Wyniki wyszukiwania - BazTech

1

Optymalizacja wybranych parametrów węzła połączenia płyty balkonowej ze ścianą na podstawie modelowania matematycznego przepływu ciepła

Jezierski Walery, Leszczyński Cezary

Izolacje

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2024

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T. 29, nr 2

82--89

PL

W artykule opisano wyniki analizy i optymalizacji wybranych parametrów węzła połączenia płyty balkonowej ze ścianą na podstawie modeli matematycznych. Wyniki opierają się na poprzednim badaniu – ocena istotności wpływu 15 różnych czynników, charakteryzujących parametry tego węzła, z których sześć zostały zakwalifikowane jako istotne. W niniejszym badaniu dla istotnych czynników opracowano modele matematyczne zależności temperatury ϑimg (funkcja Y1) w miejscu występowania najniższej temperatury w analizowanym węźle oraz liniowego współczynnika przenikania ciepła ψim (funkcja Y2) mostka termicznego, występującego w tym miejscu, od czynników: X1 – grubość izolacji termicznej górnej części płyty balkonowej; X2 – grubość izolacji termicznej dolnej części płyty balkonowej; X3 – grubość izolacji termicznej górnej części stropu wewnątrz budynku; X4 – grubość izolacji termicznej ściany zewnętrznej; X5 – współczynnik przewodzenia ciepła izolacji termicznej ściany zewnętrznej; X6 – grubość płyty balkonowej. Na podstawie wyników eksperymentu obliczeniowego, uzyskanych na drodze symulacji z wykorzystaniem oprogramowania THERM 7.6 opracowano deterministyczne modele matematyczne tych zależności. Modele pozwoliły oszacować stopień i charakter wpływu badanych czynników na temperaturę ϑimg i liniowy współczynnik przenikania ciepła ψim oraz przeprowadzić optymalizację parametrów. Informacja może być przydatna dla naukowców, inżynierów i decydentów, przy podejmowaniu prawidłowych decyzji na etapie projektowania nowych budynków mieszkalnych.

EN

The article describes the results of the analysis and optimization of selected parameters of the junction between the balcony slab an he wall based on a mathematical model. The results are based on a previous study after assessing the significance of the influence of 15 different factors characterizing the parameters of this node, from which 6 significant ones were selected. In this study, mathematical models of the dependence of the temperature ϑimg (function Y1) at the location of the lowest temperature in the analyzed node and the linear heat transfer coefficient ψim (function Y2) of the thermal bridge occurring in this location on the following factors were developed for important factors: X1 – thermal insulation thickness the upper part of the balcony slab; X2 – thickness of thermal insulation of the lower part of the balcony slab; X3 – thickness of thermal insulation of the upper part of the ceiling inside the building; X4 – thickness of thermal insulation of the external wall; X5 – thermal conductivity coefficient of external wall thermal insulation; X6 – thickness of the balcony slab. Based on the results of the computational experiment obtained by simulation using THERM 7.6 software, deterministic mathematical models of these relationships were developed. The models made it possible to estimate the degree and nature of the influence of the studied factors on temperature ϑimg and linear heat transfer coefficient ψim, and optimize the parameters. The information may be useful for scientists, engineers and decision-makers when making correct decisions at the stage of designing new residential buildings.

2

Crustal thermal structure of the Pan-African remobilized basement complex in north-central Nigeria: an integrated and interactive approach for geothermal prospectivity

Aisabokhae Joseph

Acta Geophysica

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2024

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Vol. 72, no. 1

115--128

EN

In this study, an interactive analysis combined measurements of surface radiogenic heat production (RHP) and sub-surface heat flow data to predict the crustal thermal regime of the area. The radioactive decay of 40 K, 232Th and 238U radionuclides in combination with other processes generate a significant quantity of heat within the earth’s crust which can be utilized to produce green energy. Statistical analysis involving a box-whisker plot was used to optimize the generated RHP data with median RHP value of each lithologic unit presented as 3.2 gW m-3 (diorite), 2.9 gW m-3 (granodiorite), 3.1 gW m-3 (granite) and 2.7 gW m-3 (quartzdiorite). The results are in tandem with similar studies around the globe and are in near approximation to measurements that depict high heat production character. Heat generation predictions were extrapolated from the RHP values and displayed in percentile plots. The study showed that quartzdiorite presented the largest variation (from 5.2740 to 8.7185 HGU) in the region, followed by granite (from 6.1127 to 8.7445 HGU), then diorite (from 6.499 to 8.8975 HGU) and granodiorite (from 5.9870 to 8.3762 HGU). Heat flow measurements in 12 site holes within the granitoid emplacement showed averaged values of 48.5, 40.9, 48.5 and 28.9 mW m-2 for diorite, granodiorite, granite and quartzdiorite plutons, respectively. The analyzed thermal properties in this study suggest that the surface plutons are not deep-seated. An explanation for the high thermal condition of the deep-seated crustal rocks was adduced to tectonic events that distributed radioelements into reactivated inter-rift crustal blocks.

3

Badanie efektywności folii refleksyjnych w przegrodach budowlanych w zależności od warunków wymiany ciepła

Wilk-Słomka Beata, Belok Janusz, Orlik-Kożdoń Bożena, Steidl Tomasz

Materiały Budowlane

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2023

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nr 4

30--35

PL

W artykule zaprezentowano wyniki badań dotyczących oceny skuteczności działania folii refleksyjnych w systemach ściennych i dachowych, pod względem poprawy ich izolacyjności cieplnej. W przypadku wybranych rozwiązań przegród pionowych (z folią i bez folii), stosując metodę skrzynki grzejnej, wyznaczono współczynniki przejmowania ciepła przez powierzchnie z powłokami refleksyjnymi na podstawie pomiaru temperatury i gęstości strumienia ciepła. Celem badań było określenie efektywności działania folii refleksyjnych w określonych warunkach wymiany ciepła, biorąc pod uwagę charakter dominującego źródła ciepła w pomieszczeniu.

EN

The authors simply refer to the results of research on the evaluation of reflective technologies in walls and roof systems, in terms of improving the thermal insulation of these elements. For selected vertical partition solutions (with foil, without foil) using the heat box method, heat transfer coefficients for surfaces with reflective coatings were determined based on temperature measurements and heat flux density. The purpose of the study was to determine the effectiveness of reflective foils under specific heat transfer conditions taking into account the nature of the dominant heat source in the room.

4

Mathematical modeling of the phenomena that occur in a biological tissue containing photosensitizer

Jasiński Marek, Zadoń Maria

Journal of Applied Mathematics and Computational Mechanics

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2022

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Vol. 21, nr 4

40--51

EN

The aim of the study is to analyze photothermal and photochemical phenomena that occur during photodynamic therapy (PDT). In this type of therapy, under the influence of the laser, reactions take place related to the transformation of triplet oxygen form into its singlet form which is cytotoxic to the tissue. The increases in temperature resulting from the laser-tissue interaction during PDT are not big; however, they can lead to changes in tissue perfusion, which can affect oxygen delivery to the tissue. The proposed model uses optical diffusion equation, Pennes bioheat transfer equation, and reactions equations for PDT. The main findings of the analysis show the impact of temperature on the value of the perfusion coefficient and triplet oxygen distributions at the end of the treatment procedure.

5

An effect of binary fluid on the thermal performance of pulsation heat pipe

Barrak Anwar S., Ali Nawfal M, Ali Hussein Hayder Mohammed

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 1

21--34

EN

A pulsation heat pipe is an efficient heat pipe used in many engineering applications. This study aims to test the effect of working fluids on the thermal performance of pulsation heat pipe. Seven turned pulsation heat pipes were designed and manufactured from a copper pipe with a 3.5 mm inner diameter. The lengths of an evaporation part, an adiabatic passage, and a condenser part were 300 mm, 210 mm, and 300 mm, respectively. In this study, three different fluids were used as the working fluid: distilled water, methanol, and binary fluid (a mixture of water and methanol) with a 50% filling ratio. Compared to water, the experimental results suggested that methanol had a better thermal performance when used as a working fluid in the PHP. On the other hand, a binary fluid enhanced the lower thermal performance of water (29% reduction in the thermal resistance and a 20% increase in the effective thermal conductivity of the PHP).

6

Wstępna analiza wymagań stawianych układom klimatyzacji w pojazdach kołowych wysokiej mobilności

Kosobudzki Mariusz, Grzenia Hubert

Journal of TransLogistics

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2021

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Vol. 7, nr 1

69--84

PL

W artykule przedstawiono wstępną analizę wymagań dotyczących mocy urządzeń układu klimatyzacji odpowiedzialnych za wytworzenie strumieni ciepła do ogrzewania i chłodzenia wnętrza kabiny pasażerskiej pojazdu kołowego wysokiej mobilności w różnych warunkach ruchu. Punktem wyjścia do analizy było zbudowanie modelu matematycznego opisującego strumienie ciepła oddziaływujące na kabinę pasażerską. W obliczeniach analitycznych uwzględniono dane geometryczne kabiny oraz rodzaj materiałów wykorzystanych do jej wytworzenia. Obliczenia wykonano dla kilku reprezentatywnych wariantów użytkowania pojazdu, otrzymując graniczne wartości mocy układu chłodzenia i ogrzewania wnętrza kabiny.

EN

The article presents a preliminary analysis of the power requirements of the air-conditioning system devices responsible for the generation of heat fluxes for heating and cooling the interior of the passenger compartment of a high-mobility wheeled vehicle in various traffic conditions. The starting point for the analysis was building a mathematical model describing the heat fluxes affecting the passenger compartment. The analytical calculations took into account the geometric data of the compartment and the type of materials used for its production. The calculations were made for several representative variants of the vehicle use, obtaining the limit values of the power of the cooling and heating system of the compartment interior.

7

Numerical solution of singularly perturbed two parameter problems using exponential splines

Padmaja P., Aparna P., Gorla Rama Subba Reddy, Pothanna N.

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 2

160--172

EN

In this paper, we have studied a method based on exponential splines for numerical solution of singularly perturbed two parameter boundary value problems. The boundary value problem is solved on a Shishkin mesh by using exponential splines. Numerical results are tabulated for different values of the perturbation parameters. From the numerical results, it is found that the method approximates the exact solution very well.

8

Discussion of the heat flux calculation method during pool boiling on meshed heaters

Orman Łukasz J., Radek Norbert, Pietraszek Jacek, Gontarski Dariusz

System Safety : Human - Technical Facility - Environment

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2020

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Vol. 2, nr 1

247--252

EN

The paper discusses nucleate boiling heat transfer on meshed surfaces during pool boiling of distilled water and ethyl alcohol of very high purity. It presents a correlation for heat flux developed for heaters covered with microstructural coatings made of meshes. The experimental results have been compared with the calculation results performed using the correlation and have been followed by discussion. Conclusions regarding the heat flux determination method have been drawn with the particular focus on the usefulness of the considered model for heat flux calculationson samples with sintered mesh layers.

9

Analiza strat mocy czynnej w układzie kompensatora mocy biernej w wykonaniu przeciwwybuchowym z osłoną ognioszczelną

Pasko Marian, Adrikowski Tomasz, Buła Dawid, Błaszczok Damian

Przegląd Elektrotechniczny

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2020

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R. 96, nr 3

166--169

PL

W pracy przedstawiono wyniki badania strat mocy w układzie kompensatora mocy biernej zbudowanego z baterii kondensatorów i dławików ochronnych. Zaprezentowane wyniki poddano analizie pod kątem możliwości zabudowania kompensatora w przeciwwybuchowej obudowie ognioszczelnej do zastosowania w sieci niskiego napięcia wyrobisk kopalni z zagrożeniem wybuchu metanu i pyłu węglowego.

EN

The results of power losses in the reactive power compensator built of capacitor banks and protective chokes have been presented in the paper. The showed results were analyzed for the possibility of installing the compensator in a flameproof explosion-proof enclosure for use in the low-voltage network of mine headings with the risk of methane and coal dust explosion.

10

Analysis of time-fractional heat transfer and its thermal deflection in a circular plate by a moving heat source

Thakare S., Warbhe M.

International Journal of Applied Mechanics and Engineering

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2020

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Vol. 25, no. 3

158--168

EN

Mathematical modeling of a thin circular plate has been made by considering a nonlocal Caputo type time fractional heat conduction equation of order […], by the action of a moving heat source. Physically convective heat exchange boundary conditions are applied at lower, upper and outer curved surface of the plate. Temperature distribution and thermal deflection has been investigated by a quasi-static approach in the context of fractional order heat conduction. The integral transformation technique is used to analyze the analytical solution to the problem. Numerical computation including the effect of the fractional order parameter has been done for temperature and deflection and illustrated graphically for an aluminum material.

11

Agregaty adsorpcyjne – jak się sprawy mają? Przegląd konstrukcji modyfikowanych złóż adsorpcyjnych

Grabowska Karolina, Krzywański Jarosław, Sosnowski Marcin, Nowak Wojciech

Energetyka Cieplna i Zawodowa

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2019

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Nr 5

112--119

PL

Podstawowy mankament adsorpcyjnych systemów chłodniczych to dziś niska sprawność procesu roboczego, która jest skutkiem występowania dużych oporów przepływu ciepła na granicy wymiennik ciepła - usypany sorbent. Jednak z uwagi na proekologiczność tej technologii oraz możliwość efektywnego zagospodarowania niskotemperaturowych źródeł energii cieplnej do zasilania tych urządzeń, poszukiwana jest innowacyjna konstrukcja złoża, która pozwoli zintensyfikować procesy wymiany ciepła i masy zachodzące w sekcji sorpcyjnej agregatów.

12

Modelling of the airflow in the passenger coach

Sarna Izabela, Palmowska Agnieszka

Architecture Civil Engineering Environment

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2019

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Vol. 12, no. 4

125--133

EN

In this paper currents requirements of HVAC designing (Heating, Ventilation and Air Conditioning) in railway vehicles have been presented. The data were based on railway standards [1, 2]. The aim of this study was to carry out the numerical calculation of airflow combined with heat exchange in a passenger coach. ANSYS CFX 12.1 software was used to carry out the simulation. Two cases of boundary conditions were considered, the first obtained from design calculations common for ordinary buildings and information included in standards and the second only based on the information included in standards. After analysing of the results, it was found that the distribution of air velocity in a coach was similar in both cases, average air velocity was 0.79 m/s. However, the distribution of air temperature was different. For case 1 the average indoor air temperature was 25.07°C and for case 2 was 23.53°C. The method of determining the heat solar gains had a great impact on the results. A further possibility of a model improvement was indicated for example human models will be introduced in coaches, in order to verify the conditions of their thermal comfort, and air recirculation.

13

On application of fractal magnetization in Curie depth estimation from magnetic anomalies

Li Chun Feng, Zhou Duo, Wang Jian

Acta Geophysica

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2019

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Vol. 67, no. 5

1319--1327

EN

As an independent geothermal proxy, the Curie-point depth has important geodynamic implications, but its estimation from magnetic anomalies requires an understanding of the spatial correlation of source magnetization, mathematically characterized by a fractal exponent. In this paper, we show that fractal exponent and Curie depth are so strongly inter-connected that attempts to simultaneous or iterative estimation of both of them often turn out to be futile. In cases of true large Curie depths, the iterative “de-fractal” method has a tendency of overcorrecting fractal exponents and thereby producing erroneously small Curie depths and smearing out true geological trends. While true fractal exponent can no way be constant over a large area, a regionally fxed fractal exponent is better than any mathematical treatments that are beyond the limit of data resolution and the underlying physics.

14

Numerical studies for solving a free convection boundary-layer flow over a vertical plate

Othman M. I. A., Mahdy A. M. S.

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 1

41--48

EN

In this paper, the aim of this study is to present a reliable combination of the shifted Legendre collocation method to approximate of the problem of free convection boundarylayer flow over a vertical plate as produced by a body force about a flat plate in the direction of the generating body force. The proposed method is based on replacement of the unknown function by truncated series of well known shifted Legendre expansion of functions. An approximate formula of the integer derivative is introduced. Special attention is given to study the convergence analysis and derive an upper bound of the error of the presented approximate formula. The introduced method converts the proposed equation by means of collocation points to a system of algebraic equations with shift Legendre coefficients. Thus, by solving this system of equations, the shifted Legendre coefficients are obtained. Boundary conditions in an unbounded domain, i.e. boundary condition at infinity, pose a problem in general for the numerical solution methods. The obtained results are in good agreement with those provided previously by the iterative numerical method. As a result, without taking or estimating missing boundary conditions, the shifted Legendre collocation method provides a simple, non-iterative and effective way for determining the solutions of nonlinear free convection boundary layer problems possessing the boundary conditions at infinity.

15

An interface anticrack in a periodic two-layer piezoelectric space under vertically uniform heat flow

Kaczyński A., Kaczyński B.

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 3

667--681

EN

This paper aims to investigate 3D static thermoelectroelastic problem of a uniform heat flow in a bi-material periodically layered space disturbed by a thermally and electrically-insulated rigid sheet-like inclusion (so-called anticrack) situated at one of the interfaces. An approximate analysis of the considered laminated composite is given in the framework of the homogenized model with microlocal parameters. Accurate results are obtained by constructing suitable potential solutions and reducing to the corresponding homogeneous thermoelectromechanical (or thermomechanical) anticrack problems. The governing boundary integral equation for a planar interface anticrack of arbitrary shape is derived in terms of a normal stress discontinuity. As an illustration, a complete solution for a rigid circular inclusion is obtained in terms of elementary functions and interpreter from the failure perspective. Unlike existing solutions for defects at the interface of materials, the solution obtained displays no oscillatory behavior.

16

Modelling of thermal damage process in soft tissue subjected to laser irradiation

Jasiński M.

Journal of Applied Mathematics and Computational Mechanics

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2018

|

Vol. 17, nr 2

29--41

EN

The numerical analysis of thermal damage process proceeding in biological tissue during laser irradiation is presented. Heat transfer in the tissue is assumed to be transient and two-dimensional. The internal heat source resulting from the laser irradiation based on the solution of the diffusion equation is taken into account. The tissue is regarded as a homogeneous domain with perfusion coefficient and effective scattering coefficient treated as dependent on tissue injury. At the stage of numerical realization, the boundary element method and the finite difference method have been used. In the final part of the paper the results of computations are shown.

17

Projektowanie ocieplenia w obrębie dylatacji budynków

Krause P., Steidl T.

Izolacje

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2018

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R. 23, nr 10

46--49

PL

W artykule przedstawiono analizę rozwiązań projektowych na przykładzie wybranych szczelin dylatacyjnych, w aspekcie poprawnego projektowania detalu projektowego.

EN

The paper presents an analysis of design solutions concerning correct design of details, using the example of selected expansion joints.

18

A Numerical Study of the Relation Between the Acoustic Generator Geometry and the Heat Transfer Conditions

Rulik S., Wróblewski W., Rusin K.

Archive of Mechanical Engineering

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2018

|

Vol. LXV, nr 1

5--26

EN

Modern gas turbine systems operate in temperatures ranging from 1200°C to even 1500°C, which creates bigger problems related to the blade material thermal strength. In order to ensure appropriate protection of the turbine blades, a sophisticated cooling system is used. Current emphasis is placed on the application of non-stationary flow effects to improve cooling conditions, e.g., the unsteady-jet heat transfer or the heat transfer enhancement using high-amplitude oscillatory motion. The presented research follows a similar direction. A new concept is proposed of intensification of the heat transfer in the cooling channels with the use of an acoustic wave generator. The acoustic wave is generated by an appropriately shaped fixed cavity or group of cavities. The phenomenon is related to the coupling mechanism between the vortex shedding generated at the leading edge and the acoustic waves generated within the cavity area. Strong instabilities can be observed within a certain range of the free flow velocities. The presented study includes determination of the relationship between the amplitude of acoustic oscillations and the cooling conditions within the cavity. Different geometries of the acoustic generator are investigated. Calculations are also performed for variable flow conditions. The research presented in this paper is based on a numerical model prepared using the Ansys CFX-17.0 commercial CFD code.

19

Use of fractional calculus in modeling of heat transfer process through external building partitions

Szymanek E.

Acta Innovations

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2018

|

no. 27

61--70

EN

This paper is devoted to experimental and numerical studies of heat distribution in an external building bulkhead. It analyzes the variation of temperature across the width of the bulkheads including the impact of changing external conditions. Mathematical model used in the research is formulated based on a fractional differential equation, which was proven to be a useful tool for describing this type of process in previous paper. Numerical results are compared with experiment data for different bulkhead configurations.

20

Ciepło w napędach hydraulicznych

Klarecki K.

Utrzymanie Ruchu

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2017

|

Nr 4

60--63

PL

W artykule opisano wyniki testów nagrzewania się i naturalnego chłodzenia układów hydraulicznych. Rezultaty wskazują, że w pewnych przypadkach możliwe jest dobranie za małej chłodnicy, jeżeli jej dobór będzie oparty na pomiarach przyrostu temperatury cieczy roboczej w czasie normalnej eksploatacji układu hydraulicznego. W artykule podano również wskazówki, jak się takiego przypadku ustrzec.