Fiber energy efficiency Part I: Extended entropy model

2014 ◽  
Vol 29 (2) ◽  
pp. 322-331 ◽  
Author(s):  
Anders Karlström ◽  
Karin Eriksson
Keyword(s):  
Energy Efficiency ◽  
Temperature Profile ◽  
Dynamic Models ◽  
Fluid Dynamic ◽  
Multiscale Model ◽  
Process Conditions ◽  
Entropy Model ◽  
Refining Zone ◽  
Energy Balances ◽  
Flat Zone

Abstract This is the first in a series of papers presenting the development of a comprehensive multiscale model with focus on fiber energy efficiency in thermo mechanical pulp processes. The fiber energy efficiency is related to the defibration and fibrillation work obtained when fibers and fiber bundles interact with the refining bars. The fiber energy efficiency differs from the total refining energy efficiency which includes the thermodynamical work as well. Extracting defibration and fibrillation work along the radius in the refining zone gives information valuable for fiber development studies.Models for this process must handle physical variables as well as machine specific parameters at different scales. To span the material and energy balances, spatial measurements from the refining zone must be available. In this paper, measurements of temperature profile and plate gaps from a full-scale CD-refiner are considered as model inputs together with a number of process variables. This enables the distributed consistency in the refining zone as well as the split of the total work between the flat zone and the CD-zone to be derived. As the temperature profile and the plate gap are available in the flat zone and the CD-zone at different process conditions it is also shown that the distributed pulp dynamic viscosity can be obtained. This is normally unknown in refining processes but certainly useful for all fluid dynamic models describing the bar-to-fiber interactions. Finally, it is shown that the inclusion of the machine parameters will be vital to get good estimates of the refining conditions and especially the split between the thermodynamical work and the defibration/fibrillation work.

scholarly journals TMP properties and refiner conditions in a CD82 chip refiner at different operation points. Part II: Comparison of the five tests

2018 ◽  
Vol 33 (1) ◽  
pp. 82-94
Author(s):  
Rita Ferritsius ◽  
Olof Ferritsius ◽  
Jan Hill ◽  
Anders Karlström ◽  
Karin Eriksson
Keyword(s):  
Specific Energy ◽  
Specific Energy Consumption ◽  
Optimal Operation ◽  
Operating Conditions ◽  
Process Conditions ◽  
Residence Times ◽  
Entropy Model ◽  
Refining Zone ◽  
Tensile Index ◽  
Pulp Properties

Abstract This paper is part two of a study on a CD 82 TMP chip refiner where relations between changes in the process conditions and changes in the properties of the produced pulp are investigated. Focus is on the ratio between tensile index and specific energy consumption when results from five tests are compared. Pulp properties were measured for composite pulp samples taken from the refiner blow line. Residence times and pulp consistencies were estimated by use of the extended entropy model. Clearly, an increase in specific energy does not necessarily implicate an increase in strength properties of the pulp produced. It is of high importance to have access to information about the refining zone conditions when searching for an optimal operation point in terms of the ratio between tensile index and specific energy. In these tests, this ratio had a maximum at about 55 % measured blow line consistency. Unfavourable operating conditions were identified at high pulp consistencies, especially after the FZ, where pulp consistencies well above 70 % were observed. The estimated residence time for each refining zone responded differently when applying changes in production rate, plate gaps and dilution water flow rates. In conclusion, the results associated with estimated pulp consistencies where easier to interpret compared with results for residence times, implying that additional tests are required for the latter variable. In addition to tensile index, pulp properties like freeness, Somerville shives and light scattering coefficient were included in the analysis.

scholarly journals Temperature Profile in Rubber Injection Molding: Application of a Recently Developed Testing Method to Improve the Process Simulation and Calculation of Curing Kinetics

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 380
Author(s):  
Martin Traintinger ◽  
Roman Christopher Kerschbaumer ◽  
Bernhard Lechner ◽  
Walter Friesenbichler ◽  
Thomas Lucyshyn
Keyword(s):  
Injection Molding ◽  
Temperature Profile ◽  
Pressure Sensors ◽  
Simulation Software ◽  
Relative Degree ◽  
Actual State ◽  
Process Conditions ◽  
Inlet Temperature ◽  
Degree Of Cure ◽  
Mass Temperature

Injection molding of rubber compounds is an easily conducted yet sophisticated method for rubber processing. Simulation software is used to examine the optimal process conditions, identify failure scenarios, and save resources. Due to the complexity of the entire process, various aspects have to be considered in the numerical approach. This contribution focused on a comparison of process simulations with various definitions of the material’s inlet temperature, ranging from a stepwise increase, but constant temperature, to an exact axial mass temperature profile prior to injection. The latter was obtained with a specially designed, unique test stand consisting of a plasticizing cylinder equipped with pressure sensors, a throttle valve for pressure adjustments, and a measurement bar with thermocouples for the determination of the actual state of the mass temperature. For the verification of the theoretical calculations, practical experiments were conducted on a rubber injection molding machine equipped with the mold used in the simulation. The moldings, obtained at different vulcanization time, were characterized mechanically and the results were normalized to a relative degree of cure in order to enable comparison of the real process and the simulation. Considering the actual state of the mass temperature, the simulation showed an excellent correlation of the measured and calculated mass temperatures in the cold runner. Additionally, the relative degree of cure was closer to reality when the mass temperature profile after dosing was applied in the simulation.

Towards real-time fire data synthesis using numerical simulations

2021 ◽  
pp. 073490412199344
Author(s):  
Wolfram Jahn ◽  
Frane Sazunic ◽  
Carlos Sing-Long
Keyword(s):  
Real Time ◽  
Computational Fluid Dynamic ◽  
Dynamic Models ◽  
Fluid Dynamic ◽  
Near Field ◽  
Computing Time ◽  
Temperature Correction ◽  
Dynamic Simulations ◽  
Conservation Of Energy ◽  
Fire Scenarios

Synthesising data from fire scenarios using fire simulations requires iterative running of these simulations. For real-time synthesising, faster-than-real-time simulations are thus necessary. In this article, different model types are assessed according to their complexity to determine the trade-off between the accuracy of the output and the required computing time. A threshold grid size for real-time computational fluid dynamic simulations is identified, and the implications of simplifying existing field fire models by turning off sub-models are assessed. In addition, a temperature correction for two zone models based on the conservation of energy of the hot layer is introduced, to account for spatial variations of temperature in the near field of the fire. The main conclusions are that real-time fire simulations with spatial resolution are possible and that it is not necessary to solve all fine-scale physics to reproduce temperature measurements accurately. There remains, however, a gap in performance between computational fluid dynamic models and zone models that must be explored to achieve faster-than-real-time fire simulations.

Hyperbolic versus Parabolic Asymptotics in Kinetic Theory toward Fluid Dynamic Models

2013 ◽  
Vol 73 (4) ◽  
pp. 1327-1346 ◽  
Author(s):  
Abdelghani Bellouquid ◽  
Juan Calvo ◽  
Juan Nieto ◽  
Juan Soler
Keyword(s):  
Kinetic Theory ◽  
Dynamic Models ◽  
Fluid Dynamic

Theoretical Assessment of Convective and Radiative Heat Losses in a One-Dimensional Multiregion Premixed Flame With Counter-Flow Design Crossing Through Biofuel Particles

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Mehdi Bidabadi ◽  
Saman Hosseinzadeh ◽  
Sadegh Sadeghi ◽  
Mostafa Setareh
Keyword(s):  
Temperature Profile ◽  
Radiative Heat ◽  
Flame Structure ◽  
Flame Temperature ◽  
Heat Losses ◽  
Flame Velocity ◽  
Mass Fractions ◽  
Interface Matching ◽  
Energy Balances ◽  
Stagnation Plane

Due to perspective of biomass usage as a viable source of energy, this paper suggests a potential theoretical approach for studying multiregion nonadiabatic premixed flames with counterflow design crossing through the mixture of air (oxidizer) and lycopodium particles (biofuel). In this research, convective and radiative heat losses are analytically described. Due to the properties of lycopodium, roles of drying and vaporization are included so that the flame structure is created from preheating, drying, vaporization, reaction, and postflame regions. To follow temperature profile and mass fraction of the biofuel in solid and gaseous phases, dimensionalized and nondimensionalized forms of mass and energy balances are expressed. To ensure the continuity and calculate the positions of drying, vaporization, and flame fronts, interface matching conditions are derived employing matlab and mathematica software. For validation purpose, results for temperature profile is compared with those provided in a previous research study and an appropriate is observed under the same conditions. Finally, changes in flame velocity, flame temperature, solid and gaseous fuel mass fractions, and particle size with position measured from the position of stagnation plane, strain rate, and heat transfer coefficient in the presence/absence of losses are evaluated.

scholarly journals Energy Efficiency of a Solar Wall with Transparent Insulation in Polish Climatic Conditions

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 859
Author(s):  
Jadwiga Świrska-Perkowska ◽  
Andrzej Kucharczyk ◽  
Jerzy Wyrwał
Keyword(s):  
Energy Efficiency ◽  
Climatic Conditions ◽  
Temperate Climate ◽  
Heating Period ◽  
Conductivity Equation ◽  
Building Envelopes ◽  
Thermal Conductivity Equation ◽  
Proposed Model ◽  
Solar Wall ◽  
Energy Balances

A numerical model of a solar wall (SW) with transparent insulation (TI) is proposed in this article. The model is based on the finite-difference method and thermal conductivity equation, with a heat source term for the absorber. Using this model, the energy efficiency of a solar wall with transparent insulation (SW-TI) with honeycomb insulation made of modified cellulose acetate was analyzed in the case of different climatic conditions prevailing in Poland, different orientations of the envelope, and different insulation thicknesses. Simulations were carried out throughout the whole heating period. Monthly energy balances and temperature distributions for the analyzed envelopes at individual moments of the heating period are the basic results of the simulations. It was found that the use of 108 and 88 mm thick insulation was the most recommended in the considered temperate climate. Placing transparent insulation on a wall with an eastern or western orientation caused the annual heat balance of the envelope to decrease by 24–31% in relation to the value of this balance in the case of a southern orientation. The monthly heat balances obtained using the proposed model give results consistent with the method of calculating heat gains for opaque building envelopes with transparent insulation included in the PN-EN ISO 13790:2008 standard.

On Assessing the Quality of Particle Tracking Through Computational Fluid Dynamic Models

2002 ◽  
Vol 124 (2) ◽  
pp. 166-175 ◽  
Author(s):  
Mauro Tambasco ◽  
David A. Steinman
Keyword(s):  
Velocity Field ◽  
Computational Fluid Dynamic ◽  
Particle Deposition ◽  
Dynamic Models ◽  
Fluid Dynamic ◽  
Mass Conservation ◽  
Carotid Bifurcation ◽  
Quantitative Information ◽  
Flow Models ◽  
Path Dependent

Quantification of particle deposition patterns, transit times, and shear exposure is important for computational fluid dynamic (CFD) studies involving respiratory and arterial models. To numerically compute such path-dependent quantities, it is necessary to employ a Lagrangian approach where particles are tracked through a pre-computed velocity field. However, it is difficult to determine in advance whether a particular velocity field is sufficiently resolved for the purposes of tracking particles accurately. Towards this end, we propose the use of volumetric residence time (VRT)—previously defined for 2-D studies of platelet activation and here extended to more physiologically relevant 3-D models—as a means of quantifying whether a volume of Lagrangian fluid elements (LFE’s) seeded uniformly and contiguously at the model inlet remains uniform throughout the flow domain. Such “Lagrangian mass conservation” is shown to be satisfied when VRT=1 throughout the model domain. To demonstrate this novel concept, we computed maps of VRT and particle deposition in 3-D steady flow models of a stenosed carotid bifurcation constructed with one adaptively refined and three nominally uniform finite element meshes of increasing element density. A key finding was that uniform VRT could not be achieved for even the most resolved meshes and densest LFE seeding, suggesting that care should be taken when extracting quantitative information about path-dependent quantities. The VRT maps were found to be useful for identifying regions of a mesh that were under-resolved for such Lagrangian studies, and for guiding the construction of more adequately resolved meshes.

scholarly journals Energy efficiency of food production wastewater anaerobic-aerobic treatment

2019 ◽  
Vol 140 ◽  
pp. 01001 ◽  
Author(s):  
Rustem Khabibullin ◽  
Thao Le Huong ◽  
Olga Ivanchenko ◽  
Andrey Petrov
Keyword(s):  
Energy Efficiency ◽  
Wastewater Treatment ◽  
Food Production ◽  
Functional Dependence ◽  
Organic Load ◽  
Specific Yield ◽  
Process Conditions ◽  
Resource Saving ◽  
Specific Flow ◽  
Load Rate

The advanced energyand resource saving technologies of food production wastewater treatment include anaerobic and aerobic steps. At present, various methods of intensification and optimization are used to increase the efficiency of anaerobic processes of wastewater treatment, including selection of active microbial communities, providing the optimum temperature regime, immobilizing biomass by granulation or biofilm formation, reducing various inhibitory effects, phase separation or pre-acidification, chemical or biological pretreatment of wastewater. The aim of this investigation was researching the effect of hydraulic and organic load rates on the energy efficiency of the wastewater treatment process and evaluating the energy efficiency depending on process conditions. Experimental laboratory installation included subsequently connected bioreactors, one from which acted as first stage and other bioreactors as the second stages of anaerobic process. It was shown that the biogas formation at the first and second stages differs significantly. A small volume of released biogas on the first stage allows us to ignore it, but characteristics of biogas formation at the second stage bioreactors are close and are described by general functional dependence. The specific yield of biogas from the organic matter consumed Ybg is independent of the specific organic load rate L, but is dependent on the specific flow rate of the treated water D.

scholarly journals The information system for the regional energy balance formation

2019 ◽  
Vol 77 ◽  
pp. 02005
Author(s):  
Roman Muzychuk
Keyword(s):  
Energy Efficiency ◽  
Information System ◽  
Energy Balance ◽  
Energy Sector ◽  
Statistical Information ◽  
Energy Resources ◽  
Regional Energy ◽  
Energy Complex ◽  
Energy Balances

A study of the energy efficiency of the fuel and energy complex of the regions has a great attention. For an integrated introduction of trends and patterns in the energy sector, approaches we use based on the analysis of the fuel and energy balance (FEB). The function of FEB is to show the availability and use of energy resources in a certain territory and determination of indices of energy efficiency. The article presents an approach to the formation of fuel and energy balances based on the available statistical information.

scholarly journals Digital Twin for Monitoring of Industrial Multi-Effect Evaporation

Processes ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 537 ◽  
Author(s):  
Rafael M. Soares ◽  
Maurício M. Câmara ◽  
Thiago Feital ◽  
José Carlos Pinto
Keyword(s):  
Real Time ◽  
Fluid Dynamic ◽  
Successful Implementation ◽  
Processing Unit ◽  
Digital Twin ◽  
Dynamic Mass ◽  
Digital Twins ◽  
Process Operation ◽  
Energy Balances ◽  
Mass And Energy Balances

Digital twins are rigorous mathematical models that can be used to represent the operation of real systems. This connection allows for deeper understanding of the actual states of the analyzed system through estimation of variables that are difficult to measure otherwise. In this context, the present manuscript describes the successful implementation of a digital twin to represent a four-stage multi-effect evaporation train from an industrial sugar-cane processing unit. Particularly, the complex phenomenological effects, including the coupling between thermodynamic and fluid dynamic effects, and the low level of instrumentation in the plant constitute major challenges for adequate process operation. For this reason, dynamic mass and energy balances were developed, implemented and validated with actual industrial data, in order to provide process information for decision-making in real time. For example, the digital twin was able to indicate failure of process sensors and to provide estimates for the affected variables in real time, improving the robustness of the operation and constituting an important tool for process monitoring.

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