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Publications from the year 2017
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Thermal-FSI modeling of flow and heat transfer in a heat exchangerbased on minichanels
- Sebastian Kornet
- Paweł Ziółkowski
- Paweł Jóźwik
- Piotr Ziółkowski
- Michał Stajnke
- Janusz Badur
In this paper selected numerical modelling problems for an advanced thermal-FSI ("Fluid Solid Interaction") mini-channel heat exchanger model are presented. Special attention is given to the heat transfer between the separated mediums for different mass flows. Similar modelling problems have also been discussed in the literature dedicated to numerical and theoretical modelling problems for typical heat exchangers [1, 2, 3]. Basic tests, including a comparison with experimental data, have been conducted using a Mini-channel Plate Heat Exchanger (MPHE). The MPHE was made out of two gasketed brazed plates with 40 mm long rectangular cross section channels (width—1 mm, depth—700 µm).The thermal-FSI analysis was applied for the heat exchanger model with one hot and one cold water flow passage through the mini-channels. Satisfactory agreement between the modelling results and the experimental data [4] was obtained.
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Thermodynamic and economic analysis of nuclear power unit operating in partial cogeneration mode to produce electricity and district heat
- Marcin Jaskólski
- Andrzej Reński
- Tomasz Minkiewicz
This paper presents the methodology of techno-economic analysis for a nuclear unit operating in partial cogeneration mode and its application for the case study: a nuclear power plant planned in Poland. The research objectives were: to propose EPR, AP1000 and ESBWR nuclear condensing-extraction turbine systems modifications required for operation in cogeneration, to determine optimal heat production and heat transport line (HTL) parameters, to evaluate the technological feasibility of proposed solutions, to analyze profitability and competitiveness of the system versus coal-fired technologies. To adapt nuclear turbine to operation in partial cogeneration mode, the steam must be extracted from low-pressure (LP) section of the turbine and crossover pipe connecting high-pressure (HP) or intermediate-pressure (IP) section with LP section. Thermodynamic analysis proved that the operation of nuclear power plant at peak thermal load up to 250 MW neither requires to change primary cycle arrangements of considered nuclear units nor thermal capacities of nuclear reactors. Total annual costs of nuclear power plant operating in partial cogeneration were the lowest of all considered heat and power options, with all types of reactors, for the emission allowance price of 27 EUR/t CO2-eq. The specific cost of heat from nuclear cogeneration option was 10.3 -12.7 EUR/GJ
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Thermodynamic and geometrical characteristics of mixed convection heat transfer in the shell and coil tube heat exchanger with baffles
- Rafał Andrzejczyk
- Tomasz Muszyński
The article presents passive heat transfer enhancement method in the form of baffles to increase the energy efficiency of the shell coil heat exchanger. Conducted literature review shows that, despite numer- ous studies, there is little work on the intensification of heat transfer at the shell side. Most of the work focuses on the impact of geometrical parameters of the coil itself. This article successfully proves that it is possible to increase the efficiency of heat exchange in the heat exchanger shell type coil with baffle inserts. This work shows that, due to the presence of mixed convection, natural convection has a signif- icant effect for small values of Reynolds numbers and large heat flux. Also, the baffle and inlet configu- ration have a high impact on results. Presented simple experimental correlation gives a satisfactory compliance with experimental results. It should be noted that the correlation can be applied for all of the presented heat exchanger configurations.
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Thermogravimetric analysis/ pyrolysis of used tyres and waste rubber
- Katarzyna Januszewicz
- Marek Klein
- Ewa Klugmann-Radziemska
- Dariusz Kardas
The process of pyrolysis is investigated in this paper. The pyrolysis results of two samples: waste tyres and rubber at different heating rates (10, 20, 50 K/min), were compared. In other experiments the degradation of two pyrolysis products, char and oil was examined. The kinetic study using the thermogravimetry equipment (TG) was done, which allowed determination of the kinetic mechanism of the process. The elemental analysis of the samples was performed.
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Thermoplastic polyurethanes derived from petrochemical or renewable resources: A comprehensive review
- Janusz Datta
- Paulina Kasprzyk
Thermoplastic polyurethanes (TPUs) materials are obtained by the reaction of polyol (ether-, ester-, and carbonate-based diols with average molecular weight in the range from 1,000 to 3,000 g/mol) with aliphatic or aromatic diisocyanates. Synthesized materials consist of the hard and soft segments which are separated in different level. All mechanical and thermal properties of TPUs depend on the chemical structure of used monomers, volume fraction, and interaction between the hard and soft segments. Presented work is the review of the synthesis and the structure–properties relationship analysis in the case of TPU. The most popular reactants used for the production of the TPUs have petrochemical-based origin. A new alternative route in the area of TPUs synthesis is using of plant oils based polyols and diols and also partially natural diisocyanates. A comprehensive discussion provided for the chemical and physical characteristics of potential novel polyurethane monomers derived from natural resources used at synthesis of TPUs is presented
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Thermoplastic polyurethanes with glycolysate intermediates from polyurethane waste recycling
- Tamara Calvo-Correas
- Lorena Ugarte
- Patrycja Jutrzenka Trzebiatowska
- Sanzberro Rafael
- Janusz Datta
- M. Ángeles Corcueraa
- Arantxa Eceiza
The polyol is a major component in polyurethane formulations and therefore introducing to the formulation recycled polyol (obtained during decomposition process) allows decreasing the usage of pure petrochemical components. In this work, thermoplastic polyurethanes were prepared using various mixtures of a petrochemical macrodiol poly(ethylene-butylene adipate)diol (PEBA) and a recycled glycolysate intermediate, called glycolysate polyol, in a two-step synthesis procedure with 4,4-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD). The glycolysate polyol was obtained during glycolysis process of polyurethane elastomer using ethylene glycol as a decomposing agent. Glycolysate polyol showed a higher hydroxyl value (199 mg KOH g−1) and glass transition temperature (Tg, −50.1 °C) than pure macrodiol (PEBA). The maximum concentration of glycolysate polyol was 25 wt% over the total polyol. Synthesized polyurethanes had similar chemical structure compared to the polyurethane synthesized without glycolysate polyol, confirmed by Fourier transform infrared spectroscopy. On the one hand, higher contents of glycolysate polyol resulted in higher Tg and a slightly lower thermal stability analyzed by thermogravimetric analysis. On the other hand, improved thermomechanical and mechanical properties were obtained in polyurethanes with partial replacement of pure macrodiol.
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Threats to Armenia’s Security in the National Strategy and Practice with Special Emphasis on External Security,
- Krystyna Gomółka
The national security strategy adopted in 2007 provided a detailed definition of security and identified its threats. The key threat to the Armenian state was considered to be the Nagorno-Karabakh conflict. The document indicated the Collective Security Treaty Organisation main guarantor of security, with Russia being Armenia’s main partner in bilateral relations. The second position in the strategy was assigned to cooperation with the NATO and the OSCE. One of the priorities identified was to intensify the economic and trade connections with the European Union and participation in the European Neighbourhood Policy as a step towards integration with European structures. As to bilateral relations, the most significant were Armenia’s contacts with Georgia and Iran. If we compare the assumptions of the strategy with the policy pursued by Armenia after 2007, it is clear that the measures taken are in line with the provisions of the document. By the end of 2016, the most serious threat to Armenia – the Nagorno-Karabakh issue – remained unresolved. Russia reinforced its position as Armenia’s strategic ally. The talks conducted between Armenia and the NATO are of little significance in view of the obligations assumed by Armenia. The same goes for the talks with the European Union after Armenia’s withdrawal from signing the association agreement, accession to the Eurasian Economic Union on 01 January 2015 and signing bilateral agreements with the Russian Federation.
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Thriving in multicultural workplace
- Beata Basińska
Thriving at work is defined as the psychological state that links both a sense of vitality and learning. The vitality component of thriving may be seen as positive energy, while learning enhances a sense of competence and efficacy. Thriving sheds new light on individual psychological functioning and the experience of growth in the work context. Thriving at work promotes growth through playing an active role in interaction with other people. In particular, thriving can offer a positive insight into social interactions at work and the subjective well-being of employees in a multicultural work setting. The aim of the quantitative study was to examine the relationship between thriving (proximal factor) and subjective well-being (distal factor) including its affective and cognitive aspects in the model of intercultural interaction at work. Correlational design was applied. The results of the studies conducted in a quantitative design indicated that learning is more salient than vitality in a multicultural work setting. The findings suggest that among these two components of thriving, learning is more salient than vitality. Thriving was associated with affective well-being, specifically, vitality was moderately associated with positive and negative emotions while learning was slightly associated with positive emotions. Additionally, the different role of the two components of thriving in the cognitive aspect of subjective well-being was revealed. Organizational satisfaction (overall satisfaction) was dependent on vitality. In contrast, job-related interpersonal satisfaction (satisfaction with work in a multicultural environment) was dependent on both components of thriving, vitality and learning. To the best of the author’s knowledge this is the first study to empirically test thriving in the model of intercultural interaction at work. Specifically it focuses on proximal (vitality and learning) and distal outcomes (subjective well-being).
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Timber - material of the future. Examples of small wooden architecture structures.
- Dorota Wojtowicz-Jankowska
- Tomasz Żmijewski
The aim of this article is to present various types of wood-based products, classified as engineered timber, while specifying the implications of their structural properties for their forms. Timber is used as a construction material due to its fire resistance, good structural characteristics and insulating properties. The advent of new technologies of wood processing and wood-based materials production has converted timber into a high-tech material, thus encouraging the architects to consider it ever more often in their projects. As wooden technologies overcome constraints, timber begins to compete with steel and concrete. The design characteristics of new wood-based products allow wooden structures to be higher, have larger spans, and more diverse forms than ever. Wood-based materials include materials made of solid wood, veneers, strand, and wood which, due to its inferior quality, would otherwise be unfit for constructions. Elements and layers of these products are glued using different kinds of strong and water-resistant adhesives. The article presents the history of development of new wood technologies, discussing increasingly popular wood-based materials such as glued laminated timber, cross-laminated timber, or structural composite lumber. The paper analyses their technical and fire-resistance properties, and points to ecological aspect, as a factors contributing to the growing popularity of these materials. Finally, the timber’s characteristics are contrasted with those of steel and concrete. The article lists examples of wooden objects representing the so-called small architecture structures from across Europe. They illustrate the potential, the uniqueness and the versatility that wood-based materials offer for constructors and architects. All these features form sufficient grounds for stating that timber truly is a construction material of the 21st century.
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Timber Frame Houses with Different Insulation Materials - Seismic Analysis
- Marcin Szczepański
- Wojciech Migda
- Robert Jankowski
The aim of this article is to present results of a dynamic numerical analysis focused on the response of two timber frame building structures exposed to seismic excitations. The first structure was insulated with mineral wool, while the second one with polyurethane foam. Specifications and technology involved in the models' construction are based on the previously conducted experimental study, upon which numerical structural models were proposed. The displacements of selected node were measured and compared between two models during the numerical investigation. The results of the study confirm that using a polyurethan foam leads to much lower displacement values comparing to the case when the mineral wood is applied as an insulation material. Thus, a positive outcome of using polyurethane foam insulation in timber frame structures exposed to seismic excitations is visible.
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Time evolution of Electrochemical Impedance spectra of cathodically protected steel in artificial seawater
- Michał Narożny
- Krzysztof Żakowski
- Kazimierz Darowicki
Usability of Electrochemical Impedance Spectroscopy data for better cathodic protection control was investigated. Carbon steel – S235JR2 grade specimen were exposed in artificial seawater environment. Samples were polarized and their potentials corresponded to four different cathodic protection degrees. Time evolution of Electrochemical Impedance spectra was investigated. Goodness of fit function (X2) was analysed in terms of proper time-constant quantity determination. It was possible to observe and detect occurrence of new phenomena by X2 evaluation. Weight-loss corrosion coupons were used to calculate corrosion rates. At initial stage of exposition impedance measurements complemented proper protection potential data. Quantity of physical and electrochemical processes was evaluated and linked to the state of specimen providing valuable supplementary data. EIS proved to be useful for hydrogen evolution detection which is a great risk which has to be recognised and prevented.
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Time window based features extraction from temperature modulated gas sensors for prediction of ammonia concentration
- Paweł Kalinowski
- Łukasz Woźniak
- Grzegorz Jasiński
- Piotr Jasiński
Electronic gas recognition systems, in literature commonly referred as electronic noses, enable the recognition of a type and a concentration of various volatile compounds. Typical electronic gas-analyzing device consists of four main elements, namely, gas delivery subsystem, an array of gas sensors, data acquisition and power supply circuits and data analysis software. The commercially available metal-oxide TGS sensors are widely used in such instruments. They are inexpensive and considered to be reliable. However, such sensors also have limitations. One of the most important problems of utilization of TGS sensors is the drift of their responses. It can lead to incorrect interpretation of the results of measurements. This can be a serious problem in the systems, which are designed to detect e.g. harmful gases. Drift can be caused by poisoning or aging of sensor as well as by the influence of temperature, humidity and gas flow rate. There are approaches to mitigate of this effect. One of them is based on the design of the proper data analysis procedures and algorithms. In this work the method of features extraction from continuous measurements of temperature modulated TGS sensor is presented. Namely, the voltage applied to the sensor heater is switched between two values, while the gas flow rate of the measurement cell is maintained constant. The presented method enables the extraction of the features at any time of measurements using time window with the fixed width. The calibration using LS-SVM regression is utilized for the purpose of prediction of ammonia concentration in humidified atmosphere. The validation measurements were conducted two weeks after the calibration procedure.
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TiO2 /SrTiO3 and SrTiO3 microspheres decorated with Rh, Ru or Pt nanoparticles: Highly UV–vis responsible photoactivity and mechanism
- Ewelina Grabowska
- Martyna Marchelek
- Tomasz Klimczuk
- W. Lisowski
- Adriana Zaleska-Medynska
A series of TiO2/SrTiO3 and SrTiO3 microspheres decorated by Rh, Ru or Pt NPs were prepared by facile hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) with energy-dispersive Xray (EDX) spectroscopy, scanning electron microscopy (SEM), photoluminescence spectrometry (PL), Fourier transform infrared (FT-IR) and Raman spectra and diffuse reflectance spectroscopy (DRS). The formation mechanism of TiO2/SrTiO3 and SrTiO3 microspheres was proposed and the photocatalytic properties of the samples were characterized using phenol as the pollutant under the UV–vis and light irradiation. The gas chromatography-mass spectrometry was employed to detect organic intermediates to establish degradation pathway of isotopically labeled (1-13C) phenol. The role of the active species in the process of the degradation was evaluated using different types of active species scavengers as well as hydroxyl radical test with coumarin were also carried out. The PL spectra indicate that the formation of TiO2/SrTiO3 and SrTiO3 decreased the recombination rate of photogenerated carriers. The obtained results revealed that the samples showed an enhanced photocatalytic activity for the degradation of organic pollutant. The SrTiO3/Rh(0.05) photocatalyst showed a higher photodegradation rate under UV–vis and Vis light (3.6 and 1.2 lmol dm3 min1, respectively) compared to the unmodified SrTiO3 (0.6 and 0.2 lmol dm3 min1, respectively). The active species trapping experiments indicated that under UV– vis as well as Vis illumination O 2 are the main active species in the degradation process. The main byproducts detected in phenol oxidation were catechol, hydroquinone, malonic, fumaric and maleic acid. Moreover, GC–MS results indicated the formation of isotopically labeled and unlabeled maleic acid which could be generated by two different pathways: trough decomposition of catechol and hydroquinone at the same time.
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To what extent can hyperelastic models make sense the effect of clay surface treatment on the mechanical properties of elastomeric nanocomposites?
- Seyed Paran
- Mohammad Saeb
- Krzysztof Formela
- Vahabodin Goodarzi
- Poornima Vijayan
- Debora Puglia
- Hossein Khonakdar
- Sabu Thomas
The poor knowledge about nonlinear mechanical behavior of elastomer nanocomposites arises from the incomplete information on the interface. Application of hyperelastic models provides more insights into the nature and the situation of interaction between the elastomeric matrix and nanofillers. The current work seeks to address the effect of interphase strength on tensile properties of the elastomer nanocomposites under large deformations. Acrylonitrile butadiene rubber (NBR)/clay nanocomposite is selected for modeling on account of complexities associated with exfoliation/intercalation of clay platelets. In particular, it is aimed to specify to what extent hyperelastic models can capture the effect of clay surface functionalization on the mechanical behavior of nanocomposites. Attachment of silane functional groups to the clay surface is confirmed by Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, and thermogravimetric analyses. Different hyperelastic models are examined to detect the characteristic of NBR/clay nanocomposites. The powerfulness/weakness of the used models are featured by calculating the strain energy functions and material parameters, meanwhile, by comparing model outputs with experimental data of tensile tests.
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Toksyczność - parametr sumaryczny do oceny obciążenia danego elementu środowiska przez ksenobityki
- Monika Wieczerzak
- Błażej Kudłak
- Jacek Namieśnik
Wyemitowane zanieczyszczenia pochodzenia antropogenicznego przedostają się do poszczególnych elementów środowiska, gdzie mogą negatywnie oddziaływać na organizmy zwierzęce i roślinne. Systematyczny monitoring stopnia zanieczyszczenia środowiska powiązany z szybkim systemem reagowania wydaje się jednym z lepszych rozwiązań kwestii kontroli jakości środowiska. Jednak klasyczne metody instrumentalnej analizy próbek środowiskowych nie zawsze są środowiskowo przyjazne za to często są kosztowne oraz charakteryzują się potrzebą użycia toksycznych rozpuszczalników, dodatkowo nie zawsze istnieje konieczność i możliwość oznaczenia wszystkich składników badanej próbki. Z tej przyczyny wydaje się być zasadnym wykorzystanie testów toksykologicznych, jako parametru sumarycznego do określenia stanu danego elementu środowiska. Nowoczesne techniki bioanalityczne umożliwiają uzyskanie ilościowych i jakościowych informacji o badanej próbce środowiskowej, nie wyklucza to jednak zastosowania technik instrumentalnych, dlatego najwydajniejszym rozwiązaniem byłoby połączenie danych uzyskanych z obu źródeł, celem uzyskania pełniejszej informacji o stanie środowiska.
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Tomografia perfuzyjna pCT w diagnostyce cukrzycowej mikroangiopatii płucnej
- Maciej Browarczyk
Niniejsza rozprawa jest poświęcona zagadnieniom diagnostyki mikroangiopatii płucnej ze szczególnym uwzględnieniem perfuzyjnej tomografii komputerowej (pCT). Retinopatia, nefropatia i neuropatia są znanymi powikłaniami cukrzycy. Mało poznany jest wpływ cukrzycy na funkcjonowanie układu oddechowego. Obecnie stosowana metoda diagnostyki cukrzycowej mikroangiopatii płucnej ma ograniczoną wiarygodność. W rozprawie została przedstawiona nowa metoda diagnostyki mikroangiopatii płucnej wykorzystująca wyniki badania pCT. Badanie pCT polega na rejestrowaniu czasowej sekwencji skanów odpowiedzi badanej tkanki po dożylnej iniekcji środka kontrastowego. Na tej podstawie tworzony jest czasowy przebieg przejścia środka kontrastowego dla każdego piksela. Pierwsze przejście znacznika jest aproksymowane i na tej podstawie, piksel po pikselu, obliczane są parametry perfuzji. Najczęściej wykorzystywaną funkcją aproksymującą jest funkcja gamma−variate. Jednakże, jak pokazują badania, ta sama funkcja nie zawsze sprawdza się w przypadku różnych organów podlegających modelowaniu. W rozprawie zaproponowano dwie funkcje aproksymujące, wcześniej niewykorzystywane do modelowania pierwszego przejścia znacznika. Została przeprowadzona analiza porównawcza funkcji gamma−variate oraz dwóch nowych funkcji aproksymujących pierwsze przejście znacznika w badaniu pCT płuc. Został zbadany także wpływ wyboru użytej funkcji na wartość i dokładność parametru perfuzji blood volume BV.
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Tools for road infrastructure safety management in Poland
- Wojciech Kustra
- Lech Michalski
The objective of road safety infrastructure management is to ensure that when roads are planned, designed, built and used road risks can be systematically identified, assessed, removed and mitigated. There are a number of approaches to road safety management. European Union Directive 2008/96/EC requires EU member states to use four basic tools of road safety infrastructure management. An overview of the methods in these countries shows a variety of approaches to how these tools are used in practice. The paper presents a systematics of these tools and a concept of how they could be developed in Poland. It looks at the life cycle of a road structure and the requirements of risk management processes. The paper focuses on elements of scientific support to help build the necessary tools. To help with assessing the impact of a road project on the safety of related roads, a method was developed for long-term forecasts of accidents and accident victims and accident cost estimation as well as a risk classification to identify risks that are not acceptable risks. With regard to road safety audits and road safety inspection, a set of principles was developed to identify risks and the basic classification of errors and omissions. In the case of road network safety management, measures of individual and societal risk were selected. A method for classifying dangerous road sections was developed as well. An estimation is given of the consequences and effects of applying the tools of road safety management on the network of national roads in Poland until 2020
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Top k Recommendations using Contextual Conditional Preferences Model
- Aleksandra Karpus
- Tommaso Di Noia
- Krzysztof Goczyła
Recommender systems are software tools and techniques which aim at suggesting to users items they might be interested in. Context-aware recommender systems are a particular category of recommender systems which exploit contextual information to provide more adequate recommendations. However, recommendation engines still suffer from the cold-start problem, namely where not enough information about users and their ratings is available. In this paper we introduce a method for generating a list of top k recommendations in a new user cold-start situations. It is based on a user model called Contextual Conditional Preferences and utilizes a satisfiability measure proposed in this paper. We analyze accuracy measures as well as serendipity, novelty and diversity of results obtained using three context-aware publicly available datasets in comparison with several contextual and traditional state-of-the-art baselines. We show that our method is applicable in the new user cold-start situations as well as in typical scenarios.