrams are fitted by the Bingham plastic model, the parameters τy/φ3 and φ-1 In η/μ are constants which are proportional to the degree of flocculationThe present study showed that these rheological parameters were proportional to the value of α determined from the hindered-settling measurements (α is defined as the ratio of the volume of fluid immobilized by the floc structure to the volume of solids in the floc structure). The materials studied included suspensions of thorium oxide in water and methanol and of titania, kaolin, alumina, and graphite in water. The particle size range was from 0.40 to 17.0 μValues of the attractive force between particles calculated from the rheological and hindered-settling data were in good agreement with each other and with the theoretical values calculated from the Derjaguin-Verwey-Overbeek theory of colloid stability. The good agreement among the different values suggests that the present approach may be generally applicable to a variety of different systems.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690090308
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  • 9
    Electronic Resource
    Electronic Resource
    Increased polarization caused by films covering hyperfiltration membranes (1971)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 910-915 
    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: No. Abstract.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690170425
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  • 10
    Electronic Resource
    Electronic Resource
    Dropwise condensation phenomena (1973)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 19 (1973), S. 839-845 
    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: Dropwise condensation of water vapor on long vertical tubes was investigated as to in situ cleaning and promoting techniques for a variety of tube materials.Excess promoter on the tube surface significantly reduces heat transfer but appears to be slowly removed by draining.Measured steamside heat transfer coefficients for copper, gold, Admiralty, Cu-Ni 90-10, and Monel tubes are adequately correlated by the theory of Mikic (1969) modifide to include the effect of wall thickness.A photographic study revealed that falling drops are elongated into rivulets on long vertical surfaces. Short (〈 65 mm) rivulets and small, barely visible drops over most of the area are evidence of excellent dropwise condensation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690190424
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