bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluid Flow through 90 Degree Bends
Authors: Spedding P.L. , Benard E. , Mcnally G.M. 
Published: August 2010

AbstractPressure drop measurement and prediction in curved pipes and elbow bends is reviewed for both laminar and turbulent single‐phase fluid flow. For curved pipe under laminar flow, the pressure loss can be predicted both theoretically and using empirical relations. The transitional Reynolds number can be predicted from an empirical relation. Turbulent flow in curved pipes can only be theoretically predicted for large bends but there are a large number of empirical relations that have proved to be accurate. Elbow bends have proven to be difficult to both measure and represent the pressure loss. Methods of overcoming such problems are outlined. There was no reliable method of theoretically predicting pressure drop in elbow bends. Experimental measurements showed considerable scatter unless care was taken to eliminate extraneous effects. Reliable data are highlighted and an empirical method is proposed for calculation of pressure drop in elbow bends.
Momentum Balance for Two‐Phase Horizontal Pipe Flow Part 2: Testing of Models
Authors: Spedding P. L. , Cole J. S. , Donnelly G. F. 
Published: August 2010

AbstractMomentum balance models were tested against reliable data for both holdup and pressure drop. The best prediction performance was achieved using a model that considered the actual shape of the liquid phase in the pipe. In such circumstances the momentum balance calculation tended to under predict both the holdup and pressure drop for some of the annular and stratified regimes. Suggestions are made for improvements in the momentum balance approach.
Stabilization of the Dynamic Behavior of a UNIPOL Process for Polyethylene Production
Authors: Ghasem Nayef Mohamed , Hussain Mohamed Azlan 
Published: August 2010

AbstractPolyolefins have become one of the most important plastics worldwide due to continuous improvements in catalysts and processes. Gas‐phase polymerization of olefins is one of the most important polymerization processes. Compared to other processes such as slurry and solution polymerization, gas‐phase processes have many distinct advantages, e.g. reduced capital and operating costs. Moreover, gas‐phase polymerization offers a large variety of products, which could not be produced by other processes. However, sheeting and agglomeration of polymer particles are two serious problems, which can occur in modern gas‐phase polymerization processes. Overheating of particles may occur due to very high reaction rates. The temperature of a particle can then rise above the softening temperature. In this work, recent theories of bifurcation and chaos are used to analyze the dynamic behavior of the UNIPOL process for the gas‐phase production of polyethylene using a Ziegler‐Natta catalyst. The dynamic behavior covers a wide range of the design and operating parameters domain for this industrially important unit. A conventional proportional‐integral‐derivative (PID) controller was implemented to stabilize the desired operating point on the unstable steady‐state branch to a certain range of catalyst injection rate. By contrast, it was found that the controlled process can go through a period doubling sequence leading to chaotic strange attractors. The practical implications of this analysis can be very serious, since chaos is shown to exist close to the desired operating point where high polyethylene production rates can be achieved.
The Optimisation of Drying Schedules for Pinus radiata Sapwood Boards
Authors: Langrish T.A.G. , Nijdam J. J. , Keey R. B. 
Published: August 2010

AbstractOptimal drying schedules have been predicted for the drying of Pinus radiata sapwood from an initial moisture content of 140% over a drying time of twenty‐four hours for 50mm‐thick boards. Initially, a single pair of dry and wet‐bulb temperatures (108d̀C. 60d̀C) over the full time period is estimated to keep the total tangential strain under 50% of the predicted limiting failure value. However, after twelve hours drying, more severe conditions may be used, with the final moisture content predicted to be reduced from 8.2% for a constant set of conditions throughout the schedule (108d̀C, 60d̀C) to 2.4% when the dry‐bulb temperature is raised from 108d̀C to 122d̀C after twelve hours. It is also possible to use a linearly increasing dry‐bulb temperature after twelve hours, rising from 108d̀C to 155d̀C at the end of drying with a predicted final moisture content of 0.2%. However, to reduce the moisture content to only 10%, there is little difference between the ramped and two‐step schedules, both yielding a total drying time of eighteen hours. The two‐step schedule would be the easier to in practice.
Progress in the Modelling of Air Flow Patterns in Softwood Timber Kilns
Authors: Langrish T.A.G. , Keey R. B. 
Published: August 2010

AbstractProgress in modelling air flow patterns in timber kilns using computational fluid dynamics (CFD) is reviewed in this work. These simulations are intended to predict the distribution of the flow in the fillet spaces between boards in a hydraulic model of a timber kiln. Here, the flow regime between the boards is transitional between laminar and turbulent flow, with Reynolds numbers of the order of 5000. Running the simulation as a transient calculation has shown few problems with convergence issues, reaching a mass residual of 0.2% of the total inflow after 40 to 100 iterations per time step for time steps of 0.01 s. Grid sensitivity studies have shown that non‐uniform grids are necessary because of the sudden changes in flow cross section, and the flow simulations are insensitive to grid refinement for non‐uniform grids with more than 300,000 cells. The best agreement between the experimentally‐measured flow distributions between fillet spaces and those predicted by the simulation have been achieved for (effective) bulk viscosities between the laminar viscosity for water and ten times that value. This change in viscosity is not very large (less than an order of magnitude), given that effective turbulent viscosities are typically several orders of magnitude greater than laminar ones. This result is consistent with the transitional flows here. The effect of weights above the stack can reduce the degree of non‐uniformity in air velocities through the stack, especially when thick weights are used, because the stack may then be separated from the eddy at the top of the plenum chamber.
The Deposition of Calcium Oxalate and Amorphous Silica Scale under Dynamic Conditions which Simulate sugar mill Evaporators
Authors: Yu H. , Sheikholeslami R. , Doherty W.O.S. 
Published: August 2010

AbstractComposite fouling of calcium oxalate monohydrate (COM) and amorphous silica (SiO2) in sugar mill evaporators poses a major processing problem. The significance of COM‐SiO2 interactions during composite scale formation has been recognized previously and their effects on the fouling behaviour of both species have been demonstrated in batch tests. This work investigates the mechanisms of composite fouling of COM and SiO2 in a dynamic system under subcooled flow‐boiling and continuous evaporation. The experimental approach used in this study is novel. It simulates the operation cycle in the latter effects of sugar mill evaporators within one experimental run whilst maintaining a relatively simple process. The composite fouling behaviour of COM and SiO2 has been tested in aqueous solutions with a range of COM/SiO2 supersaturation ratios to determine the critical feed composition at which the maximum degree of composite fouling occurred. The synergistic effect of COM on composite fouling occurred at an intermediate concentration of COM (50 ppm) whereas antagonism was obtained at either low or high COM concentration (20 and 100 ppm). This may be due to changes in the magnitude of the interfacial energy barrier between the surface of the particles and the wall, and to the differences in the physical properties of the fouling species such as particle size.
Using a “Campus as a Classroom Concept” to Highlight Sustainability Practice to Engineers and Scientists
Authors: Evans G. , Scaife P. , Maddox B. , Galvin K. 
Published: August 2010

AbstractChemical engineering at the University of Newcastle has introduced a “Systems Thinking” approach in response to the changing needs of today's young engineers, particularly in relation to sustainable development and interaction with the wider community. The basic concepts are reinforced to the students in the form of case studies. The activities cover a broad range of traditional chemical engineering principles, including fluid mechanics, heat and mass transfer, process flowsheeting, and design. The case studies have the additional dimensions of life cycle modelling, environmental impact assessment, and direct interaction with the broader community. In this paper, two examples, involving Building Design and On‐Site Water Management, are presented, including a brief description, desired learning outcomes, results and general observations. Generally, it was found that the case studies provided an excellent framework for establishing a systems approach to arriving at solutions, and acted as a focus for quantitative analysis using the various tools taught during the course. Most importantly, the material presented assisted students to understand the practices which contribute to the transition to a sustainable society.
Experimental Results and Models for Solid/Liquid Fluidized Beds Involving Newtonian and Non‐Newtonian Liquids
Authors: Aghajani M. , Müller‐Steinhagen H. , Jamialahmadi M. 
Published: August 2010

AbstractFluidization technology relies almost solely on fluid/particle interaction wherein the liquid phase may exhibit Newtonian or non‐Newtonian behavior. The steady motion of particles and the velocity‐voidage relationship are the most important design parameters for fluidization, providing the basis for the prediction of heat and mass transfer coefficients and information on hydrodynamic conditions. A summary of the literature on particle settling velocity, minimum fluidization velocity and velocity voidage relationship is supplemented by new experimental results, which extend the range of investigated solid and liquid phase physical properties. Correlations for particle settling velocity and velocity‐voidage relationship are developed and verified against experimental data.
Hydrogen Economy Options for Australia
Authors: Mclellan B. , Diniz Costa J. C. Da , Dicks A.L. , Rudolph V. , Pagan R.J. , Sheng C. , Wall T.F. 
Published: August 2010

AbstractGlobal concerns over the effects of current carbon dioxide (CO2) emissions have lead to extensive research on the use of hydrogen as a potential energy carrier for a lower emissions society. Hydrogen can be produced from both fossil and renewable energy sources. The hydrogen economy, in which hydrogen will be a carrier of energy from renewable sources, is a long‐term development and any increasing demand for hydrogen will probably be covered initially from fossil sources. Technologies for hydrogen generation from renewable energies are being explored, whereas technologies for hydrogen production from fossil fuels have to a certain extent reached maturity. This paper addresses the major hydrogen generation processes and utilisation technology (fuel cells) currently available for the move from a fossil fuelsbased economy to a hydrogen economy. In particular, it illustrates the applicability of different hydrogen sources using Australia as an example.
Research and Development Trends in Biodiesel
Authors: Rudolph V. , He Y. 
Published: August 2010

AbstractBiodiesel, a derivative from plant oils or animal fats, has gained widespread acceptance in recent years as a sustainable alternative fuel to petroleum diesel due to its environmental benefits and renewability. Although there are several different ways in which biodiesel can be used or formulated as a fuel such as direct blending, microemulsions and thermal cracking, the most widespread remains the alkyl esters of fatty acids obtained through transesterification of the oils or fats. In transesterification, triglycerides which are the main chemical in oils or fats are converted into esters through reaction with simple alcohols. The physical and chemical properties of the esters thus obtained are very similar to those of the petroleum diesel.This paper reviews the current technologies available for the transesterifications of vegetable oils and animal fats and identifies that the biggest factor deterring a greater market uptake of biodiesel is its cost. It concludes that, in addition to government policy framework, e.g. to reduce the pump price of biodiesel through fuel tax exemption, further technological development presents significant scope for improvement. At present, there are no suitable and developed transesterification technologies that can handle cheap, low‐quality feedstocks including waste animal fats and spent cooking oils. These feedstocks contain high percentages of water and free fatty acids which are extremely detrimental to the yield and reaction rates of the transesterification processes. This paper also suggests some future research and development directions and requirements for more competitive biodiesel production.
An Assessment of Tarong Bottom Ash for Use on Agricultural Soils
Authors: Wearing C. , Birch C.J. , Nairn J.D. 
Published: August 2010

AbstractCoal combustion by‐products (CCBs), including fly ash and bottom ash, present a waste disposal problem in Australia due to a continuing demand for coal‐fired power. Pozzolanic Enterprises handle ash produced by the Tarong Energy coalfired power station in South West Queensland, which produces approximately 1,200,000 tonnes per annum of CCB's. This comprises roughly 1,100,000 tonnes of fly ash arid 100,000 tonnes of furnace bottom ash. The volume and unique properties of the Tarong bottom ash present a significant opportunity for agronomic use. Of particular interest is the ability of Tarong bottom ash to markedly improve the water‐holding capacity of soils. Given that Australia's rural environment is currently enduring a ‘one‐in‐one‐hundred‐year’ drought a study of the ability of Tarong bottom ash to improve water holding capacity is timely. This paper details physical and chemical properties relevant to agronomic use, and water‐holding capacity of ash/hoil blends, along with experiences in its field use in crop production.
The Validation of a Simple Gaussian Dispersion Model for Determining Odour Emission Rates from Area Sources
Authors: Galvin G. , Lowe S. , Smith R. 
Published: August 2010

AbstractThe accuracy of dispersion models is a widely debated topic. The goal of this research was to assess If the odour emission rates (OER) predicted using a simple Gaussian model were comparable to the more intensive and expensive wind tunnel‐based odour measurement technique. A Gaussian dispersion model (STINK) was used to determine odour emission rates from piggery ponds. These values were then compared to those measured simultaneoirsly on the pond sugaces using a wind tunnel, and analysed using dynamic olfactometry. Results of linear regressions showed a moderate relationship for two of the three seasons studied, and a very good relationship for the other season studied. Overall, the model showed a good correlation between calculated downwind, and calculated on‐pond, odour emission rates. The use of the STINK model shows promise as an alternative to the inore labour‐intensive direct emission rate measurement technique.
Methanol as Anti‐solvent for Recycling of Caustic Soda Solution Used in Aluminum products manufacturing
Authors: Fukui K. , Maeda K. , Yanagisawa T. , Honda K. , Yoshida M. 
Published: August 2010

AbstractThe recycling of caustic soda solution in aluminum processing is proposed in order to decrease the energy consumption and environmental impact. Methanol as an anti‐solvent in the caustic soda solution was found to be the most effective solvent for reducing gibbsite solubility. The gibbsite solubility in caustic soda was significantly reduced when methanol was added by more than 40 wt%. It was found that the gibbsite solubility with 55 w t% methanol was about a half of that without methanol. Methanol has low latent heat, and can be economically separated from the caustic soda solution. This recycling leads to an increase in the dissolution rate of alumina and/or aluminum, at atmospheric pressure, with a more concentrated caustic soda solution (up to 500 g/L NaOH). A more concentrated caustic soda solution can be recycled more economically, for example, that used in the die recovery process in aluminum forming plants. Optimization by the controlled addition or mixing of methanol in the caustic solution easily controls the growth rate and nucleation rate of gibbsite crystals in the crystallizer. Synergy of these advantages of the present recycling method may contribute to more cost effective operations, and minimization of environmental impacts from the disposal of spent caustic soda solution.
Prediction of Hydrogen Content in Coal using Back Propagation Neural Network
Authors: Ju L. C. , Tadé M. O. , Zhu J. N. , Yao H. M. 
Published: August 2010

AbstractThis paper introduces the concept of sample study risk in neural network (NN), and studies the prediction of hydrogen content in coal using Back Propagation Neural Networks (BP NN). Targeting the problem of training convergence quality impaired by the interfering information of some samples in BP NN, the validity of the concept of sample study in NN, and the feasibility of analyzing chemical elements in coal using NN are discussed.
Application of a Robust Interval Observer to an Anaerobic Digestion Process
Authors: Alcaraz‐González V. , Steyer J. P. , Harmand J. , Rapaport A. , González‐Alvarez V. , Pelayo‐Ortiz C. 
Published: August 2010

AbstractA new robust state estimation scheme is proposed for chemical and biochemical processes. This scheme is a nonlinear interval observer which is robust in the face of uncertainties of the inputs, load disturbances and the nonlinearity of the system, while maintaining excellent stability conditions. We show that this observer yields satisfactory estimates of the unmeasured states within a guaranteed interval determined by the available measurements and some reasonable hypotheses about the observer inputs. For demonstrating the effectiveness and applicability of the proposed estimation scheme, we apply it in an actual anaerobic digestion pilot plant for wastewater treatment in the presence of uncertainties including measuring errors, sensor failures, time varying inputs and unmeasured disturbances. On‐line implementation results reveal that the proposed robust nonlinear interval observer is a practical and encouraging approach to the robust state estimation in uncertain nonlinear processes.
A Novel Method for the Control of Plants with actuator Saturation Nonlinearities
Authors: Gu Dan‐Ying , Cai Yun‐Ze , Zhang Wei‐Dong 
Published: August 2010

AbstractThe objective of this paper is to develop a simple and practical anti‐windup controller for systems with saturation non‐linearity. Most present methods are based on the idea that when the controller output differs from the plant input, then corrective feedback is employed to reduce the discrepancy. Alternatively, some recent design methods propose that the saturation can be avoided by directly making the controller output in a permissible range. This paper will give such a scheme. It is essentially a modification, or compensation, to existing controllers that can be designed in various ways for linear systems. The scheme is realized by adding a filter to the controller, and is tuned only for a few parameters in order to cope with the saturation. It is simple and efficient in practical applications. Illustrative examples are provided to show the advantage of the proposed method.
Approximate Decoupling of Multivariable Control Systems: A Time‐domain Approach
Authors: Mao Wei‐Jie , Liu Shao 
Published: August 2010

AbstractA new approximate decoupling method for linear time‐invariant systems based on the concept of energetic diagonal dominance is proposed in this paper. It is a time‐domain approach and the design procedure is simpler than that of frequency‐domain approach. The conditions for the energetic decoupling with simultaneous stabilizability are established in terms of linear matrix inequalities (LMIs). It is very convenient to solve this problem using the powerful LMI toolbox. The results are derived first for proper systems with nonsingular D, and then extended to strictly proper systems. Illustrative examples demonstrate that this method has satisfactory decoupling performance.
A New Method for the Static Output Feedback Stabilization
Authors: Xiang Ji , Su Hong Ye , Chu Jian 
Published: August 2010

AbstractThe problem of the static output feedback stabilization is the solvability of the two invert‐coupled matrix inequalities. This is non‐linear optimal problem and cannot be solved directly. In this paper, the relation of the two coupled matrix inequalities is studied and a sufficient condition of the solvability for the stabilization problem is proposed on a structural Lyapunov matrix. The corresponding algorithm is presented, which is non‐iterative and simply solved by linear matrix inequality (LMI) tools. Examples are given to show the simplicity and effectiveness of the proposed method.
A New Particle Predictor for Fault Prediction of Nonlinear Time‐varying Systems
Authors: Chen M.Z. , Zhou D.H. , Liu G.P. 
Published: August 2010

AbstractFault prediction (FP) is a new research area in fault detection and diagnosis. It has both safety and economic benefits in industrial systems by preventing future serious process faults and improving process maintenance schedules. Fault prediction differs from fault detection because it deals with future faults, whereas the latter considers faults that occurred in the past. As the future fault is uncertain, a probability to describe it may be needed, however calculating the fault probability remains an open problem. This paper proposes a new particle predictor‐based method by which a solution to fault prediction is derived for nonlinear time‐varying systems. Simulation results illustrate the effectiveness of the proposed approach.