University of Tehran
Energy Equipment and Systems
2383-1111
2345-251X
6
2
2018
06
01
Analysis and simulation of dynamic performance for DFIG-based wind farm connected to a distrubition system
117
130
EN
Ghazanfar
Shahgholian
0000-0003-2774-4694
Smart Microgrid Research Center, Najafabad Branch, Islamic Azad University, Najafabad, Iran
shahgholian@iaun.ac.ir
10.22059/ees.2018.31531
Local renewable resources such as wind and solar are often available in remote locations. Wind farms consist of many individual wind turbines which are connected to the electric power transmission network. A wind farm can use the wind resources from a certain area efficiently. Double-fed induction generator (DFIG) is a generating principle widely used in wind turbine (WT). DFIG are able to generate active and reactive powers in an independent way. The objective of this paper is to study the improvement in dynamic performance conurbation from wind farms. Simulation studies were carried out in a two-machine power system. Different operating scenarios have been considered. Finally, some simulations are shown to support the improvement in dynamic performance of the DFIG based WT.
DFIG,Wind Farm,Dynamic Performance
https://www.energyequipsys.com/article_31531.html
https://www.energyequipsys.com/article_31531_ebb207246512fba680b9517ae11f2dd4.pdf
University of Tehran
Energy Equipment and Systems
2383-1111
2345-251X
6
2
2018
06
01
Mini two-shaft gas turbine exergy analysis with a proposal to decrease exergy destruction
131
141
EN
Milad
Babadi Soultanzadeh
0000-0003-3155-2994
Department of Mechanical Engineering, Khomeinishahr Branch, Islamic Azad University, Isfahan, Iran
milad.bbdsltnzd@gmail.com
Mojtaba
Haratian
0000-0003-3879-5841
Department of Mechanical Engineering, Khomeinishahr Branch, Islamic Azad University, Isfahan, Iran
haratian@iaukhsh.ac.ir
MohammadSaleh
Teymouri
Young Researchers and Elite club, Islamic Azad university Khomeini Shahr Branch, Isfahan, Iran
sally_tm32@hotmail.com
10.22059/ees.2018.31532
In this case study, exergy analysis is applied to a mini two-shaft gas turbine which is located in Islamic Azad University Khomeini Shahr Branch`s Thermodynamics laboratory and a proposal presented to make exergy destruction less using a Heat Recovery Water Heater (HRWH). Calculations were done for N<sub>2</sub>=20000 (rpm) constant and various N<sub>1</sub> and after that for N<sub>1</sub>=60000 (rpm) constant and various N<sub>2</sub>. Results revealed that the highest exergy destruction rate occurs in combustion chamber in all conditions and a huge part of exergy destruction through the turbine exhaust. Increase in N<sub>1</sub> leads to increases in all component exergy destruction rates. On the other hand, power turbine is the only component which is affected by changes in N<sub>2</sub> and the exergy destruction rate increases with increase in N<sub>2</sub>. Moreover, exergy gained rate within HRWH increased with increase in N<sub>1</sub> and is almost constant with changes in N<sub>2</sub>. In the same vein, exergetic efficiency of HRWH and exergy gained rate within HRWH are increased with decrease in water outlet temperature of HRWH.
Gas Turbine,Exergy Analysis,Second Law Efficiency,Exergy Recovery
https://www.energyequipsys.com/article_31532.html
https://www.energyequipsys.com/article_31532_9b61d31c7865c5188653428bad118290.pdf
University of Tehran
Energy Equipment and Systems
2383-1111
2345-251X
6
2
2018
06
01
Numerical study of natural convection heat transfer of Al2 O3/Water nanofluid in a Γ-shaped microchannel
143
154
EN
Amireh
Nourbakhsh
Department of Mechanical Engineering, Bu-Ali Sina University, Hamedan, Iran
nourbakhsh.nourbakhsh@basu.ac.ir
Morteza
Bayareh
Department of Mechanical Engineering, Shahrekord University, Shahrekord, Iran
m.bayareh@eng.sku.ac.ir
10.22059/ees.2018.31533
Finite-volume procedure is presented for solving the natural convection of the laminar nanofluid flow in a Γ shaped microchannel in this article. Modified Navier-Stokes equations for nanofluids are the basic equations for this problem. Slip flow region, including the effects of velocity slip and temperature jump at the wall, are the main characteristics of flow in the slip flow region. Steady state equations were solved by using time marching method. In provided FORTRAN code, the finite volume method and an explicit fourth-order Runge–Kutta integration algorithm were applied to find the steady state solutions. Also an artificial compressibility technique was used to couple the continuity to the momentum equations as it is simpler and converges faster. The Grashof numbers from to were considered. The results showed that Nusselt number increases with the Grashof number and the parameter R (the ratio of minimum diameter of nanoparticles and maximum one).. As the parameter R increases, the distortion of the isotherm lines increases to some extent.
Microchannel,Velocity Slip,Temperature Jump,Grashof Number,Nanoparticle
https://www.energyequipsys.com/article_31533.html
https://www.energyequipsys.com/article_31533_8df07a838c08b342b44c4283b4bce61d.pdf
University of Tehran
Energy Equipment and Systems
2383-1111
2345-251X
6
2
2018
06
01
Design and operation optimization of an air conditioning system through simulation: an hour-by-hour simulation study
155
165
EN
Mohammad
Ahmadzadehtalatapeh
Department of Marine and Mechanical Engineering, Chabahar Maritime University, 99717-56499, Chabahar, Iran
m_ahmadzadeh56@yahoo.com
Yat
HuangYau
Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
10.22059/ees.2018.31534
In the present research, performance validation of a Heating, Ventilation, and Air Conditioning (HVAC) system operating in a library building was conducted. The operating HVAC system was studied in terms of the provided indoor air conditions and energy consumption level. The fieldwork measurements showed that the HVAC system is not capable of providing the desired indoor air conditions based on the ASHRAE standards. Therefore, two deciding design and operating parameters namely, chilled water cooling coil number of rows and chilled water temperate were investigated to achieve possible improvement in the system performance. For this purpose, different numbers of rows for cooling coil design at different chilled water temperatures were examined. TRNSYS software was employed to investigate the hourly effect of the variables on the system for a whole year of operation.Based on the simulation results, the provided indoor air conditions were appropriate and within the comfort area with the two-row configuration cooling coil. However, the energy performance of the system indicated that the two-row configuration with 10 chilled water temperature was superior in terms of energy consumption, and could provide the desired indoor air conditions, thus it was recommended to be implemented in the existing system.
energy consumption,HVAC System,Indoor Air Conditions,TRNSYS
https://www.energyequipsys.com/article_31534.html
https://www.energyequipsys.com/article_31534_6482a412882eb97276825e13c11aa2b4.pdf
University of Tehran
Energy Equipment and Systems
2383-1111
2345-251X
6
2
2018
06
01
Experimental and numerical study of natural ventilation in four-sided wind tower traps
167
179
EN
Davoud
Jafari
Faculty of Engineering, Shahrekord University, Shahrekord, Iran
j.davoud@yahoo.com
Alireza
Shateri
Faculty of Engineering, Shahrekord University, Shahrekord, Iran
shateri@eng.sku.ac.ir
Afshin
Ahmadi Nadooshan
0000-0003-4345-9527
Faculty of Engineering, Shahrekord University, Shahrekord, Iran
ahmadi@sku.ac.ir
10.22059/ees.2018.31535
In the past, wind towers were applied as the main architectural part of building construction in the desert areas of Iran. These almost high structures were used as cooling load suppliers at residential buildings. In the present study, the effect of symmetric four-sided wind tower in flow induction to the bottom space has been analysed by using a wind tunnel and numerical simulations. In the numerical simulation, the flow is assumed to be three-dimensional, unsteady, compressible and turbulent. The experimental studies have been performed by placing a model of these structures at a laboratory wind tunnel. At this state, crossing airflow through every channel is measured for analysing the induction performance of wind tower at different angles of wind blowing. Moreover, the turbulence effect is analysed by adding horizontal and vertical blades and crowns at the top and bottom of the internal gate of traps for attaining better performance. Two different geometries are used for simulations. The results showed that inserting the blade and crown at the bottom and topaffect on the flow rate have effect on the flow rate. For instance, inserting horizontal blades and crown at the top of the model leads to 8 and 16% increase in the flow rate, respectively. The results of the numerical simulations have shown acceptable agreement with experimental results.
Wind Tower,Wind Tunnel,Natural Ventilation,numerical simulation
https://www.energyequipsys.com/article_31535.html
https://www.energyequipsys.com/article_31535_b4aed3f40490bd2b096cdd73bdf0920e.pdf
University of Tehran
Energy Equipment and Systems
2383-1111
2345-251X
6
2
2018
06
01
Development of a mathematical model to design an offshore wind and wave hybrid energy system
181
200
EN
Shahram
Derakhshan
School of Mechanical Engineering, Iran University of Science & Technology, Tehran, Iran
shderakhshann@iust.ac.ir
Mahdi
Moghimi
0000-0002-5450-3338
School of Mechanical Engineering, Iran University of Science & Technology, Tehran, Iran
moghimi@iust.ac.ir
Hadi
Motawej
School of Mechanical Engineering, Iran University of Science & Technology, Tehran, Iran
hadimotawej@yahoo.com
10.22059/ees.2018.31536
Fossil Fuels are always considered as environmental pollutants. On the other hand, the political and economic situations highly affect the price of these fuels. Offshore wind and wave, as renewable energy sources, represent the better alternatives for electricity generation. Therefore, it is necessary that wind speeds effectively be estimated due to the absence of field measurements of the wind speed above the surface of the sea in many regions. In this paper, the annual-average wind speed above the sea is calculated mathematically. Wind data obtained from onshore monitoring stations were analyzed to obtain wind power density above the sea. In addition, this study provides information on the variation of the wave energy using Beaufort scale and wind speeds. This allows an approximate estimation of energies corresponding to various wave heights in that region. Besides, a mathematical model was developed to assess wave and wind hybrid energy system. Thus, using a mathematical model, wind-wave hybrid system components were: wind turbine, wave converter and foundation. The wave energy converter (WEC) selected for the hybrid device is Wavestar prototype which was combined with a wind turbine. As for case study, the wind speed as well as the resulting wind and wave power potential in the area of Eastern Mediterranean Sea and the North Sea were determined and the assessment were done for the designed hybrid system. It can be concluded that the annual energy production from hybrid wind-wave device in the North Sea is 64.3% more than its value in the Mediterranean Sea.
Offshore Wind Energy,Wind Power Density,Mean Wind Speed,Wave Energy,Hybrid Energy System
https://www.energyequipsys.com/article_31536.html
https://www.energyequipsys.com/article_31536_17bcf591fae23a1f7cff40d87338b2d6.pdf
University of Tehran
Energy Equipment and Systems
2383-1111
2345-251X
6
2
2018
06
01
Enhancers of the energy efficiency in tea processing industry
201
209
EN
Saeed
Hadipour Zimsar
Department of Agricultural Management, Rasht Branch, Islamic Azad University, Rasht, Iran
saeedhadipoor1@gmail.com
Saeed
Firouzi
Department of Agronomy, Rasht Branch, Islamic Azad University, Rasht, Iran
firouzi@iaurasht.ac.ir
Mohammad Sadegh
Allahyari
Department of Agricultural Management, Rasht Branch, Islamic Azad University, Rasht, Iran
allahyari@iaurasht.ac.ir
10.22059/ees.2018.31537
The cost reduction of green tea processing, the control of fossil fuel resources, and the curbing of corresponding greenhouse gases emission depend on the energy efficiency of tea processing units. Therefore, it is imperative to identify and analyze factors determining energy efficiency of these agro-industrial units. To this end, the present descriptive survey was carried out on 40 managers of tea factories in Guilan Province, Iran. At the first phase of the study, the experts and managers of the tea manufacturing units were given an open-response question to identify the factors affecting energy productivity of tea industry. Then, the factors were divided into three broad categories of technical, managerial-policy, and knowledge-skill. The statistical analysis of final questionnaire data showed that “the correct and sound design of the new hot air furnaces”, “the enhancement of technical knowledge of technicians in withering, fermentation, drying and storage units”, and “optimum scheduling of withering operation with respect to the final status of green tea leaf” were found to be the most important technical, managerial-policy, and knowledge-skill factors determining the improvement of energy productivity in tea factories of Guilan Province, respectively. Accordingly, it is recommended to hold training courses to enhance energy productivity knowledge of tea factory managers, to improve the technical knowledge of technicians in withering, rolling, fermentation, drying, and storage units, to renew machinery and equipment of tea factories, to enforce manufacturing units to comply with relevant quality standards, and to allocate financial supports through low-interest loans for mounting tea processing machinery and equipment with high energy efficiency.
Electricity,Fuel,Energy Use Efficiency,Tea Industry
https://www.energyequipsys.com/article_31537.html
https://www.energyequipsys.com/article_31537_089ac0b34bbc5187a2fd44dbbd237e56.pdf
University of Tehran
Energy Equipment and Systems
2383-1111
2345-251X
6
2
2018
06
01
Simulation and modeling of hydrogen production from glucose biomass model compound via hydro-thermal gasification
211
219
EN
Mohammad Rasoul
Omidvar
Department of Mechanical Engineering, Najafabad branch, Islamic Azad University, Najafabad, Iran
Amir Homayoon
Meghdadi Isfahani
Modern Manufacturing Technologies Research Center, Najafabad branch, Islamic Azad University, Najafabad, Iran
amir_meghdadi@yahoo.com
10.22059/ees.2018.31540
Glucose is a 6-carbon carbohydrate compound present in plants and the ingredient for hemicellulose which makes up 30% of plants’ total mass. The current study uses glucose as reactant and evaluates hydrogen generation at different temperatures and different amounts of input flow of glucose – water mixture. Hydrothermal gasification method is used for hydrogen generation in an open system with controlled volume with temperature changing in the range of 375 to 1000ºC, water intake flow of 800 kg/h and biomass intake flow of 2000 kg/h.
Hydrogen,Temperature,Supercritical Water,Methane,Carbon dioxide,Biomass,Gibbs Reactor
https://www.energyequipsys.com/article_31540.html
https://www.energyequipsys.com/article_31540_ce2b2be4d238a9dde062330fc9bfcd8f.pdf
University of Tehran
Energy Equipment and Systems
2383-1111
2345-251X
6
2
2018
06
01
Experimental values for adjusting an automatic control valve in gas pipeline transportation
221
233
EN
Mehdi
Mahmoodi
Babol Noshirvani University of Technology, Babol, Iran
mehdymahmoody@gmail.com
Mofid
Gorji Bandpy
Babol Noshirvani University of Technology, Babol, Iran
gorji@nit.ac.ir
10.22059/ees.2018.31541
When a natural gas pipeline ruptures, the adjacent automatic line control valves (ALCVs) should close quickly to prevent leakage or explosion. The differential pressure set point (DPS) at each valve location is the main criteria for value setting in ALCV action. If the DPS is not properly adjusted, the ALCV may mistakenly close or it may not take any action at proper time. This study focused on the DPS values prediction for setting ALCV installed on a gas pipeline with 1mm orifice diameter. The effect of characteristic parameters such as pipeline operational pressure (POP) and pipeline pressure drop rate (ROD) due to rupture or major leak was experimentally investigated on DPS. Twenty-five different conditions with double set of typical mentioned characteristic parameters were chosen. For each condition, the differential pressure (DP) was measured over 180 seconds by analyzing the experimental values. Therefore, 25 maximum DP values (DPSs) were obtained. The DPS increases by increase in ROD or decreasing POP parameters. Because of using nitrogen gas instead of natural gas due to safety reasons, the DPS results can be practically applied by adding a safety factor of 15%. The diagram of DPS with respect to ROD and non-dimensional DPS (DOP) versus non-dimensional ROD (RTP) was provided for different POPs.
Automatic Control Valve,Operating Pressure,Adjusting Values,Pressure Drop Rate,Gas Pipeline
https://www.energyequipsys.com/article_31541.html
https://www.energyequipsys.com/article_31541_1512fb231969bb17cfe2352cd93f672e.pdf