The effect of materials on energy consumption, carbon production and thermal comfort in office building in hot and humid, hot and dry and cold, Iran
jalil
shaeri
Faculty of art and architecture, Shiraz university
author
roza
vakilinazhad
Faculty of art and architecture, Shiraz university, Shiraz, Iran
author
Mahmood
Yaghoubi
School of Mechanical Engineering, Shiraz University
author
Mohammad
Aliabadi
Faculty of Art and Architecture, Shiraz University
author
text
article
2020
per
Thermal properties of materials are one of the important factors determining cooling and heating load of the building. Buildings environmental sustainability is affected by energy consumption and harmful emissions of materials. Therefore, in addition to thermal properties, material life cycle and embodied energy and carbon should also be considered. The purpose of this study is to investigate the effect of different materials on thermal performance and energy efficiency in office buildings. For this purpose, materials with different thermal properties in 18 states are considered in a typical building for ceilings, floors, exterior and interior walls. Thermal simulations have been done using Designbuilder Software for Bushehr, Shiraz and Tabriz for a typical year. Based on the results, the best and worst modes in terms of energy consumption and produced carbon are the same in three cities but not similar to discomfort hours. This is due to the difference in amount of cooling and heating loads in various climates. The difference between the best and worst modes is 24 to 46 percent in energy consumption, 25 to 43 percent in carbon dioxide and depending on the climate 6 to 134 percent in discomfort hours.
Iranian Journal of Mechanical Engineering Transactions of ISME
ISME
2538-4775
21
v.
4
no.
2020
33
6
https://jmep.isme.ir/article_43458_30e5d6bec22238be7a93b29fa9c6aa28.pdf
Investigation of Entropy generation in Axisymmetric Stagnation Point Flow of Nano Fluid Impinging on the Cylinder With Constant Wall Temperature
حمید
محمدیون
آزاد اسلامی واحد شاهرود*مهندسی مکانیک
author
mohammad
mohammadiun
Department of mechanical engineering, shahrood branch, islamic azad university, shahrood, iran
author
mohammad hosein
dibaiee bonab
Department of mechanical engineering, shahrood branch, islamic azad university, shahrood, iran
author
mohsen
darabi
Young Researchers and Elite Club, Shahrood Branch, Islamic Azad University, Shahrood, Iran
author
seyed reza
hejazi
Department of mathematics, shahrood university of technology
author
text
article
2020
per
In this research dimensionless temperature, convection heat transfer and entropy generation for the steady state flow in the stagnation point of nanofluid impinging on an infinite cylinder have been investigated. The impinging free stream is steady with a constant strain rate . Similarity solution of the Navier-Stokes and energy equations is derived in this problem. A reduction of these equations is obtained by use of appropriate transformations introduced in this research. The general self similar solution is obtained when the wall temperature is constant. All the solutions above are presented for Reynolds numbers ranging from 0.1 to 1000 and selected values of particle fractions where a is radius of the cylinder and is kinematic viscosity of the base fluid. Results show that for all Reynolds numbers, as the particle fraction increases, the depth of diffusion of the fluid velocity field in radial and axial directions and shear-stresses decreases whereas convective heat transfer coefficient and Nusselt number increases also maximum value of entropy generation has been calculated.
Iranian Journal of Mechanical Engineering Transactions of ISME
ISME
2538-4775
21
v.
4
no.
2020
58
34
https://jmep.isme.ir/article_43459_a4eabd8aa8bcc82c89679e506e5feb90.pdf
Exergy and environmental analysis of a power and heat co-generation system fed by rice husk
Parisa
Mojaver
Department of Mechanical Engineering, Faculty of Engineering, Urmia Univeristy, Urmia, Iran
author
Shahram
Khalilarya
Department of Mechanical Engineering, Faculty of Engineering, Urmia University, Urmia, Iran
author
Ata
Chitsaz
Assistance Professor, Department of Mechanical Engineering, Urmia University, Urmia, Iran
author
text
article
2020
per
In the present study, a power and heat cogeneration system consisting of solid oxide fuel cell and biomass gas is introduced. In this system, heat pipes were used to transfer heat from the after burner to the gasifier. The results show that as the fuel cell temperature increases, the efficiency of the system increases and the irreversibility decreases. Cold gas efficiency of biomass gasification and exergy efficiency are achieved 91.74% and 45.79%, respectively, at the current density of 4000 A/m2 and outlet solid oxide fuel cell temperature of 850 °C. Hydrogen percent is 35% in the gas composition of the gas outlet.
Iranian Journal of Mechanical Engineering Transactions of ISME
ISME
2538-4775
21
v.
4
no.
2020
59
82
https://jmep.isme.ir/article_43460_7c137671eeaa7a4440b5cb80a2411933.pdf
Estimation of fouling profile in boiler tubes using inverse heat transfer method, laminar flow
Koorosh
Goudarzi
Department of Mechanical engineering,Yasouj University
author
Amin
Moosaei
Yasouj University
author
Maryam
Bahrami
Yasouj University
author
text
article
2020
per
One of the effective factors in decreasing the efficiency of boilers during the operation period is sediment. The sediment sits as a layer on the boiler's heat transfer surfaces and reduces the boiler's thermal efficiency due to the thermal resistance it creates. For this reason, it is very important to determine the amount of sediment and to accurately measure it in boiler pipes.
In this paper, it is assumed that no information is available on the distribution of sediment in boiler pipes, so the sediment profile is estimated using temperature simulation on the inner wall of boiler pipes as well as conjugate gradient method. In this method, the error rate was calculated by estimating the function of multi-criteria sediment profile , which indicates the high accuracy of the conjugate gradient method in sediment estimation. The amount of sediment exceeded a specified value.
Iranian Journal of Mechanical Engineering Transactions of ISME
ISME
2538-4775
21
v.
4
no.
2020
83
106
https://jmep.isme.ir/article_43461_4eb364b7bd2a3cac9fb4c3c7ed3f043a.pdf
Improve the performance of a rotor blade by changing the distance between the tipping point and axial displacement of the blade
iraj
mirzaee
Department of mechanical engineering, Orumieh University compound, Orumieh, Iran.
author
amir shayan
azadeh
Department of mechanical engineering, Orumieh University compound, Orumieh, Iran.
author
Nader
pormahmod
Department of mechanical engineering, Orumieh University compound, Orumieh, Iran.
author
text
article
2020
per
Improving the performance of gas turbines in today's world is an important and key issue, of course, in optimizing the performance of its core components. As an important part of the gas turbine, the compressor has always attracted particular attention. Many studies and experiments have been done to increase its efficiency. On the other hand, numerical analyzes and modeling are rapidly expanding due to the high cost of experimental tests and the rigidity of test conditions. The study of numerical methods and turbulence models continues to provide a more complete and better simulation of all aspects of fluid problems, and new aspects of this field are unveiled every day. The purpose of this study is to simulate the flow of a single stage of the NASA rotor 37, and then improve the geometry of the rotor based on the adjustment of the tip clearance and the axial displacement of the blade. First, the best turbulence model (k-ε RNG) was selected for simulation. Then, with regard to the two parameters of axial displacement and tip clearance, optimization of the rotor function was investigated. At first simulations were examined based on axial displacement for five states. In the following, four sizes for Blade No. 2 (best efficiency for axial displacement) were considered, which achieved the highest efficiency for the design level tip clearance (0.365 mm).
Iranian Journal of Mechanical Engineering Transactions of ISME
ISME
2538-4775
21
v.
4
no.
2020
107
129
https://jmep.isme.ir/article_43614_e9f2813bbb2085e713b840c2a9daa285.pdf
Effect of blade section profile on the starting time of a micro-wind turbine
Abolfazl
Pourrajabian
Department of Energy, Materials and Energy Research Center (MERC), Karaj, Iran
author
Morteza
Rahmanpour
Faculty of Mechanical Engineering, Azarbayejan Shahid Madani University, Tabriz, Iran
author
text
article
2020
per
The study investigates the effect of airfoil used in a horizontal axis wind turbine blade on its power coefficient and also the starting time. Although the effect of airfoil type used in wind turbine blades is known from the aerodynamics viewpoint and researchers have tried to use airfoils with high aerodynamic efficiency, the appropriate choose of an airfoil requires more investigation from the standpoint of starting. In this study, the output power and the starting time of a small horizontal axis wind turbine are calculated via blade element momentum theory. For that purpose, a numerical scheme is developed and validated by the experimental data. Thereafter, the four airfoils namely NACA4412, SD7062, SG6040 and SG6043 are selected and the effect of employing these profiles on the turbine performance is examined. The results reveal that the use of SG6043 airfoil not only leads to more output power but it also results in shorter starting time. The superiority of SG6043 over other airfoils are due to its higher lift to drag ratio and also its lower surface area.
Iranian Journal of Mechanical Engineering Transactions of ISME
ISME
2538-4775
21
v.
4
no.
2020
130
148
https://jmep.isme.ir/article_43462_61dbdea1fdaad27c48b92eb121340056.pdf
Numerical Investigation of Heat and Fluid Flow in an Open Square Cavity with Nanofluids Newtonian & non Newtonian
Mohsen
Mazidi
Department of Mechanical Engineering, Islamic Azad University, Bafgh Branch, Bafgh, Iran
author
Seid Amir Abbas
Oloomi
Assistant Professor, Department of Mechanical Engineering, Yazd Branch, Islamic Azad University, Yazd, Iran
author
seyed ali agha
mirjalily
Islamic Azad University of Yazd
author
text
article
2020
per
In the present study, mixed convection heat transfer of two-phase Newtonian and non-Newtonian nanofluids was examined in a ventilated cavity with internal barrier. Water - Aluminum oxide and water - copper oxide nanofluids are considered as working fluid, and the governing equations are discrete using a finite volume numerical method and solved by the Eulerian-Eulerian two-phase method. In this research, heat source has a constant thermal flux and all cavity walls are also thermally insulated; Finally, the effect of parameters such as Grashof number, volumetric fraction of nanoparticles, Reynolds number, type of nanofluid and different locations of the heat source were considered and Aluminum oxide nanoparticle with an ethylene glycol based fluid, which is converted to Bingham-type non-Newtonian fluid, has also been investigated. The results of this study show that with a Reynolds No. of 100 and Grashof No. of 105, the average Nusselt was 24.61% higher than that of pure water at the presence of copper oxide nanoparticles, and also by increasing the volume fraction of nanoparticles from 0.02 to 0.05, average Nusselt increase by 2.11 percent, indicating that water-copper oxide nanofluid has a better heat transfer than pure water.
Iranian Journal of Mechanical Engineering Transactions of ISME
ISME
2538-4775
21
v.
4
no.
2020
149
173
https://jmep.isme.ir/article_43463_8e29d8154067c78cf1c2428f90a879ce.pdf
Natural convection heat transfer of nanofluid in an enclosure saturated with square and circular blocks
Esmael
Ghaedi
IAU, Bushehr Branch
author
Taher
Armaghani
IAU, Mahdishahr Branch, Iran
author
Reza
Sepahi Samian
Amirkabir Uni of Tech. Mech Dep
author
text
article
2020
per
In this paper natural convection heat transfer of nanofluid simulated in a box with square and circular blocks. Governing equations is solved using finite volume method by Fluent software and Nusselt number near the hot wall at different Darcy numbers, is obtained for box with square or circular blocks. Results show that when there is a few blocks, temperature contour and streamlines depend on blocks geometry while increasing the number of blocks decrease this dependency. For box containing heater element in square arrangement, conduction heat transfer is dominant while in horizontal arrangement convection is dominant. By growth of Rayleigh number and consequently increasing of rotational flow convection portion in heat transfer increases. Although most portion of heat transfer is by conduction and convection has little effect. In the next part of research effect of nanoparticle concentration in heat transfer is studied. Results show an increase in average Nusselt number and heat transfer coefficient for higher volumetric concentrations of nanoparticles. Time taken to reach steady state for water based nanofluid is less than time for water/ Copper oxide, ethylene glycol, and water/ Copper oxide, propylene glycol. Variation of heat transfer coefficient in term of Nusselt number for Copper oxide, ethylene glycol, and Copper oxide, propylene glycol nanofluids with increase of nanoparticle concentration is independent of Rayligh number
Iranian Journal of Mechanical Engineering Transactions of ISME
ISME
2538-4775
21
v.
4
no.
2020
174
196
https://jmep.isme.ir/article_43464_00aa0de774ee5c193c91eee1b49edd4c.pdf
Feasibility and exergoeconomic analysis of a cogeneration system for a hospital based on the solar organic Rankine cycle in Iran
Zeinab
Aghaziarati
Department of mechanical engineering, Arak university of technology, Arak
author
Abolfazl
Hajizadeh Aghdam
Arak university of technology
author
text
article
2020
per
In this paper, an exergoeconomic analysis of a cogeneration system of heating, cooling and power has been done for the needs of a 100-bed hospital. The electricity required for the hospital is produced by an organic Rankine cycle. Using the heat exchanger in the cycle, the heating load of the hospital is provided. The steam output of the turbine has also been used to launch a cascade refrigeration cycle and to provide a cooling load for the hospital. The combination of absorption and compression refrigeration cycles provides for the preservation of some of the drug items that should be stored at very low temperatures. To supply heat in the boiler of this plant, three types of collectors including linear parabolic, Fresnel Linear Collector and Dish Collector have been used and compared. The results showed that collectors are more critical than the other parts of the economy due to the high initial investment cost. Also, the LFR collector from the economic point of view showed better system performance than others. The system was tested for performance in 9 different provinces of Iran with different radiation intensity levels. The results showed that Bushehr and Golestan provinces had the highest and lowest potential, respectively. Also, the effect of radiation intensity and operating fluid on the system was investigated.
Iranian Journal of Mechanical Engineering Transactions of ISME
ISME
2538-4775
21
v.
4
no.
2020
197
219
https://jmep.isme.ir/article_43465_3658adcc40af234dfcfe124ab2f7ddea.pdf
Experimental Study of Small Scale Drip Irrigation Using Positive Displacement Solar Pump in Direct Coupling Conditions
Mahmood
Chahartaghi
Faculty of Mechanical Engineering, Shahrood University of Technology
author
Mehdi
Hedayatpour
Faculty of Mechanical Engineering/ Shahrood University of Technology
author
text
article
2020
per
In this paper, experimental performance of a solar photovoltaic positive displacement pump connected to drip irrigation system has been studied in direct coupling condition. Also, a mathematical model has been presented to predict the main parameters of the system. The values of solar radiation, water discharge, emitter line pressure, panel surface temperature, ambient temperature, current and output voltage of solar panel have been measured in actual operation time. The results illustrate that the positive displacement pump discharge shows three different behaviors in a day. The output flow of the pump tends to be constant after a mid-day threshold radiation. The amount of discharge and line pressure in the morning and evening, when the sun radiation is in a low level, are ascending and descending, respectively. One of the important factors in the performance of the panel is the surface temperature of the panel, with the maximum observed temperature being 60.7 degrees Celsius.
Iranian Journal of Mechanical Engineering Transactions of ISME
ISME
2538-4775
21
v.
4
no.
2020
220
238
https://jmep.isme.ir/article_43466_a1a17d77762af862ec1d38ad13fcba30.pdf