Semnan University Press
Journal of Heat and Mass Transfer Research(JHMTR)
2345-508X
2383-3068
1
2
2014
10
01
Investigation of shell and tube heat exchangers by using a design of experiment
59
66
EN
S.
Balamurugan
Department of Mechanical Engineering, Coimbatore Institute of Technology, Coimbatore – 641 014, Tamilnadu, INDIA.
D.P.
Samsoloman
Department of Mechanical Engineering, Coimbatore Institute of Technology, Coimbatore – 641 014, Tamilnadu, INDIA.
10.22075/jhmtr.2014.180
Heat exchangers are one of the most important devices of mechanical systems in modernsociety. Most industrial processes involve the transfer of heat and more often they requirethe heat transfer process to be controlled. A heat exchanger is the heat exchanged betweentwo media, one being cold and the other being hot. There are different types of heatexchanger, but the type which is widely used in industrial application is the shell and tube.In this study, experiments conducted based on fully replicable five-factor, five-level centralcomposite design. Regression modelsare developed to analyse the effects of shell and tubeheat exchange process parameter such as inlet temperature of hot fluid and flow rates ofcold and hot fluid. The output parameters of a heat exchanger are used for analysing thedirect and interactive effects of heat exchange process parameters.
Shell and Tube Heat,Exchanger,DOE,Experiment
http://jhmtr.journals.semnan.ac.ir/article_180.html
http://jhmtr.journals.semnan.ac.ir/article_180_932bd6d823e4bfe335387f3e66ee5018.pdf
Semnan University Press
Journal of Heat and Mass Transfer Research(JHMTR)
2345-508X
2383-3068
1
2
2014
10
01
Magnetohydrodynamic mixed convection effects on the removal process of fluid particles from an open cavity in a horizontal channel
67
74
EN
Rouhollah Yadollahi
Farsani
Associate Lecturer, Ardal Center, Shahrekord branch, Islamic Azad University, Shahrekord, Iran
Behzad
Ghasemi
Chemical Engineering Professor, Engineering Faculty, Shahrekord University, Shahrekord, Iran
behzadgh@yahoo.com
Saiied Mostafa
Aminossadati
Senior Lecturer, School of Mechanical and Mining Engineering, the University of Queensland, QLD 4072, Australia
uqsamino@uq.edu.au
10.22075/jhmtr.2014.181
This paper presents the results of a numerical study on the heat transfer performance and the removal process of fluid particles under the influence of magnetohydrodynamic mixed convection in a horizontal channel with an open cavity. The bottom wall of the cavity is heated at a constant temperature (Th) while the top wall of the channel is maintained at a relatively low temperature (Tc). Air with a uniform velocity (u0) and temperature (Tc) is introduced to the channel. The analysis is carried out for a range of values of the Grashof number (103≤Gr≤106), the Reynolds number (1≤Re≤100), and the Hartmann number (0≤Ha≤100).The results show that the heat transfer rate increases as the Grashof number increases and decreases as the Reynolds and Hartmann numbers increase. It is also shown that the removal process accelerates as the Grashof number increases and, however, decelerates as the Reynolds and Hartmann numbers increase.
Magnetohydrodynamic,Mixed convection,Channel,Fluid particles,Removal process
http://jhmtr.journals.semnan.ac.ir/article_181.html
http://jhmtr.journals.semnan.ac.ir/article_181_fe179474ce0c256e7e619b28fa46e037.pdf
Semnan University Press
Journal of Heat and Mass Transfer Research(JHMTR)
2345-508X
2383-3068
1
2
2014
10
01
The effect of Geometrical parameters on heat transfer coefficient in helical double tube exchangers
75
82
EN
Seyed Faramarz
Ranjbar
Mechanical Engineering Faculty, University of Tabriz, Tabriz, Iran
Mir Hatef
Seyyedvalilu
Mechanical Engineering Faculty, University of Tabriz, Tabriz, Iran
s.hatef90@ms.tabrizu.ac.ir
10.22075/jhmtr.2014.182
Helical coil heat exchangers are widely used in industrial applications ranging fromcryogenic processes, air-conditioning, and nuclear reactors to waste heat recovery due totheir compact size and high heat transfer coefficient. In this kind of heat exchangers, flowand heat transfer are complicated. This paper reports a numerical investigation of theinfluence of different parameters such as coil radius, coil pitch and diameter of tubeon the characteristics of heat transfer in helical double tube heat exchangers usingthe well-known Fluent CFD software. Modeling of the study was implemented based onprinciples of heat transfer, fluid mechanics, and thermodynamics. By imposing boundaryconditions and selecting of an appropriate grid, whereby the results are independent ofmeshing, the obtained results were compared and validated with existing experimentalresults in the open literature. The results indicate that heat transfer augments by increasingof the inner Dean number, inner tube diameter, curvature ratio, and by the reduction of thepitch of the heat exchanger coil.
Helical double tube,Heat exchanger,Curvature ratio,Dean number,Overall heat transfer coefficient
http://jhmtr.journals.semnan.ac.ir/article_182.html
http://jhmtr.journals.semnan.ac.ir/article_182_7553a3f224c4efe7d924b793aadafbac.pdf
Semnan University Press
Journal of Heat and Mass Transfer Research(JHMTR)
2345-508X
2383-3068
1
2
2014
10
01
Numerical modelling of double-diffusive natural convection within an arc shaped enclosure filled with a porous medium
83
91
EN
Ariyan
Zare Ghadi
Faculty of Mechanical Engineering, Semnan University, Semnan, Iran
azghadi@semnan.ac.ir
Ali
Haghighi Asl
Faculty of Chemical Engineering, Semnan University, Semnan, Iran
ahaghighi@semnan.ac.ir
Mohammad Sadegh
Valipour
Faculty of Mechanical Engineering, Semnan University, Semnan, Iran
msvalipour@semnan.ac.ir
10.22075/jhmtr.2014.183
Numerical study of double-diffusive natural convective heat transfer in a curved cavity filledwith a porous medium has been carried out in the current study. Polar system has beenselected as coordinate system. As a result, all equations have been discredited in r and θdirections. Brinkmann extended Darcy model has been utilized to express fluid flow inporous matrix in the enclosure. Smaller and larger curved walls are supposed to be hot andcold sources, respectively. Other two walls are insulated. The numerical solution has beenobtained based on the finite volume methodology via staggered grid system, which will beexplained in detail in its respective section. Finally, at the result section the effects of allpertinent parameters i.e. Grashof number, Lewis number, Darcy number, and Buoyancy ratioon the fluid motion and medium thermal behavior have been illustratively discussed. Resultsreveal that an increasing in Lewis number has a negative effect on heat transfer, while it hasa positive impact on mass transfer. It is also seen that the flow intensity is increased bydecreasing Lewis number. In addition, it is observed that for the aiding flow case, averageNu and Sh numbers decrease with increasing buoyancy ratio, while for opposing flow casesNu and Sh augment with decreasing buoyancy ratio.
FVM method,Double-diffusive convection,Arc-shaped cavity,Porous media
http://jhmtr.journals.semnan.ac.ir/article_183.html
http://jhmtr.journals.semnan.ac.ir/article_183_cb5d247f1c29c0c2ac9ae02e10b034fe.pdf
Semnan University Press
Journal of Heat and Mass Transfer Research(JHMTR)
2345-508X
2383-3068
1
2
2014
10
01
Numerical simulation of turbulent compressible flows in a C-D nozzle with different divergence angles
93
100
EN
Mohammad Hadi
Hamedi Estakhrsar
Malek-Ashtar University of Technology, Tehran, Iran.
hadihamedi20@gmail.com
Mehdi
Jahromi
Malek-Ashtar University of Technology, Tehran, Iran
jahromi@iust.ac.ir
10.22075/jhmtr.2014.184
Compressible gas flow inside a convergent-divergent nozzle and its exhaust plume atdifferent nozzle pressure ratios (NPR) have been numerically studied with severalturbulence models. The numerical results reveal that, the SST k–ω model give the bestresults compared with other models in time and accuracy. The effect of changes in value ofdivergence half-angle (ε ) on the nozzle performance, thrust coefficient ( Cf ) anddischarge coefficient ( C d) has been investigated numerically. The predicted results showthat for a given divergence angle, the thrust coefficient (Cf ) increases by increasing nozzlepressure ratio. Also, for a given nozzle pressure ratio, the thrust coefficient increases as thenozzle divergence angle decreases. When the CD nozzle is chocking, the value of dischargecoefficient is independent of nozzle pressure ratio and also for a given nozzle pressure ratio,the discharge coefficient increases as the divergence nozzle angle (ε) increases.
Numerical Simulation,converging-diverging nozzle,Divergence angle,Thrust coefficient,Discharge coefficient,Static temperature
http://jhmtr.journals.semnan.ac.ir/article_184.html
http://jhmtr.journals.semnan.ac.ir/article_184_307e64ccb3b05405719a0be38a3d6895.pdf
Semnan University Press
Journal of Heat and Mass Transfer Research(JHMTR)
2345-508X
2383-3068
1
2
2014
10
01
Removal of copper ions from aqueous solutions using polypyrrole and its nanocomposites
101
106
EN
Somayeh
Nobahar
School of Chemical, Petroleum, and Gas Engineering, Semnan University,Semnan, Iran.
somayenobahar@yahoo.com
Mehdi
Parvini
School of Chemical, Petroleum, and Gas Engineering, Semnan University,Semnan, Iran.
m.parvini@sun.semnan.ac.ir
Hossein
Eisazadeh
Chemical Engineering Department, Shomal University, Amol, Iran.
eisazadeh@hotmail.com
10.22075/jhmtr.2014.185
In this article, preparation of polypyrrole and its nanocomposites as adsorbents werediscussed and the capability of separation of copper ions from aqueous solution were studied.Polypyrrole was prepared by chemical oxidative polymerization method of pyrrole usingFeCl3 as an oxidant. The removal of Cu (II) was investigated using PPy, PPy/TiO2 andPPy/TiO2/DHSNa nanocomposites. The products were investigated in terms of morphologyand chemical structure with scanning electron microscopy (SEM) and Fourier-transforminfrared spectroscopy (FTIR). Batch studies were performed to evaluate the influence ofvarious experimental parameters such as pH, ion dosage and contact time. Optimumconditions for copper ions removal were found to be pH 3, ion dosage of 50 mg L-1 and theequilibrium time equals to 30 minutes. It was also found that the equilibrium adsorptionisotherm was better described by Freundlich adsorption isotherm model.
Polypyrrole,Nanocomposite,Morphology,Cu (II) removal
http://jhmtr.journals.semnan.ac.ir/article_185.html
http://jhmtr.journals.semnan.ac.ir/article_185_9f7910b1ea67ce0485294199c01b198d.pdf
Semnan University Press
Journal of Heat and Mass Transfer Research(JHMTR)
2345-508X
2383-3068
1
2
2014
10
01
Investigation of the thermo-hydraulic behavior of the fluid flow over a square ribbed channel
101
106
EN
Ali
Sarreshtedari
School of Mechanical
Engineering, University of Shahrood, Shahrood, Semnan, Iran.
sarreshtehdari@gmail.com
Alireza
Zamani Aghaee
School of Mechanical
Engineering, University of Shahrood, Shahrood, Semnan, Iran.
10.22075/jhmtr.2014.186
The thermo-hydraulic behavior of the air flow over a two dimensional ribbed channel wasnumerically investigated in various rib-width ratio configurations (B/H=0.5-1.75) atdifferent Reynolds numbers, ranging from 6000 to 18000. The capability of differentturbulence models, including standard k-ε, RNG k-ε, standard k-ω, and SST k-ω, inpredicting the heat transfer rate was compared with the experimental results and it wasshowed that the k-ε turbulent models best adapt with the measured data. Four mainparameters, namely, the Nusselt number, friction factor, skin friction factor, and the thermalenhancement factor were examined through the simulations. Results indicate that anincrease in the Reynolds number caused the Nusselt number to increase and the frictionfactor to drop. It was found that the thermal enhancement factor augmented by an increasein the Reynolds number, and also, for a wider rib, i.e. at the higher the B/H ratio, a lowerthermal enhancement factor was obtained.
Turbulent flow,Ribbed channel,Heat transfer,pressure drop,Thermal-enhancement
http://jhmtr.journals.semnan.ac.ir/article_186.html
http://jhmtr.journals.semnan.ac.ir/article_186_124c349b2b6c919f3219fe4ddf2e4049.pdf