2022 - Repozytorium publikacji - Politechnika Gdańska

Pokaż publikacje z roku

Publikacje z roku 2022

Pokaż wszystkie

Numerical analysis of high temperature minichannel heat exchanger for recuperative microturbine system
- Jan Wajs
- Tomasz Kura
- Dariusz Mikielewicz
- Elżbieta Fornalik-Wajs
- Jarosław Mikielewicz
2022 Pełny tekst ENERGY
Considering the development of energy sector, distributed small-scale power generation, e.g., gas micro-CHP, is attracting considerable interest. In such installations, the heat exchanger is one of the key components possessing a significant influence on overall performance. Most studies concentrate on units operating below 900C, which do not fulfil the requirements of gas micro-CHP. Therefore, there remains a challenge to design a compact heat exchanger with passive technologies of heat transfer enhancement. This work describes the implementation of the own construction of a plate minichannel heat exchanger for high-efficiency gas microturbine engines with an external combustion chamber, supplied with air at a temperature of about 1000C. The results of this study will greatly contribute to the increase of system efficiency. To understand transport phenomena occurring inside it, a numerical model of the entire heat exchanger was developed in OpenFOAM. Defined boundary conditions were based on experimental data used also to validate the numerical model. The pressure drop experimental and numerical results agreed within the 2%-14% range, while the heat rate ones e within the 1%-8% of the range. In addition, numerical analysis exhibited the limits of thermal and exergetic efficiency values possible to be obtained, when the boundary conditions are strongly controlled.
Numerical analysis of lumbar spine injury during road safety barrier collision
- Łukasz Pachocki
2022
Purpose: Enhancing road safety is a critical goal worldwide, necessitating the development of clear standards for road safety systems. This study focuses on lumbar spine (L-spine) compression injuries during collisions with concrete road safety barriers (RSBs). It aims to analyze internal forces during impact to understand L-spine injury biomechanics in such accidents. Methods: The research included a literature review, analyzing American guidelines and European standard EN1317. A normative TB41 crash test with a concrete RSB class H2/W5/B was conducted, followed by a finite element model creation and validation. Additionally, a TB32 test simulation with the same barrier and a 50th percentile female body model was performed to analyze L-spine displacements. These displacements were applied to a detailed L-spine model based on THUMS v.6.1, modified for validation test compliance. Results: Numerical models for the concrete RSB and L-spine were validated against experimental data. The TB41 crash test showed that connections between barrier segments experienced splitting failure, with a maximum dynamic compressive force of 350 kN and bending moments up to 130 kNm. The TB32 crash test indicated that vehicle collision energy dissipation caused the car to launch upwards and land along the barrier. This resulted in high internal forces in the L-spine, particularly in the L3 vertebra with a compressive force of about 2.7 kN and a bending moment of 39.5 Nm. Conclusions: The study observed splitting failure in the H2/W5/B concrete barrier during the TB41 test. Discrepancies were noted between the safety levels indicated by impact severity indices and those suggested by L-spine injury measures. These findings suggest a need to reevaluate the current standards for road safety systems, considering both barrier integrity and potential spinal injuries.
Numerical analysis of vacuum drying of a porous body in the integrated domain
- Milad Amiri
- Mohammad Bagher Ayani
- Paweł Ziółkowski
- Dariusz Mikielewicz
2022 Pełny tekst JOURNAL OF FOOD PROCESS ENGINEERING
n the present study, the vacuum drying process of an apple slice is numerically modeled based on a control volume method. Transient two-dimensional Navier– Stokes, energy, moisture, and Luikov equations are solved by numerical coding (Fortran) to simulate the simultaneous heat and mass transfer in the ambient and apple slice, respectively. The privilege of using Luikov's model is that the capillary forces are considered, and a differentiation between air, vapor, liquid, and solid is made. Luikov described the two phenomena associated with the transport of air, vapor, and liquids through the porous media as molecular transport and molar transport. The ambient pressure linearly reduced within a minute until it reached a constant value. One of the intellectually demanding preoccupations among researchers is how to simulate the sample and its surroundings with high accuracy of boundary conditions, which enables to avoid the use of empirical transfer coefficients. This study can be scrutinized from various dimensions, among which nonuse of boundary condition between a porous sample and its surroundings is the most conspicuous novelty. Results showed that although at 50 s, isothermal and iso-moisture lines inside the sample are symmetric, they are not symmetric at 100, 200, and 400 s. In addition, at first minute, pump operation leads to vary the density of the isothermal and isomoisture lines around the sample, but at 100, 200, and 400 s, higher temperature and moisture gradients have been achieved at the right and top of the sample surface
Numerical analysis on axial capacity of steel built-up battened columns
- Paweł Pieczka
- Piotr Iwicki
2022 Pełny tekst Archives of Civil Engineering
This paper deals with the numerical analysis aimed at study the bearing capacity of pinended steel built-up columns under axial compression. Finite element (FE) models were performed for the columns presented in the literature. The main problem discussed in the article is the shape and magnitude of geometric imperfections introduced into the numerical FE model, necessary to obtain the load capacity consistent with the experimental strength tests. Three types of numerical analysis that can be used in Abaqus program to calculate the load bearing capacity have been described. The imperfections possible to introduce for built-up columns were presented and an equivalent imperfection corresponding to both imperfections recommended by Eurocode 3 (global of the entire column and local of the chord) for built-up members was proposed. The results of the geometrically and materially nonlinear static analysis were compared with the calculations according to the code procedures (Eurocode 3 and PN-B03200:1990) and the results of experimental tests.
Numerical investigations of discrete crack propagation in Montevideo splitting test using cohesive elements and real concrete micro-structure
- Beniamin Kondys
- Jerzy Bobiński
- Ireneusz Marzec
2022
The paper is aimed at accurately predicting the discrete fracture process in concrete specimens under complex stress states in two dimensional (2D) simulations. Plain concrete specimens subjected to Montevideo splitting test (MVD) were used for consideration due to non-negligible shear stresses impact in this type of test. In order to reflect the heterogeneous nature of the concrete, the meso-structure of the samples was included in the numerical models. The concrete was modelled as a four-phase material consisting of a cement matrix with air voids, aggregates and Interfacial Transitions Zones (ITZ) between aggregates and cement matrix. The meso-structure was created on the basis of X-ray μCT image of real specimens. The analysis was performed using the finite element method (FEM) with cohesive interface elements in a quasi-static approach carried out by Abaqus. The results of the numerical simulations were compared with the values obtained experimentally in terms of crack patterns and force versus crack mouth opening displacement (CMOD) diagrams.
Numerical methodology for evaluation the combustion and emissions characteristics on WLTP in the light duty dual-fuel diesel vehicle
- Denys Stepanenko
- Zbigniew Kneba
- Jacek Rudnicki
2022 Pełny tekst Combustion Engines
The worldwide aim of reducing environmental impact from internal combustion engines bring more and more stringent emission regulations. In 2017 by EU has been adopted new harmonized test procedure called WLTP. In general terms this test was designed for determining the levels of harmful emissions and fuel consumption of traditional and hybrid cars. This procedure contains specific driving scenarios which representing reallife driving patterns. Test cycles contain vehicle velocity versus time profiles and directly in powertrain analysis on the test benches cannot be used. In order to back calculate drive cycles to engine rpm versus torque profiles a simple longitudinal vehicle dynamics method was used in this paper. Moreover, in order to determine most representative engine operation points duing WLTP a density based grid clustering method was implemented. The experimental part of the study focuses on the comparative evaluation of the effect of various diesel to LPG substitution ratios (0% LPG, 10% LPG, 20% LPG and 30% LPG) on combustion and emission characteristics of dual-fuel diesel engine
Numerical modelling and analysis of steel specimens subjected to marine immersed corrosion and tensile load
- Krzysztof Wołoszyk
- Yordan Garbatov
2022 Pełny tekst
The present study develops numerical models to analyse the behaviour of steel specimens subjected to marine immersed corrosion degradation and tensile load. The finite element method with the use of the explicit dynamic solver LS-DYNA, satisfying the quasi-static conditions, is employed. Two numerical models are developed, where in the first one, the scans of surfaces gathered from corroded plate specimens are implemented directly to the finite element model. In the second one, the corroded surfaces are generated using random fields. Three different plate thicknesses are investigated. The mechanical properties, i.e., yield stress, Young’s modulus, ultimate tensile stress, and total elongation, of specimens subjected to tensile loading for each numerical model are analysed. The results are validated against the experimental test, and failure modes are compared. It was found that both numerical models can estimate the mechanical properties of the corroded plate specimens and are very close to those of the experiment test. Thus, the random field modelling was very efficient in generating the real corroded plate surfaces of analysed specimens.
Numerical Modelling for Prediction of Compression Index from Soil Index Properties in Jimma town, Ethiopia
- Worku Firomsa Kabeta
- Feyessa Fufa Fekadu
- Keneni Feyissa Yerosan
2022 Pełny tekst U.Porto Journal of Engineering
In this study, correlations are developed to predict compression index (Cc) from index parameters so that one can be able to model Jimma soils with compression index using simple laboratory tests. Undisturbed and disturbed soil samples from twelve different locations in Jimma town were collected. Laboratory tests like specific gravity, grain size analysis, Atterberg limit, and one-dimensional consolidation test for a total of twenty-four test samples were conducted. From one-dimensional consolidation tests, compressibility soil parameters (Cc and Cs) are determined. From the results of limited tests, an indicative good correlation is observed between Cc and LL, PL, and PI. However, a Poor correlation is developed between Cc and PL when related to the other parameters. The developed correlations will be important inputs in modeling Jimma clay soils with regression model and artificial neural networks (ANN) analysis using simple index tests. In addition, the results of this study can serve as a basis for further study of such correlations on different clay soils in the country. In this study, regression analysis was used to explore the significance of individual independent (index) soil properties. Regression model and correlation of compression index for liquid limit, plastic limit, and plasticity index were obtained from the linear regression analysis and ANN. This correlation will be helpful for geotechnical engineers in developing the coefficient of compression (Cc) value of expansive/clay soil from index properties. Finally, based on the general findings of the study, suitable recommendations have been forwarded.
Numerical Modelling of Forced Convection of Nanofluids in Smooth, Round Tubes: A Review
- Janusz Cieśliński
2022 Pełny tekst ENERGIES
A comprehensive review of published works dealing with numerical modelling of forced convection heat transfer and hydrodynamics of nanofluids is presented. Due to the extensive literature, the review is limited to straight, smooth, circular tubes, as this is the basic geometry in shell-and-tube exchangers. Works on numerical modelling of forced convection in tubes are presented chronologically in the first part of the article. Particular attention was paid to the method of the solution of governing equations, geometry of the heating section, and boundary conditions assumed. Influence of nanoparticles on heat transfer and flow resistance are discussed. Basic information is summarized in tabular form, separately for single-phase approach and two-phase models. The second part of the article contains the correlation equations proposed in the presented papers for the calculation of the Nusselt (Nu) number or heat transfer coefficient, separately for laminar and turbulent flow. Details of the type of nanofluids, the concentration of nanoparticles, and the Reynolds (Re) number range are also presented. Finally, advantages and disadvantages of individual numerical approaches are discussed.
Numerically Efficient Miniaturization-Oriented Optimization of an Ultra-Wideband Spline-Parameterized Antenna
- Adrian Bekasiewicz
- Piotr Kurgan
- Sławomir Kozieł
2022 Pełny tekst IEEE Access
Design of ultra-wideband radiators for modern handheld applications is a challenging task that involves not only selection of an appropriate topology, but also its tuning oriented towards balancing the electrical performance and size. In this work, a low-cost design of a compact, broadband, spline-parameterized monopole antenna has been considered. The framework used for the structure design implements trust-region-based methods, space mapping correction mechanisms, and a meta-optimization loop that permits a gradual increase of the problem dimensionality. The optimized structure is characterized by small dimensions of 11.4 mm × 17.2 mm and an overall footprint of only 195 mm2. The radiator operates within 3.1 GHz to 12 GHz bandwidth with the reflection coefficient amplitude level of around –10 dB. The computational cost of the structure design amounts to just 163 simulations of the high-fidelity EM model, which is low having in mind that the antenna is represented by a total of 38 adjustable parameters. The optimized radiator has been compared against state-of-the-art structures from the literature. Benchmarking of the presented optimization algorithm has also been performed. Numerical results have been confirmed by measurements of the fabricated antenna prototype.
Nutrients and Bioactive Components of Human Milk After one Year of Lactation. Implication for Human Milk Banks
- Elena Sinkiewicz-Darol
- Dorota Martysiak-Żurowska
- Małgorzata Puta
- Iwona Adamczyk
- Olga Barbarska
- Aleksandra Wesołowska
- Urszula Bernatowicz-Łojko
2022 JOURNAL OF PEDIATRIC GASTROENTEROLOGY AND NUTRITION
Objective: Specifying the nutrient content and bioactive compounds in milk from long-term lactation for the purpose of finding additional sources of donors’ milk for HMBs. Method: Human milk samples were collected from 43 mothers of term infants (term infant human milk, TIHM) (3–6 weeks of lactation) and 50 mothers who have breastfed for over a year (long-nursing human milk, LNHM). The milk collection time was 24 hours. The analyses of fat, protein, carbohydrate and energy content were performed with human milk analyser MIRIS; lactoferrin and vitamin C content using RP-HPLC; total antioxidant activity (TAC) and lysozyme by ELISA; and the activity of glutathione peroxidase (GPx) and catalase (CAT) via spectrophotometric methods. Sociodemographic characteristics of both groups of mothers have been compiled. Results: Higher fat content and energy value was found in LNHM than in TIHM. Protein content in LNHM and TIHM did not differ. Carbohydrate content was lower in LNHM than in TIHM. TAC, CAT and GPx activity were higher in LNHM compared to TIHM. No significant differences in the content of lysozyme, lactoferrin and vitamin C between the studied groups were found. Conclusions: The findings suggest that after 12 months of lactation, human milk still has significant nutritional value, does not lose bioactive components and can be considered for use in human milk banks
O nieposzanowaniu języka w chromatografii
- Zygfryd Witkiewicz
- Waldemar Wardencki
2022 Analityka: Nauka i Praktyka
W pracy przedstawiono najczęstsze błęy popełniane w języku polskim w mowie i piśmie dotyczące chromatografii.
O symbolicznej pregnancji
- Przemysław Parszutowicz
2022 Pełny tekst Archiwum Historii Filozofii i Myśli Społecznej
The aim of the article is to introduce and demonstrate the specificity of Cassirer ̓s concept of symbolic pregnancy. This concept is considered by many scholars to be the most important, root concept of his entire philosophy of symbolic forms. It constitutes the originality of his phenomenology in comparison with that of Husserl, Brentano, Scheler or Heidegger.
O związku pomiędzy obserwacją przyrody i projektowaniem. W kierunku struktur bionicznych i zrównoważonych
- Anna Górka
- Agnieszka Kurkowska
2022
Przyroda dostarcza wielu inspiracji dla projektowania architektonicznego. Doznania i refleksje dotyczące ukształtowania i struktury form bionicznych wynikających z wnikliwych obserwacji w terenie wykorzystać można w twórczym procesie projektowania bezpiecznych schronień, posługując się szkicem, modelem i jego umiejscowieniem w konkretnym miejscu. Przedstawiony proces twórczy stał się doświadczeniem uczestników Szkoły Letniej, poprzez „zanurzenie w Kaszubach”, stworzenie modeli schronień opartych na lokalnych elementach przyrodniczych .
Ocena nośności konstrukcji pylonu Mostu Rędzińskiego po 10 latach eksploatacji. Propozycje działań utrzymaniowych
- Krzysztof Żółtowski
- Mikołaj Binczyk
- Przemysław Kalitowski
2022 Przegląd Budowlany
Pylon mostu podwieszonego jest głównym elementem konstrukcyjnym przenoszącym niemal całe obciążenie z przęseł na fundamenty. W Moście Rędzińskim bardzo ważną rolę w pracy pylonu odgrywa rygiel dolny. Jest to żelbetowy element obciążony rozporem wynikającym z pochylenia nóg pylonu oraz reakcjami z przęseł. Jest zatem silnie rozciąganą i zginaną belką, ekscentrycznie sprężoną. Po ujawnieniu zarysowań w ryglu przystąpiono do kompleksowej oceny problemu. W artykule opisano budowę modelu numerycznego oraz wykonane obliczenia. Rezultaty obliczeń wskazały na silną zależność pomiędzy rozkładem poprzecznym reakcji z przęseł, a wytężeniem rygla. Wynika to z zastosowania sprężenia ekscentrycznego oraz trudności w precyzyjnym określeniu rozkładu sił przekazywanych przez przęsło bezpośrednio na rygiel. Podsumowaniem przeprowadzonych analiz jest propozycja wykonania dodatkowego sprężenia zewnętrznego rygla dolnego pylonu w celu podniesienia nośności oraz wydłużenia trwałości.
Ocena własności dynamicznych silnika z zapłonem samoczynnym na podstawie zmian wartości wskaźnika działania.
- Jacek Rudnicki
2022 Pełny tekst Journal of Polish CIMEEAC
W artykule przedstawiono koncepcję metody pozwalającej na ocenę działania silnika pracującego na charakterystyce regulatorowej w nagłej zmiany obciążenia i związanej z tym akceleracji/deceleracji. Do analizy przebiegu zmian podstawowych własności użytkowych silnika w tym czasie wykorzystane zostało wartościujące (ilościowe) ujęcie działania interpretowanego jako pewna wielkość fizyczna. Podejście takie umożliwia jednoczesne uwzględnienie wykonywania określonej pracy (podejście energetyczne) oraz czasu, w którym ta praca jest wykonana.
Ocena wpływu wymiarów wypełnienia kontrolowanego i rezystywności cieplnej ziemi rodzimej na obciążalność długotrwałą kabli elektroenergetycznych
- Stanisław Czapp
- Marian Czapp
- Seweryn Szultka
- Adam Tomaszewski
2022
Rezystywność cieplna ziemi ma istotny wpływ na obciążalność prądową długotrwałą elektroenergetycznych linii kablowych. W przypadku niekorzystnej rezystywności cieplnej można zastosować wypełnienie kontrolowane, czyli wymianę ziemi wokół kabli na substancję o znanych parametrach cieplnych. Wyznaczenie obciążalności długotrwałej z wypełnieniem kontrolowanym jest kłopotliwe, ponieważ na jej wartość wpływ ma zarówno rezystywność cieplna, jak i geometria tego wypełnienia. W rozdziale przeanalizowano wpływ rezystywności cieplnej ziemi rodzimej oraz wymiarów wypełnienia kontrolowanego na obciążalność prądową długotrwałą przykładowej linii kablowej. Analizy wykonano z wykorzystaniem programu ANSYS Fluent. Zaproponowano współczynniki poprawkowe obciążalności linii w zależności od wymiarów omawianego wypełnienia.
Ochrona i konserwacja architektury modernistycznej Gdyni - niektóre kierunki obecnych działań
- Robert Hirsch
2022
Tekst przedstawia bieżące działania konserwatorskie i restauratorskie dotyczące architektury modernistycznej Gdyni
Ochrona mat wibroizolacyjnych przed uszkodzeniami na skutek obciążeń od nawierzchni kolejowych
- Remigiusz Duszyński
2022 Pełny tekst Przegląd Komunikacyjny
Wykorzystanie mat wibroizolacyjnych staje się coraz powszechniejsze. Na rynku dostępne są maty wykonane z poliuretanu, wełny mineralnej oraz granulatu gumowego łączonego spoiwem poliuretanowym. Producenci deklarują dla swoich wyrobów skuteczne tłumienie drgań, niski współczynnik przesztywnienia dynamicznego, a także zwiększenie trwałości nawierzchni. Deklarowane zalety są jednak ściśle związane z rodzajem konstrukcji dróg szynowych. O ile w przypadku mat podpłytowych nie występują krytyczne czynniki mogące w krótkim czasie prowadzić do uszkodzenia mat o tyle maty podtłuczniowe, stosowane w nawierzchniach podsypkowych, poddane są destrukcyjnemu oddziaływaniu ułożonego na ich powierzchni tłucznia.
Ochrona przeciwporażeniowa w sieciach elektroenergetycznych o napięciu wyższym niż 1 kV
- Stanisław Czapp
2022 Pełny tekst Inżynier Budownictwa
W artykule przedstawiono wymagania norm odnoszące się do ochrony przeciwporażeniowej w stacjach elektroenergetycznych wysokiego napięcia oraz w elektroenergetycznych liniach napowietrznych wysokiego napięcia. Omówiono również wpływ doziemienia po stronie wyższego napięcia w stacjach transformatorowych SN/nn na zagrożenie porażeniowe w sieciach rozdzielczych niskiego napięcia.