Validation of Twin-Screw Polymer Extruder Modeling

2002 ◽  
Author(s):  
Yogesh Jaluria
Keyword(s):  
Numerical Modeling ◽  
Numerical Models ◽  
Polymeric Materials ◽  
Operating Conditions ◽  
Design Parameters ◽  
Design And Optimization ◽  
Single Screw Extruder ◽  
Twin Screw ◽  
Accuracy Of Results ◽  
Mathematical And Numerical Modeling

The mathematical and numerical modeling of twin-screw polymer extruders is examined with respect to accuracy of results and validity of the simulation. A numerical model is developed incorporating the translation region, which is similar to a single-screw extruder channel, and the intermeshing, or nip, region. The numerical modeling is carried out for steady and time-dependent operation, considering various polymeric materials like polyethylene and corn meal. A range of design parameters and operating conditions are considered. The results are evaluated in terms of the expected physical behavior of the system and compared with experimental results available in the literature to determine the accuracy of the predictions. In many cases, only qualitative comparisons are possible since the operating conditions and design parameters are not explicitly known. However, the basic trends are as expected and good quantitative comparisons with experimental data is used to validate the model. Validated numerical models can extend the domain of relevant inputs for process design and optimization.

Experimental Validation of Computer Models for Food and Polymer Extrusion

2003 ◽  
Author(s):  
Yogesh Jaluria
Keyword(s):  
Numerical Modeling ◽  
Numerical Models ◽  
Strong Support ◽  
Chemical Conversion ◽  
Operating Conditions ◽  
Experimental Results ◽  
Twin Screw Extruders ◽  
Twin Screw ◽  
Temperature Dependent Properties ◽  
Good Agreement

The accuracy and validity of the mathematical and numerical modeling of extruders for polymers and for food are considered in terms of experimental results obtained on typical full-size single and twin-screw extruders. The fluid is treated as non-Newtonian and with strong temperature-dependent properties. The chemical conversion of food during extrusion is also considered. The numerical modeling is employed for steady-state transport, for a range of operating conditions. Following grid-independence studies, the results obtained are first considered in terms of the expected physical behavior of the process, yielding good agreement with observations presented in the literature. The results are then compared with detailed and qualitative experimental results available from previous investigations to evaluate their accuracy. Good agreement with experimental data is obtained, lending strong support to the mathematical and numerical models.

On the Coupling of Inverse Design and Optimization Techniques for Turbomachinery Blade Design

2006 ◽  
Author(s):  
Duccio Bonaiuti ◽  
Mehrdad Zangeneh
Keyword(s):  
Mechanical Design ◽  
Design Method ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Optimization Techniques ◽  
Operating Conditions ◽  
Inverse Design ◽  
Design Parameters ◽  
Optimization Strategy ◽  
Design And Optimization

Optimization strategies have been used in recent years for the aerodynamic and mechanical design of turbomachine components. One crucial aspect in the use of such methodologies is the choice of the geometrical parameterization, which determines the complexity of the objective function to be optimized. In the present paper, an optimization strategy for the aerodynamic design of turbomachines is presented, where the blade parameterization is based on the use of a three-dimensional inverse design method. The blade geometry is described by means of aerodynamic parameters, like the blade loading, which are closely related to the aerodynamic performance to be optimized, thus leading to a simple shape of the optimization function. On the basis of this consideration, it is possible to use simple approximation functions for describing the correlations between the input design parameters and the performance ones. The Response Surface Methodology coupled with the Design of Experiments (DOE) technique was used for this purpose. CFD analyses were run to evaluate the configurations required by the DOE to generate the database. Optimization algorithms were then applied to the approximated functions in order to determine the optimal configuration or the set of optimal ones (Pareto front). The method was applied for the aerodynamic redesign of two different turbomachine components: a centrifugal compressor stage and a single-stage axial compressor. In both cases, both design and off-design operating conditions were analyzed and optimized.

scholarly journals The influence of selected design and operating parameters on the dynamics of the steam micro-turbine

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Grzegorz Żywica ◽  
Jan Kiciński
Keyword(s):  
Computational Analysis ◽  
Numerical Models ◽  
Dynamic Properties ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Heat And Power ◽  
Operating Conditions ◽  
Design Parameters ◽  
Load Analysis ◽  
Micro Turbine

AbstractThe topic of the article is the analysis of the influence of selected design parameters and operating conditions on the radial steam micro-turbine, which was adapted to operate with low-boiling agent in the Organic Rankine Cycle (ORC). In the following parts of this article the results of the thermal load analysis, the residual unbalance and the stiffness of bearing supports are discussed. Advanced computational methods and numerical models have been used. Computational analysis showed that the steam micro-turbine is characterized by very good dynamic properties and is resistant to extreme operating conditions. The prototype of micro-turbine has passed a series of test calculations. It has been found that it can be subjected to experimental research in the micro combined heat and power system.

Design and Optimization of Multiple Microchannel Heat Transfer Systems

2013 ◽  
Vol 6 (1) ◽  
Author(s):  
Jingru Zhang ◽  
Po Ting Lin ◽  
Yogesh Jaluria
Keyword(s):  
Pressure Drop ◽  
Thermal Resistance ◽  
Optimization Problems ◽  
Numerical Models ◽  
Heat Removal ◽  
Operating Conditions ◽  
Maximum Temperature ◽  
Channel Height ◽  
Physical Constraints ◽  
Design And Optimization

In this paper, two different configurations of multiple microchannel heat sinks, with fluid flow, are investigated for heat removal: straight and U-shaped channel designs. Numerical models are utilized to study the multiphysics behavior in the microchannels and these are validated by comparisons with experimental results. The main focus of this work is on the design and optimization of these systems and to outline the methodology that may be used for other similar thermal systems. Three responses, including thermal resistance, pressure drop, and maximum temperature, are parametrically modeled with respect to various design variables and operating conditions such as dimensions of the channels, total number of channels, and flow rate. Multi-objective optimization problems, which minimize the thermal resistance and the pressure drop simultaneously, are formulated and studied. Physical constraints in terms of channel height, maximum temperature, and pressure are further investigated. The Pareto frontiers are studied and the trade-off behavior between the thermal resistance and the pressure drop are discussed. Characteristic results are presented and discussed.

Utilization of Expansion Work in Transcritical CO2 Heat Pumps in Combined Heating and Cooling

2008 ◽  
Author(s):  
Nikola Stosic ◽  
Ian K. Smith
Keyword(s):  
Control Strategies ◽  
Industrial Process ◽  
Power Input ◽  
Heat Pumps ◽  
Operating Conditions ◽  
Hot Water ◽  
Design Parameters ◽  
Working Fluid ◽  
Heating And Cooling ◽  
Twin Screw

The use of CO2 as a refrigerant in transcritical vapour compression cycles has significant advantages, for systems which require simultaneous heating and cooling at approximately equal rates. However, then need for a compressor, to operate across high pressure differences, and the large throttle losses associated with these pressure differences have limited its use. This paper describes a study carried out to evaluate the efficiency gains and cost benefits possible from such a system when a twin screw machine is used to both compress and expand the working fluid in a single unit. It also shows the values of the critical design parameters required to optimise the system’s potential advantages when used in larger combined heating and cooling systems in industrial process and heat generation plants. The results show that recovery of work from the expansion process improves the COP by 15 to 20%. For the design conditions specified in this paper, this implies that the expander is worth fitting if it can be installed for a cost of less than approximately €750/kW of shaft power input. Thus, depending on the operating conditions, transcritical CO2 heat pumps using a compressor-expander can produce hot water at 90°C with a COP of approximately 6, with thermal outputs of up to 1.5 MW. This could be extended with simple control strategies up to outputs of 10 MW.

Investigation of characteristics of discharge pressure pulsation in a twin-screw refrigeration compressor

2018 ◽  
Vol 233 (6) ◽  
pp. 2206-2224
Author(s):  
Wenqing Chen ◽  
Xiaokun Wu ◽  
Ziwen Xing ◽  
Xiaolin Wang
Keyword(s):  
Rotational Speed ◽  
Pressure Pulsation ◽  
Design Parameters ◽  
Part Load ◽  
Design And Optimization ◽  
Feed Pressure ◽  
Twin Screw ◽  
Design Value ◽  
Discharge Pressure ◽  
Refrigeration Compressor

In this paper, characteristics of discharge pressure pulsation in a twin-screw refrigeration compressor are investigated. A thermodynamic model is developed and validated using data from a comprehensive experimental study. This validated model is then applied to investigate effects of key parameters including condensing temperature, compressor rotational speed, super-feed pressure, part-load operation, and design parameters on the discharge pressure pulsation. The results showed that the discharge pressure pulsation was mainly due to periodic variations of mass and energy flow from the working volumes to the discharge chamber. As the condensing temperature increased or decreased from the design condition, the compressor was in either over- or undercompression leading to an increase in the amplitude of the pressure pulsation. The gas super-feed pressure could increase the pressure pulsation at condensing temperatures below the design value and reduce the pressure pulsation at condensing temperatures above the design value. The analysis also demonstrated that the pressure pulsation was lower at part-load conditions. However, the compressor rotational speed increased both the amplitude and frequency of the pressure pulsation. Theoretical analysis of design parameters indicated that a large discharge volume with a high number of lobes could lower the pressure pulsation. These analyses provide useful information for the compressor design and optimization.

Numerical Modeling of Reflux Solar Receivers

1993 ◽  
Vol 115 (2) ◽  
pp. 93-100 ◽  
Author(s):  
R. E. Hogan
Keyword(s):  
Experimental Data ◽  
Numerical Modeling ◽  
Energy Transfer ◽  
Thermal Resistance ◽  
Numerical Models ◽  
Control Volume ◽  
Operating Conditions ◽  
Working Fluid ◽  
Detailed Model ◽  
Finite Control

Using reflux solar receivers to collect solar energy for dish-Stirling electric power generation systems is presently being investigated by several organizations, including Sandia National Laboratories, Albuquerque, N. Mex. In support of this program, Sandia has developed two numerical models describing the thermal performance of pool-boiler and heat-pipe reflux receivers. Both models are applicable to axisymmetric geometries and they both consider the radiative and convective energy transfer within the receiver cavity, the conductive and convective energy transfer from the receiver housing, and the energy transfer to the receiver working fluid. The primary difference between the models is the level of detail in modeling the heat conduction through the receiver walls. The more detailed model uses a two-dimensional finite control volume method, whereas the simpler model uses a one-dimensional thermal resistance approach. The numerical modeling concepts presented are applicable to conventional tube-type solar receivers, as well as to reflux receivers. Good agreement between the two models is demonstrated by comparing the predicted and measured performance of a pool-boiler reflux receiver being tested at Sandia. For design operating conditions, the receiver thermal efficiencies agree within 1 percent and the average receiver cavity temperature within 1.3 percent. The thermal efficiency and receiver temperatures predicted by the simpler thermal resistance model agree well with experimental data from on-sun tests of the Sandia reflux pool-boiler receiver. An analysis of these comparisons identifies several plausible explanations for the differences between the predicted results and the experimental data.

Determination of the phase structure of polymerblends by electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 492-493
Author(s):  
Dr. G. Kaemof
Keyword(s):  
Screw Extruder ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Single Screw Extruder ◽  
Transmission Electron ◽  
The Matrix ◽  
Twin Screw ◽  
Special Case ◽  
Microscopic Investigations

A mixture of polycarbonate (PC) and styrene-acrylonitrile-copolymer (SAN) represents a very good example for the efficiency of electron microscopic investigations concerning the determination of optimum production procedures for high grade product properties.The following parameters have been varied:components of charge (PC : SAN 50 : 50, 60 : 40, 70 : 30), kind of compounding machine (single screw extruder, twin screw extruder, discontinuous kneader), mass-temperature (lowest and highest possible temperature).The transmission electron microscopic investigations (TEM) were carried out on ultra thin sections, the PC-phase of which was selectively etched by triethylamine.The phase transition (matrix to disperse phase) does not occur - as might be expected - at a PC to SAN ratio of 50 : 50, but at a ratio of 65 : 35. Our results show that the matrix is preferably formed by the components with the lower melting viscosity (in this special case SAN), even at concentrations of less than 50 %.

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