scholarly journals Development of an Analytical Model to Describe the Disperse Melting in Wave-Dispersion Screws

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 946
Author(s):  
Marius Dörner ◽  
Christian Marschik ◽  
Volker Schöppner ◽  
Georg Steinbichler
Keyword(s):  
Analytical Model ◽  
Melting Process ◽  
Wave Dispersion ◽  
Melting Behavior ◽  
Mean Deviation ◽  
Correct Process ◽  
Melt Temperature ◽  
Bed Temperature ◽  
Screw Length ◽  
Cooling Effects

The progressive development of new screw concepts in single screw extrusion also makes it necessary to develop new models for the correct process description. When looking at wave-dispersion screws, the disperse melting behavior should be mentioned in particular, which has so far been less researched and modeled than the conventional melting behavior, as it occurs in standard screws. Therefore, an analytical model is presented in this paper, which considers the disperse melting under consideration of the melt and solid temperature. The basic assumption is Fourier heat conduction from the melt surrounding the particles into the particles. Furthermore, the melt temperature development by dissipation and the cooling effects were modeled analytically. Additionally, the solid bed temperature was modeled by a 2D-FDM method. By dividing the screw into several calculation sections with constant boundary conditions, it was subsequently possible to calculate the melting process over the screw length. The model developed shows comprehensible results in verification and successfully reproduces the solids content over the screw length with a mean deviation of absolute 11% in validation tests using cooling/pulling-out experiments.

Design analysis of a standard injection screw for plasticising polycarbonate resins

2016 ◽  
Vol 36 (5) ◽  
pp. 537-548 ◽  
Author(s):  
Ming-Shyan Huang
Keyword(s):  
Simulation Analysis ◽  
Melt Temperature ◽  
Factors Affecting ◽  
Control Factors ◽  
Screw Length ◽  
Plastic Injection Moulding ◽  
Screw Diameter ◽  
Grey Relational ◽  
Injection Screw ◽  
Simulation Programme

Abstract The industrial use of plastic injection moulding machines is widespread. However, few studies have examined the injection screw, which is one of the key components of moulding machines. Studies have demonstrated that a properly designed injection screw improves both the moulding quality and the production rate. Factors that affect the plasticisation properties of conventional standard reciprocating screws include the screw geometry, the screw operation settings, and the processed resins. An ideal standard reciprocating screw exhibits a high plasticising capacity and excellent melt temperature homogeneity; however, these properties typically conflict. Through simulation analysis, this study investigated the optimal design of a standard reciprocating injection screw used for plasticising polycarbonate resins. First, the Taguchi method was integrated with a commercial simulation programme to identify the key control factors affecting the plasticising rate of a screw and the temperature uniformity of the melt. Simulation results revealed that the screw diameter, rotation speed, metering channel depth, ratio of the screw length to the screw diameter, and compression ratio substantially influence performance. Consequently, grey relational analysis was adopted to optimise the design of an injection screw that ensures sufficient quality according to the plasticisation rate and the homogeneity of molten plastic.

The Melting Behavior of Poly(Ethylene Terephthalate)/ Attapulgite Nanocomposites

2013 ◽  
Vol 773 ◽  
pp. 530-533
Author(s):  
Chen Liu ◽  
Xiang Hui Lu ◽  
Xue Qi ◽  
Peng Li
Keyword(s):  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Ethylene Terephthalate ◽  
Melting Process ◽  
Melting Behavior ◽  
Crystallization Time ◽  
Scanning Calorimetry ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene ◽  
Crystallization From The Melt

The melting and recrystallization behavior of Poly(ethylene terephthalate) (PET)/ Attapulgite(At)nanocomposites after isothermal crystallization from the melt was studied by Step-scan differential scanning calorimetry (SDSC). The influence of At contents, crystallization temperature and crystallization time on the melting process were examined. Two melting endotherms(in the SDSC CP.A curves, reversible part) and one recrystallization exotherm (in the SDSC CP.IsoK curves, irreversible part)of PET/At nanocomposites after isothermal crystallization were observed during the melt process. This ascribes to the melting-recrystallization mechanism .The low temperature endotherm attributes to the melting of primary crystal formed during the isothermal treating and the high temperature endotherm resulting from the melting of recrystallization materials. The reason why more recrystallization happened with the increase of At content was given and the process of recrystallization was described in detail. The effects of crystal perfection and recrystallization were minimized by increasing of crystallization temperature and time.

An Analytical Model to Predict Condensation of R-410A in a Horizontal Rectangular Channel

2000 ◽  
Vol 122 (3) ◽  
pp. 613-620 ◽  
Author(s):  
Z. Guo ◽  
N. K. Anand
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Analytical Model ◽  
Rectangular Channel ◽  
Weighted Average ◽  
Condensation Heat Transfer ◽  
Mean Deviation ◽  
Transfer Coefficients ◽  
Condensation Heat Transfer Coefficient

An analytical model to predict condensation heat transfer coefficient in a horizontal rectangular channel was developed. The total local condensation heat transfer coefficient was represented as the weighted average of heat transfer coefficients for each wall. The analytical predictions compared well with the experimental data on the condensation of R-410A in a rectangular channel. The mean deviation was 6.75 percent. [S0022-1481(00)00503-X]

Effect of Melting Process on Zr Content and Grain Refinement in ZE41A Alloy

2011 ◽  
Vol 284-286 ◽  
pp. 1651-1655
Author(s):  
Hong Hui Liu ◽  
Zhi Liang Ning ◽  
Fu Yang Cao ◽  
Yu Chen Zhang ◽  
Jian Fei Sun
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Isothermal Holding ◽  
Melting Process ◽  
Melt Temperature ◽  
Zr Addition

The effects of melting process on Zr content and grain size in ZE41A alloy were investigated in this study. The results show that the soluble Zr increases with the increased addition content of Mg-Zr master, up to 0.87%. The ratio of Zr addition content to soluble Zr content changes within 3.86-4.8. The melt temperature has little effect on soluble Zr content. Grain size grows and both soluble Zr and total Zr decrease with the prolonged isothermal holding of the melt.

Analytical Model to Determine the Strength of Form-Fit Connection Joined by Die-Less Hydroforming

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Christian Weddeling ◽  
Soeren Gies ◽  
Nooman Ben Khalifa ◽  
A. Erman Tekkaya
Keyword(s):  
Analytical Model ◽  
Load Transfer ◽  
Dissimilar Materials ◽  
Experimental Investigations ◽  
Mean Deviation ◽  
Material Parameters ◽  
Load Transfer Mechanism ◽  
Fundamental Understanding ◽  
Increasing Demand ◽  
Tube Geometry

Modern lightweight concept structures are increasingly composed of several dissimilar materials. Due to the different material properties of the joining partners, conventional and widely used joining techniques often reach their technological limits when applied in the manufacturing of such multimaterial structures. This leads to an increasing demand for appropriate joining technologies, like joining by die-less hydroforming (DHF) for connecting tubular workpieces. The present work introduces an analytical model to determine the achievable strength of form-fit connections. This approach, taking into account the material parameters as well as the groove and tube geometry, is based on a membrane analysis assuming constant wall thicknesses. Besides a fundamental understanding of the load transfer mechanism, this analytic approach allows a reliable joining zone design. To validate the model, experimental investigations using aluminum specimens are performed. A mean deviation between the calculated and the measured joint strength of about 19% was found. This denotes a good suitability of the analytical approach for the design process of the joining zone.

PHASE CHANGES IN ICOSAHEDRAL 54-, 55-, 56-ATOM PLATINUM CLUSTERS

2004 ◽  
Vol 15 (07) ◽  
pp. 981-988 ◽  
Author(s):  
ALI SEBETCI ◽  
ZIYA B. GÜVENÇ ◽  
HATICE KÖKTEN
Keyword(s):  
Global Minimum ◽  
Melting Process ◽  
Melting Behavior ◽  
Phase Changes ◽  
Dynamics Simulation ◽  
Analysis Method ◽  
Embedded Atom ◽  
Platinum Clusters ◽  
Specific Temperature ◽  
Physical Quantities

Using the Voter and Chen version of an embedded-atom model, derived by fitting simultaneously to experimental data both the diatomic molecule and bulk platinum, we have studied the melting behavior of free, icosahedral, 54-, 55- and 56-atom platinum clusters in the molecular dynamics simulation technique. We present an atom-resolved analysis method that includes physical quantities such as the root-mean-square bond-length fluctuation and coordination number for individual atoms as functions of temperature. The effect of a central atom in the icosahedral structure to the melting process is discussed. The results show that the global minimum structures of the 54-, 55- and 56-atom Pt clusters do not melt at a specific temperature, rather, melting processes take place over a finite temperature range. The heat capacity peaks are not δ-functions, but instead remain finite. An ensemble of clusters in the melting region is a mixture of solid-like and liquid-like clusters.

scholarly journals Modeling an RF Cold Crucible Induction Heated Melter With Subsidence

2004 ◽  
Author(s):  
Grant Hawkes
Keyword(s):  
Vector Potential ◽  
Molten Glass ◽  
Melting Process ◽  
Power Input ◽  
Magnetic Vector Potential ◽  
Cold Crucible ◽  
Magnetic Vector ◽  
Melt Temperature ◽  
Experimental Apparatus ◽  
Energy Equations

A method to reduce radioactive waste volume that includes melting glass in a cold crucible radio frequency induction heated melter has been investigated numerically. The purpose of the study is to correlate the numerical investigation with an experimental apparatus that melts glass in the above mentioned melter. Unique to this model is the subsidence of the glass as it changes from a powder to molten glass and drastically changes density. A model has been created that couples the magnetic vector potential (real and imaginary) to a transient startup of the melting process. This magnetic field is coupled to the mass, momentum, and energy equations that vary with time and position as the melt grows. The coupling occurs with the electrical conductivity of the glass as it rises above the melt temperature of the glass and heat is generated. Natural convection within the molten glass helps determine the shape of the melt as it progresses in time. An electromagnetic force is also implemented that is dependent on the electrical properties and frequency of the coil. This study shows the progression of the melt shape with time along with temperatures, power input, velocities, and magnetic vector potential. Coupled to all of this is a generator that will be used for this lab sized experiment. The coupling with the 60 kW generator occurs with the impedance of the melt as it progresses and changes with time. A power controller has been implemented that controls the primary coil current depending on the power that is induced into the molten glass region.

scholarly journals Application of a Modeling Tool to Describe Fly Ash Generation, Composition, and Melting Behavior in a Wheat Straw Fired Commercial Power Plant

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1510
Author(s):  
Ibai Funcia ◽  
Fernando Bimbela ◽  
Javier Gil ◽  
Luis M. Gandía
Keyword(s):  
Fly Ash ◽  
Wheat Straw ◽  
Melting Behavior ◽  
Major Elements ◽  
Solid Particles ◽  
Biomass Combustion ◽  
Chemical Fractionation ◽  
Ash Melting ◽  
Cooling Effects ◽  
Entrainment Effect

Ash behavior is a key operational aspect of industrial-scale power generation by means of biomass combustion. In this work, FactSageTM 6.4 software was used to develop and assess three models of wheat straw combustion in a vibrating grate-fired commercial boiler of 16 MWth, aiming to describe the inorganic elements release as well as fly ash melting behavior and composition. Simulations were carried out solving four consecutive calculation stages corresponding to the main plant sections. Chemical fractionation was adopted in order to distinguish between reactive, inert and partially reactive biomass fractions. The developed models allow take into account different levels of partial reactivity, values of the temperature for each sub-stage on the grate, and ways to apply entrained streams based on data from the elemental analyses of the fly ashes. To this end, two one-week experimental campaigns were conducted in the plant to carry out the sampling. It has been found that considering chemical fractionation is indispensable to describe the entrainment of solid particles in the gas stream. In addition, the best results are obtained by adopting a small reactivity (2%) of the inert fraction. As for fly ash composition, the concentrations of the major elements showed good agreement with the results from the chemical analyses. In the case of S and Cl, calculations revealed a match with gas cooling effects in the superheaters as well as an entrainment effect. The melting behavior together with the presence of KCl and K2SO4 condensates, point out at possible corrosion phenomena in walls at temperatures of 700–750 °C.

Development Features of Thermal and Gas-Dynamic Performance of Mineral Wool Cupola Furnace

2019 ◽  
Vol 946 ◽  
pp. 480-485
Author(s):  
V.I. Matyukhin ◽  
S.Ya. Zhuravlev ◽  
A.V. Khandoshka
Keyword(s):  
Dynamic Performance ◽  
Melting Process ◽  
High Heat ◽  
Mineral Wool ◽  
Utilization Efficiency ◽  
Balance Model ◽  
Cupola Furnace ◽  
Gas Dynamic ◽  
Bed Temperature ◽  
Dynamic Performance Analysis

Major unit for mineral melt production in industry is a shaft (cupola) furnace. Such type units are noted for the ease of fabrication and maintenance, high melting rate (up to 100-150 t/m2 per day), as well as high heat utilization efficiency (up to 60-80 % of the total supply). Design disadvantages may include inefficient workspace side-view, poor thermal and gas dynamic performance, lack of practical methods to impact the melting process. Another pressing problem is related to melt production in the amount of no more than 3 t/h, with the average coke consumption of up to 24-270 kg/t, and the overheating temperature level of no more than 1350-1400 °С. Thermal and gas dynamic performance analysis of mineral wool cupola furnace, based on evaluation of zone balance model demonstrated that mineral melt is produced under conditions of essential nonuniformity of the bed temperature, gas phase composition and heat exchange conditions, both throughout the bed height and the unit cross section.

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