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RISS 인기검색어
- 검색키워드
- 저자 : Amir Heydarinasab (검색결과 5 건)
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Magnetic field effect on laminar heat transfer in a pipe for thermal entry region
Asadolah Malekzadeh,Amir Heydarinasab,Mohammad Jahangiri 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.4
The influence of a transverse magnetic field on the local heat transfer of an electrically-conducting laminar fluid flow with high Prandtl number through a pipe was studied experimentally. Experiments indicated an increase in the local Nusselt number. The coupled set of the equations of motion and the energy equation including the viscous and Joule dissipation terms becomes non-linear and is solved numerically using a finite difference scheme. Favorable comparisons with experimental results confirm the correctness of the numerical results. It is found that the influence of magnetic field can be diminished by reducing the angle between the flow direction and the direction of magnetic field. The wall temperature reduces as the value of Hartmann number increases and the reduction rate of the wall temperature decreases as the value of Hartmann number exceeds a certain value. The average Nusselt number asymptotically approaches its limit as the Hartmann number becomes larger. Also, curve fitting can be employed to derive an equation for the average Nusselt number as a function of the Hartmann number. This equation is similar to the Sieder-Tate equation. It is observed that increasing the Hartmann number has no considerable effect on the thermal boundary layer thickness but decreases the temperature of fluid layers inside the boundary layer.
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Magnetic field effect on fluid flow characteristics in a pipe for laminar flow
Asadolah Malekzadeh,Amir Heydarinasab,Bahram Dabir 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.2
The influence of a magnetic field on the skin friction factor of steady fully-developed laminar flow through a pipe was studied experimentally. A mathematical model was introduced and a finite difference scheme used to solve the governing equations in terms of vorticity-stream function. The model predictions agree favourably with experimental results. It is observed that the pressure drop varies in proportion to the square of the product of the magnetic field and the sine of the magnetic field angle. Also, the pressure drop is proportional to the flow rate. This situation is similar to what applies in the absence of a magnetic field. It is found that a transverse magnetic field changes the axial velocity profile from the parabolic to a relatively flat shape. At first, the radial velocity rises more rapidly and then gradually decreases along the pipe until falling to zero. A numerical correlation can be written for the considerable distance required for the new axial velocity profile to establish. Owing to the changes taking place in the axial velocity profile, it exhibits a higher skin friction factor. The new axial velocity profile asymptotically approaches its limit as the Hartmann number becomes large.
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Kamran Valizadeh,Amir Heydarinasab,Seyed Saeid Hosseini,Saeed Bazgir 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.106 No.-
In this research, to prepare a polymer membrane with hydrophilic nature that has anti-fouling and antiadhesionproperties first, polyvinyl imidazole (PVI) Polymer was bonded as a surface modifier of fluorinatedpolyvinylidene (PVDF) membranes by Atom transfer radical polymerization (ATRP) method. Therefore, to confirm the chemical changes of the hydrophilic membrane surface such as PVI polymerchain bonding and to investigate the uniform distribution of the polymer in the modified membranepores and surface, experiments such as attenuated general reflectance (ATR-FTIR), nuclear magnetic resonance(H-NMR), Water contact angle (WCA) and scanning electron microscopy (SEM), zeta potential,Atomic force microscopy (AFM) spectroscopy, Thermo-gravimetric analysis (TGA), X-ray energy scattering(EDX), X-ray diffraction (XRD) patterns were performed. The results showed that the WCA for M1membrane was about 83.37 ± 1.77 and Mb6 membrane was about 35.45 ± 1.45, which improved theWCA rate ofMb6 membrane surface by about 57.10%.Therefore, the total Anti-fouling rate and Flux recoveryratio (FRR) and rejection oil rate increased by about 35.2%, 18.65% and 10%, respectively. This studyaimed to investigate the surface modification of membranes prepared with hydrophilic polymer PVI toseparate oil from the oil-in-water emulsion, which is a suitable method and potential approach in controllinglarge-volume oil-in-water emulsion effluents.
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Ali Taghvaie Nakhjiri,Amir Heydarinasab 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.78 No.-
This paper deals with developing a theoretical modeling and a two dimensional (2D) computationalsimulation to evaluate the CO2 separation percentage from CO2/CH4 gaseous mixture under non-wettingmode of operation inside the membrane pores and counter-current adjustment of liquid and gasflows. Asthe novelty, the effect of ethylenediamine (EDA), 2-(1-piperazinyl)-ethylamine (PZEA) and potassiumsarcosinate (PS) liquid absorbents on the CO2 separation performance is studied and the most efficientabsorbent is introduced. The results show that PZEA can sequester 88.75% of inlet CO2 while theseparation percentage of CO2 using PS and EDA is 82.2 and 81%, respectively. In addition, themathematical model outcomes corroborate that increase in some operational factors and hollowfibermodule specifications such as liquidflow rate,fiber packing density, module length and number offibersencourages the separation efficiency of CO2 due to enhancing the residence time, contact area andconsequently mass transfer rates inside the HFMC while increment of tortuosity factor and gasflow ratenegatively deteriorates the separation percentage of CO2 which is able to be justified due to enhancementof mass transfer resistance through the pores of microporous membrane.
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Mitra Sherafati,Ali Shokuhi Rad,Mehdi Ardjmand,Amir Heydarinasab,Majid Peyravi,Mahmoud Mirzaei 한국물리학회 2018 Current Applied Physics Vol.18 No.9
Zigzag (5, 0) BeO nanotube (BeONT) has been examined in detail towards adsorption properties of adenine nucleobase on its surface via D2-DFT calculation method in the gas and water phases. A detailed surface study reveals that there are four orientations for nucleobase adsorption that none of the vibrational spectrums demonstrated imaginary frequency, recognizing that all of the relaxed structures are at the minimum of energy. The minimum and maximum adsorption energies are both in chemisorption regime with calculated values of −140 (−118 BSSE corrected) and −191 (−168 BSSE corrected) in the gas phase, and −181 and −310 kJ/mol in the water phase, using meta-hybrid functional (□B97XD) and 6-31G** basis set. For all positions, BeONT showed p-type semiconducting property because of receiving electronic charge from adenine molecule. Our findings suggest that BeONT could be used as a possible strong carrier for adenine molecule in practical applications.
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