PL
 |
EN
Ograniczanie wyników
Czasopisma help
  1. 38 International Journal of Applied Mechanics and Engineering
  2. 7 Applied Mechanics and Engineering
  3. 5 Archives of Thermodynamics
  4. 2 Journal of Theoretical and Applied Mechanics
  5. 2 Mechanics and Mechanical Engineering
Więcej...
Autorzy help
  1. 6 Pop I.
  2. 4 Mansour M. A.
  3. 4 Raptis A.
  4. 4 Takhar H. S.
  5. 4 Wyczółkowski R.
Więcej...
Lata help
  1. 4 2023
  2. 3 2022
  3. 1 2021
  4. 1 2020
  5. 3 2019
Więcej...
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 70

Liczba wyników na stronie
first rewind previous Strona / 4 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  free convection
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 4 next fast forward last
1
Content available Similarity solution for MHD nanofluid flow with heat generation in the presence of radiation and chemical reaction effects
Palani G., Arutchelvi A.
International Journal of Applied Mechanics and Engineering
|
2023
|
Vol. 28, no. 1
71--83
EN
An analysis has been carried out to study the two-dimensional free convective boundary layer MHD nanofluid flow past an inclined plate with heat generation, chemical reaction and radiation effects under convective boundary conditions. The partial differential equations describing the flow are coupled nonlinear. They have been reduced to nonlinear ordinary differential equations by utilizing a similarity transformation, which is then solved numerically with the aid of the Runge-Kutta-based shooting technique. Graphs depict the influence of different controlling factors on the velocity, temperature, and concentration profiles. Numerical findings for skin friction, Nusselt number and Sherwood number are reviewed for distinct physical parameter values. In a limited sense, there is a good correlation between the current study's results and those of the earlier published work.
2
Content available Impacts of chemical reaction, thermal radiation, and heat source/sink on unsteady MHD natural convective flow through an oscillatory infinite vertical plate in porous medium
Saikia Dibya Jyoti, Ahmed Nazibuddin
International Journal of Applied Mechanics and Engineering
|
2023
|
Vol. 28, no. 4
114--136
EN
The main objective of this exploration is to analyze the effects of heat source/sink, chemical reactions, and radiation on the unsteady free convective flow through a porous medium using an infinitely oscillating vertical plate. The Laplace transformation tactics is utilized to solve the governing equations for concentration, energy, and momentum. The simulation results demonstrate that the chemical reaction parameter dwindles both primary and secondary velocities. It has been noted that an upsurge in heat generation (heat source) enhances the temperature field, while a decrease in heat absorption (heat sink) leads to a reduction in the temperature field. Furthermore, the radiation parameter causes a drop in both temperature and velocity patterns. The equation for skin friction is derived and presented graphically, and 3-dimensional surface plots are provided to depict the Nusselt number and Sherwood number. Additionally, graphical illustrations are employed to showcase the influence of various non-dimensional variables on concentration, temperature, and velocity patterns.
3
Content available Experimental Investigation on Free Convective Heat Transfer Performance of Oxide Nanofluids Along a Vertical Cylinder
Ravi Babu S., Pradeep Kumar P., Basha S. A., Maruthi Rao M.
Ecological Engineering & Environmental Technology
|
2023
|
Vol. 24, iss. 5
185--194
EN
The multi criterion decision making (MCDM) method and experimental investigation on free convective heat transfer performance of oxide-based water nanofluids along a vertical cylinder are the two methods used to compare the performance in this paper. Al2O3, CuO, TiO2, SiO2, Fe3O4, and ZnO were the metal oxide nanoparticles used in the study to make water-based metal oxide nanofluids with volume fractions ranging from 0% to 1%. Two step method was used to create nanofluids. Thermo-physical properties like density, specific heat, viscosity, and thermal conductivity were measured after the various nanofluids were synthesized. Then, the performance of each nanofluid was evaluated based on various attributes using the weighted sum model (WSM) method, and the ranking of nanofluids was given. To begin, water served as the medium for free convection heat transfer experiments to validate the experimental setup. Free convection heat transfer experiments were carried out using metal oxide-based water nanofluids as mediums at volume fractions ranging from 0% to 1% for various heat inputs in the range of 30 W and 50 W. The heat transfer coefficient augments with percentage volume concentration up to 0.1 % for all types of nanofluids and then decreases until it reaches 0.6% volume fraction. Al2O3-water nanofluid performs better than other metal oxide nanofluids in both WSM and experimental methods.
4
Content available Soret and dufour effects on chemically reacting and viscous dissipating nanofluid flowing past a moving porous plate in the presence of a heat source/sink
Aastha Aastha, Chand Khem
Acta Mechanica et Automatica
|
2023
|
Vol. 17, no. 2
263--271
EN
This study performed a numerical investigation of the Soret and Dufour effects on unsteady free convective chemically reacting nanofluid flowing past a vertically moving porous plate in the presence of viscous dissipation and a heat source/sink. The equations direct-ing the flow are non-dimensionalised, modified to ordinary differential equations and emerging equations are resolved computationally by using the bvp4c function in MATLAB software. The results obtained from this analysis indicate that the resulting velocity of the nanofluid increases with increasing Grashof number, mass Grashof number and porosity parameter. An increase in the Dufour number increases the fluid temperature, whereas the concentration profile declines with the increase in the Schmidt number. It is also observed that the skin fric-tion coefficient, Nusselt number and Sherwood number increase with increasing magnetic field parameter, Eckert number and Schmidt number, respectively. The present study reveals the impact of Soret and Dufour effects on heat and mass transfer rates in chemically re-acting and viscous dissipating nanofluids.
5
Content available remote Wpływ konwekcji swobodnej na efektywność odprowadzania ciepła w modułach PV/T
Niedzielski Przemysław, Dionizy Mateusz, Raj Ewa, Lisik Zbigniew
Przegląd Elektrotechniczny
|
2022
|
R. 98, nr 1
196--199
PL
W artykule przedstawiono wpływ konwekcji swobodnej na efektywność odprowadzania ciepła w modułach fotowoltaiczno-termicznych (PV/T). Omówiono wpływ ustawienie kąta nachylenia paneli (od -90° do 90°) na pole temperaturowe na powierzchni ich części kolektorowej. Przeprowadzona analiza pozwoliła stwierdzić, przy jakiej wartości przepływu objętościowego i ciśnienia w układzie cieczowym wpływ będzie miała konwekcja swobodna, a kiedy jest ona zjawiskiem pomijalnym.
EN
The paper presents influence of the free convection of heat transfer efficiency in PV/T modules. The impact of setting the tilt angle of the module (in the range from -90° to 90°) on the temperature field on the surface of the collector part is discussed. The conducted analysis allowed to determine at which values of the flow rate and the pressure drop in the liquid system, the free convection must be considered and when it is a negligible effect.
6
Content available remote Experimental analysis of ACP on photovoltaics as free convection for increasing output power
Sofijan Armin, Suprapto Bhakti Yudho, Nawawi Zainuddin
Przegląd Elektrotechniczny
|
2022
|
R. 98, nr 5
121--125
EN
This experiment uses perforated ACP as a cooling medium mounted on the back of a 100 Wp polycrystalline type photovoltaic panel, ACP with a hole diameter of 10 mm as passive cooling, which functions to reduce the temperature of the photovoltaic panel which has increased due to an increase in temperature. Radiation and excess heat from the Sun from 09.00 am to 15.00 pm, which is the peak of solar heat in subtropical areas such as Indonesia. The decrease in the temperature of the PV panels installed using the ACP cooler with a maximum of 9.13C due to the free convection process will cause an increase in the maximum output power of the PV panel of 11.15 W.
PL
W tym eksperymencie zastosowano perforowany ACP jako czynnik chłodzący zamontowany z tyłu panelu fotowoltaicznego typu polikrystalicznego o mocy 100 Wp, ACP o średnicy otworu 10 mm jako chłodzenie pasywne, którego zadaniem jest obniżenie temperatury panelu fotowoltaicznego, która wzrosła ze względu na wzrost temperatury. Promieniowanie i nadmiar ciepła ze Słońca od 09:00 do 15:00, co jest szczytem ciepła słonecznego w obszarach podzwrotnikowych, takich jak Indonezja. Spadek temperatury paneli fotowoltaicznych zainstalowanych przy użyciu chłodnicy ACP o maksymalnie 9,13C w wyniku procesu konwekcji swobodnej spowoduje wzrost maksymalnej mocy wyjściowej panelu fotowoltaicznego o 11,15 W.
7
Content available Effect of MHD on unsteady oscillatory Couette flow through porous media
Sharma Bhupendra K., Sharma Pawan Kumar, Cauhan Sudhir Kumar
International Journal of Applied Mechanics and Engineering
|
2022
|
Vol. 27, no. 1
188--202
EN
This paper describes the effects of a magnetic field on unsteady free convection oscillatory systems. When temperature and species concentration fluctuate with time around a non-zero constant, "Couette flow" across a porous medium occurs. The system of non-linear ODEs that governs the flow is solved analytically using the perturbation approach because the amplitude of fluctuations is very tiny. Mean flow and transient velocity, transient concentration, transient temperature, heat transfer, mean skin friction and phase and amplitude of skin friction. All have approximate solutions. The influence of different parameters on flow characteristics has been specified and discussed.
8
Content available Heat transfer effects on free convection of viscous dissipative fluid flow over an inclined plate with thermal radiation in the presence of induced magnetic field
Kumar P. Pramod, Malga Bala Siddulu, Appidi Lakshmi, Matta Sweta
International Journal of Applied Mechanics and Engineering
|
2021
|
Vol. 26, no. 1
122--134
EN
The principal objective of the present paper is to know the reaction of thermal radiation and the effects of magnetic fields on a viscous dissipative free convection fluid flow past an inclined infinite plate in the presence of an induced magnetic field. The Galerkin finite element technique is applied to solve the nonlinear coupled partial differential equations and effects of thermal radiation and other physical and flow parameters on velocity, induced magnetic field, along with temperature profiles are explained through graphs. It is noticed that as the thermal radiation increases velocity and temperature profiles decrease and the induced magnetic field profiles increases.
9
Content available A numerical study of dissipative chemically reactive radiative MHD flow past a vertical cone with nonuniform mass flux
Sambath P., Sankar D. S., Viswanathan K. K.
International Journal of Applied Mechanics and Engineering
|
2020
|
Vol. 25, no. 1
159--176
EN
A computational model is presented to explore the properties of heat source, chemically reacting radiative, viscous dissipative MHD flow of an incompressible viscous fluid past an upright cone under inhomogeneous mass flux. A numerical study has been carried out to explore the mass flux features with the help of Crank-Nicolson finite difference scheme. This investigation reveals the influence of distinct significant parameters and the obtained outputs for the transient momentum, temperature and concentration distribution near the boundary layer is discussed and portrayed graphically for the active parameters such as the Schmidt number Sc, thermal radiation Rd, viscous dissipation parameter […], chemical reaction parameter […], MHD parameter M and heat generation parameter ]…]. The significant effect of parameters on shear stress, heat and mass transfer rates are also illustrated.
10
Content available Wpływ ożebrowania rury na warunki wymiany ciepła przy konwekcji swobodnej w powietrzu
Tychanicz-Kwiecień Maria, Mazur Aleksandra, Gil Paweł, Gałek Rafał
Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika
|
2019
|
z. 91 [299], nr 1-2
93--107
PL
Artykuł przedstawia wstępne wyniki pomiarów cieplnych rurowego wymiennika ciepła typu woda–powietrze, wykonanego z odcinków rur gładkich oraz ożebrowanych z żebrami śrubowymi. Stanowisko pomiarowe znajduje się na wyposażeniu Zakładu Termodynamiki Wydziału Budowy Maszyn i Lotnictwa Politechniki Rzeszowskiej. Dokonano pomiarów mocy cieplnej traconej przez przenikanie na rurze gładkiej oraz ożebrowanej w funkcji różnicy temperatury wody wlotowej i temperatury otoczenia oraz współczynników przenikania ciepła: rury gładkiej – odniesionego do powierzchni zewnętrznej oraz dla rury ożebrowanej – odniesionego do powierzchni całkowitej ożebrowania. Wyniki pomiarów wskazują, że moc cieplna rozpraszana do otoczenia wzrasta niemal trzykrotnie w wyniku zastosowania ożebrowania w stosunku do powierzchni gładkiej. Z kolei współczynnik przenikania ciepła określony dla rury gładkiej osiągnął wartość wielokrotnie większą niż dla rury ożebrowanej.
EN
The article presents preliminary results of thermal parameter measurements of an air-water tubular heat exchanger made of smooth- and finned pipes. The experimental set-up is the equipment of The Department of Thermodynamics at Rzeszow University of Technology. The following parameters have been measured as a function of temperature difference between inlet water temperature and ambient temperature: dissipated thermal power for smooth- and finned pipes and the heat transfer coefficient for a smooth pipe related to the external surface and heat transfer coefficient for a finned pipe related to the overall finned surface. The results indicate that dissipated thermal power increased almost three times for the finned pipe with regard to the smooth pipe. The heat transfer coefficient obtained for a smooth pipe was considerably greater than for a finned pipe.
11
Content available Unsteady MHD thermal diffusive and radiative fluid flow past a vertical porous plate with chemical reaction in slip flow regime
Ravi Kumar D., Jayarami Reddy K., Raju M. C.
International Journal of Applied Mechanics and Engineering
|
2019
|
Vol. 24, no. 1
117--129
EN
An analytical solution of an MHD free convective thermal diffusive flow of a viscous, incompressible, electrically conducting and heat-absorbing fluid past a infinite vertical permeable porous plate in the presence of radiation and chemical reaction is presented. The flow is considered under the influence of a magnetic field applied normal to the flow. The plate is assumed to move with a constant velocity in the direction of fluid flow in slip flow regime, while free stream velocity is assumed to follow the exponentially increasing small perturbation law. The velocity, temperature, concentration, skin friction, Nusselt number and Sherwood number distributions are derived and have shown through graphs and tables by using the simple perturbation technique.
12
Content available Radiation and chemical reaction effects on unsteady MHD free convection parabolic flow past an infinite isothermal vertical plate with viscous dissipation
Reddy B. Prabhakar
International Journal of Applied Mechanics and Engineering
|
2019
|
Vol. 24, no. 2
343--358
EN
The numerical investigation of the effects of radiation and chemical reaction on an unsteady MHD free convection flow with a parabolic starting motion of an infinite isothermal vertical porous plate taking into account the viscous dissipation effect has been carried out. The fluid is considered a gray, absorbing emitting radiation but a non-scattering medium. The dimensionless governing equations for this investigation are solved numerically by applying the Ritz finite element method. Numerical results for the velocity profiles, temperature profiles and concentration profiles as well as the skin-friction are presented through graphs and tables for different values of the physical parameters involved. Results obtained show a decrease in the temperature and velocity in the boundary layer as the radiation parameter increased. The velocity increases with an increase in the thermal and mass Grashof numbers and decreases with an increase in the magnetic parameter. Further, the concentration and velocity decreases with increasing the Schmidt number and chemical reaction parameter. These findings are in very good agreement with the studies reported earlier.
13
Content available remote Applying CFD for studying the dynamic and thermal behavior of an indirect solar dryer: paramertric analysis
Khaldi S., Korti A. N., Abboudi S.
Mechanics and Mechanical Engineering
|
2018
|
Vol. 22, nr 1
253--272
EN
In this work, an indirect solar dryer integrated thermal storage for drying figs. (Ficuscarica) is studied numerically. Unsteady turbulent airflow and heat transfer through a two-dimensional model is carried out for a typical day of August under the climatic conditions of Tlemcen (Algeria). Effects of air inlet size and thickness of the packed bed on the dynamic and thermal behaviors of the dryer with and without packed bed have been discussed. The study shows that: (1) Increase the inlet size from 0.04 m to 0.10 m can accelerate the extraction of air by about 13% and reduce the maximum crops temperature by about 14%. (2) The packed bed can reduce the mass flow rate extracted by 22% and the fluctuations of air temperature by 1.3%. (3) A packed bed with a thickness of 0.15 m can extend the operating time of the dryer up to 23%.
14
Tradycyjna lodownia - ekoenergetyczny magazyn żywności
Gosz M., Andrzejczyk R.
Przemysł Spożywczy
|
2017
|
T. 71, nr 10
40--43
PL
W artykule omówiono konstrukcję oraz zasadę działania naturalnych przechowalni żywności, tzw. lodowni. Przedstawiono kilka przykładów takich konstrukcji wraz z opisem ich budowy. Na przykładzie jednego rozwiązania szczegółowo opisano zasadę działania procesów zachodzących wewnątrz przechowalni. Podkreślono neutralność tego typu budowli wobec środowiska. Przedstawiono zalety i wady analizowanego rozwiązania na tle sprężarkowych urządzeń chłodniczych.
EN
The article describes the structure and principle of operation of natural food coolers, the so-called icehouses. Several examples of such storage were presented along with a description of their construction. Based on the example of one solution there was explained in detail the principle of the processes, taking place inside the vault. The authors hale stressed the environmental neutrality of this type of buildings. The summary compares the advantages and disadvantages of the analyzed solution against compressor refrigeration equipment.
15
Content available A study of chemically reactive species and thermal radiation effects on an unsteady MHD free convection flow through a porous medium past a flat plate with ramped wall temperature
Pandit K. K., Sarma D., Singh S. I.
International Journal of Applied Mechanics and Engineering
|
2017
|
Vol. 22, no. 4
945--964
EN
An investigation of the effects of a chemical reaction and thermal radiation on unsteady MHD free convection heat and mass transfer flow of an electrically conducting, viscous, incompressible fluid past a vertical infinite flat plate embedded in a porous medium is carried out. The flow is induced by a general time-dependent movement of the vertical plate, and the cases of ramped temperature and isothermal plates are studied. An exact solution of the governing equations is obtained in closed form by the Laplace Transform technique. Some applications of practical interest for different types of plate motions are discussed. The numerical values of fluid velocity, temperature and species concentration are displayed graphically whereas the numerical values of skin friction, Nusselt number and Sherwood number are presented in a tabular form for various values of pertinent flow parameters for both ramped temperature and isothermal plates.
16
Content available remote Experimental investigation of free convection of glycol-Al2O3 nanofluid from horizontal tube
Cieśliński J. T., Smoleń S., Sawicka D.
Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika
|
2016
|
z. 88 [293], nr 4
315--322
EN
Nanofluids are considered to be a new generation of coolants, both in single- and two phase systems. Furthermore, nanofluids or nanocomposites may be used as a media in thermal energy storage (TES) in such systems as sensible heat storage (SHS) and phase change materials (PCM). In the SHS systems the dominating mechanism of the heat transfer is natural convection. However, in the literature only a few investigations of free convection of nanofluids have been discussed. This paper presents preliminary results of the experimental investigation of natural convection heat transfer of glycol-Al2O3 nanofluid from horizontal tube.
PL
Nanociecze uważane są za nową generację czynników chłodzących w układach jednofazowych oraz dwufazowych. Ponadto, nanociecze i nanokomponenty mogą być użyte jako środki magazynowania energii cieplnej (TES) w takich systemach jak SHS czy PCM. W systemach wykorzystujących ciepło jawne dominującym sposobem wymiany ciepła jest konwekcja swobodna. Mimo tego, jak dotąd, przeprowadzono niewiele badań eksperymentalnych i numerycznych dotyczących zjawiska konwekcji swobodnej nanocieczy. W pracy zaprezentowano wstępne wyniki badań eksperymentalnych wymiany ciepła podczas konwekcji swobodnej nanocieczy glikol-Al2O3 na poziomej rurce.
17
Content available Effect of slip condition on vertical channel flow in the presence of radiation
Guria M.
International Journal of Applied Mechanics and Engineering
|
2016
|
Vol. 21, no. 2
341--358
EN
An analysis is made on the three dimensional flow of a viscous incompressible fluid through a vertical channel in the presence of radiation in slip flow regime. The right plate is subjected to an uniform injection and the left plate to a periodic suction velocity distribution. The velocity and temperature fields have been derived using the perturbation technique. It is found that the velocity decreases with the increase of the slip parameter. It is also found that the velocity decreases with the increase of the radiation parameter but near the right plate it increases. For cooling of the plate, the velocity increases with the increase of the Grashoff number and decreases near the right plate but the reverse effect is observed for heating the plate.
18
Content available remote Free convection on the outer surface of vertical longitudinally finned tubes
Niezgoda-Żelasko B., Żelasko J.
Czasopismo Techniczne. Mechanika
|
2015
|
Y. 112, iss. 1-M
75--85
EN
The paper presents methods of determination and the results of experimental studies of heat transfer coefficients on the outer surface of longitudinally finned tubes under free convection conditions.
PL
Artykuł przedstawia metody wyznaczania współczynników przejmowania ciepła w warunkach konwekcji swobodnej na zewnętrznej powierzchni rur ożebrowanych wzdłużnie.
19
Content available Analysis of components effecting free convection intensity in steel rectangular sections
Wyczółkowski R.
Archives of Thermodynamics
|
2015
|
Vol. 36, no. 3
105--121
EN
Free convection is one of the heat transfer modes which occurs within the heat-treated bundles of steel rectangular section. A comprehensive study of this phenomenon is necessary for optimizing the heating process of this type of charge. The free convection intensity is represented by the Rayleigh number Ra. The value of this criterion depends on the following parameters: the mean section temperature, temperature difference within the section, kinematic coefficient of viscosity, volume expansion coefficient and the Prandtl number. The paper presents the analysis of the impact of these factors on free convection in steel rectangular sections. The starting point for this analysis were the results of experimental examinations. It was found that the highest intensity of this process occurs for the temperature of 100°C. This is mainly caused by changes in the temperature difference observed in the area of sections and changes in kinematic coefficient of viscosity of air. The increase in the value of the Rayleigh number criterion at the initial stage is attributable to changes in the parameter of temperature difference within the section. After exceeding 100°C, the main effect on convection is from changes in air viscosity. Thus, with further increase in temperature, the Rayleigh number starts to decline rapidly despite further rise in the difference in temperature.
20
Content available Use of the Schlieren Method to the Convection Analysis in the Steel Charge of Mixed Porosity
Wyczółkowski R., Kolmasiak C., Urbaniak D., Wyleciał T.
Archives of Metallurgy and Materials
|
2015
|
Vol. 60, iss. 4
2949--2954
EN
The paper presents experimental studies devoted to the convection phenomenon within the steel charge of mixed porosity. Such charges constitute bundles of hollow long elements such as pipes or rectangular sections which are heat treated. A significant portion of the gas phase in the volume of the charge makes that natural convection of the gas occurring within the individual elements may have an effect on the course of heating. To the tests the Schlieren method was used which is one of the optical visualization methods applied to the analysis of the flow phenomena in the transparent and non luminous media such as air or water. The tested samples have the form of porous charge beds made from pipes and rectangular profiles. During the experiments the samples were heating up for the constant heat flux rate. The direction of flux was vertical, from the bottom to the top.
PL
W artykule przedstawiono badania eksperymentalne poświęcone analizie zjawiska konwekcji w obrębie wsadu stalowego o porowatości mieszanej. Wsad taki stanowią obrabiane cieplnie wiązki pustych elementów długich, takich jak rur czy profili prostokątnych. Znaczny udział fazy gazowej w objętości tego wsadu powoduje, iż na przebieg nagrzewania może wpływać konwekcja swobodna gazu zachodząca wewnątrz poszczególnych elementów. Do badań zastosowano metodę Schlierena, która jest jedną z optycznych metod wizualizacji stosowanych do analizy zjawisk przepływowych w ośrodkach przeźroczystych i nieświecących, takich jak powietrze czy woda. Badanymi próbkami były złoża wsadu porowatego zbudowane z rur oraz profili prostokątnych. Proces obserwowano przy nagrzewaniu próbek, skierowanym pionowo w górę strumieniem ciepła o stałej wartości.
first rewind previous Strona / 4 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.