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Tytuł:
Optimization of geometric and flow parameters of solar air heater roughened with artificial roughness by Taguchi method
Autorzy:
Sahu, Mukesh Kumar
Mishra, Shivam
Kumar, Avinash
Powiązania:
https://bibliotekanauki.pl/articles/27312207.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
roughness
nusselt number
friction factor
Taguchi method
optimization
Opis:
The paper presents the investigation of the optimum design parameters of a solar air heater (SAH) having wire ribs as artificial roughness by using the Taguchi method. The solar air heater has arc shape roughness geometry with apex upstream flow on the absorber plate. The objective of this paper is to obtain a set of parameters that deliver maximum thermo-hydraulic performance. For this objective, a new parameter the thermo-hydraulic improvement parameter (ηTHIP), has been introduced. For the present analysis, the effects of Reynolds number (Re), relative roughness pitch (P/e), angle of attack (α), and relative roughness height (e/Dh), denoted by A, B, C, and D, respectively, have been considered. An (L18 = 61 · 3 2 ) orthogonal array (OA) was chosen as an experimental plan for applying the Taguchi method. The set of control factors for the solar air heater SAH which delivers the maximum Nusselt number (Nu), and minimum friction factor (fr) – are A6B2C2, and A1B1C3 respectively. To obtain the maximum THIP the experimental set-up requires only one single run using the parameter A6B2C2, hence there is no need to run it all 54 times.
Źródło:
Archives of Thermodynamics; 2023, 44, 3; 3--33
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation of local heat transfer distribution on surfaces with a non-uniform temperature under an array of impinging jets with various nozzle shapes
Autorzy:
Marzec, K.
Kucaba-Piętal, A.
Powiązania:
https://bibliotekanauki.pl/articles/279593.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
impinging jet
heat transfer
Nusselt number
nozzle shape
Opis:
Numerical calculations of heat transfer characteristics of an impingement cooling system with a non-uniform temperature on a cooled surface using ANSYS CFX have been performed. The influence of a surface heat flux qw(x) and a nozzle shape on the Nusselt number distribution on the cooled surface has been studied. The setup consisted of a cylindrical plenum with an inline array of ten impingement jets. Cylindrical, convergent divergent shapes of nozzles and linear temperature distribution on the cooled surface have been considered for various heat fluxes qw (x). Results indicate that geometry of the cylindrical nozzles resulted in the highest Nusselt numbers along the cooled surface. The line of the averaged Nusselt number has a trend to increase in the direction of the flow for the cooling system with increasing values of the surface heat flux q(x). This tendency can be observed for all presented shapes of jets. On the other hand, for decreasing functions of the heat flux qw (x), the Nusselt number distribution is more uniform. It can be observed for all types of nozzles. Very similar values of the Nusselt number occur especially for the non-uniform heat flux 5000-2500W/m². For constant values of the heat flux q(x) = 5000W/m², the line of the average Nusselt number has a trend to increase slightly in the direction of the flow. Numerical analysis of different mesh density results in good convergence of the GCI index, what excludes mesh size dependency. The presented study is an extension of the paper (Marzec and Kucaba-Piętal, 2016) and aims at answering the question how the Nusselt number distribution on the cooled surface is affected by various geometries of nozzles for a non-uniform surface heat flux qw (x).
Źródło:
Journal of Theoretical and Applied Mechanics; 2017, 55, 4; 1313-1324
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
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:
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:
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:
The heat transfer and flow structure analyses of low concentration copper nanofluids in a strong magnetic field
Autorzy:
Roszko, A.
Fornalik-Wajs, E.
Powiązania:
https://bibliotekanauki.pl/articles/175547.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nanofluids
heat transfer
flow structure
fast Fourier transform
Nusselt number ratio
thermomagnetic Rayleigh number
Opis:
Main aim of this paper was to analyze the influence of strong magnetic field on the enhancement or suppression of nanofluids transport processes. The second objective was to determine how the flow structure changed under the influence of a magnetic field. Analyzed diamagnetic nanofluids composed of distilled water and the copper nanoparticles of 40–60 nm size in three different concentrations (50, 500, and 1000 ppm). The experimental enclosure position in the magnet test section caused the most intricate interaction of the acting forces: the gravitational and magnetic buoyancy ones, and made the interpretation of results very difficult. The Nusselt number ratio and the thermomagnetic Rayleigh number were determined for heat transfer analysis, while the fast Fourier transform was performed for the nanofluid flow structure analysis. Spectral analysis for all examined nanofluids was presented. Influence of nanoparticles concentration was clearly visible, while the direct impact of magnetic field on the heat transfer and flow structure should be still investigated.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2015, 128; 29-42
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Behaviour of a non-newtonian fluid in a helical tube under the influence of thermal buoyancy
Autorzy:
Ramla, Mohamed
Laidoudi, Houssem
Bouzit, Mohamed
Powiązania:
https://bibliotekanauki.pl/articles/2105993.pdf
Data publikacji:
2022
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
helical heat exchanger
mixed convection
forced convection
power-law fluids
Nusselt number
Opis:
This work is an evaluative study of heat transfer in the helical-type heat exchanger. The fluid used is non-Newtonian in nature and is defined by Oswald’s model. The work was performed numerically by solving each of the Navier–Stokes equations and the energy equation using the package ANSYS-CFX. Following are the aspects that have been dealt with in this paper: the effects of thermal buoyan-cy, fluid nature and the tube shape on the heat transfer, and the fluid comportment. The interpretation of the obtained results was done by analyzing the isotherms and the streamlines. The mean values of the Nusselt number were also obtained in terms of the studied parame-ters. The results of this research enabled us to arrive at the following conclusion: the intensity of thermal buoyancy and the nature of the fluid affect the heat transfer distribution but keep the overall rate of heat transfer the same.
Źródło:
Acta Mechanica et Automatica; 2022, 16, 2; 111--118
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The complex Ginzburg Landau model for an oscillatory convection in a rotating fluid layer
Autorzy:
Manjula, S. H.
Kiran, P.
Reddy, P. Raj
Bhadauria, B. S.
Powiązania:
https://bibliotekanauki.pl/articles/266148.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
konwekcja
teoria nieliniowa
liczba Nusselta
convection
finite amplitude
nonlinear theory
rotation modulation
Nusselt number
Opis:
A weakly nonlinear thermal instability is investigated under rotation speed modulation. Using the perturbation analysis, a nonlinear physical model is simplified to determine the convective amplitude for oscillatory mode. A non-autonomous complex Ginzburg-Landau equation for the finite amplitude of convection is derived based on a small perturbed parameter. The effect of rotation is found either to stabilize or destabilize the system. The Nusselt number is obtained numerically to present the results of heat transfer. It is found that modulation has a significant effect on heat transport for lower values of ωf while no effect for higher values. It is also found that modulation can be used alternately to control the heat transfer in the system. Further, oscillatory mode enhances heat transfer rather than stationary mode.
Źródło:
International Journal of Applied Mechanics and Engineering; 2020, 25, 1; 75-91
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of reduced heat transfer in a micropolar fluid in natural convection
Autorzy:
Rup, K.
Dróżdż, A.
Powiązania:
https://bibliotekanauki.pl/articles/240722.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
micropolar fluid
microrotation
boundary layer theory
Local Nusselt number
teoria warstwy przyściennej
Liczba Nusselta
Opis:
This paper presents the numerical solution to the unsteady natural convection problem in micropolar fluid in the vicinity of a vertical plate, heat flux of which rises suddenly at a given moment. In order to solve this problem the method of finite differences was applied. The numerical results have been presented for a range of values of the dimensionless material properties and fluid Prandtl number. The analysis of the results shows that the intensity of the heat transfer in micropolar fluid is lower compared to the Newtonian fluid.
Źródło:
Archives of Thermodynamics; 2013, 34, 3; 45-59
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Soret and Dufour effects on MHD free convective flow past a vertical porous plate in the presence of heat generation
Autorzy:
Reddy, G. V. R.
Powiązania:
https://bibliotekanauki.pl/articles/264624.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
promieniowanie
wymiana ciepła
wymiana masy
tarcie
radiation
heat and mass transfer
skin-friction
Nusselt number
Sherwood number
Opis:
An MHD fluid flow is examined over a vertical plate in the presence of Dufour and Soret effects. The resulting momentum, energy and concentration equations are then made similar by introducing the usual similarity transformations. These similar equations are then solved numerically using the Runge-Kutta fourth order method with shooting technique. The effects of various parameters on the dimensionless velocity, temperature and concentration profiles as well as the local values of the skin-friction coefficient, the Nusselt number and Sherwood number are displayed graphically and in a tabular form. A comparison with previously published work is obtained and an excellent agreement is found.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 3; 649-665
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Model matematyczny oraz badania aerodynamiczne i przepływowo-cieplne chłodnicy samochodowej
Mathematical model and experimental study of a plate-fin-and-tube heat exchanger
Autorzy:
Taler, D.
Powiązania:
https://bibliotekanauki.pl/articles/263742.pdf
Data publikacji:
2001
Wydawca:
Sieć Badawcza Łukasiewicz. Przemysłowy Instytut Motoryzacji
Tematy:
badanie aerodynamiczne
chłodnica samochodowa
liczba Nusselta
model matematyczny
experimental study
heat exchanger
mathematical model
Nusselt number
Opis:
Przedstawiono analityczny model wymiany ciepła w chłodnicy samochodowej stanowiącej krzyżowo-prądowej lamelowy wymiennik ciepła. Wyprowadzono wzory na rozkład temperatury cieczy wewnątrz rury oraz temperatury powietrza w dwubiegowej chłodnicy o dwóch rzędach rur. Za pomocą wyprowadzonych wzorów można określić strumienie ciepła przekazywane przez poszczególne rzędy rur, a także moc chłodnicy przy zadanych temperaturach wlotowych i strumieniowych masowych czynników. W pracy omówiono wyniki badań aerodynamicznych, hydraulicznych i cieplnych chłodnicy silnika o pojemności skokowej 1580 m[^3]. Na podstawie przeprowadzonych badań wyznaczono wzory na współczynniki charakteryzujące opory przepływu powietrza i płynu chłodzącego oraz wzór na liczbę Nusselta od strony powietrza.
An analytical mathematical model of two-row plate-fin exchangers is presented. The temperature distributions on the fluid and air sides can easily be calculated using the developed model. The comparison of calculated results with experimental data for the automotive radiator shows that the mathematical model is very accurate. The results of the experimental investigation of the plate-fin-and-tube automotive radiator are presented. The tested two-pass radiator consists of two inline rows of tubes with smooth plate fins. The objective was to derive the correlations for the friction factors and the air-side heat transfer coefficient as a function of the Reynolds numbers. The air side heattransfer coefficient was determined from the condition that the calculated and measured coolant outlet temperatures aer equal.
Źródło:
Archiwum Motoryzacji; 2001, 4; 145-162
1234-754X
2084-476X
Pojawia się w:
Archiwum Motoryzacji
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 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:
Enhancement of heat transfer in helical coil heat exchangers using nano-fluids
Autorzy:
Parveez, Malik
Hanief, Mohammad
Powiązania:
https://bibliotekanauki.pl/articles/2173429.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nano-fluids
heat transfer
Nusselt number
Prandtl number
volume fraction
nanopłyny
przenoszenie ciepła
liczba Nusselta
liczba Prandtla
ułamek objętościowy
Opis:
Investigation for heat transfer behaviour of Al2O3 and CuO nano-fluid in helical coil heat exchangers was carried out in this study. The thermo-physical properties of the fluids have temperature dependent nature. The main emphasis was to depict the influence of nano-particle concentration by volume on the characteristics of temperature, rate of heat transfer and heat transfer coefficients (convective). In order to enhance efficiency, density and thermal conductivity are considered to be the most important variables. In comparison to water and for equal flow rate, the rate of heat transfer of nano-fluid increases conspicuously. Efficiency of the helical coil heat exchanger increased by 38.80%.
Źródło:
Chemical and Process Engineering; 2022, 43, 2; 279--283
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
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:
Heat transfer and friction factor correlation for inclined spherical ball roughened solar air heater
Autorzy:
Murmu, Ramesh
Kumar, Parmanand
Singh, Hari N.
Powiązania:
https://bibliotekanauki.pl/articles/240765.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
renewable energy
spherical ball
relative roughness pitch
relative roughness height
nusselt number
friction factor
angle of attack
Opis:
Flow mechanism under roughened solar air heater is quite complex. This paper is an effort towards determining the governing equations for heat transfer and friction factor for inclined spherical balls roughened ducts. With the availability of these equations, it is easier to predict the thermal and thermohydraulic performance of such roughened solar air heaters. The governing equations are derived based on the experimental data generated under actual outdoor condition at the test rig designed and fabricated at the terrace of the Mechanical Engineering Department, the National Institute of Technology Jamshedpur in India, in terms of roughness and flow parameters. Maximum augmentation in Nusselt number and friction factor for varying relative roughness pitch, relative roughness height, spherical ball height to diameter ratio, and angle of attack was respectively found to be of the order of 2.1 to 3.54 times, 1.87 to 3.21 times, 2.89 to 3.27 times and 1.74 to 3.56 times for Nusselt number and 0.84 to 1.79 times, 1.46 to 1.91 times, 1.67 to 2.34 times and 1.21 to 2.67 times for friction factor in comparison to non-roughened duct. The optimum roughness parameters under present investigation have been found.
Źródło:
Archives of Thermodynamics; 2020, 41, 2; 3-34
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
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
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:
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:
Enhancement of turbulent airflow and heat transfer through a rectangular microchannel with different types of baffles
Autorzy:
Saha, Sandip
Raut, Santanu
Das, Apurba Narayan
Powiązania:
https://bibliotekanauki.pl/articles/2141504.pdf
Data publikacji:
2021
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
turbulent air flow
heat transfer
local Nusselt number
friction coefficient
turbulentny przepływ powietrza
wymiana ciepła
liczba Nusselta
współczynnik tarcia
Opis:
The objective of this work is to discuss the turbulent air hydro-thermal phenomena over a rectangular microchannel with different types of baffle (rectangular, triangular, and trapezoidal) mounted on both the walls of the microchannel. The finite volume method with the second order upwind scheme has been utilized to discretize the governing equations and to study the turbulent airflow characteristics; the SST k-ꞷ turbulence model has been adopted. For nine different cases, the different characteristics of fluid flow phenomena and thermal behaviour with the variations in the Reynolds number ranging from [5,000-25,000] and for three different values of inter baffle spacing have been studied in this manuscript. Due to the presence of baffle, it is revealed that the vortex arises on the upper wall and the thermal phenomena enhances with the decrease in inter baffle spacing.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2021, 20, 3; 41-52
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Convective heat transfer in a micropolar fluid over an unsteady stretching surface
Autorzy:
Prasad, K. V.
Vaidya, H.
Vajravelu, K.
Powiązania:
https://bibliotekanauki.pl/articles/266164.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
przepływ niestacjonarny
wymiana ciepła
tarcie
metoda Keller-box
unsteady flow
microrotation
heat transfer
skin friction
Nusselt number
Keller-box method
Opis:
An unsteady boundary layer free convective flow and heat transfer of a viscous incompressible, microploar fluid over a vertical stretching sheet is investigated. The stretching velocity is assumed to vary linearly with the distance along the sheet. Two equal and opposite forces are impulsively applied along the x-axis so that the sheet is stretched, keeping the origin fixed in the micropolar fluid. The transformed highly non-linear boundary layer equations are solved numerically by an implicit finite difference scheme for the transient, state from the initial to the final steady-state. To validate the numerical method, comparisons are made with the available results in the literature for some special cases and the results are found to be in good agreement. The obtained numerical results are analyzed graphically for the velocity, the microrotation, and the temperature distribution; whereas the skin friction, the couple stress coefficient and the Nusselt number are tabulated for different values of the pertinent parameters. Results exhibit a drag reduction and an increase in the surface heat transfer rate in the micropolar fluid flow compared to the Newtonian fluid flow.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 2; 407-422
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Symulacja konwekcji wymuszonej w przewodach prostoosiowych przy przepływie laminarnym metodą elementów brzegowych
Boundary elements method simulation of laminar flow forced convection in duct
Autorzy:
Teleszewski, T.
Powiązania:
https://bibliotekanauki.pl/articles/371849.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
konwekcja wymuszona
przewody prostoosiowe
liczba Nusselta
metoda elementów brzegowych (MEB)
forced convection
flow in ducts
Nusselt number
boundary element method (BEM)
Opis:
W pracy przedstawiono algorytm symulacji konwekcji wymuszonej MEB przy przepływie laminarnym w przewodach prostoosiowych niezależnie od kształtu poprzecznego przewodu. Weryfikacja algorytmu została wykonana poprzez porównanie rezultatów MEB z rozwiązaniem analitycznym. W publikacji wyznaczono zależność liczby Nusselta od liczby boków w przewodach o przekroju wielokąta foremnego.
The paper presents the numerical algorithm Boundary Element Method to simulation modelling forced convection in a duct. The efficiency and the credibility of proposed algorithm were verified by numerical tests in theoretical solution. A numerical examples are presented fully developed forced convection through pentagon duct. In this study is proposed for determining the Nusselt number in regular polygonal channels.
Źródło:
Zeszyty Naukowe. Inżynieria Środowiska / Uniwersytet Zielonogórski; 2014, 153 (33); 117-127
1895-7323
Pojawia się w:
Zeszyty Naukowe. Inżynieria Środowiska / Uniwersytet Zielonogórski
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of aiding buoyancy on heat transfer from an isothermal square cylinder in power-law fluids
Autorzy:
Mishra, Pragya
Mishra, Lubhani
Tiwari, Anurag Kumar
Powiązania:
https://bibliotekanauki.pl/articles/2173431.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
square cylinder
aiding-buoyancy
Nusselt number
mixed convection
power-law fluids
konwekcja mieszana
płyny potęgowe
kwadratowy cylinder
wspomaganie pływalności
liczba Nusselta
Opis:
The aim of the present study was to explore the influence of aiding buoyancy on mixed convection heat transfer in power-law fluids from an isothermally heated unconfined square cylinder. Extensive numerical results on drag coefficient and surface averaged values of the Nusselt number are reported over a wide range of parameters i.e. Richardson number, 01 Ri 5, power-law index, 04 18, Reynolds number, 01 Re 40, and Prandtl number, 1 Pr 100. Further, streamline profiles and isotherm contours are presented herein to provide an insight view of the detailed flow kinematics
Źródło:
Chemical and Process Engineering; 2022, 43, 2; 265--270
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
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