Heat transfer in agitated vessels with special types of impellers.

Ishibashi, K.; Yamanaka, Akihiro; Mitsuishi, Nobuo

doi:10.1252/jcej.12.230

Cited by 28 publications

(7 citation statements)

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“…To date, few studies have identified correlations for heat transfer on a cooled impeller. Nagata et al (1972), Mitsuishi and Miyairi (1973) and Ishibashi et al (1979) presented heat transfer correlations for helical-screw and helical-ribbon impellers. In all the cases (for moving or non-moving walls), for laminar regime researchers recommended a value of 1/3 for the Reynolds number exponent x, 1/3 for the Prandtl number exponent y and 0.14 for the viscosity ratio exponent z.…”

Section: Heat Transfer On the Cooled Stirrer Wallsmentioning

confidence: 99%

Numerical modeling of coupled phenomena in a mechanically stirred molten-glass bath heated by induction

Jacoutot

Fautrelle

Gagnoud

et al. 2008

Chemical Engineering Science

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A mechanically stirred molten-glass bath heated by direct induction in a cold crucible was numerically modeled. The aim of the study was to develop numerical tools to understand thermal, hydrodynamic and electromagnetic phenomena that occur in the bath. Models and coupling between these phenomena are described. This coupling and the high content of elements in the 3D mesh result in a long calculation time. The study demonstrates how to couple programs to yield the highest degree of accuracy in the shortest calculation time possible. Numerical studies are also used to characterize the fluid dynamic behavior and heat transfer in an industrial-size tank. Classical correlations commonly used to characterize stirrer efficiency and heat transfer for fluids with constant physical properties were adapted for molten glass. The power number N p and the Nusselt number Nu are used as macroscopic indicators. The results of these global studies will be useful for the operation and optimization of the vitrification facilities. ᭧

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Section: Heat Transfer On the Cooled Stirrer Wallsmentioning

confidence: 99%

Numerical modeling of coupled phenomena in a mechanically stirred molten-glass bath heated by induction

Jacoutot

Fautrelle

Gagnoud

et al. 2008

Chemical Engineering Science

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“…The correlation M1 was obtained for the heat transfer inside the draft tube; M2 represents the correlation for the heat transfer outside the tube. The correlation I was obtained by Ishibashi et al (1979) for helical ribbon blades in which a heat transfer liquid was circulated. Overall, on a heat transfer basis, the screw rotating in a draft coil gives comparable if not better results than similar close clearance agitators.…”

Section: Resultsmentioning

confidence: 99%

“…The Ellis model was used to characterize the viscosity and the effective viscosity concept was used for correlating the data. , , Nagata et al (1972a) and Ishibashi et al (1979) have studied the heat transfer to or from the impeller blades. According to the results obtained by Ishibashi et al (1979) and , the heat transfer rate to the impeller could be considerably larger than that to the jacketed wall.…”

Section: Literature Reviewmentioning

confidence: 99%

“…, , Nagata et al (1972a) and Ishibashi et al (1979) have studied the heat transfer to or from the impeller blades. According to the results obtained by Ishibashi et al (1979) and , the heat transfer rate to the impeller could be considerably larger than that to the jacketed wall. More recently, Kuriyama et al (1981Kuriyama et al ( , 1983 have examined the heat transfer and the temperature distribution for a double helical ribbon agitator.…”

Section: Literature Reviewmentioning

confidence: 99%

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Heat transfer to newtonian and non‐newtonian liquids in a screw agitator and draft coil system

1994

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Heat transfer has been investigated for several Newtonian and non‐Newtonian liquids mixed in a flat bottomed vessel equipped with a screw agitator and a coil acting simultaneously as draft tube and heat exchanger. Heat transfer rates from coil to liquid were determined for different coil designs, rheological properties and operating conditions in the heating and cooling modes. A circulation Reynolds number is defined, the characteristic length being the effective height of the heat exchanger (the coil) and the characteristic velocity being the circulation velocity of the fluid which was determined experimentally. Using this Reynolds number, it was possible to establish a single correlation for the Nusselt number as a function of Reynolds and Prandtl numbers. Geometric ratios do not appear in this correlation which could adequately represent more than 200 experimental data. A similar single correlation could not be obtained when using the conventional mixing Reynolds number. This novel system is shown to be very efficient for handling rheologically complex fluids.

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“…Therefore, for mixing of a highly viscous liquid, either ribbon or screw impellers are usually applied. These impellers guarantee relatively high heat transfer coefficients from the vessel wall to the mixing liquid (Carreau et al, 1976;Ishibashi et al, 1979;Kuriyama et al, 1981Kuriyama et al, ,1983Nagata, 1975) and short mixing times (Rieger et al, 1986). However, due to a large diameter (ribbon impellers) and small clearance between the impeller edge and the tank wall, these impellers require high power; hence, it is very important to know exactly the power demand in this case (Takahashi et al, 1982a).…”

Section: Introductionmentioning

confidence: 99%