Natural Convection and Entropy Generation in Γ-Shaped Enclosure Using Lattice Boltzmann Method
E.
Fattahi
Faculty of Mechanical Engineering, Babol University of Technology Babol, Iran
author
M.
Farhadi
Faculty of Mechanical Engineering, Babol University of Technology Babol, Iran
author
K.
Sedighi
Faculty of Mechanical Engineering, Babol University of Technology Babol, Iran
author
text
article
2013
eng
This work presents a numerical analysis of entropy generation in Γ-Shaped enclosure that was submitted to the natural convection process using a simple thermal lattice Boltzmann method (TLBM) with the Boussinesq approximation. A 2D thermal lattice Boltzmann method with 9 velocities, D2Q9, is used to solve the thermal flow problem. The simulations are performed at a constant Prandtl number (Pr = 0.71) and Rayleigh numbers ranging from 103 to 106 at the macroscopic scale (Kn = 10-4). In every case, an appropriate value of the characteristic velocity is chosen using a simple model based on the kinetic theory. By considering the obtained dimensionless velocity and temperature values, the distributions of entropy generation due to heat transfer and fluid friction are determined. It is found that for an enclosure with high value of Rayleigh number (i.e., Ra=105), the total entropy generation due to fluid friction and total Nu number increases with decreasing the aspect ratio.
Transp Phenom Nano Micro Scales
University of Sistan and Baluchestan,
Iranian Society Of Mechanical Engineers
2322-3634
1
v.
1
no.
2013
1
18
http://tpnms.usb.ac.ir/article_991_ed33fb88310481a59b7edd67542621f9.pdf
dx.doi.org/10.7508/tpnms.2013.01.001
Modeling of Activated Carbon Preparation from Spanish Anthracite Based on ANFIS Structure
S.
Rashidi
Department of Chemical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
author
M.A.
Fanaei
Department of Chemical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
author
A.
Ahmadpour
author
text
article
2013
eng
Carbon nanostructures are famous structures which are used in several industries such as separation, treatment, energy storage (i.e. methane and hydrogen storage), etc. A successful modeling of activated carbon preparation is very important in saving time and money. There are some attempts to achieve the appropriate theoretical modeling of activated carbon preparation but most of them were almost unsuccessful due to the complexity between the input and output variables. In this paper the empirical modeling of activated carbon preparation from Spanish anthracite based on adaptive neuro-fuzzy inference system (ANFIS) is investigated. ANFIS model is established to delineate the relationship between the BET surface area of the prepared activated carbon with initial and operational conditions; agent type, agent ratio, activation temperature, activation time and nitrogen flow. The results show that the selected model have a good accuracy with a coefficient of determination values (R2) of 0.9885 and average relative error (ARE) of 0.00268.
Transp Phenom Nano Micro Scales
University of Sistan and Baluchestan,
Iranian Society Of Mechanical Engineers
2322-3634
1
v.
1
no.
2013
19
25
http://tpnms.usb.ac.ir/article_992_1e5844e35c4560564226b256369531cd.pdf
dx.doi.org/10.7508/tpnms.2013.01.002
Numerical Study of Mixed Convection of Nanofluid in a Concentric Annulus with Rotating Inner Cylinder
G. A.
Sheikhzadeh
Department of Mechanical Engineering, University of Kashan, Kashan, Iran
author
H.
Teimouri
Department of Mechanical Engineering, University of Kashan, Kashan, Iran
author
M.
Mahmoodi
Department of Mechanical Engineering, University of Kashan, Kashan, Iran
Department of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran
author
text
article
2013
eng
In this work, the steady and laminar mixed convection of nanofluid in horizontal concentric annulus withrotating inner cylinder is investigated numerically. The inner and outer cylinders are kept at constanttemperature Ti and To respectively, where Ti>To. The annular space is filled with Alumina-water nanofluid.The governing equations with the corresponded boundary conditions in the polar coordinate are discretizedusing the ﬁnite volume method where pressure-velocity coupling is done by the SIMPLER algorithm.Numerical results have been obtained for Rayleigh number ranging from 102 to 105, Reynolds number from 1 to 300 and nanoparticles volume fraction from 0.01 to 0.06. The effects of the Reynolds and Rayleigh numbers, average diameter of nanoparticles and the volume fraction of the nanoparticles on the fluid flow and heat transfer inside the annuli are investigated. According to the results, the average Nusselt number decreases with increasing the Reynolds number. However, the average Nusselt number increases by increasing the Rayleigh number. Moreover, the maximum average Nusselt number occurs for an optimal nanoparticle volume fraction except situations that heat conduction predominates over the heat convection. In these conditions the average Nusselt number is close to unity.
Transp Phenom Nano Micro Scales
University of Sistan and Baluchestan,
Iranian Society Of Mechanical Engineers
2322-3634
1
v.
1
no.
2013
26
36
http://tpnms.usb.ac.ir/article_993_6b72c034dcb4abb14c68e9aaea3b1951.pdf
dx.doi.org/10.7508/tpnms.2013.01.003
Numerical Analysis of Inlet Gas-Mixture Flow Rate Effects on Carbon Nanotube Growth Rate
B.
Zahed
Mechanical Engineering Department, University of Sistan and Baluchestan, Zahedan, I.R. Iran
author
T.
Fanaei S.
Electrical and Electronic Department, University of Sistan and Baluchestan, Zahedan, I.R.Iran
author
H.
Ateshi
Chemical Engineering Department, University of Sistan and Baluchestan, Zahedan, I.R. Iran
author
text
article
2013
eng
The growth rate and uniformity of Carbon Nano Tubes (CNTs) based on Chemical Vapor Deposition (CVD) technique is investigated by using a numerical model. In this reactor, inlet gas mixture, including xylene as carbon source and mixture of argon and hydrogen as carrier gas enters into a horizontal CVD reactor at atmospheric pressure. Based on the gas phase and surface reactions, released carbon atoms are grown as CNTs on the iron catalysts at the reactor hot walls. The effect of inlet gas-mixture flow rate, on CNTs growth rate and its uniformity is discussed. In addition the velocity and temperature profile and also species concentrations throughout the reactor are presented.
Transp Phenom Nano Micro Scales
University of Sistan and Baluchestan,
Iranian Society Of Mechanical Engineers
2322-3634
1
v.
1
no.
2013
37
44
http://tpnms.usb.ac.ir/article_994_52a54eb2f90863cb821e6c9896191495.pdf
dx.doi.org/10.7508/tpnms.2013.01.004
Preparation of γ-Al2O3 and Prioritization of Affecting Factors on the Crystallite Size Using Taguchi Method
M.
Shayesteh
Deparetment of Chemical Engineering, University of Sistan and Bluchestan, Zahedan, Iran
author
M.
Shafiee Afarani
Department of Materials Engineering, University of Sistan and Bluchestan, Zahedan, Iran
author
A.
Samimi
Deparetment of Chemical Engineering, University of Sistan and Bluchestan, Zahedan, Iran
author
M.
Khorram
Deparetment of Chemical Engineering, University of Sistan and Bluchestan, Zahedan, Iran
author
text
article
2013
eng
In this work, boehmite sol was prepared by a previously applied and validated method; hydrolysis of aluminum chloride hexa-hydrate. In order to obtain precise results, the effect of pH after adding precipitating agent, aging time, peptizing temperature and ultrasonic vibration time on the crystallite size of final precipitate were investigated in a narrow range. The preparation conditions applied in the production step of nanocrystalline boehmite affected on the desired alumina phase. Experiments were set based on the statistical design of experiments (Taguchi method). Furthermore the influence of calcination on crystallization and phase transformation of the precipitate was investigated using X-ray diffractometry (XRD) and simultaneous thermal analysis (STA) techniques. To evaluate the results, the obtained data were statistically analyzed. Considering the statisti cal analysis of experiments, the pH after adding precipitating agent is the major parameter affecting crystallite size. In contrast, aging time has the smallest effect on the crystallite size. In addition, Transmission electron microscopy (TEM) of the samples revealed that the particle size of the powders was well distributed in the nano-size range. Taguchi prediction on the crystallite size was 2.096±0.139 nm (with confidence interval of 95%) which confirmed by a verification experiment (2.064 nm).
Transp Phenom Nano Micro Scales
University of Sistan and Baluchestan,
Iranian Society Of Mechanical Engineers
2322-3634
1
v.
1
no.
2013
45
52
http://tpnms.usb.ac.ir/article_995_e336e2525dd3abae3cac0ffda37cb23a.pdf
dx.doi.org/10.7508/tpnms.2013.01.005
Study on Thermal and Hydrodynamic Indexes of a Nanofluid Flow in a Micro Heat Sink
M.
Izadi
Mechanical Engineering Department, Shahrood University of Technology, Shahrood, Iran
author
M. M.
Shahmardan
Mechanical Engineering Department, Shahrood University of Technology, Shahrood, Iran
author
A. M.
Rashidi
Nanotechnology Research Center, Research Institute of Petroleum Industry (R.I.P.I)
author
text
article
2013
eng
The paper numerically presents laminar forced convection of a nanofluid flowing in a duct at microscale. Results were compared with both analytical and experimental data and observed good concordance with previous studies available in the literature. Influences of Brinkman and Reynolds number on thermal and hydrodynamic indexes have been investigated. For a given nanofluid, no change in efficiency (heat dissipation to pumping power) was observed with an increasing in Reynolds number. It was shown that the pressure was decrease with an increase in Brinkman number. Dependency of Nu increment changes with substrate material.
Transp Phenom Nano Micro Scales
University of Sistan and Baluchestan,
Iranian Society Of Mechanical Engineers
2322-3634
1
v.
1
no.
2013
53
63
http://tpnms.usb.ac.ir/article_996_bc15214e1358cf5ff5b5df0d67140891.pdf
dx.doi.org/10.7508/tpnms.2013.01.006
Investigation of the Effect of Nanoparticles Mean Diameter on Turbulent Mixed Convection of a Nanofluid in a Horizontal Curved tube Using a Two Phase Approach
O.
Ghaffari
Mechanical Engineering Department, University of Sistan and Baluchestan, Zahedan, I.R. Iran
author
A.
Behzadmehr
Mechanical Engineering Department, University of Sistan and Baluchestan, Zahedan, I.R. Iran
author
text
article
2013
eng
Turbulent mixed convection of a nanofluid (water/Al2O3, Φ=.02) has been studied numerically. Two-phase mixture model has been used to investigate the effects of nanoparticles mean diameter on the flow parameters. Nanoparticles distribution at the tube cross section shows that the particles are uniformly dispersed. The non-uniformity of the particles distribution occurs in the case of large nanoparticles and/or high value of the Grashof numbers. The study of particle size effect showed that the effective Nusselt number and turbulent intensity increases with the decreased of particle size.
Transp Phenom Nano Micro Scales
University of Sistan and Baluchestan,
Iranian Society Of Mechanical Engineers
2322-3634
1
v.
1
no.
2013
64
74
http://tpnms.usb.ac.ir/article_997_d472c32290701d713a0453f8ff4f880f.pdf
dx.doi.org/10.7508/tpnms.2013.01.007