Limitations of the Zwietering correlation and the resulting form for a new approach based on power at just suspended speed

Date

2015-06-28

Author

Kresta, Suzanne M
Ayrancı Tansık, İnci

Metadata

Show full item record

Item Usage Stats

167
views

0
downloads

Design specifications for solids suspension (just suspended speed-N-js) in stirred tanks are currently based on the original form of the Zwietering correlation. There are several limitations of this correlation which can lead to poor predictions. The limitations, however, are not clearly defined. In this paper we review the reported limitations of applicability of the Zwietering correlation in detail, and propose ways to predict N-js which extend some of these limits. New data is reported and a detailed analysis of the effects of off-bottom clearance and solids concentration is presented. These results show two things: first that the effect of off-bottom clearance cannot be explicitly accounted for using the Zwietering equation form. S values that exactly match the geometry of the system must be used. Second, the current exponent on solids concentration is applicable only up to 2 wt% solids (X = 2). Three new exponents are proposed based on the particle type: 0.17, 0.23, and 0.32. Using a modified exponent of 0.23, which represents the entire data set with some scatter, N-js can be predicted up to 35 wt% solids (X = 54). A new correlation that is a combination of Zwietering and Baldi, and is robust in scale-up based on constant power/mass is proposed.

URI

https://hdl.handle.net/11511/71361

Conference Name

15th European Conference of Mixing, 28 Haziran - 03 Temmuz 2015

Collections

Department of Chemical Engineering, Conference / Seminar

Suggestions

OpenMETU
Core

Critical analysis of Zwietering correlation for solids suspension in stirred tanks Ayrancı Tansık, İnci (Elsevier BV, 2014-03-01) Design specifications for solids suspension (just suspended speed-N-js) in stirred tanks are currently based on the original form of the Zwietering correlation. There are several limitations of this correlation which can lead to poor predictions. The limitations, however, are not clearly defined. In this paper we review the reported limitations of applicability of the Zwietering correlation in detail, and propose ways to predict N-js which extend some of these limits. New data is reported and a detailed ana...
Application of pressure gauge measurement method beyond its limits Kutukcu, Basak; Ayrancı Tansık, İnci (Elsevier BV, 2019-01-01) The key design parameter for most solid-liquid operations in a stirred tank is the just suspended speed, N-js. In majority of the literature N-js is determined by visual observation of the tank bottom. This method is observer dependent, and the results may vary up to 38% between two observers. A more recent method, pressure gauge measurement (PGM) method, is promising as it is based on pressure measurements at the bottom of the tank, and therefore is observer independent. This method also does not require a...
Evaluation of elastomeric bearing performance at low temperatures Yakut, Ahmet (American Society of Civil Engineers (ASCE), 2002-08-01) Recent studies on elastomeric bearings led to changes in the design specifications, which tend to indicate that bearings fabricated in the past, would fail the current test requirements. This is contrary to the fact that there have been no reported problems of poor bearing performance in low-temperature regions. AASHTO requires low-temperature tests to determine the change in the shear modulus, which is limited to a certain value. This criterion does not adequately address the performance of the bearings, b...
Experimental investigation of a pressure swirl atomizer spry Marchione, T.; Allouis, Christophe Gerard; Amoresano, A.; Beretta, F. (2007-09-01) The fuel injector has an important role in the process for an efficient combustion because it increases the specific surface area of the fuel and it allows one to reach high rates of mixing and evaporation. This paper has focused on the behavior of kerosene Jet A-1 spray produced by commercial pressure swirl atomizers in terms of mean diameter distributions, velocity component profiles, and cone angle variations over time. The analysis has been carried out experimentally with the aid of a phase-Doppler anem...
Performance analysis of a compression ignition internal combustion engine using superheated ethanol vapor Aksu, Çağdaş; Bayka, Ahmet Demir; Department of Mechanical Engineering (2011) The aim of this study is to experimentally measure performance characteristics of a compression ignition (CI) internal combustion engine using superheated ethanol vapor. The engine is a 1.3L inline 4 cylinder direct injection (DI) turbocharged compression ignition (CI) engine. While the engine will be fed with superheated ethanol as homogeneous fuel-air mixture through intake manifold, the amount of diesel fuel that the engine requires to run at idle will also be supplied in order to initiate combustion. Et...

Citation Formats

S. M. Kresta and İ. Ayrancı Tansık, “Limitations of the Zwietering correlation and the resulting form for a new approach based on power at just suspended speed,” presented at the 15th European Conference of Mixing, 28 Haziran - 03 Temmuz 2015, 2015, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/71361.