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Wyszukujesz frazę "residence time distribution" wg kryterium: Temat


Wyświetlanie 1-13 z 13
Tytuł:
68Ge/68Ga radioisotope generator as a source of radiotracers for water flow investigations
Autorzy:
Palige, J.
Majkowska, A.
Herdzik, I.
Ptaszek, S.
Powiązania:
https://bibliotekanauki.pl/articles/146239.pdf
Data publikacji:
2011
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
Ga-68
generator
residence time distribution (RTD)
Opis:
Radiotracer experiments on the model of rectangular settler with a volume of 3 m3, with a consecutive application as a tracer of the aqueous phase fluoresceine (representative tracer of water), eluate from a 68Ge/68Ga radioisotope generator (0.1 N HCl solution) and chelates after Ga ions complexation with 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) and 1,4,7,10-tetrazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) were carried out. The obtained residence time distribution (RTD) functions indicate that only the complex compounds of gallium are stable in the water phase and are not adsorb on the vessel walls, so they can be recommended as tracers of the water phase.
Źródło:
Nukleonika; 2011, 56, 1; 77-80
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A sensitivity analysis of kinetic characterizations in continuous flotation circuits under moderate deviations with respect to perfect mixing
Autorzy:
Vinnett, Luis
Pino-Muñoz, Catalina A.
Yianatos, Juan
Díaz, Francisco
Henríquez, Felipe
Powiązania:
https://bibliotekanauki.pl/articles/2146941.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
flotation kinetics
residence time distribution
perfect mixing
flotation rate distribution
industrial flotation circuit
Opis:
This paper studies the effect of moderate deviations with respect to perfect mixing on the estimated kinetic parameters in industrial flotation banks. Radioactive tracer tests and mass balance surveys were performed to characterize the mixing regimes and Cu kinetic responses. For three models (Single Rate Constant, Rectangular and Gamma), two approaches to incorporate the residence time distributions (RTD) in the kinetic characterizations of rougher banks were compared: (i) RTDs measured from the radioactive tracer tests; and (ii) pure perfect mixing in each flotation machine. The measured RTDs did not present significant bypass in the evaluated banks. In all cases, comparable model fitting was obtained with both RTD approaches, which indicates that the kinetic models add sufficient flexibility to compensate for moderate biases in the mixing regime. The studied kinetic models showed non-significant differences in the estimated maximum recoveries (R∞), mean (kmean) and median (k50) rate constants when comparing the process modelling from measured RTDs and pure perfect mixing. However, the Gamma model was more sensitive to the RTD assumption in terms of the shapes of the flotation rate distributions. From the results, kinetic characterizations focused only on model fitting, or on R∞ and kmean (or k50) estimations have low sensitivity to the assumption of perfect mixing when the RTDs present moderate deviations with respect to this regime. Special attention must be paid when characterizing floating components as the perfect mixing assumption may bias the shapes of the flotation rate distributions.
Źródło:
Physicochemical Problems of Mineral Processing; 2022, 58, 5; art. no. 152420
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Twin Screw Extrusion for Continuous Processing of Energetic Materials
Autorzy:
Dombe, G.
Mehilal, D.
Bhongale, C.
Singh, P. P.
Bhattacharya, B.
Powiązania:
https://bibliotekanauki.pl/articles/358044.pdf
Data publikacji:
2015
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
twin screw extruder
energetic materials
rheology
safety
residence time distribution
Opis:
Continuous processing of energetic materials using a twin screw extruder is gaining importance as it is a safe and cost-effective alternative to conventional batch processing. The continuous process based on a twin screw extruder combines the capabilities of intensive mixing and high pressure extrusion. It is used for processing a variety of energetic materials, such as gun and rocket propellants, plastic bonded explosives, pyrotechnics, thermo-baric explosives, etc. The twin screw extruder process demands various safety features for the processing of energetic materials. Therefore, exhaustive characterisation of the energetic materials in terms of safety and rheology, coupled with characterisation of the mechanical components of the extruder, are essential for designing a safe continuous process. In this article, a technological overview of continuous processing for energetic materials is presented, along with its various features, process design methodology and safety issues.
Źródło:
Central European Journal of Energetic Materials; 2015, 12, 3; 507-522
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental study and mathematical modeling of the residence time distribution in magnetic mixer
Autorzy:
Rakoczy, R.
Kordas, M.
Grądzik, P.
Konopacki, M.
Story, G.
Powiązania:
https://bibliotekanauki.pl/articles/778204.pdf
Data publikacji:
2013
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
mixing model
residence time distribution
modelling
magnetic field
Opis:
This study reports on research results in the field of a mixing process under the action of a transverse rotating magnetic field (TRMF). The main objective of this paper is to present the effect of this type of a magnetic field on residence time distribution (RTD) measurements. This paper evaluates the performance of a magnetic mixer by comparing the results of an experimental investigations in a pilot set-up and theoretical values obtained from mathematical model. This model consisting of the set of ideal continuous stirred tank reactors (CSTR) fitted well the experimental data.
Źródło:
Polish Journal of Chemical Technology; 2013, 15, 2; 53-60
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement of liquid holdup and axial dispersion in trickle bed reactors using radiotracer technique
Autorzy:
Pant, H.
Saroha, A.
Nigam, K.
Powiązania:
https://bibliotekanauki.pl/articles/146732.pdf
Data publikacji:
2000
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
axial dispersion model
holdup
mean residence time
Peclet number
residence time distribution
trickle-bed reactor
Opis:
The holdup and axial dispersion of aqueous phase has been measured in trickle bed reactors as a function of liquid and gas flow rates using radioisotope tracer technique. Experiments were carried out in a glass column of inner diameter 15.2´10-2 m column for air-water system using three different types of packings i.e. non-porous glass beads, porous catalysts of tablet and extrudate shape. The range of liquid and gas flow rates used were 8.3´10-5-3.3´10-4 m3/s and 0-6.67´10-4 m3/s, respectively. Residence time distributions of liquid phase were measured and mean residence times were determined. The values of liquid holdup were calculated from the measured mean residence times. It was observed that liquid holdup increased with increase in liquid flow rates and was independent of increase in gas flow rates used in the study. Two-parameter axial dispersion model was used to simulate measured residence time distribution data and values of mean residence time and Peclet number were obtained. It was observed that values of Peclet number increases with increase in liquid flow rate for glass beads and tablets and remains almost constant for extrudates. The values of mean residence time obtained from model simulation were found to be in good agreement with the values measured experimentally.
Źródło:
Nukleonika; 2000, 45, 4; 235-241
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Model migracji jonu wskaźnikowego w poziomie wodonośnym czwartorzędu w widłach Dunajca i Białej
A transport model for chemical indicator in the Quaternary aquifer of the area between the Dunajec and Biała rivers
Autorzy:
Kania, J.
Haładus, A.
Szczepański, A.
Zdechlik, R.
Wojtal, G.
Powiązania:
https://bibliotekanauki.pl/articles/2062542.pdf
Data publikacji:
2012
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
model transportu zanieczyszczeń
rozkład czasów przepływu
średni czas przepływu
solute transport model
residence time distribution (RTD)
mean residence time (MRT)
Opis:
Modelowanie transportu zanieczyszczeń w wodach podziemnych poziomu czwartorzędowego w widłach Dunajca i Białej zrealizowano dla nieustalonych warunków migracji na bazie ustalonego, dwuwymiarowego pola hydrodynamicznego. Rozkład stężeń jonu wskaźnikowego odtworzony na modelu migracji zanieczyszczeń według stanu na 2009 r. uwzględnia wyniki opróbowań wód podziemnych w kilkudziesięciu punktach, jak też występujące długoletnie przesunięcie czasowe w odpowiedzi otwartego systemu zlewniowego na zmianę ładunku wprowadzanych zanieczyszczeń.
Modelling of transient transport of contaminants in the Quaternary aquifer of the area between the Dunajec and Biała rivers was performed for the assumed hydrodynamic steady state conditions. Spatial distribution of chemical indicator for year 2009, calculated with the aid of the transport model, reflects the results of groundwater sampling at several points as well as time lag in the response of the groundwater flow system to the change in the contaminant load.
Źródło:
Biuletyn Państwowego Instytutu Geologicznego; 2012, 451 Hydrogeologia z. 13; 137--144
0867-6143
Pojawia się w:
Biuletyn Państwowego Instytutu Geologicznego
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling and simulation of vertical roller mill using population balance model
Autorzy:
Fatahi, Rasoul
Barani, Kianoush
Powiązania:
https://bibliotekanauki.pl/articles/1449686.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
vertical roller mill
modeling
simulation
cement grinding
residence time distribution
Opis:
There are few studies concerning the process simulation of vertical roller mills (VRMs). In this research work, the application of population balance model for simulation of a VRM in a cement clinker grinding circuit was investigated. The residence time distribution (RTD) was measured, and the tank-in-series and Weller models were employed to describe the residence time distribution. Two sampling surveys were carried out on the VRM circuit. The data from the first survey were used for model calibration, and the specific breakage rates were back-calculated. The model parameters obtained were used for simulation of the second survey, and validation of the model. The results showed that the clinker particle spent a short time inside the VRM and the mean residence time is about 67s. The tanks-in series model compares to Weller model was more proper to describe the residence time distributions in the VRM. The simulation results showed that the specific breakage rates increased with increasing particle size. However, the particles larger than 25.4 mm particles sizes are too large to be properly nipped by master rollers. Finally, it can be concluded that the grinding process of the VRM is very well-predictable with the population balance model.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 1; 24-33
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Investigation of the Hydrodynamic Conditions in A Multi-Strand Cc Tundish with Closed Outlets
Numeryczne badania hydrodynamiki przepływu w wielowylewowej kadzi pośredniej z zamkniętymi wylewami
Autorzy:
Merder, T.
Powiązania:
https://bibliotekanauki.pl/articles/353484.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
numerical modeling
residence time distribution
tundish
closing strand
symulacje numeryczne
krzywe RTD
kadź pośrednia
Opis:
In industrial conditions there are situations when the CC machine works under emergency. It can be result of mechanical or electrical causes, breakout of billet or problem with supplying new parts of liquid steel to the CC machine. As a consequence one or two outlets of the tundish should be closed. However, closing one of the outlets influences the hydrodynamic and thermal conditions occurring in the tundish. Thus, the important information is which of the outlets should be closed to conduct further continuous casting process correctly. The following research was conducted to analyze the influence of liquid steel flow behaviour in the multi-strand tundish when all outlets do not work. Such problem was solved by means of numerical methods based on Navier-Stokes equations (k–ɛ standard turbulence model). Numerical simulations were done using the educational version of CFD program (Computational Fluid Dynamics) – ANSYSFluent. As a result forecasted velocity fields and RTD curves (Residence Time Distribution) were obtained. RTD characteristics were used to determine kinetics of liquid steel mixing and also to calculate parts of particular flow areas for studied cases.
W warunkach przemysłowych zdarzają się sytuacje, kiedy maszyna COS pracuje w stanie awaryjnym. Wynikać to może z powodu usterek mechanicznych lub elektrycznych, przerwania wlewka ciągłego lub być wywołane dostarczeniem nowej partii ciekłej stali na stanowisko COS. Prowadzi to do zamknięcia jednego lub dwóch wylewów w kadzi pośredniej. Zamknięcie któregokolwiek z wylewów wpływa na warunki hydrodynamiczne i termiczne panujące wewnątrz kadzi. Istotną informacją jest więc to, które z otworów wylewowych powinny być zamknięte, aby proces ciągłego odlewania przebiegał prawidłowo. Niniejsze badania mają na celu analizę wpływu zachowania przepływu ciekłej stali w wielowylewowej kadzi pośredniej, kiedy nie pracują wszystkie otwory wylewowe. Tak postawiony problem rozwiązywano metodami numerycznymi opartymi na równaniach Naviera-Stokesa przy użyciu modelu turbulencji standard k–ɛ. Symulacje numeryczne przeprowadzono z wykorzystaniem edukacyjnej wersji programu CFD (Computational Fluid Dynamics) – ANSYSFluent. W wyniku obliczeń numerycznych otrzymano prognozowane rozkłady pól prędkości i krzywe RTD (Residence Time Distribution). Opracowane charakterystyki RTD posłużyły do określenie kinetyki mieszania stali, oraz wyliczenia udziałów poszczególnych stref przepływu dla rozpatrywanych przypadków.
Źródło:
Archives of Metallurgy and Materials; 2014, 59, 3; 887-892
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Process Design for Size-Controlled Flame Spray Synthesis of Li4Ti5O12 and Electrochemical Performance
Autorzy:
Waser, O.
Brenner, O.
Groehn, A.J.
Pratsinis, S.E.
Powiązania:
https://bibliotekanauki.pl/articles/952680.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Li-ion battery
Li4Ti5O12
size control
residence time distribution computational fluid
dynamics
flame synthesis of electroceramics
bateria litowo-jonowa
kontrola rozmiaru
płyn obliczeniowy do dystrybucji czasu przebywania
dynamika
synteza płomieniowa elektroceramiki
Opis:
Inexpensive synthesis of electroceramic materials is required for efficient energy storage. Here the design of a scalable process, flame spray pyrolysis (FSP), for synthesis of size-controlled nanomaterials is investigated focusing on understanding the role of air entrainment (AE) during their aerosol synthesis with emphasis on battery materials. The AE into the enclosed FSP reactor is analysed quantitatively by computational fluid dynamics (CFD) and calculated temperatures are verified by Fourier transform infrared spectroscopy (FTIR). Various Li4Ti5O12 (LTO) particle compositions are made and characterized by N2 adsorption, electron microscopy and X-ray diffraction while the electrochemical performance of LTO is tested at various charging rates. Increasing AE decreases recirculation in the enclosing tube leading to lower reactor temperatures and particle concentrations by air dilution as well as shorter and narrower residence time distributions. As a result, particle growth by coagulation - coalescence decreases leading to smaller primary particles that are mostly pure LTO exhibiting high C-rate performance with more than 120 mAh/g galvanostatic specific charge at 40C, outperforming commercial LTO. The effect of AE on FSP-made particle characteristics is demonstrated also in combustion synthesis of LiFePO4 and ZrO2.
Źródło:
Chemical and Process Engineering; 2017, 38, 1; 51-66
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Radioisotope tracer study in an indirectly heated rotary dryer
Autorzy:
Pant, H.
Powiązania:
https://bibliotekanauki.pl/articles/147094.pdf
Data publikacji:
2002
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
holdup
lanthanum-140
mean residence time
radioisotope tracer
residence time distribution
rotary dryer
variance
Opis:
A radioisotope tracer study was carried-out in a pilot scale indirectly heated rotary dryer to measure residence time distribution (RTD) of sand particles. Lanthanum-140 labeled sand was used as a tracer. Mean residence time (MRT) and variance of the tracer distribution curves were calculated from the measured RTD curves. From the calculated MRTs, solid holdup in the dryer was estimated. The qualitative comparison of the dimensionless variance with the data published in the literature led to the conclusion that the rotary dryer behaves as a plug flow system. The results of the study were used to design a full-scale industrial rotary dryer.
Źródło:
Nukleonika; 2002, 47, 4; 173-176
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Radiotracer investigations of municipal sewage treatment stations
Autorzy:
Farooq, M.
Khan, I.
Ghiyas-ud-Din, Ghiyas-ud-Din
Gul, S.
Palige, J.
Dobrowolski, A.
Powiązania:
https://bibliotekanauki.pl/articles/971492.pdf
Data publikacji:
2003
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
wastewater treatment
residence time distribution
activated sludge
radiotracer
Opis:
Tracer techniques, which are well-established methods in process dynamics studies in industry, were applied to investigate the dynamics of sewage treatment process. The concept of residence time distribution (RTD) was used to investigate the efficiency of the primary clarifier, aeration tank and secondary clarifier of a sewage treatment plant. Preliminary treatment and modeling of the tracer data was performed using the software DTS Pro Ver. 4.20. A big short - circuiting (by-passing) with a large volume of stagnant zones were found in the primary and secondary clarifiers, while no stagnant zone was detected in the aeration tank.
Źródło:
Nukleonika; 2003, 48, 1; 57-61
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation of residence time distribution and mixing in reactors with recirculation using 2D approach
Autorzy:
Zima, P.
Powiązania:
https://bibliotekanauki.pl/articles/1934023.pdf
Data publikacji:
2011
Wydawca:
Politechnika Gdańska
Tematy:
mathematical modeling
residence time distribution
reactors with recirculation
2D approach
Opis:
In this paper, we propose a 2D approach in order to create a mathematical model for the determination of the residence time distribution for a flow reactor with recirculation. Apart from characterizing the functional residence time distribution, this model can help improve the operation of the reactor at the design stage. The mathematical model was validated by comparison with experiments carried out in a hydraulic laboratory.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2011, 15, 3-4; 297-315
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of the shape of turbulence inhibitors on the hydrodynamic conditions occuring in a tundish
Wpływ kształtu inhibitora turbulencji na warunki hydrodynamiczne panujące w kadzi pośredniej
Autorzy:
Merder, T.
Powiązania:
https://bibliotekanauki.pl/articles/355771.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
tundish
continuous casting
numerical modeling
residence time distribution (RTD)
kadź pośrednia
odlewanie ciągłe
modelowanie numeryczne
charakterystyka RTD
Opis:
The article presents results of the research that was carried out taking into account the influence of the (impact pads) turbulence inhibitor geometry and its equipment of the working space on the hydrodynamic conditions occurring in T-type tundish. Four different turbulence inhibitors were discussed. They differ in shape and configuration of external walls. The research was conducted basing on the numerical simulations as well as on tests performed on physical water model. As a result of calculations the velocity field distribution, turbulence field and marker concentration distribution in the liquid steel for the tested geometrical variants of turbulence inhibitors were obtained. Worked out RTD curves (Residence Time Distribution) allowed to determine the kinetics of steel mixing (the range of transient zone was estimated), and the percentage participation of the particular flow zones. The test carried out on the water model concerned one of the tested turbulence inhibitors. Research was done to verify the parameter settings of the numerical model applied in calculations. Obtained results gave valuable information about the work of the object after applying different turbulence inhibitors.
Artykuł przedstawia wyniki badań wpływu geometrii i sposobu zabudowy inhibitora turbulencji na warunki hydrodynamiczne panujące w przestrzeni roboczej kadzi pośredniej typu T. Rozpatrywano cztery warianty geometryczne inhibitora turbulencji. Inhibitory turbulencji różniły się kształtem i ukształtowaniem ścian wewnętrznych. Badania zrealizowano w oparciu o technikę modelowania numerycznego, oraz eksperyment na fizycznym modelu wodnym. W wyniku obliczeń uzyskano pola prędkości, turbulencji oraz rozkładu stężeń znacznika wprowadzonego do ciekłej stali w przestrzeni kadzi pośredniej dla rozpatrywanych wariantów geometrycznych inhibitora turbulencji. Opracowane charakterystyki RTD (Residence Time Distribution) umożliwiły określenie kinetyki mieszania stali (oszacowano zakres strefy przejściowej), oraz udziały procentowe poszczególnych stref przepływu. Badania uzupełniono o eksperyment na fizycznym modelu wodnym. Dotyczył on jednego z proponowanych wariantów inhibitora turbulencji. Wykonano je w celu weryfikacji doboru parametrów modelu numerycznego w przyjętych w obliczeniach. Uzyskane wyniki dostarczyły cennych informacji o pracy obiektu po zastosowaniu różnych inhibitorów turbulencji.
Źródło:
Archives of Metallurgy and Materials; 2013, 58, 4; 1111-1117
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-13 z 13

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