Numerical simulation of thermoacoustic refrigerator and study of resonator length and working fluid on its operation
Reza
Alishirazi
Msc. Student, Department of Mechanical Engineering, Islamic Azad University, Central Tehran Branch,
author
Armen
Adamian
Assistant professor, Department of Mechanical Engineering, Islamic Azad University, Central Tehran Branch,
author
Hossein
Mahbadi
Associate professor, Islamic Azad University, Central Tehran Branch
author
text
article
2016
per
In this study, the effect of resonator length and working fluid on operation of heat-driven thermoacoustic refrigerator is investigated. The working fluid is considered to be Helium, Nitrogen and Argon. The simulation is carried out via a numerical method and the results are compared with DELTA-EC software. The results of these two methods are in good agreement with each other. The simulations show that increase in the resonator length results to increase in pressure amplitude for all mentioned working fluids and the frequency reduces by applying the Helium, Nitrogen and Argon respectively. Increasing the resonator length from 0.5m through 1.4m leads to reduction of the coefficient of performance for Nitrogen and Argon while this coefficient increases for Helium. The best coefficient of performance is gained for Helium gas and resonator length equal to 1.4m.
نشریه پژوهشی مهندسی مکانیک ایران
ISME
2538-4775
18
v.
2
no.
2016
6
21
http://jmep.isme.ir/article_22947_5325b576f18a3cd8ae106817e4ab05ac.pdf
Investigation of tensile properties of tensile properties of polypropylene/ graphene/ nano clay nanocomposits applying the response surface methodology
Gholamhossein
Payeganeh
Associate professor, Department of Mechanical Engineering, Shahid Rajaee Teacher Training University
author
Ismail
Ghasemi
Plastic Dept., Iran Polymer & petrochemical Institute
author
Azam
Kazemnejad
Department of Mechanical Engineering, Shahid Rajaee Teacher Training University
author
text
article
2016
per
In this study, using design of experiments, the effect of the total weight percentage of graphene nanosheets and nano clay and their weight ratio and weight percentage of compatibilizer (PPg-MA) on the tensile properties of polypropylene/ graphene/ nano clay/ PP-g-MA nanocomposites were investigated. Design of experiments and analysis of experimental data with Minitab 16 software and response surface methodology were carried out. Making nanocomposites, based on the melt mixing was performed. All combinations and pure states materials were mixed together in a co-rotating twin-screw extruder and then injection molded into standard tensile test samples. The tensile properties of all samples including tensile strength, Young's modulus and elongation at break was studied experimentally. Statistical models provided by response surface methodology had good agreement with experimental findings. Statistical analysis showed that with increasing the percentage of nanoparticles, tensile strength and elongation at break of nanocomposites reduced. Also increasing the percentage of nanoparticles increase the stiffness of nanocomposites without compatibilizer, however, with the increasing amount of compatibilizer, reduced modulus. Compounds morphology by Scanning Electron Microscopy (SEM) was performed. Micrographes showed better dispersion of the particles in lower percentages.
نشریه پژوهشی مهندسی مکانیک ایران
ISME
2538-4775
18
v.
2
no.
2016
22
41
http://jmep.isme.ir/article_22948_3eafa587e786715bc3827f547a02eb3a.pdf
Droplet formation in microchannel under influence of electric field using the Boltzmann lattice method
صنم
وزیری
دانشگاه آزاد تهران مرکز
author
Mohammad
Eftekhari Yazdi
Assistant professor, Islamic Azad University, Central Tehran Branch
author
Armen
Adamian
Assistant professor, Department of Mechanical Engineering, Islamic Azad University, Central Tehran Branch
author
text
article
2016
per
The phenomena of formation and detachment of droplets are one of fundamental issues instudying two-phase flows and have been seen in lots of natural phenomenon and processes,such as spraying processes, ink jet printing, emulsion, etc. Between different numericalmethods, the lattice Boltzmann method (LBM) has been developed in to an alternative andpromising numerical scheme for simulating multi-component fluid flows. In this project,formation and detachment of droplets were simulated, using LBM and particularly indexfunction model. Results were validated using two-phase flows methods. After code validation,the formation and detachment of droplets in a cross-junction micro channel and under theelectric field effects were studied. To survey different effects on this phenomenon,dimensionless numbers were studied.Finally, the effect of variation of permittivity, conductivity and capillary number for dropletswere studied under different situations. Results show that the electric force have a positiveeffect in expedition of droplet formation, and also index function model proved its very usefulabilities. We have smaller drops with high frequency which shows that we can control thedroplet formation.
نشریه پژوهشی مهندسی مکانیک ایران
ISME
2538-4775
18
v.
2
no.
2016
42
63
http://jmep.isme.ir/article_22944_083a92a62c5064aee1b22fc0e1e447de.pdf
Develop an equation to calculate the amount of gas leakage from buried distribution gas pipelines
Amir
Ebrahimi Moghadam
دانشجوی کارشناسی ارشد-دانشگاه صنعتی شاهرود
author
mahmood
farzaneh-gord
استاد-گروه مهندسی مکانیک-دانشگاه شاهرود
author
مهدی
دیمی دشت بیاض
استادیار-گروه مهندسی مکانیک-دانشگاه حکیم سبزواری
author
text
article
2016
per
This paper, paid to calculate and develop an equation to determine the amount of the natural gas leakage, from a small hole located on the surface of the buried gas pipe lines. The studied case designed and meshed by Gambit software and then numerical solution is done by using Fluent software. The pipe is located in the town border distribution pipelines, flow is turbulent and soil considered as a porous zone. The results indicate that at the small hole diameters, discharge speed reaches the sound speed and at the so-called, choking occurs in the flow. Also after permeation of natural gas into the soil, and hitting the soil particles and the air moving through soil, a pair of vortex is created inside the soil. Volumetric flow rate of leaked gas has a second order and linear relation with hole diameter and pressure of initial point. Finally, its paid to develop an equation to calculate the amount of leaked gas.
نشریه پژوهشی مهندسی مکانیک ایران
ISME
2538-4775
18
v.
2
no.
2016
64
86
http://jmep.isme.ir/article_22945_47910613d807742fd5ff34e655c9f41d.pdf
Improving the performance of lattice Boltzmann method in order to numerical study of gas flows in nano scale porous media
Amir Homayoon
Meghdadi Esfahani
Department of Mechanical Engineering, Islamic Azad University of Najafabad
author
text
article
2016
per
The standard Lattice Boltzmann Method, LBM, is usually able to predict the results of micro scale flows which are corresponding to the slip flow regime, while it has not sufficient accuracy for nano scale flows which are corresponding to the transition flow regime. In this paper, by improving the lattice Boltzmann method, pressure driven flow through non-porous nano channels and nano channels filled with porous media has been modeled for wide range of Knudsen numbers, Kn, covering the slip and transition regimes. The results show that the presented lattice Boltzmann model is able to predict the flow features in micro and nano scales for wide range of Knudsen numbers by modifying the relaxation time. In the presented research, the effects of the Knudsen number and porosity on the flow rate, Darcy number and pressure drop are reported. Also, for the first time, the Knudsen’s minimum effect for micro/nano channels filled with porous media is observed and evaluated. For the pressure driven flows in non-porous channels this effect occurs at Kn=1, while the results show that for the nano channels filled with porous media this effect occurs at Kn=0.1 because of the tortuosity effects.
نشریه پژوهشی مهندسی مکانیک ایران
ISME
2538-4775
18
v.
2
no.
2016
87
105
http://jmep.isme.ir/article_22946_aafd91b8df230a89844278bb436f1582.pdf