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Non-Newtonian losses through diaphragm valves
Author(s)
Kazadi, Dieudonne Matang'a
Date Issued
2005
Type
Thesis
Publisher
Cape Peninsula University of Technology
Abstract
The prediction of head losses in a pipe system is very important because head losses
affect the performance of fluid machinery such as pumps. In a pipe system, two kinds of
losses are observed: major losses and minor losses. In Newtonian and non-Newtonian
flow, major losses are those that are due to friction in straight pipes and minor losses are
those that are due to pipe fittings such as contractions, expansions, bends and valves.
Minor losses must be accurately predicted in a pipe system because they are not
negligible and can sometimes outweigh major losses (Edwards et al., 1985). There is
presently little data for the prediction of non-Newtonian head losses in pipe fittings in the
literature and little consensus amongst researchers (Pienaar et al., 2004).
In the case of diaphragm valves, usually, only one loss coefficient value is given in
turbulent flow or in laminar flow with no reference to a specific size of the valve,
assuming geometrical similarity that would lead to dynamic similarity. However, no one
has done a systematic study of various sizes of diaphragm valves from the same
manufacturer to establish if this is true. This could be the main reason for discrepancies
found in the literature (Hooper, 1981; Perry & Chilton, 1973; Miller, 1978 and Pienaar et
al., 2004). This work addresses this issue.
A literature revIew on the flow of Newtonian and non-Newtonian fluids has been
presented. The work of Hooper (1981) on diaphragm valves and the works of Edwards et
al., (1985), BaneIjee et aI., (1994) and Turian et al., (1997) for non-Newtonian fluids in
globe and gate valves were found to be relevant to this work.
affect the performance of fluid machinery such as pumps. In a pipe system, two kinds of
losses are observed: major losses and minor losses. In Newtonian and non-Newtonian
flow, major losses are those that are due to friction in straight pipes and minor losses are
those that are due to pipe fittings such as contractions, expansions, bends and valves.
Minor losses must be accurately predicted in a pipe system because they are not
negligible and can sometimes outweigh major losses (Edwards et al., 1985). There is
presently little data for the prediction of non-Newtonian head losses in pipe fittings in the
literature and little consensus amongst researchers (Pienaar et al., 2004).
In the case of diaphragm valves, usually, only one loss coefficient value is given in
turbulent flow or in laminar flow with no reference to a specific size of the valve,
assuming geometrical similarity that would lead to dynamic similarity. However, no one
has done a systematic study of various sizes of diaphragm valves from the same
manufacturer to establish if this is true. This could be the main reason for discrepancies
found in the literature (Hooper, 1981; Perry & Chilton, 1973; Miller, 1978 and Pienaar et
al., 2004). This work addresses this issue.
A literature revIew on the flow of Newtonian and non-Newtonian fluids has been
presented. The work of Hooper (1981) on diaphragm valves and the works of Edwards et
al., (1985), BaneIjee et aI., (1994) and Turian et al., (1997) for non-Newtonian fluids in
globe and gate valves were found to be relevant to this work.
Additional information
Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2005
Subjects
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