Nonisothermal nip flow in calendering operations

Dobbels, Frans; Mewis, Jan

doi:10.1002/aic.690230304

Cited by 21 publications

(13 citation statements)

References 22 publications

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“…The measured value used for the optical constant is CPIB = 1. 21 Pa-' (at t = 25°C) for a polyisobutene melt. The temperature in the calender gap during the measurements is constant at 25°C.…”

Section: Resultsmentioning

confidence: 99%

Comparison of calculated with measured flow fields in the gap between two rotating rolls

1994

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Velocity, pressure, temperature, and stress fields are calculated for the flow of a polymer between two counterdirectionally rotating rolls. The rheological behavior of the polymer is described by the Carreau equation, while elasticity is neglected. The results of the numerical calculations are compared with measurements. The stress field is measured by the birefringence method. The local principal stresses in the fluid are determined from the measured anisotropy of the sheared fluid for the penetrating monochromatic light by means of the stress optical law. The equations of motion and continuity are solved with a Finite Element Method (FEM) based on the Galerkin weighted residual method. The computer code is combined with a Boundary Element Method (BEM) algorithm using the Dual Reciprocity Method (DRM) to solve the coupled equation of energy. Results are shown for a shear-thinning polyisobutene melt in a calender with totally submerged rolls. The calculated results for the principal stress differences are compared to the measured results and confirm fairly well. The influence of friction is discussed. 0 1994

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Section: Resultsmentioning

confidence: 99%

Comparison of calculated with measured flow fields in the gap between two rotating rolls

1994

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“…Each cylinder has a radius R, rotating with a constant angular velocity, ω, resulting in a linear velocity at its surface given by U = ωR. The minimum gap half-height, H 0 , is such that H 0 R and the one-half exiting sheet thickness is represented by H. The geometry of the roll surface is given as h (x) = H 0 1 + x 2 /2RH 0 [6]. We assume that the roll surfaces are found at a constant temperature, T 0 .…”

Section: A Formulationmentioning

confidence: 99%

“…However, in this work they determined the temperature profile, disregarding the influence of the temperature on the final exiting sheet thickness. In this direction, Middleman [6] developed a simple model of the sensitivity of calendered thickness to temperature fluctuations. He concluded that "a 3 • variation in temperature will cause more than 20 percent variation in calendered thickness!".…”

Section: Introductionmentioning

confidence: 99%

Influence of Viscous Dissipation on the Exiting Sheet Thickness in the Calendering of Newtonian Fluids

2020

International Journal of Materials

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In this work we treat theoretically the calendering process of Newtonian fluids with finite sheet initial thickness, taking into account that the viscosity of the fluid is a welldefined function of the temperature. We predict the influence of the temperature-dependent viscosity on the exiting sheet thickness in the calendering process. The mass, momentum and energy balance equations, based on the lubrication theory, were nondimensionalized and solved for the velocity, pressure and temperature fields by using perturbation and numerical techniques, where the exiting sheet thickness represents an eigenvalue of the mathematical problem. The numerical results show that the inclusion of temperature-dependent viscosity effect reduces about 20% the leave-off distance in comparison with the case of temperature-independent viscosity.

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“…As described in an extensive review by Williams, 7) supercritical extraction has been increasingly popular in many chemical and food processing industries. In the past few years, it has been applied to the field of oil recovery from fossil fuels such as coal,1'2'4* oil shale4~6) and tar sand.4'6) The purpose of this study is to assess the applicability of sub-to supercritical extraction for the recovery of oil from used automotive tires.…”

Section: Discussionmentioning

confidence: 99%

Pressure distribution in a two-roll mill.

Murakámi

Chung

Tenda

et al. 1985

J. Chem. Eng. Japan

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An asymmetric pressure distribution in a pair of rolls rotating at equal and unequal speed for Newtonian fluid was obtained by lubrication model analysis and was compared with experimental values. The work was carried out with a pair of rolls of radius /?=8.2cm in the range of fluid viscosity \i=1.5-15Pa s, half of minimumnip clearance h0 =35-390/an, meanroll speed um=0.26-1.56m/s and roll speed ratio Nr=0.5-1. The experimental pressure profiles and force separating rolls are well represented by the calculated values in the region of N'ca (=fiuf(R/h0)2/y)<2.5 x 107, where y is liquid surface tension. In the range of 7Vc'a>2.5 x 107, the absolute values of the minimum pressure decrease with increasing N 'ca. The theoretical pressure distribution can be well corrected by considering that the liquid film separating point predicted by the theory comes near to the minimumnip.

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Nonisothermal nip flow in calendering operations

Cited by 21 publications

References 22 publications

Comparison of calculated with measured flow fields in the gap between two rotating rolls

Comparison of calculated with measured flow fields in the gap between two rotating rolls

Influence of Viscous Dissipation on the Exiting Sheet Thickness in the Calendering of Newtonian Fluids

Pressure distribution in a two-roll mill.

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