Resistance Coefficients for Non-Newtonian Flows in Pipe Fittings

The focus of this chapter is to provide a review of the loss coefficient data for laminar flow of non-Newtonian fluids in pipe fittings. Since the total pressure change in a piping system generally consists of three components: (i) the frictional pressure loss in the pipe, (ii) the frictional pressure loss arising from flow through fittings and (iii) the pressure loss or gain resulting from elevation changes, this review will also deal with laminar and turbulent pipe flow of non-Newtonian fluids and the application of viscometry for flow in pipes and fittings. The rheological models relevant to industrial fluids such as mine tailings and sewage sludges are introduced, with particular emphasis on yield stress, or viscoplastic, fluids. Hooper (1981) presented a two-K method for determining the loss coefficient for laminar and turbulent flow through various fittings and valves. This method consists of two factors, one for laminar flow, K1 and the other for turbulent flow, Kturb. Unlike that for Kturb, there is little data available for K1. Experimental data over the full range of laminar and turbulent flow are presented for flow of Newtonian and non-Newtonian fluids in various fittings. The experimental procedures for the accurate determination of loss coefficients are described. Current practice for laminar flow through various fittings is to present the loss coefficient as a function of an appropriate Reynolds number. Different Reynolds numbers developed for non-Newtonian fluids have been evaluated to determine their ability to establish the necessary requirement of dynamic similarity for flow of viscoplastic fluids in various fittings. The laminar to turbulent transition in pipe fittings are also discussed. The experimental work done to date on contractions, expansions, valves and orifices is reviewed in addition to similar work published in literature. The magnitude of errors that can be obtained using the incorrect loss coefficient is demonstrated by means of a worked example. This chapter will provide the pipeline design engineer dealing with non-Newtonian fluids with the necessary information critical for energy efficient design

Optimization of Polymer Dosing for Improved Belt Press Performance in Wastewater Treatment Plants

A factorial trial approach was used to determine the relationship between process parameters and filtrate suspended solids, solids capture, cake solids, and yield stress. The work was conducted in a large-scale wastewater treatment plant where there is sludge thickening on a linear screen before filter press. The work demonstrated that there is a relationship between filtrate suspended solids, the rheology of sludge, and the optimum dewatering of the filter belt press. A relationship between the yield stress of the sludge on the BFP and the filtrate suspended solids was found. The sludge flow rate was the most influential parameter on the filtrate suspended solids and solids capture as well as yield stress. The linear screen speed was a significant main parameter for cake solids. The results showed clearly that the interaction between sludge flow rate and either polymer dosing rate or polymer concentration was consistently more significant than polymer concentration and polymer dosing rate individually. An important outcome from this work is that it shows that changes in polymer concentration rather than polymer dosing rate are more important for optimization and control

β-FeOOH/TiO2 Heterojunction for Visible Light-Driven Photocatalytic Inactivation of E. coli

In this work, we report on the photocatalytic properties of β-FeOOH/TiO2 heterojunction material for the inactivation of Escherischia coli. XRD, HRTEM, EELS, ELNEFS were used to characterize the as-prepared material. A log reduction of the initial bacterial population was achieved after 45 min of irradiation in the presence of 0.1 mL of hydrogen peroxide. The enhanced photocatalytic activity was due to the effective charge transfer between Ti4+, Fe3+, and O2+ as shown from the EELS analysis of the heterojunction structure. The role of various reactive species formed due to the photocatalytic reaction was also investigated. Presence of •OH radicals in the bulk solution was the key factor in the photocatalytic inactivation of E. coli

Effect of temperature and concentration of oxidising agent on the synthesis duration of TiO2 from titanium isopropoxide

CPUT Research Da

Modeling pressure losses for Newtonian and non-Newtonian laminar and turbulent flow in long square edged orifices

A lack of experimental data and predictive models prompted the determination of loss characteristics of four sharp square-edged orifices for laminar to turbulent flow regime (1 ≤ Re ≤ 100,000). Novel experimental data for β ratios of 0.36, 0.4, 0.5 and 0.7 obtained with Newtonian and non-Newtonian fluids and an empirical correlation for predicting pressure losses through long square edged orifice plates is presented. For turbulent flow, new experimental results compared well with existing predictive models, thus validating the experimental results. Comparison of existing correlations as well as the new correlation shows that, although with some shortcomings, good progress is made toward a design correlation that spans a wide range of laminar to turbulent flow conditions for long orifices

Development of a symmetrical converging-diverging tube (C-D tube) flow meter for non-Newtonian fluids

16th International Conference on Transport & Sedimentation of Solid Particle

Pressure losses and limiting Reynolds number for non-Newtonian fluids in short square-edged orifice plates

Correlations predicting the pressure loss coefficient along with the laminar, transitional, and turbulent limiting Reynolds numbers with the β ratio are presented for short square-edged orifice plates. The knowledge of pressure losses across orifices is a very important industrial problem while predicting pressure losses in piping systems. Similarly, it is important to define stable operating regions for the application of a short orifice at lower Reynolds numbers. This work experimentally determined pressure loss coefficients for square-edged orifices for orifice-to-diameter ratios of ββ = 0.2, 0.3, 0.57, and 0.7 for Newtonian and non-Newtonian fluids in both laminar and turbulent flow regimes

Evaluating resistance coefficients of straight-through diaphragm control valves

Despite the extensive use of straight-through diaphragm valves in many diverse industrial applications, very few studies of frictional pressure loss for straight-through diaphragm valves have been reported in the open literature. The few that are available are for fully opened valves based on the tacit assumption that different sized diaphragm valves are geometrically similar. In this study, the pressure drops across five straight-through diaphragm valves were measured in four aperture positions. Resistance coefficients were determined by experimentally establishing pressure gradients upstream and downstream of the valves. The experiments were carried out using Newtonian and non-Newtonian fluids over a wide range of Reynolds numbers with the emphasis on obtaining laminar flow data. The Hooper 2-k correlation was corroborated and found to be valid at Reynolds numbers <10 for straight-through diaphragm valves. At higher Reynolds numbers the resistance coefficient is shown to be dependent on the size and the opening of the valve. Three different approaches (domain separation, simple summation, and selective combination) using a two-constant model to predict the experimental resistance coefficients were explored. Comparison of the correlations with experimental data and existing models has shown that the simple summation two-constant model approach has substantial merit. Considering the complexities of accounting for the valve size, the valve opening position, the type of fluid over a Reynolds number range of 0.1–100 000, this model gives pipeline design engineers a simple, semi-empirical correlation for the estimation of resistance coefficients of straight-through diaphragm control valves

A functional relation between solvent surface tension and particle growth rate

Nanotechnology Conferenc

Waste water sludge pipeline predictions using conventional viscometry and ultrasound based rheometry

18th International Conference on TRANSPORT AND SEDIMENTATION OF SOLID PARTICLES 11-15 September 2017, Prague, Czech RepublicTo optimise the design and operational management of wastewater treatment plants (WWTP’s) there needs to be an understanding of the viscous properties of wastewater sludges, which at higher concentrations become non-Newtonian. Worldwide, there is more and more pressure to attain higher sludge concentrations which complicates mixing and pumping. Pipeline design at higher concentrations also requires prior knowledge of sludge rheology. The comparison of the rheological parameters of wastewater sludge world-wide has been hampered due to different rheological measurement techniques and interpretation of results used. For the past seven years wastewater sludges have been rheologically characterised in Sweden and in South Africa, using the same tube viscometer. Seventy-six sludges were tested in tube and rotary viscometers at 16 WWTPs in Sweden and South Africa with solids concentrations ranging from 2 to 8%. A correlation could be obtained of the rheological parameters as a function of sludge concentration. In addition to this, a real-time in-line fluid visualisation and characterisation system, was also used to determine the rheology of the sludge. Three wastewater sludge concentrations were rheologically characterised using the FlowViz system and a conventional tube viscometer. It is demonstrated that a significant effect on pressure drop predictions occurs when using results from the Flow-Viz system compared to tube viscometry, which is mainly due to more accurate determination of the yield stress. This work provides confidence for the pursuit of the development of a universal correlation for sludge rheological parameters using in-line real time rheological parameters for improved pipeline design