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Tytuł:
Application of Nanoparticles in the Process of Phase Change Paraffin in a Chamber
Autorzy:
Alizadeh, As’ad
Powiązania:
https://bibliotekanauki.pl/articles/102698.pdf
Data publikacji:
2019
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
aluminum oxide
phase change material
nusselt number
nanoparticles
tlenek glinu
materiał o przemianie fazowej
liczba Nusselta
nanocząstki
Opis:
In this study, melting of a phase changing material enriched with nanoparticles in a circular ring-rectangular enclosure was investigated and the results were analyzed. At the beginning of the melting process in the absence of a natural displacement, the mechanism of conduction heat transfer around the hot cylinder is the dominant mechanism. Over time, natural displacement gradually appears and deforms the melting boundary above the cylinder. Over time, when the thickness of the liquid phase grows, the thermal resistance increases, this can be verified by reviewing the Nusselt chart. So this phenomenon reduces the rate of melting and temperature changes. The results show that increasing the nanoparticle volume fraction due to increased conductivity and decreasing latent heat causes an increase in the melting rate and the amount of energy absorbed. From the study of various volume fractions, it can be concluded that the use of a higher volume fraction of 3% is more appropriate both in terms of energy and in terms of the melting rate. However, it should be taken into account that if the melting rate exceeds this value, it may cause agglomeration and deposition of nanoparticles and reducing system efficiency.
Źródło:
Advances in Science and Technology. Research Journal; 2019, 13, 3; 113-119
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analogy between thermal and mass diffusion effects of a free convective flow in rectangular enclosure
Autorzy:
Ambethkar, Vusala
Powiązania:
https://bibliotekanauki.pl/articles/1839737.pdf
Data publikacji:
2020
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
free convective flow
thermal diffusion effects
mass diffusion effects
rectangular enclosure
average Nusselt number
average Sherwood number
empirical correlations
swobodny przepływ konwekcyjny
efekty dyfuzji termicznej
efekty dyfuzji masowej
korelacje empiryczne
średnia liczba Sherwooda
średnia liczba Nusselta
Opis:
In this investigation, the analogy between thermal and mass diffusive effects of a free convective flow in a rectangular enclosure is emphasized. The upwind finite volume method is used to discretize the governing equations of the continuity, momentum, energy and mass transfer. The novelty in this exploration is to appropriately modify the well-known Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm so that it suits to the present problem and thereby, the new flow variables such as the temperature and the concentration are computed. An empirical correlation for the average Sherwood number (Sh) that does not exist in literature is suggested in this work. The average Sherwood numbers for distinct fluids (gases and liquids) are calculated, and mass diffusion effects within the horizontal rectangle are analyzed. The average Nusselt numbers (Nu) are calculated for distinct fluids such as liquids (Pr ≫1), liquid metals (Pr≪1) and gases (Pr < 1) for different Rayleigh numbers in the range of 3x105 ≤ RaL ≤ 7x10 9 from relevant empirical correlations existing in the literature. Accordingly, the thermal diffusion effects within the horizontal rectangle are analyzed.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2020, 19, 4; 5-20
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analogy between thermal and mass diffusion effects of a free convective flow in rectangular enclosure
Autorzy:
Ambethkar, Vusala
Powiązania:
https://bibliotekanauki.pl/articles/1839750.pdf
Data publikacji:
2020
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
free convective flow
thermal diffusion effects
mass diffusion effects
rectangular enclosure
average Nusselt number
average Sherwood number
empirical correlations
swobodny przepływ konwekcyjny
efekty dyfuzji termicznej
efekty dyfuzji masowej
korelacje empiryczne
średnia liczba Sherwooda
średnia liczba Nusselta
Opis:
In this investigation, the analogy between thermal and mass diffusive effects of a free convective flow in a rectangular enclosure is emphasized. The upwind finite volume method is used to discretize the governing equations of the continuity, momentum, energy and mass transfer. The novelty in this exploration is to appropriately modify the well-known Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm so that it suits to the present problem and thereby, the new flow variables such as the temperature and the concentration are computed. An empirical correlation for the average Sherwood number (Sh) that does not exist in literature is suggested in this work. The average Sherwood numbers for distinct fluids (gases and liquids) are calculated, and mass diffusion effects within the horizontal rectangle are analyzed. The average Nusselt numbers (Nu) are calculated for distinct fluids such as liquids (Pr ≫1), liquid metals (Pr≪1) and gases (Pr < 1) for different Rayleigh numbers in the range of 3x105 ≤ RaL ≤ 7x10 9 from relevant empirical correlations existing in the literature. Accordingly, the thermal diffusion effects within the horizontal rectangle are analyzed.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2020, 19, 4; 5-20
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of aspect ratio of enclosure on free convection from horizontal cylinders in Bingham plastic fluids
Autorzy:
Baranwal, Ashok Kumar
Gupta, Anoop Kumar
Tiwari, Anurag Kumar
Melnik, Roderick
Powiązania:
https://bibliotekanauki.pl/articles/2173430.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Bingham plastic fluids
aspect ratio
Rayleigh number
Nusselt number
natural convection
płyn plastikowy Bingham
współczynnik proporcji
liczba Rayleigha
liczba Nusselta
naturalna konwekcja
Opis:
Heat transfer in steady free convection from differentially heated cylinders enclosed in a rectangular duct filled with Bingham plastic fluids has been solved numerically for the ranges of the dimensionless groups as, Rayleigh number, 102 Ra 106; Prandtl number, 10 Pr 100 and, Bingham number, 0 Bn 50 for aspect ratios AR = 05, 0.6, 0.7, 0.8, 0.9 and 2. The streamlines, isotherm contours, yield surfaces, local and average Nusselt numbers were analysed and discussed. It is found that as the aspect ratio of the enclosure increases from 0.5 to 0.9, the average Nusselt number on the surface of the hot cylinder increases as a larger amount of fluid takes part in convection. Moreover, at sufficiently large Bingham numbers, yield stress forces dominate over buoyancy causing the flow to cease and thus the Nusselt number approaches its conduction limit. Finally, the Nusselt number approaches its conduction limit once the maximum Bingham number is reached.
Źródło:
Chemical and Process Engineering; 2022, 43, 2; 271--277
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On numerical modelling of heat transfer and fluid flow in a scraped surface heat exchanger
Autorzy:
Błasiak, P.
Gnutek, Z.
Powiązania:
https://bibliotekanauki.pl/articles/240070.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
scraped surface heat exchanger
nusselt number
thermal boundary layer
wymiennik ciepła
liczby Nusselta
termiczna warstwa przyścienna
Opis:
Steady state two-dimensional numerical simulation of laminar heat transfer and fluid flow in a scraped surface heat exchanger (SSHE) is presented. Typical SSHE consists of a stator, rotating shaft and scraping blades. Due to symmetry only a quarter of the heat exchanger is modelled. Governing equations for transport of mass, momentum and energy are discretised and solved with the use of commercial CFD code. The results are presented in a nondimensional form for velocity, pressure and temperature distributions. Local and averaged Nusselt number along the stator wall are calculated and depicted in graphs. It was found that the thirty fold increase of the cReynolds number, leads to heat transfer enhancement rate by three times.
Źródło:
Archives of Thermodynamics; 2014, 35, 3; 251-264
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vertical heat transport at infinite Prandtl number for micropolar fluid
Autorzy:
Caggio, M.
Kalita, P.
Łukaszewicz, G.
Mizerski, K. A.
Powiązania:
https://bibliotekanauki.pl/articles/38611128.pdf
Data publikacji:
2020
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
micropolar fluid
Rayleigh–Benard convection
heat transport
Rayleigh number
Prandtl number
Nusselt number
Opis:
We investigate the upper bound on the vertical heat transport in the fully 3D Rayleigh–Bénard convection problem at the infinite Prandtl number for a micropolar fluid. We obtain a bound, given by the cube root of the Rayleigh number, with a logarithmic correction. The derived bound is compared with the optimal known one for the Newtonian fluid. It follows that the (optimal) upper bound for the micropolar fluid is less than the corresponding bound for the Newtonian fluid at the same Rayleigh number. Moreover, strong microrotational diffusion effects can entirely suppress the heat transfer. In the Newtonian limit our purely analytical findings fully agree with estimates and scaling laws obtained from previous theories significantly relying on phenomenology.
Źródło:
Archives of Mechanics; 2020, 72, 6; 525-553
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental investigation of heat transfer characteristics of nanofluid using parallel flow, counter flow and shell and tube heat exhanger
Badanie eksperymentalne charakterystyk przewodzenia ciepła w nanopłynach w warunkach przepływu współprądowego i przeciwprądowego w płaszczowych i rurowych wymiennikach ciepła
Autorzy:
Dharmalingam, R.
Sivagnanaprabhu, K. K.
Yogaraja, J.
Gunasekaran, S.
Mohan, R.
Powiązania:
https://bibliotekanauki.pl/articles/950690.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
logarithmic mean temperature difference
heat exchanger
Nusselt number
nanofluids
overall heat transfer coefficient
średnia logarytmiczna różnica temperatur
wymiennik ciepła
liczba Nusselta
nanopłyny
współczynnik przenikania ciepła
Opis:
Cooling is indispensable for maintaining the desired performance and reliability over a very huge variety of products like electronic devices, computer, automobiles, high power laser system etc. Apart from the heat load amplification and heat fluxes caused by many industrial products, cooling is one of the major technical challenges encountered by the industries like manufacturing sectors, transportation, microelectronics, etc. Normally water, ethylene glycol and oil are being used as the fluid to carry away the heat in these devices. The development of nanofluid generally shows a better heat transfer characteristics than the water. This research work summarizes the experimental study of the forced convective heat transfer and flow characteristics of a nanofluid consisting of water and 1% Al2O3 (volume concentration) nanoparticle flowing in a parallel flow, counter flow and shell and tube heat exchanger under laminar flow conditions. The Al2O3 nanoparticles of about 50 nm diameter are used in this work. Three different mass flow rates have been selected and the experiments have been conducted and their results are reported. This result portrays that the overall heat transfer coefficient and dimensionless Nusselt number of nanofluid is slightly higher than that of the base liquid at same mass flow rate at same inlet temperature. From the experimental result it is clear that the overall heat transfer coefficient of the nanofluid increases with an increase in the mass flow rate. It shows that whenever mass flow rate increases, the overall heat transfer coefficient along with Nusselt number eventually increases irrespective of flow direction. It was also found that during the increase in mass flow rate LMTD value ultimately decreases irrespective of flow direction. However, shell and tube heat exchanger provides better heat transfer characteristics than parallel and counter flow heat exchanger due to multi pass flow of nanofluid. The overall heat transfer coefficient, Nusselt number and logarithmic mean temperature difference of the water and Al2O3 /water nanofluid are also studied and the results are plotted graphically.
Chłodzenie jest niezbędne dla właściwego funkcjonowania i niezawodności różnorodnych produktów, jak urządzenia elektroniczne, komputery, samochody, systemy laserowe wielkiej mocy, itp. W sytuacji wzrostu obciążenia cieplnego i strumieni ciepła wytwarzanych przez urządzenia przemysłowe, chłodzenie jest jednym z najważniejszych wyzwań występujących w różnych gałęziach przemysłu, transporcie, mikroelektronice, itp. Płynami, które zwykle są używane do odprowadzania ciepła z tych urządzeń są woda, glikol etylenowy i oleje. Nanopłyny, opracowane w ostatnim czasie, wykazują generalnie lepsze charakterystyki przewodnictwa cieplnego niż woda. Przedstawiona praca stanowi podsumowanie badań doświadczalnych nad wymuszonym, konwekcyjnym odprowadzaniem ciepła i charakterystykami przepływu nanopłynu składającego się z wody i cząsteczek Al2O3 (w 1% stężeniu objętościowym) w warunkach laminarnego przepływu współprądowego i przeciwprądowego w płaszczowych i rurowych wymiennikach ciepła. W przedstawionych badaniach użyto cząstek Al2O3 o średnicy ok. 50 nm. Wybrano trzy różne prędkości przepływu masy, opisano wyniki eksperymentów. Wyniki te wskazują, że całkowity współczynnik odprowadzania ciepła i bezwymiarowa liczba Nusselta nanopłynu są, przy tej samej prędkości przepływu masy i temperaturze na wlocie, nieznacznie wyższe, niż dla samego płynu bazowego. Z wyników doświadczalnych wynika, że całkowity współczynnik odprowadzania ciepła wzrasta wraz z prędkością przepływu masy. Pokazano, że gdy wzrasta prędkość przepływu masy, całkowity współczynnik odprowadzania ciepła wraz z bezwymiarową liczbą Nusselta ostatecznie wzrastają, niezależnie od kierunku przepływu. Stwierdzono także, że ze wzrostem prędkości przepływu masy wartość LMTD (średniej logarytmicznej różnicy temperatur) ostatecznie maleje, niezależnie od kierunku przepływu. Niemniej, płaszczowe i rurowe wymienniki ciepła zapewniają lepsze charakterystyki odprowadzania ciepła niż wymienniki z przepływem współprądowym i przeciwprądowym, co wynika z wielostrumieniowego przepływu nanopłynu. Badano także całkowity współczynnik odprowadzania ciepła, bezwymiarową liczbę Nusselta i średnią logarytmiczną różnicę temperatur dla wody i nanopłynu złożonego z wody i Al2O3, a wyniki przedstawiono w formie graficznej.
Źródło:
Archive of Mechanical Engineering; 2015, LXII, 4; 509-522
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation and sensitivity analysis of turbulent heat transfer and pressure drop of Al2O3/H2O nanofluid in straight pipe using response surface methodology
Autorzy:
Fadodun, Olatomide G.
Amosun, Adebimpe A.
Salau, Ayodeji O.
Olaloye, David O.
Ogundeji, Johnson A.
Ibitoye, Francis I.
Balogun, Fatai A.
Powiązania:
https://bibliotekanauki.pl/articles/239962.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nusselt number
Reynolds number
pressure drop
response surface methodology
nanofluid
single phase flow
Opis:
In this paper, investigation of the effect of Reynolds number, nanoparticle volume ratio, nanoparticle diameter and entrance temperature on the convective heat transfer and pressure drop of Al2O3/H2O nanofluid in turbulent flow through a straight pipe was carried out. The study employed a computational fluid dynamic approach using single-phase model and response surface methodology for the design of experiment. The Reynolds average Navier-Stokes equations and energy equation were solved using k-ε turbulent model. The central composite design method was used for the response-surface-methodology. Based on the number of variables and levels, the condition of 30 runs was defined and 30 simulations were performed. New models to evaluate the mean Nusselt number and pressure drop were obtained. Also, the result showed that all the four input variables are statistically significant to the pressure drop while three out of them are significant to the Nusslet number. Furthermore, sensitivity analysis carried out showed that the Reynolds number and volume fraction have a positive sensitivity to both the mean Nusselt number, and pressure drop, while the entrance temperature has negative sensitivities to both.
Źródło:
Archives of Thermodynamics; 2020, 41, 1; 3-30
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Similarity solution for combined free-forced convection past a vertical porous plate in a porous medium with a convective surface boundary condition
Autorzy:
Garg, P.
Purohit, G. N.
Chaudhary, R. C.
Powiązania:
https://bibliotekanauki.pl/articles/265568.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
płyta porowata
tarcie
ośrodek porowaty
konwekcja
combined convection
fixed vertical porous plate
skin-friction coefficient
Nusselt number
convective surface boundary condition
porous medium
Opis:
This paper studies the mathematical implications of the two dimensional viscous steady laminar combined free-forced convective flow of an incompressible fluid over a semi infinite fixed vertical porous plate embedded in a porous medium. It is assumed that the left surface of the plate is heated by convection from a hot fluid which is at a temperature higher than the temperature of the fluid on the right surface of the vertical plate. To achieve numerical consistency for the problem under consideration, the governing non linear partial differential equations are first transformed into a system of ordinary differential equations using a similarity variable and then solved numerically under conditions admitting similarity solutions. The effects of the physical parameters of both the incompressible fluid and the vertical plate on the dimensionless velocity and temperature profiles are studied and analysed and the results are depicted both graphically and in a tabular form. Finally, algebraic expressions and the numerical values are obtained for the local skin-friction coefficient and the local Nusselt number.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 4; 827-836
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical modeling of heat transfer in Al2O3/H2O nanofluid flowing through a Bessel-like converging pipe
Autorzy:
Iweka, Chukwuka S.
Fadodun, Olatomide G.
Powiązania:
https://bibliotekanauki.pl/articles/1845460.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nanofluid
Nusselt number
response surface methodology
Reynolds number
convergence
index
Opis:
This paper studies hydrodynamic and heat transfer performance of Al2O3/H2O nanofluid flowing through a Bessel-like converging pipe in laminar flow regime using the computational fluid dynamic approach. A parametric study was carried out on the effect of Reynolds number (300– 1200), convergence index (0-3) and nanoparticle concentration (0–3%) on the both hydrodynamic and thermal fields. The results showed the pressure drop profile along the axial length of the converging pipes is parabolic compared to the downward straight profile obtained in a straight pipe. Furthermore, an increase in convergence index, Reynolds number and nanoparticle concentration were found to enhance convective heat transfer performance. Also, a new empirical model was developed to estimates the average Nusselt number as a function of aforementioned variables. Finally, the result of the thermohydraulic performance evaluation criterion showed that the usage of Bessel-like converging pipes is advantageous at a low Reynolds number.
Źródło:
Archives of Thermodynamics; 2021, 42, 2; 121-153
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical modeling of heat transfer in Al2O3/H2O nanofluid flowing through a Bessel-like converging pipe
Autorzy:
Iweka, Chukwuka S.
Fadodun, Olatomide G.
Powiązania:
https://bibliotekanauki.pl/articles/1845485.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nanofluid
nusselt number
response surface methodology
Reynolds number
convergence
index
Opis:
This paper studies hydrodynamic and heat transfer performance of Al2O3/H2O nanofluid flowing through a Bessel-like converging pipe in laminar flow regime using the computational fluid dynamic approach. A parametric study was carried out on the effect of Reynolds number (300– 1200), convergence index (0-3) and nanoparticle concentration (0–3%) on the both hydrodynamic and thermal fields. The results showed the pressure drop profile along the axial length of the converging pipes is parabolic compared to the downward straight profile obtained in a straight pipe. Furthermore, an increase in convergence index, Reynolds number and nanoparticle concentration were found to enhance convective heat transfer performance. Also, a new empirical model was developed to estimates the average Nusselt number as a function of aforementioned variables. Finally, the result of the thermohydraulic performance evaluation criterion showed that the usage of Bessel-like converging pipes is advantageous at a low Reynolds number.
Źródło:
Archives of Thermodynamics; 2021, 42, 2; 121-153
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flow features of thermophoretic MHD viscous fluid flow past a converging channel with heat source and chemical reaction
Autorzy:
Kalita, B. K.
Choudhury, R.
Powiązania:
https://bibliotekanauki.pl/articles/2106445.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
magnetohydrodynamika
płyn lepki
termoforeza
liczba Nusselta
MHD
viscous fluid
heat source
thermophoresis
Nusselt number
skin friction
Opis:
A boundary layer flow of an electrically conducting viscous fluid past a converging channel in the presence of thermophoresis, heat source, chemical reaction, viscous dissipation and simultaneous heat and mass transfer characteristics is studied in the paper. An external magnetic field of uniform strength is applied transversely to the channel. The similarity solution has been used to transform the partial differential equations that represent the problem into a boundary value problem of coupled ordinary differential equations, which in turn are solved numerically using MATLAB’s built in solver bvp4c. Numerical computations are carried out to solve the problem and graphical illustrations are made to get the physical insight of the same. The convergent channel flow problem of an incompressible electrically conducting viscous fluid in the presence of a magnetic field has a wide range of applicability in different areas of engineering, specially in industrial metal casting and control of molten metal flow.
Źródło:
International Journal of Applied Mechanics and Engineering; 2021, 26, 3; 72--83
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On diffusion of chemically reactive species in a convective flow past an inclined plate with variable surface temperature and variable mass diffusion
Autorzy:
Kirubavathi, J. D.
Palani, G.
Powiązania:
https://bibliotekanauki.pl/articles/266086.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
metoda różnic skończonych
płyta pochylona
tarcie
chemically reactive species
Nusselt number
skin friction
finite-difference methods
inclined plate
Opis:
A numerical solution of a transient natural convection flow past a semi-infinite inclined plate under the combined buoyancy effects of heat and mass transfer along with chemical reaction is presented herewith. The governing boundary layer equations for the above flow problem for a first order homogeneous chemical reaction are set up and non-dimensionalised. An implicit finite difference method is employed to solve the unsteady, nonlinear, integro and coupled partial differential equation. Numerical results are presented for various parameters occurring in the problem. The unsteady velocity, temperature and concentration profiles, local and average skin friction, Nusselt number and Sherwood number are studied for both a generative and destructive reaction.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 4; 905-922
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Augmentation in heat transfer and friction of three sides over one side dimple roughened solar duct
Autorzy:
Kumar, Vikash
Powiązania:
https://bibliotekanauki.pl/articles/240256.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
dimple roughened
relative roughness pitch
relative roughness height
dimple depth to diameter ratio
nusselt number
friction factor
Opis:
Providing roughness is an effective method to heat fluids to high temperature. Present paper make use of concave dimple roughness on one and three sides of roughened ducts aimed at determining rise in heat transfer and friction of three sides over one side roughened duct. Three sides roughened duct produces high heat transfer compared to one side roughened. Results are shown as a rise in Nusselt number and friction factor of three sides over one side roughened duct. Experimental investigation was conducted under actual outdoor condition at National Institute of Technology Jamshedpur, India to test various sets of roughened collectors. Roughness parameter varied as relative roughness pitch 8–15, relative roughness height 0.018–0.045, dimple depth to diameter ratio 1–2, Reynolds number 2500– 13500 at fixed aspect ratio (width/hight) 8. Highest enhancement in Nusselt number for varying relative roughness pitch, height, and diameter ratio was respectively found as 2.6 to 3.55 times, 1.91 to 3.42 times and 3.09 to 3.94 times compared to one side dimple roughened duct. Highest rise in friction for three sides over one side roughened duct for these varying parameters was respectively found as 1.62 to 2.79 times, 1.52 to 2.34 times and 2.21 to 2.56 times. To visualize the effect of roughness parameter on heat transfer and friction factor, variation in Nusselt number and friction factor for varying roughness parameters with Reynolds number is shown.
Źródło:
Archives of Thermodynamics; 2020, 41, 3; 57-89
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal and hydraulic phenomena in boundary layer of minijets impingement on curved surfaces
Autorzy:
Kura, T.
Fornalik-Wajs, E.
Wajs, J.
Powiązania:
https://bibliotekanauki.pl/articles/240656.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
jet impingement
minijets array
boundary layer
entropy generation
Nusselt number
uderzenie
strumień
warstwa przyścienna
generowanie entropii
liczby Nusselta
Opis:
Presented work considers flow and thermal phenomena occurring during the single minijet impingement on curved surfaces, heated with a constant heat flux, as well as the array of minijets. Numerical analyses, based on the mass, momentum and energy conservation laws, were conducted, regarding single phase and two-phase simulations. Focus was placed on the proper model construction, in which turbulence and boundary layer modeling was crucial. Calculations were done for various inlet parameters. Initial single minijet results served as the basis for the main calculations, which were conducted for two jet arrays, with flat and curved heated surfaces. Such complex geometries came from the cooling systems of electrical devices, and the geometry of cylindrical heat exchanger. The results, regarding Nusselt number, heated surface temperature, turbulence kinetic energy, production of entropy and vorticity, were presented and discussed. For assumed geometrical parameters similar results were obtained.
Źródło:
Archives of Thermodynamics; 2018, 39, 1; 147-166
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 31

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