Wyniki wyszukiwania - BazTech

1

Wykorzystanie energii słonecznej - modyfikacja kąta nachylenia połaci dachu izotropowego

Tytkowski Krzysztof

Przegląd Budowlany

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2023

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R. 94, nr 11-12

93--95

PL

W pracy przedstawiono metody wykreślne i analityczne modyfikacji rozwiązania dachu wielospadowego ze względu na kąt nachylenia jednej jego połaci w celu zwiększenia efektywności wykorzystania energii słonecznej z planowanego kolektora na dachu. Przedstawione zagadnienie nie wchodzi w zakres wiedzy przekazywanej przyszłym inżynierom w ramach szeroko pojętych metod „rozwiązywania dachów”.

EN

The work presents graphical and analytical methods for modifying the multi-slope roof solution due to the angle of inclination of one of its slopes in order to increase the efficiency of using solar energy from the planned collector on the roof. The presented issue does not fall within the scope of knowledge provided to future engineers as part of the broadly understood „roof solving” methods.

2

Numerical study of heating transfer by natural convection in an inclined elliptical cylinder charged with nanofluid

Amroune Amina, Bouras Abdelkrim, Taloub Djedid, Driss Zied

International Journal of Applied Mechanics and Engineering

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2023

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Vol. 28, no. 3

28--41

EN

In this paper, thermal transfer with natural convection in a tilted annular cylinder with a Cu-water nanofluid has been numerically studied. The hot interior and cold exterior elliptical surfaces of the enclosure were maintained at constant temperatures Th and Tc , respectively. The governing equations were solved by the stream function-vorticity approach. The finite volume approach was utilized to discretise the controlling equations. The volume fraction range of the nanoparticles and the Rayleigh number was as follows: [...] respectively. The inclination angles were γ=30°,45°,and 60°. Results were given as isotherm contours, streamlines, average and local Nusselt numbers. The results indicate that the thermal transfer ratio increases with an increase in the tilt angle, regardless of the nanoparticle size values. and the impact of the inclination angle on the heating transfer rate is more important the higher the Rayleigh number and the more convection there is.

3

Investigations of the turbulent thermo-fluid performance in a circular heat exchanger with a novel flow deflector-type baffle plate

Rahman Md Atiqur, Dhiman Sushil Kumar

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 4

art. no. e145939

EN

An axial flow tubular heat exchanger has been experimentally investigated to augment the heat transfer rate with a novel swirl flow of air past the heated tubes. The novel design has been based on circular baffle plates provided with trapezoidal air deflectors of various inclination angles. The arrangement of tubes is kept the same throughout the experiment, in accordance with the longitudinal airflow direction. The tubes maintained a constant heat flux condition over the surface. Four deflectors with equal inclination angles were developed on each baffle plate, generating air swirl inside a circular duct carrying the heated tubes that increase air-side turbulence and, consequently, the surface heat transfer rate. The baffle plates were placed equidistant from each other at variable pitch ratios. The Reynolds number was kept in the range of 16000– 28000. The effect of pitch ratios and inclination angles on the thermo-fluid performance of the heat exchanger was studied. The investigations revealed an average improvement of 3.75 times in thermo-fluid performance for an exchanger with a deflector baffle plate with a baffle inclination angle of 50_ and a pitch ratio of 1.4 when compared to other inclination angles and pitch ratios.

4

Szczelność samonośnych pokryć metalowych zgodnie z wytycznymi IFD/PSD

Patoka Krzysztof

Materiały Budowlane

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2022

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nr 8

39--41

5

Stokes flow in lid-driven cavity under inclined magnetic field

Gürbüz-Çaldag M., Çelik E.

Archives of Mechanics

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2022

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Vol. 74, nr 6

549--564

EN

Stokes flow in a lid-driven cavity under the effect of an inclined magnetic field is studied. The radial basis function (RBF) approximation is employed to the magnetohydrodynamic (MHD) equations which include Navier-Stokes equations of fluid dynamics and Maxwell’s equations of electromagnetics through Ohm’s law with the Stokes approximation. Numerical results are obtained for the moderate Hartmann number (0 ≤ M ≤ 80) and different angles of a magnetic field (0 ≤ α ≤ π). It is found that the increase in the Hartmann number causes the development of new vortices under the main flow due to the impact of a magnetic field. However, the type of the inclination angle (acute or obtuse) determines the location of the vortices.

6

Zasady układania pap na dachach pochyłych o niewielkim kącie nachylenia połaci

Patoka Krzysztof

Materiały Budowlane

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2020

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nr 11

46--48

7

O czym decyduje kąt nachylenia dachu

Patoka Krzysztof

Materiały Budowlane

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2020

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nr 10

52--53

8

Experimental investigation of gravity-assisted wickless heat pipes (thermosyphons) at low heat inputs for solar application

Al-Joboory Hassan Naji Salman

Archives of Thermodynamics

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2020

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Vol. 41, no 2

257--276

EN

The performance of ten wickless heat pipes without adiabatic sections is investigated experimentally at low heat inputs 120 to 2000 W/m2 for use in solar water heaters. Three heat pipe diameter groups were tested, namely 16, 22, and 28.5 mm. Each group had evaporator lengths of 1150, 1300, and 1550 mm, respectively, with an extra evaporator length of 1800 mm added to the second group. The condenser section length of all heat pipes was 200 mm. Ethanol, methanol, and acetone were utilized as working fluids, at inventory of 25%, 50%, 70%, and 90% by evaporator volume respectively. The 22 mm diameter pipes were tested at inclination angles 30°, 45°, and 60°. Other diameter groups were tested at 45° only. Experiments revealed increased surface temperatures and heat transfer coefficients with increased pipe diameter and evaporator length, and that increased working fluid inventory caused pronounced reduction in evaporator surface temperature accompanied by improved heat transfer coefficient to reach maximum values at 50% inventory for the selected fluids. Violent noisy shocks were observed with 70% and 90% inventories with the tested heat pipes and the selected working fluids with heat flux inputs from 320–1900 W/m2. These shocks significantly affected the heat pipes heat transfer capability and operation stability. Experiments revealed a 45° and 50% optimum inclination angle of fill charge ratio respectively, and that wickless heat pipes can be satisfactorily used in solar applications. The effect of evaporator length and heat pipe diameter on the performance was included in data correlations.

9

The analysis of the solar power plant performance in temperate climate

Zdyb A., Dragan P., Jaremek A.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2018

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z. 65, nr 1

73--79

EN

Due to gradual depletion of fossil fuels resources and emission of harmful chemicals accompanying the combustion process, the interest in alternative energy sources still increases. Among many kinds of alternative sources, solar radiation is very special because of its wide availability and large technical potential. Photovoltaic systems providing the electric energy are used in many countries. The most important part of photovoltaic system is a module, which parameters (e.g. efficiency, rated power, temperature coefficients of power and efficiency, short circuit current, open circuit voltage) are determined in laboratory tests under Standard Test Conditions (STC: 25°C, 1,000 W/m2 , air mass 1.5). However, in real outdoor conditions the modules exhibit lower efficiency since local climate influences their performance and different external factors generate energy losses in the whole system. The aim of this work is the performance analysis of a solar power plant connected to the grid, which total rated power is 2.985 MW and it works in temperate climate in eastern Poland. Insolation in the location was estimated according to Solargis data and the role of the modules tilt angle, of which the value is non-typical for the considered location was studied. The tilt angle smaller than optimal angle allows increasing the amount of the solar radiation collected in the summer period. The electric energy production based on the inverters data in 2016 and 2017 as well as yearly yield are presented. The results are compared to data coming from other solar power plants, also located at high latitude.

10

Wpływ kąta nachylenia i czasu jego regulacji na nasłonecznienie kolektora lub panelu fotowoltaicznego

Olczak P., Kryzia D., Pepłowska M., Olek M.

Ciepłownictwo, Ogrzewnictwo, Wentylacja

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2018

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T. 49, nr 12

506--509

PL

Promieniowanie słoneczne docierające do powierzchni Ziemi charakteryzuje się nierównomiernością rozkładu w poszczególnych dniach w roku, co ma wpływ na uzyski energii. Jedną z metod zwiększenia rocznych uzysków energii odbiornika słonecznego jest sezonowa regulacja stopnia nachylenia jego płaszczyzny. Największy uzysk energii słonecznej występuje w sytuacji, gdy powierzchnia odbiornika jest prostopadła do kąta padania promieni słonecznych. Celem pracy jest oszacowanie najbardziej korzystnego kąta nachylenia odbiornika w okresie wiosenno-letnim oraz okresie jesienno-zimowym, zlokalizowanego w Warszawie. Ponadto określenie momentów w czasie, w którym powinna nastąpić zmiana kąta nachylenia. W pracy wykorzystano godzinowe wartości natężenia promieniowania bezpośredniego oraz rozproszonego w typowym roku meteorologicznym. Zastosowano model Haya, Davisa, Kluchera, Reindla (HDKR). Dwukrotnie w ciągu roku przestawienie kąta nachylenia powierzchni odbiornika, tj. zarówno w sezonie jesienno-zimowym, jak i wiosenno-letnim (β1 = 19°, β2 = 49°) zwiększy uzysk dostępnego nasłonecznienia w stosunku do maksymalnego uzysku liczonego bez przestawienia kąta (β = 28°) o 17 kWh (1,6%). Optymalny czas przestawienia kąta nachylenia odbiornika z położenia jesienno-zimowego na wiosenno- letnie stanowi przełom 99 i 100 dnia roku, a z położenia wiosenno-letniego na jesienno-zimowe przełom 271 i 272 dnia roku.

EN

The solar radiation reaching the Earth’s surface is characterized by uneven distribution over individual days throughout the year, which has an influence on the energy yields. One of the methods of increasing the annual energy yields on the solar receiver is the seasonal adjustment of the angle of inclination of the receiver plane. The largest yield of the solar energy occurs when the surface of the receiver is perpendicular to the angle of incidence of sunlight. The purpose of the work is to estimate, for Warsaw, the most favourable receiver inclination angle for the spring and summer and for the autumn and winter periods as well as definition of the moment in time when the angle of inclination should change. The work uses hourly values of the intensity of direct and scattered radiation for a typical meteorological year. The models of Hay, Davis, Klucher, Reindel (HDKR) were used for the calculation. The use of a seasonal solution to change the inclination angle of the surface twice a year, i.e. both in the autumn and winter and spring and summer seasons (β1 = 19°, β2 = 49°) will allow increasing the yield by 17 kWh (1.6%) of available insolation in relations to the maximum yield calculated without changing the angle (β = 28°). The optimum adjustment of the angle of inclination from the autumn-winter to spring and summer positions should be made at the turn of the 99th and 100th day of the year, and from the spring-summer to autumnwinter positions at the turn of 271 and 272 of the year.

11

Single – axis sun tracking unit with sensor control

Bugała A., Frydrychowicz-Jastrzębska G.

Computer Applications in Electrical Engineering

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2015

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Vol. 13

414--422

EN

The results of experimental verification of considerations conducted in [3] are presented, in terms of application single – axis tracking units, to increase the efficiency of the photovoltaic conversion, in comparison with fixed systems optimally oriented. The design and physical realization of a measurement stand is presented. A photovoltaic module inclination angle correlation algorithm, for a selected location and a measurement period, is described. The measurements were conducted in natural lighting conditions for different weather conditions. The current – voltage and power – voltage characteristics were compared for a fixed and vertically variable configuration. The value of the electric energy generated by tested photovoltaic modules in both cases was determined.

12

Computational simulation analysis for torus radius of edge contact in hip prostheses

Li F., Chen H, Mao K.

Acta of Bioengineering and Biomechanics

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2015

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Vol. 17, no. 3

67--73

EN

Stripe wear occurs when the components of hip prostheses move a sufficient distance laterally to contact the edge of the acetabular cup, causing abnormally high contact stresses. In this research, edge loading contact of prosthetic hip is analyzed in the most commonly used material pairs. The contact dimensions and maximal contact pressure are investigated in mutative normal edge loading with 3 different inclination angles (15°, 20°, 25°) and in alterable edge torus radius with edge loading of 2500 N and inclination of 20°. A computational case was conducted for a 14 mm radius alumina ceramic bearing with a radial clearance of 0.1 mm using a normal edge loading ranged from 0 N to 3000 N. Additionally, the Hertzian theory successfully captures principal curvature trends of the edge torus on the influence of maximal contact pressure and obtains the appropriate edge radius range for lower maximal contact pressure. This work elucidates the methods of applying classical contact theory to design the edge radius of hip bearings to better resist severe edge loading contact stresses and reduce the stripe wear.

13

Badanie wpływu położenia kątowego i wydajności wybranego działka pożarniczego na proces rozpadu prądu zwartego na strumień rozpylony

Gała J., Koszykowski R.

Logistyka

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2014

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nr 6

3736--3747

PL

W artykule zaprezentowano badania wpływu wybranych parametrów eksploatacyjnych działka wodnopianowego takich jak wydatek i kąt ustawienia względem poziomu na niektóre parametry istotne z punktu widzenia skuteczności gaśniczej takie jak: zasięg rzutu prądu zwartego, powierzchnia zraszania oraz odległość od wylotu, gdzie następuje wyraźny rozpad prądu zawartego na krople. Przedmiotem badań było stosunkowo często stosowane w PSP uniwersalne działko wodno-pianowe DWP – 24 Azimutor 3000. W pracy omówiono przebieg badań i podano sposób wyznaczania ww. wielkości. W postaci tabelarycznej i graficznej przedstawiono otrzymane wyniki w postaci zasięgów rzutu, powierzchni zraszania i odległości rozpadu strumienia na krople dla trzech różnych wydatków 1000, 2000 i 2400 dm3/min oraz dziewięciu różnych kątów pochylenia działka w zakresie 20-60° co 5°. Przeprowadzono analizę wyników i sformułowano wnioski, mające wymiar praktyczny w sensie wskazówek dla strażaków operujących zwartymi prądami wodnymi. Najistotniejszy z nich jest taki, że największą skuteczność gaśniczą badane działko osiągnęło przy następujących parametrach: wydatku – 2400 dm3/min i kącie pochylenia działka - 45°.

EN

The paper presents a study on the impact of selected operating parameters of water-foam monitor such as output and inclination angle on some parameters significant from extinguishing point of view such as maximum range of solid jet, sprinkling area and the distance from the outlet, where the decomposition of the solid jet into drops takes place. The object of the study was universal modern foam-water monitor DWP - 24 Azimutor 3000 frequently used in PSP. The experiments carried out are described in the paper. A method for determining the parameters mentioned above are also given. Results obtained are presented in the form of time-functions of the throw range, sprinkling area and the distance from outlet to the point of decomposition for three different outputs: 1000, 2000 and 2400 dm3/min, and nine different inclination angles of the tested foam-water monitor in the range of 20-60 ° every 5 °. The proper values are also included in the tables. An analysis of the results has been performed and conclusions were formulated. They have a practical importance for firefighters operating solid jets. The most important of them is that the most effective fire extinguishing effect was reached at the following input parameters: flow rate - 2400 dm3/min and an inclination angle - 45 °.

14

The effects of inclination angle and Prandtl number on the mixed convection in the inclined lid driven cavity using lattice Boltzmann method

Karimipour A., Nezhad A. H., D’Orazio A., Shirani E.

Journal of Theoretical and Applied Mechanics

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2013

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Vol. 51 nr 2

447--462

EN

The laminar mixed convection in a two-dimensional rectangular inclined cavity with moving top lid is investigated using the double population thermal lattice Boltzmann method (LBM) at different values of the Richardson number, inclination angle and the Prandtl number. In this problem, velocity components are changed by both buoyancy forces and the inclination angle of the cavity. Comparison of the present results with other available data show good agreement. As the results, the velocity and temperature profiles, the Nusselt number, streamlines and isotherms are presented and discussed. It is shown that the increase of Prandtl number enhances the heat transfer rate, especially at higher values of inclination angle and Richardson number. Moreover, the average Nusselt number at the upper limit of the considered range of the Richardson and Prandtl numbers variability increases by a factor of 9.

PL

W pracy zajęto się problemem mieszanej konwekcji laminarnej w dwuwymiarowej, prostokątnej i ukośnie usytuowanej szczelinie domkniętej od góry ruchomą pokrywą. W badaniach zastosowano metodę siatki termicznej Boltzmanna (LBM) podwójnej populacji, uwzględniając rożne wartości liczby Richardsona, kąta pochylenia szczeliny oraz liczby Prandtla. W rozważanym zagadnieniu, składowe prędkości zostały poddane zmianom indukowanym siłami wyporu oraz kątem pochylenia szczeliny. Porównanie otrzymanych wynikow analizy z dostępnymi w literaturze danymi wykazało dobrą zgodność. Rezultatem badań w pracy są także profile rozkładu prędkości i temperatury, liczba Nusselta, linie prądu oraz izotermy, które szczegółowo przedyskutowano. Pokazano, że wzrost liczby Prandtla zwiększa transfer ciepła, zwłaszcza dla wyższych wartości kąta pochylenia szczelin i liczby Richardsona. Co więcej, średnia liczba Nusselta przy górnych wartościach przyjętego zakresu zmienności liczb Richardsona i Prandtla wzrasta 9-krotnie.

15

Bulk solid stability on inclined belt conveyors

Ścieszka S. F., Adamecki D.

Scientific Problems of Machines Operation and Maintenance

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2011

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Vol. 46, nr 4

71--89

EN

A new experimental methodology is described for combined measurements of both the static and kinetic friction between bulk solid and the conveyor belt. This area of investigation has been all too often neglected. The method of testing is based on the very well known principle of operation of the inclined plane. The tester was designed having in mind that tribological phenomena are influenced by various factors; therefore, these factors should be varied widely and independently, and they should be measured easily. In this, preliminary testing using two coals, two rubber belts and several different operational conditions were used, such as loads and moisture content. The experimental results confirm that both static and kinetic angles of friction between the belts surfaces and the coals tested are considerable higher than the presently recommended maximum inclination angle for belt conveyors. Bulk materials are not the same, and this is the reason why physical testing of a bulk solid is so important to proper design of conveying systems.

PL

Przedstawiono nową eksperymentalną metodę pomiaru współczynników tarcia statycznego i kinetycznego pomiędzy materiałem sypkim (węglem) a taśmą przenośnikową. Badania te, ważne w procesie konstruowania nachylonych przenośników taśmowych, były wielokrotnie pomijane. Metoda pomiaru opiera się na powszechnie znanej koncepcji równi pochyłej, a jej oryginalność polega na szerokim zastosowaniu mechatronicznych sensorów cyfrowych, jak np. inkrementalnych sensorów położenia liniowego i kątowego oraz komputerowej akwizycji i prezentacji danych. Tester skonstruowano z uwzględnieniem wiedzy o wieloparametrowym charakterze zjawisk tribologicznych oraz potrzeby niezależnej zmiany tych parametrów i ich łatwej identyfikacji. W prezentowanych w tym artykule badaniach zastosowano dwa rodzaje węgla, dwie taśmy oraz zmienne parametry, takie jak: obciążenie taśmy węglem i wilgotność środowiska badań. Wyniki badań wykazały, że wartości kątów tarcia statycznego i kinetycznego są istotnie większe od dopuszczalnych obecnie wartości kątów nachylenia przenośników wznoszących bądź opadających. Badania potwierdziły, że materiały sypkie (w tym przypadku węgle) różnią się między sobą własnościami fizycznymi, w tym tribologicznymi, w związku z tym ich poznanie jest ważne dla właściwego konstruowania systemu transportowego.