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Non-Newtonian loss coefficients for Saunders diaphragm valves

Dissertation submitted in fulfilment of requirements for the degree
Master Technology: Chemical Engineering
at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY, 2009 / The prediction of the energy losses when designing pipeline and pumping systems requires
accurate loss coefficient data. But the loss coefficient data found in the open literature was not
adequate for predicting the loss coefficient for Saunders straight-through diaphragm valves.
As more accurate loss coefficient data to enable more efficient pipeline designs are scarce in
the open literature, it is problematic to predict the head loss due to the pipeline fittings, and
particularly for diaphragm valves. Most of the data given in the literature are for turbulent flow
based on water. Due to water shortages mining operations are forced to increase their solids
concentrations and to operate in laminar flow (Slatter, 2002). Consequently there is a need to
determine loss coefficient data in laminar flow for valves used in these industries to ensure
energy efficient designs (Pienaar et al., 2001; 2004) or if needed, to derive a new correlation to
predict losses through Saunders diaphragm valves.
However, a systematic study of various sizes of diaphragm valves of different manufacturers to
ascertain, if the same loss coefficient can be applied, has never been done. Therefore a
comparison will be made between the data produced in this work and the existing correlations.
The objective of this research was to determine loss coefficient data in laminar, transitional and
turbulent flow for the Saunders type straight-through diaphragm valves ranging from 40 mm to
100 mm in the fully open, 75 %, 50 % and 25 % open positions, using a range of Newtonian and
non-Newtonian fluids. The test work was conducted on the valve test rig in the Flow Process
Research Centre at the Cape Peninsula University of Technology.
This work investigated only Newtonian and time independent homogeneous non-Newtonian
fluids or slurries flowing through Saunders straight-through diaphragm valves in the turbulent,
transitional and laminar regimes.
Weir-type Saunders valves and time-dependent fluid behaviour were not investigated in this
Non-Newtonian Loss Coefficients for Saunders Diaphragm Valves A Mume Kabwe
The results for each test are presented in the form of valve loss coefficient (kvalve) against
Reynolds number (Re).
This thesis adds new loss coefficient data to the open literature, and a new correlation, which
will be useful for designing pipelines in industries, as well as contributing to the academic
debate in this discipline.
Date January 2009
CreatorsKabwe, Aime Mume
PublisherCape Peninsula University of Technology
Source SetsSouth African National ETD Portal
Detected LanguageEnglish

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