Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Some characteristics of transferred-Arc plasmas (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 65S 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; transferred arcs ; plasma radiation ; plasma heat transfer ; plasma columns ; plasma stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Although the theoretical foundations of the characteristics of transferred arcs were established more than three decades ago, the design of reator systems based on this method of plasma are generation is still in an early stage of development. Although deceptively simple in concept, attempts to use transferred arcs im practical applications at scales of arc length and power somewhat larger than those previously studied in the laboratory soon revealed that considerably more information was required on the arc's unique properties before a sound reactor design could be carried out. This was principally due to the much higher temperature levels (up to 20,000 K) with consequent much higher radiative power achieved in this type of arc, as well as the fluid mechanical effects of the high-velocity plasma gas flowing in the latter. These, in turn, had profound effects on the various modes of heat transfer occurring in the system, on the stability of the arc, on the injection of the material to be treated, and on the overall efficiency of energy utilization in the whole system. The objective of this paper is to summarize the experimental evidence concerning transforred arc characteristics which have been obtained by the author and his colleageus during recent years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01015874
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Heat transfer from a transferred-arc plasma to a cylindrical enclosure (1991)
    Springer
    Plasma chemistry and plasma processing 11 (1991), S. 57-79 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; transferred arc ; plasma reactor ; radiated power ; heat transfer to enclosure ; voltage gradient ; electric field
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Hear-transfer rates from an axially enclosed transferred arc to a surrounding water-cooled cylindrical sleeve, 15 cm high, were measured. The arc (argon or nitrogen) was struck between a movable cathode within the sleeve and a bath of molten copper below the sleeve, serving as anode. The distance from the bottom of the sleeve to the surface of the molten copper (L o) was constant. Variables studied were the diameterD of the sleeve (5, 7.5. and 10 cm), the length of the arc within the sleeveL (5, 10, and 15 cm), the currentI (200, 250, and 300 A) and a tangential flow of gas or vortex within the sleeve (0, ?0, and 50 liters/min). The total power transferred to the sleeve,P s was measured caloronetrically and was the sure ofP r the effective power radiated by the arc of lengthL within the sleeve.P a, the power radiated into the sleeve from the arc of length Lo below the sleeve, andP o , the power radiated from the melt surface (a constant of small value), minusP a , the power lost by convection from the sleeve (negligible, except for a strong vortex). BothP r andP o were found to be equal to the product of the Joule heat released within their respective arc lengths, IVgL and IVg0L0 (where Vg and Vg0 are the voltage gradients), and dimenonless efliciency factors, ηr and η0. which are functions ofL/D andL 0 /D, respectively, for each gas, regardless of the geometry of the sleeve, the current, and the strength of the vortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01447034
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Synthesis gas production from peat using a steam plasma (1984)
    Springer
    Plasma chemistry and plasma processing 4 (1984), S. 297-313 
    Details
    ISSN: 1572-8986
    Keywords: Nontransferred arc ; peat gasification ; plasma reaction model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A steam plasma was used to convert peat into a synthesis gas, suitable for methanol production, in a cocurrent transport reactor. A cylindrical stainless-steel reactor 20 cm in diameter and 120 cm long was used. The effects of temperature and the carbon/ steam molar ratio on the product gas composition and carbon conversion were investigated. Finely ground peat (mean particle size, 63 µm; moisture content, 15.5%) was fed continuously through the reactor top and exposed to mean reaction temperatures ranging from 1250 to 1420 K. The plasma inlet temperature was calculated to be of the order of 3500 K and total powers as high as 62 kW were used. A carbon conversion of 89% and a hydrogen-to-carbon monoxide ratio of 1.8 in the product gas were obtained. A simple model of the reacting system suggested that a conversion of 90% (needed for an industrial process) and a hydrogen-to-carbon monoxide ratio of two could be obtained with equipment modifications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00568983
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Characteristics of transferred-arc plasmas at high TiCl4 concentrations (1990)
    Springer
    Plasma chemistry and plasma processing 10 (1990), S. 99-113 
    Details
    ISSN: 1572-8986
    Keywords: Transferred arc ; metal halides ; reduction ; arc instabilities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The possibility of reducing low-boiling metal halides to the metal in thermal plasmas is attracting increasing attention. However, instability of the arcs in the presence of even low halide concentrations has so far thwarted all research efforts. An experimental study of the effects of adding TiCl4 to an argon transferred arc has shown that instabilities and eventual extinction of the arc are due to severe chemical corrosion of the thoriated tungsten cathode in the presence of chloride. The corrosion results in both the loss of cathode material and the deposition of a blanket of titanium metal on the cathode's surface which supresses electron emission. A systematic search has shown that tantalum carbide cathodes will provide stable operation. Additions of TiCI4 cause a sharp increase in total arc voltage, largely due to an increased cathode /all potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01460450
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Cathode erosion phenomena in a transferred-arc plasma reactor (1992)
    Springer
    Plasma chemistry and plasma processing 12 (1992), S. 17-33 
    Details
    ISSN: 1572-8986
    Keywords: Hot cathode erosion ; effect of plasma gas ; plasma reactors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Phenomena occurring on file surface of a thoriated tungsten cathode operating in a transferred-arc reactor were investigated. The effects of cathode geometry (pointed-tip vs. flat-tip) and plasma gas composition (argon vs. helium) on the rate and mechanisms of cathode erosion were studied experimentally by examining the morphology of the surface before and after runs of prespecified duration, up to one hour in length. For flat-tip cathodes in argon, the major characteristic was the migration of thoria and its concentration at segregated sites. Both geometries in helium operated at much higher temperatures, around the boiling point of tungsten, giving rise to extensive vaporization of cathode material, followed by apparent redeposition of the ionized species carried by file ionic current, in characteristic ringlike sites on the surface. Erosion rates were low and similar in magnitude, except for pointed-tip cathodes operated in argon, where the formation of a large molten sphere of tungsten and its subsequent release gave rise to a higher rate of erosion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01447942
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Operating characteristics and energy distribution in transferred plasma arc systems (1982)
    Springer
    Plasma chemistry and plasma processing 2 (1982), S. 361-386 
    Details
    ISSN: 1572-8986
    Keywords: Transferred arc ; characteristics ; heat transfer ; experimental
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A specially designed plasma chamber was constructed to study the operating characteristics of a dc plasma-transferred arc of argon, struck between a fluid convective cathode and a water-cooled anode. The arc voltage increased markedly with arc length and with an increase in the inlet velocity of the argon flow past the cathode tip, and much less with an increase in current. Radiation from the plasma column to the chamber walls and transfer of energy to the anode were the two principal modes of transfer of the arc energy. The former was dominant in the case of long arcs and at high inlet argon velocities. At the anode, the major contribution was from electron transfer, which occurred on a very small area of the anode (∼5 mm in diameter). Convective heat transfer from the plasma was somewhat less. In all cases, the arc energy contributions to cathode cooling and to the exit gas enthalpy were small. From total heat flux and radiative heat transfer measurements, it was estimated that the plasma temperature just above the anode was in the range 10,000–12,000 K. Preliminary experiments with an anode consisting of molten copper showed that the arc root was no longer fixed but moved around continuously. The arc was othwewise quite stable, and its operating characteristics differed little from those reported for solid anodes, in spite of the greater extent of metal vaporization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00567563
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    The drag coefficients of single spheres moving in steady and accelerated motion in a turbulent fluid (1961)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 7 (1961), S. 615-619 
    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: Drag coefficients of aerodynamically smooth spheres having a density variation of from 0.252 to 1.91 g./cc. and a diameter variation from 1.56 to 3.21 mm. were obtained for acceleration rates varying from 103.5 ft./sec.2 to -30 ft./sec.2 and for relative intensities of up to 45%. The particle-to-Eulerian macroscale ratios varied from 0.50 to 0.16, and the diameter-to-Eulerian microscale ratios varied from 10 to 2.The drag coefficients were found to be a function of the particle Reynolds number and of the relative intensity but not of the acceleration and relative macro-and-microscale variations.A transition theory for the system investigated is presented, which predicts that the product of the critical Reynolds number and the square of the relative intensity should be a constant; it is supported by the experimental results obtained.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690070417
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Effects of turbulence on the drag coefficients of spheres in a supercritical flow Ŕegime (1969)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 15 (1969), S. 184-189 
    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: Drag coefficients of aerodynamically smooth spheres varying in diameter from 0.0625 to 1.004 in. and in density from 0.195 to 7.80 g./cc. were obtained at acceleration rates ranging from 120 to -30 ft./sq.sec. The particles were subjected to relative turbulence intensities of 7 to 35% and to ratios of Eulerian macroscale to particle diameter of about 0.4 to 5.Quantitative measurement of particle drag coefficients was made possible by the use of a new particle tracing technique which permits the resolution of time to the nearest tenth of a millisecond. The resulting data extend farther into the supercritical flow regime than any other measurements previously reported.The variation in drag coefficient with Reynolds number indicates a continuous alteration in the flow pattern around a sphere in this region. The effect of turbulence is, essentially, to increase supercritical drag, although this effect was found to diminish with increasing Reynolds number. Possible mechanisms for the effects of Reynolds number and turbulence on the particle drag coefficient are suggested.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690150211
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Velocity and turbulence measurements of air flow through a packed bed (1971)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 17 (1971), S. 519-528 
    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: Mean velocity and turbulence measurements in the void spaces of a cubic packing of equal spheres have been made at Reynolds numbers of 27,000, 10,000, 5,000 and 2,500, where NRe is based on superficial air velocity and a sphere diameter of 7 cm. Two cubic arrangements were used: in the regular arrangement, the mean flow was parallel to one of the principal axes, while in the skewed arrangement, the mean flow made equal angles with the three principal axes of the packing.Transverse mean velocity and turbulence intensity profiles across the center line of a central pore have been measured behind every bank and behind the bed for the regular arrangement of ten banks of spheres. The power spectrum and probability distribution of the fluctuating velocity have also been determined.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690170309
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Motion of particles entrained in a plasma jet (1973)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 19 (1973), S. 982-990 
    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 motion of small particles (glass microspheres, 30 to 140 microns in diameter) entrained in a free argon plasma jet was studied by means of high-speed cine streak photography. Radial temperature and velocity profiles as well as axial profiles of temperature, velocity, and argon concentration in the jet were experimentally determined by means of a plasma calorimetric probe. The system was found to be characterized by low relative Reynolds numbers (0.2 to 20) and extremely high deceleration rates (about -2,000 g). Under these conditions, an increase of drag coefficient over that predicted by the standard curve was experimentally observed. This increase was attributed to the nonsteady flow field around the particle (the so-called “history term” in the equation of motion). A general computer program has been proposed which predicts the particle velocity, acceleration and temperature along its trajectory.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690190515
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...