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Number of results: 58
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Abstract

This study is focused on the image analysis of motionless hydraulic mixing process, for which pressure changes were the driving force. To improve the understanding of hydraulic mixing, mixing efficiency was assessed with dye introduction, which resulted in certain challenges. In order to overcome them, the framework and methodology consisting of three main steps were proposed and applied to an experimental case study. The experiments were recorded using a camera and then processed according to the proposed framework and methodology. The main outputs from the methodology which were based only on the recorded movie were liquid heights and colour changes during the process time. In addition, considerable attention has also been given to issues related to other colour systems and the hydrodynamic description of the process.
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Authors and Affiliations

Aleksandra Golczak
1
Waldemar Szaferski
1
ORCID: ORCID
Szymon Woziwodzki
1
Piotr T. Mitkowski
1
ORCID: ORCID

  1. Poznan University of Technology, Department of Chemical Engineering and Equipment, Berdychowo 4, 60-965 Poznan, Poland
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Abstract

Accordingly with the principles of the circular economy, mixed plastic wastes can be recycled also by thermoforming, getting new non-oriented fibers composite materials. This study highlights the mechanical behavior of new composite material plates containing recycled glass fibers as reinforcing element and ABS-PMMA mixture as matrix, as well as an efficient way to convert a manufacturing process wastes in a product. The mechanical behavior of new composite material plates was evidenced by tensile, flexural and compression tests. In addition a surface morphology analysis was performed.
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Authors and Affiliations

M.A. Platon
1
ORCID: ORCID
O. Nemeș
1 2
ORCID: ORCID
A.-E. Tiuc
1
ORCID: ORCID
C. Vilău
3
ORCID: ORCID
C.M. Dudescu
3
ORCID: ORCID
S. Pădurețu
4
ORCID: ORCID

  1. Technical University of Cluj-Napoca, Faculty of Materials and Environmental Engineering, 28 Memorandumului Street, 400114, Cluj-Napoca, Romania
  2. National Institute for Research and Development in Environmental Protection, 294 Blvd. Splaiul Independentei, Sector 6, 060031, Bucharest, Romania
  3. Technical University of Cluj-Napoca, Faculty of Automotive, Mechatronics and Mechanical Engineering, 28 Memorandumului Street, 400114, Cluj-Napoca, Romania
  4. Technical University of Cluj-Napoca, Faculty of Machine Building, 28 Memorandumului Street, 400114, Cluj-Napoca, Romania.
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Abstract

The progressive processes of globalization and changes in the global, European and local economy require integrated efforts aimed at solving problems related to development at the national regional and the local level involving the environment, energy sources, climate and technological transformation issues. European Union Member States are given right to create an individual Energy mix. Coal will continue to play a major role in Poland’s energy mix during the next decades. Polish coal reserves can provide energy security for decades.

Despite crude oil and natural gas growth in fuel consumption, coal will continue to be the stabilizer of energy security for the country and play an important role in Poland’s energy mix in the years to come. However, further coal consumption requires investments in low carbon technologies which are of high efficiency and in high-efficiency cogeneration.

The validity of the full utilization of cogeneration potential should be highlighted. Operating cogeneration plants are more expensive than power plants but they are more efficient and generate less carbon emissions. In accordance with the assumptions of the Energy policy of Poland, a low-carbon economy with renewable Energy sources and nuclear Energy should be supported and developed, however the obsolete coal generators should be replaced with low-carbon high-efficient ones.

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Authors and Affiliations

Anna Kielerz
Monika Porzerzyńska-Antonik
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Abstract

Coal in Poland is an available conventional fuel providing energy security and independence of the country. Therefore, conventional energy generation should be based on coal with the optimal development of renewable energy sources. Such a solution secures the energy supply based on coal and the independence of political and economic turmoil of global markets. Polish coal reserves can secure the energy supply for decades. Coal will surely be important for energy security in the future despite the growing share of oil and gas in energy mix. The development of renewable power generation will be possible with the conventional energy generation offsetting volatile renewable power generation as Poland’s climate doesn’t allow for the stable and effective use of renewable energy sources. Considering the policy of the European Union with respect to emission reductions of greenhouse gasses and general trends as reflected in the Paris agreement in 2016, as a country we will be forced to increase renewable energy production in our energy mix. However, this process cannot impact the energy security of the country and stability and the uninterrupted supply of energy to consumers. Therefore seeking the compromise with the current energy mix in Poland is the best way to its gradual change with the simultaneous conservation of each of the sources of energy. It’s obvious that Poland can not be lonely energy island in Europe and in the world, which increasingly develops distributed energy and/ renewable technologies as well as energy storage ones. One can notice that without renewable generation and the reduction of coal’s share in country’s energy mix we will become the importer of electricity with raising energy dependence.

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Authors and Affiliations

Anna Kielerz
Waldemar Beuch
Robert Marzec
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Abstract

The future and development of energy is one of the most important problems in both domestic and global politics. Limiting the use of fossil fuels in the energy sector results from new legal conditions related to the protection of the natural environment. These changes require the development of a new energy strategy, taking the limits of greenhouse gas emissions in the European Union and the requirements of the Community energy policy into account. One of the documents affecting the structure of Poland’s energy mix is the Directive on renewable energy sources (2009/28/EC). Poland has committed to achieving the goal of a 15% share of energy from renewable sources (RES) in gross final energy consumption by 2020. Current changes in Polish RES support systems – in particular the transition from the system of green certificates to auctions for green energy – may threaten the achievement of the above-mentioned goal. The article analyzes whether Poland will meet renewable energy obligations by 2020 under the current conditions. In addition, the article presents current energy consumption in the world and in the country, legal conditions taken into account when creating the country’s energy mix and forecasts of renewable energy demand.

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Authors and Affiliations

Anna Manowska
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Abstract

The future and the development of power industry are the one of the major issues in the domestic and global policy. The impact of the power sector on the earth climate changes and the attention for sufficient funds of energy in the following years are the primary challenges which the power industry is facing. The article delineates the current state of the domestic sector of energy production. In the prospect of the next few years, it will draw on conventional power engineering nevertheless, with the growing involvement of renewable energy sources. However, it is important to develop the new energy strategy, which will point the direction of domestic energy production sector changes. What is more relevant, the new legal regulations connected with environmental protection will definitely restrict using fossil fuels in the power industry. In addition, the paper discusses the most important aspects involved in creating a country’s energy mix. The first aspect is the current state of the energy sector in Poland, i.e. the percentage of particular technologies in the present power and electrical energy balances, the technical state of the manufacturing sector’s infrastructure. Based on historical data of Polskie Sieci Elektroenergetyczne SA regarding the energy consumption and demand, a mathematical estimation for electricity demand and its consumption forecast was performed. The obtained forecasts were then used to conduct a simulation of power and energy demand fulfillment in the national power system. Finally, several possible scenarios were presented, taking different factors affecting the energy sector in Poland into consideration.

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Authors and Affiliations

Radosław Szczerbowski
Dominika Kornobis
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Abstract

Small bucket models with many short fictitious micro-periods ensure high-quality schedules in multi-level systems, i.e., with multiple stages or dependent demand. In such models, setup times longer than a single period are, however, more likely. This paper presents new mixedinteger programming models for the proportional lot-sizing and scheduling problem (PLSP) with setup operations overlapping multiple periods with variable capacity.
A new model is proposed that explicitly determines periods overlapped by each setup operation and the time spent on setup execution during each period. The model assumes that most periods have the same length; however, a few of them are shorter, and the time interval determined by two consecutive shorter periods is always longer than a single setup operation. The computational experiments showthat the newmodel requires a significantly smaller computation effort than known models.
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Bibliography

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Authors and Affiliations

Waldemar Kaczmarczyk
1

  1. Department of Strategic Management, AGH University of Science and Technology, Al.Mickiewicza 30, 30-059, Kraków, Poland
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Abstract

This paper presents the results of research on the admixture of other rock fragments in the granodiorite aggregate (two types of hornfels) produced in Łażany II quarry. It discusses the impact of these components on the selected chemical and mechanical properties important for the use of the aggregate in road construction. Analysed granodiorite grit is a high-class construction material suitable for bituminous mixtures. Its quality is verified in accordance with the PN-EN 13043 standard. The admixture of hornfels in aggregate composition is a consequence of the natural occuring this rock in the Łażany II granodiorite deposit in the Strzegom-Sobótka massif. As there is not selective exploitation of the deposit an extracted raw material is not separated during processing As a result, the aggregate, composed predominantly of granodiorite, comprises variable admixture of hornfels. Tests of properties, such as water absorption, resistance to freezing, resistance to fragmentation, crushing strength, carried out on grain populations of various petrographic types separated from the general samples, exhibit that the presence of hornfels in the aggregate has a beneficial effect, particularly on the mechanical parameters of the produced aggregate. Moreover, two varieties of hornfels differ in terms of some chemical properties (affinity with bitumen, presence of sulphides). These features may affect the durability of the aggregate in the wearing course which is directly influenced by the exterior conditions typical for road pavements.
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Authors and Affiliations

Bartłomiej Grzesik
1
ORCID: ORCID

  1. Silesian University of Technology, Gliwice, Poland
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Abstract

The present work comprises a numerical analysis using the Ansys program to solve the problem of combined free-forced convection around a circular cylinder located in a horizontal lid-driven trapezoidal enclosure. The enclosure is filled with water. The upper moving wall and lower fixed wall are cold at a constant temperature, whereas the inclined walls are adiabatically insulated. The uniformly heated cylinder is located at different positions in the cavity. The study covers three values of Richardson number (0.01, 1, and 10). The results show that the streamlines and isotherms in the enclosure, the Nusselt number and friction factor in the moving wall, hot wall and bottom wall are strongly dependent on the position of the inner hot cylinder. The results are validated with previous work, and the comparison gives good agreement.
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Authors and Affiliations

Asmaa Ali Hussein
1

  1. Middle Technical University, Institute of Technology/Baghdad, Baghdad, Iraq
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Abstract

The research was conducted in a relatively small (26.8 ha) but quite deep (17.3 m) Lake Długie in Olsztyn, Poland. For over 20 years the lake was collecting sewage which eventually caused its complete degradation. In 1987-2000 the lake was restored using the artificial aeration method with destratification of water. The results showed that the artificial aeration effectively limited the internal loading. Application of this restoration method resulted in reduction of phosphorus compounds concentrations in the analyzed water strata. The decrease of TP in bottom sediments (to the level of 3-4 mg P g·' DW) was probably associated with the fact that a new layer of sediments was created, reflecting a change in the aquatic conditions caused by the restoration. The investigations conducted in the reference years showed that the changes were not permanent. A high concentration of phosphorus compounds in bottom sediments, low sorptivc capacity and a tendency to oxygen deficiency, indicate that further possibility to decrease the amount of phosphorus compounds in the lake by this restoration method is limited.
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Authors and Affiliations

Renata Brzozowska
Helena Gawrońska
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Abstract

Obtaining a pure product by mixing together raw materials, so as to carry out a chemical reaction at high selectivity, is a difficult part of manufacturing chemical products. How can we test reactors and mixers to ensure the efficient use of energy?

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Authors and Affiliations

Magdalena Jasińska
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Abstract

This study presents the results of tests on the mixing power and distribution of three velocity components in the mixing tank for an FBT impeller during tank emptying with an operating impeller. A laser PIV system was used to determine speed distributions. It was found that for the relative liquid height in the tank H* = H/H0 ≈ 0.65 and H* ≈ 0.45, the liquid circulation in the impeller zone changed from radial to axial and vice versa. These changes were accompanied by changes in the mixing power which even reached 40%. In the theoretical part, a method of calculating the mixing power using the classical model of the central vortex and distribution of the tangential speed in the impeller zone was proposed. Although the method turned out to be inaccurate, it was useful for determining the relative power.
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Authors and Affiliations

Jacek Stelmach
1
ORCID: ORCID
Czesław Kuncewicz
1
ORCID: ORCID
Tomáš Jirout
2
ORCID: ORCID
František Rieger
2
ORCID: ORCID

  1. Lodz University of Technology, Faculty of Process and Environmental Engineering, Wólczańska 213, 93-005 Łódź
  2. Czech Technical University in Prague, Faculty of Mechanical Engineering, Technická 4, 166 07 Praha 6
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Abstract

The production of ethyl oleate, by homogenous acid esterification of oleic acid with ethanol, have discussed experimentally and via computational simulation in a plug flow reactor. An innovative simulation model has developed to predict the esterification reaction performance in an ideal plug flow reactor. The amount of H2SO4 acid catalyst, the initial molar ratio of alcohol to oleic acid, ethanol concentration, reaction temperature, and esterification time have examined their effects on ethyl oleate production and the conversion of oleic acid. Then the simulation extended to examine the esterification reaction kinetics and determine the reaction rate coefficients. The simulation results demonstrate that the increasing of H2SO4 acid, initial molar ratio of ethanol to oleic acid, ethanol concentration, and reaction temperature improved the productivity of the ethyl oleate and reduced the reactor space-time. The kinetics results illustrated that the reaction sensitivity to the temperature unchanging by using higher ethanol concentration and alcohol to oleic acid initial ratio. Lastly, the experimental yields at different conditions were slightly higher from those simulating with average values of 93.62 and 92.29%, respectively, indicating that the phenomenon of back-mixing cannot be ignored in esterification reactors, especially with a relatively high retention time within the reactor.
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Authors and Affiliations

Suondos K.A. Barno
1
Sarmad A. Rashid
2
Ammar S. Abbas
2

  1. Presidency of the University of Baghdad, Baghdad, Iraq
  2. Chemical Engineering Department, College of Engineering, University of Baghdad, Baghdad, Iraq
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Abstract

In this study the formation of the polygenetic High Tatra granitoid magma is discussed. Felsic and mafic magma mixing and mingling processes occurred in all magma batches composing the pluton and are documented by the typical textural assemblages, which include: mafic microgranular enclaves (MME), mafic clots, felsic clots, quartz-plagioclase-titanite ocelli, biotite-quartz ocelli, poikilitic plagioclase crystals, chemically zoned K-feldspar phenocrysts with inclusion zones and calcic spikes in zoned plagioclase. Geochemical modelling indicates the predominance of the felsic component in subsequent magma batches, however, the mantle origin of the admixed magma input is suggested on the basis of geochemical and Rb-Sr, Sm-Nd and Pb isotopic data. Magma mixing is considered to be a first-order magmatic process, causing the magma diversification. The cumulate formation and the squeezing of remnant melt by filter pressing points to fractional crystallization acting as a second-order magmatic process.

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Authors and Affiliations

Aleksandra Gawęda
Krzysztof Szopa
Roman Włodyka
Jolanta Burda
Quentin Crowley
Magdalena Sikorska
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Abstract

The paper presents the results of research and analysis of the effect of joining by the RFSSW method of alclad sheets made of Al2024 with an anodic oxide coating, with the using the tool with modified geometry of the front surface of inner sleeve. The different effects of the modifications made on the phenomenon of plasticization and stirring of materials in the process of creating a weld, microstructure of welds and mechanical strength of lap joints were shown. The tests were carried out on 1.27 mm thick sheets, with the use of an unmodified tool and modified tools with three variants of the geometry. The welds and the joints samples were subjected to metallographic and strength tests. It has been shown that the use of a properly selected modified geometry has a beneficial effect on the transport of materials to be joined in the joint zone (flow pattern of plasticized layers and the stirring effect) during the welding, which translates into the strength of the joints and the nature of the weld failure.
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Authors and Affiliations

W. Łogin
1
ORCID: ORCID
R.E. Śliwa
2
ORCID: ORCID
R. Ostrowski
2
ORCID: ORCID

  1. Development Project Office, Polskie Zakłady Lotnicze w Mielcu Sp. z o.o., Poland
  2. Rzeszów University of Technology, 12 Powstańców Warszawy Av., 35-959 Rzeszów, Poland
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Abstract

We demonstrate in this study that a rotating magnetic field (RMF) and spinning magnetic particles using this kind of magnetic field give rise to a motion mechanism capable of triggering mixing effect in liquids. In this experimental work two mixing mechanisms were used, magnetohydrodynamics due to the Lorentz force and mixing due to magnetic particles under the action of RMF, acted upon by the Kelvin force. To evidence these mechanisms,we report mixing time measured during the neutralization process (weak acid-strong base) under the action of RMF with and without magnetic particles. The efficiency of the mixing process was enhanced by a maximum of 6.5% and 12.8% owing to the application of RMF and the synergistic effect of magnetic field and magnetic particles, respectively.
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Authors and Affiliations

Rafał Rakoczy
1
ORCID: ORCID
Marian Kordas
1
ORCID: ORCID
Agata Markowska-Szczupak
1
ORCID: ORCID
Maciej Konopacki
1
ORCID: ORCID
Adrian Augustyniak
1
ORCID: ORCID
Joanna Jabłońska
1
Oliwia Paszkiewicz
1
ORCID: ORCID
Kamila Dubrowska
1
Grzegorz Story
1
Anna Story
1
Katarzyna Ziętarska
1
Dawid Sołoducha
1
Tomasz Borowski
1
Marta Roszak
2
Bartłomiej Grygorcewicz
2
ORCID: ORCID
Barbara Dołęgowska
2
ORCID: ORCID

  1. West Pomeranian University of Technology in Szczecin, Faculty of Chemical Technology and Engineering, Department of Chemical and Process Engineering, al. Piastów 42,71-065 Szczecin, Poland
  2. Pomeranian Medical University in Szczecin, Chair of Microbiology, Immunology and Laboratory Medicine, Department of Laboratory Medicine, al. Powstańców Wielkopolskich 72, 70-111 Szczecin, Poland
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Abstract

The current trend in the preparation of green sand mixtures emphasizes the acceleration of the mixing process while maintaining the quality of the mixture. This requirement results in the necessity of determining the optimal conditions for mixing the mixture with a given mixer. This work aims to determine the optimal mixing conditions for the newly introduced eddy mixer LM-3e from the company Multiserw-Morek in the sand laboratory at the Department of Metallurgical Technologies, Faculty of Materials and Technology, VŠB - Technical University of Ostrava. The main monitored properties of mixtures will be green compressive strength and moisture of the mixture. The measured properties of the mixture mixed on the eddy mixer will be compared with the properties of the mixture mixed on the existing LM-2e wheel mixer. The result of the experiment confirmed that the eddy mixer is suitable for the preparation of a mixture of the same quality as the wheel mixer but with a significantly reduced mixing time.
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Bibliography

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Authors and Affiliations

Š. Kielar
1
M. Bašistová
1
ORCID: ORCID
P. Lichy
1
ORCID: ORCID

  1. VSB - Technical University of Ostrava Faculty of Materials Science and Technology, Czech Republic
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Abstract

In 2008, the European Union adopted the climate and energy package. It foresees the three most important goals to achieve by 2020 in the field of energy: 20% reduction in greenhouse gas emissions, 20% share of energy from renewable sources in total energy consumption in the EU, 20% increase in EU energy efficiency. Therefore, individual countries were obliged to move away from fossil fuels for renewable energy production. Depending on the capabilities of each country and the development of renewable energy, various goals have been set for individual countries. For Poland, the share of RES energy in total energy consumption has been set at 15% (Directive 2009). The Polish energy policy until 2030 includes state strategies in the field of implementation of tasks and objectives in the area of energy resulting from the need to build national security and EU regulation. The challenges of the current national energy industry include increasing demand for energy and implementation of international commitments in the area of environmental and climate protection (Policy 2009). Contemporary domestic energy is characterized by a high share of fossil fuels, mainly coal, in the production of electricity and heat, and the different share of RES energy in individual technologies and energy sectors. Poland has significant natural resources, which are a source of biomass for energy purposes. Large energy units dominate in the national consumption of biomass while the share of heating plants is still insignificant (Olsztyńska 2018). The aim of the article is to analyze, based on available data and own observations of the author, the share of biomass in the national energy and heat, as well as defining factors affecting the level of biomass use in the area of Polish power industry.

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Authors and Affiliations

Ilona Olsztyńska
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Abstract

Laminar mixed convection heat transfer in a vented square cavity separated by a porous layer filled with different nanofluids (Fe3O4, Cu, Ag and Al2O3) has been investigated numerically. The governing equations of mixed convection flow for a Newtonian nanofluid are assumed to be two-dimensional, steady and laminar. These equations are solved numerically by using the finite volume technique. The effects of significant parameters such as the Reynolds number (10 ≤ Re ≤ 1000), Grashof number (103 ≤ Gr ≤ 106), nanoparticle volume fraction (0.1 ≤ ϕ ≤ 0.6), porous layer thickness (0 ≤ γ ≤ 1) and porous layer position (0.1 ≤ δ ≤ 0.9) are studied. Numerical simulation details are visualized in terms of streamline, isotherm contours, and average Nusselt number along the heated source. It has been shown that variations in Reynolds and Darcy numbers have an impact on the flow pattern and heat transfer within a cavity. For higher Reynolds (Re >100), Grashof (Gr > 105) numbers and nanoparticles volume fractions the heat transfer rate is enhanced and it is optimal at lower values of Darcy number (Da = 10-5). In addition, it is noticed that the porous layer thickness and location have a significant effect on the control of the heat transfer rate inside the cavity. Furthermore, it is worth noticing that Ag nanoparticles presented the largest heated transfer rate compared to other nanoparticles.
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Authors and Affiliations

Hamdi Messaoud
1
Sahi Adel
1
Ourrad Ouerdia
2

  1. Université de Bejaia, Laboratoire de Physique Théorique, Faculté de Technologie, Algeria
  2. Université de Bejaia, Laboratoire de Physique Théorique, Faculté des Sciences Exactes, Algeria
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Abstract

This paper is concerned with the rotational motion of the impeller and the thermal buoyancy within a mechanical mixer. The task was investigated numerically using the ANSYS-CFX simulator. The programmer is based on the finite volume method to solve the differential equations of fluid motion and heat transfer. The impeller has hot surfaces while the vessel has cold walls. The rotational movement of the impeller was controlled by the Reynolds number, while the intensity of the thermal buoyancy effect was controlled by the Richardson number. The equations were solved for a steady flow. After analyzing the results of this research, we were able to conclude that there is no effect of the values of Richardson number on the power number. Also, with the presence of the thermal buoyancy effect, the quality of the fluid mixing becomes more important. The increasing Richardson number increases the value of the Nusselt number of the impeller.
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Authors and Affiliations

Souad Hassouni
1
Houssem Laidoudi
2
Oluwole Daniel Makinde
3
Mohamed Bouzit
2
Boumediene Haddou
1

  1. University of Science and Technology of Oran Mohamed-Boudiaf, Faculty of Chemistry, BP 1505, El-Menaouer, Oran, 31000, Algeria
  2. University of Science and Technology of Oran Mohamed-Boudiaf, Laboratory of Sciences and Marine Engineering, Faculty of Mechanica lEngineering, BP 1505, El-Menaouer, Oran, 31000, Algeria
  3. Stellenbosch University, Faculty of Military Science, Private Bag X2, Saldanha 7395, South Africa
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Abstract

Shell and tube heat exchangers are commonly used in a wide range of practical engineering. The key issue in such a system is the heat exchange between the hot and cold working media. An increased cost of production of these devices has forced all manufacturing companies to reduce the total amount of used materials by better optimizing their construction. Numerous studies on the heat exchanger design codes have been carried out, basically focusing on the use of fully time-dependent partial differential equations for mass, momentum, and energy balance. They are very complex and time-consuming, especially when the designers want to have full information in a full 3D system. The paper presents the 1D mathematical model for analysis of the thermal performance of the counter-current heat exchanger comprised of mixed time-dependent and time-independent equations, solved by the upwind numerical solution method, which allows for a reduction in the CPU time for obtaining the proper solution. The comparison of numerical results obtained from an in-house program called Upwind Heat Exchanger Solver written in a Fortran code, with those derived using commercial software package ASPEN, and those obtained experimentally, shows very good agreement in terms of the temperature and pressure distribution predictions. The proposed method for fast designing calculations appears beneficial for other tube shapes and types of heat exchangers.
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Authors and Affiliations

Dariusz Kardaś
1
Izabela Wardach-Święcicka
1
Artur Grajewski
2

  1. The Szewalski Institute of Fluid Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-231 Gdansk, Poland
  2. HEXONIC Sp. z o.o., Warszawska 50, 82-100 Nowy Dwór Gdanski, Poland
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Abstract

Complex rheological properties of yield-stress materials may lead to the generation of an intensive mixing zone near a rotating impeller. From the practical point of view, the zone should cover most of the stirred liquid. According to the literature review, several parameters may affect the size of the mixing zone, in particular forces exerted on the liquid. This paper presents both experimental and numerical investigation of axial and tangential forces generated during mechanical mixing of yield-stress fluids in a stirred tank. The tested fluids were aqueous solutions of Carbopol Ultrez 30 of concentration either 0.2 or 0.6 wt% and pH = 5:0. The study was performed for three types of impeller, pitched blade turbine, Prochem Maxflo T and Rushton turbine, in a broad range of their rotational speed, N = 60 - 900 rpm. The axial and tangential forces were calculated from the apparent mass of the stirred tank and torque, respectively. The experimental results were compared with CFD predictions, revealing their good agreement. Analysis of the generated forces showed that they are dependent on the rheological characteristic of liquid and the impeller type. It was also found that although axial force was smaller than tangential force, it significantly increased the resultant force.
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Authors and Affiliations

Anna Story
1
Grzegorz Story
1
Zdzisław Jaworski
1

  1. West Pomeranian University of Technology in Szczecin, Faculty of Chemical Technology and Engineering, Department of Chemical and Process Engineering, al. Piastów 42,71-065 Szczecin, Poland
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Abstract

Unsteady motion of the impeller is one of the several methods to improve mixing in unbaffled vessel. It is very important in pharmaceutical industry, crystallization processes or some chemical reaction with catalyst where baffles are not recommended. The literature data shows that unsteady mixing cause generation of axial flow for radial impellers (Rushton turbine). The purpose of this study was to investigate axial force for axial impellers like A315, HE-3 and SC-3. Moreover, the momentum number, flow number and pumping efficiency were analysed. Results shows that axial force for unsteady mixing is higher in comparison to steady-state mixing. Also, the comparison of axial force between impellers shows that blades influence momentum number and flow number. Impellers with larger blade surface generate stronger axial force. The obtained results reveal that unsteady mixing with axial impellers could be apply for solid-liquid mixing as suitable alternative to steady-state mixing.
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Authors and Affiliations

Szymon Woziwodzki
1

  1. Poznan University of Technology, Department of Chemical Engineering and Equipment, Berdychowo 4, 60-965 Poznan, Poland
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Abstract

The aim of the research presented in this paper was to determine the effect of vessel scale on gas hold- up in gas-liquid systems. The agitated vessel with internal diameters of T = 0:288 m and T = 0:634 m was filled with a liquid up to the height H = T. For the purpose of measurements, two high-speed impellers were used: Rushton turbine impeller (RT) or A 315 impeller.Within the study, the following parameters were altered: superficial gas velocity, impeller speed, impeller type and concentration of aqueous sucrose solution. In addition, influence of the vessel scale on gas hold-up value was analysed. Experimental results were mathematically described. Equations (5)–(7) do not have equivalents in the literature.
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Authors and Affiliations

Magdalena Cudak
1

  1. West Pomeranian University of Technology, Szczecin, Faculty of Chemical Technology and Engineering, al. Piastów 42, 71-065 Szczecin, Poland

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