Research Article
Ayda Montaser Koohsari; Rima Fayaz; Behrouz Mohammad Kari
Abstract
As part of sustainable architecture principles and practices, designers need to define building's architectural requirements based on climatic conditions, environmental preservation and reduction in energy consumption. The natural energy sources such as solar radiation affect thermal and lighting performances ...
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As part of sustainable architecture principles and practices, designers need to define building's architectural requirements based on climatic conditions, environmental preservation and reduction in energy consumption. The natural energy sources such as solar radiation affect thermal and lighting performances of buildings depending on its facade characteristics. Traditionally, buildings thermal and lighting analyses are employed independently. As non-linear relationships are often disclosed, an integrated thermal and lighting approach is necessary to optimize the façade configuration. This paper presents an integrated model of thermal and lighting energy simulation which investigates 1650 window configurations, and sunshade size in a residential building in a mild climate to find the optimum solution. The integrated thermal and daylight simulations are carried out using Energy PlusV8-1-0, Daysim 1.08 and Radiance 2.01 software. Calculations are performed on hourly basis for an entire year. First, climatic parameters are validated by on-site measurement. Then all thermal and lighting parameters of the simulated model are defined. Next, the optimal results of the window and sunshade characteristics in four main dimensions (South, North, East, and West) are presented by genetic algorithm approach. The results show that, the window orientation affects up to 10% on energy saving, and horizontal windows with higher sill levels are more energy-efficient in south and east orientations. The optimal sunshade angel of the south orientation is 65-85 degree and its optimal range of Window Wall Ratio(WWR) is 15-25%.
Research Article
Javad Faiz; Arash Hakimi Tehrani; Ghazanfar shahgholian; Amir Masoud Takbash
Abstract
Pitch control is one of t he major aspects of wind turbine control, particularly over high wi nd s p e e d a n d oscillations. General El e c t r i c (GE) model of wi n d t ur bi ne i s practically compatible with the structure of the wind turbines. I t ...
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Pitch control is one of t he major aspects of wind turbine control, particularly over high wi nd s p e e d a n d oscillations. General El e c t r i c (GE) model of wi n d t ur bi ne i s practically compatible with the structure of the wind turbines. I t h a s b e e n p r o v e d t h a t simulation results using this model are closer to the actual case, compared to other available models. Therefore, in this paper the GE model is used to evaluate the eff ectiveness of three different controllers including Fuzzy controller, self-organized Fuzzy controller (SOFC) and PI controller i n pitch control of the wi nd turbine. Afterward, the results of the controller applications as well as the no controller case in t h e pitch control are compared. The results show a better performance of SOFC in damping the oscillations and overshoot of the wind turbine shaft speed. Finally,electrical power limit and converter cost, the economic analysis of pitch controller application are carriedout. It is shown that the application of the SOFC results are around $142,646 saving.
Research Article
Gholam Reza Arab Markadeh; Nasrin Banimehdi
Abstract
This paper proposes an improved direct active and reactive power control (DPC) strategy for a grid-connected doubly fed induction generator (DFIG) based wind-turbine system under unbalanced grid voltage condition. The method produces required rotor voltage references based on the sliding mode control ...
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This paper proposes an improved direct active and reactive power control (DPC) strategy for a grid-connected doubly fed induction generator (DFIG) based wind-turbine system under unbalanced grid voltage condition. The method produces required rotor voltage references based on the sliding mode control (SMC) approach in stationary reference frame, without the requirement of synchronous coordinate transformation, and therefore causes a simpler design for power control system. Under unbalanced grid voltage condition, two control targets obtained simultaneously, i.e., removing stator active and reactive power oscillations. Moreover this method reduces the THD of stator current. Also it is shown that the proposed control method not only has a high-speed dynamic response but is stable during wind speed and system parameters variations. Simulation results for a 2kw DFIG confirm prominence of proposed control strategy.
Research Article
Roonak Daghigh; Abdellah Shafieian
Abstract
This study analyzes the thermal performance of solar thermal energy using double-pass absorber plate in Sanandaj, Iran. To this end, a mathematical model was encoded according to the energy and exergy balance equations and solved by MATLAB software. Given the environmental conditions and radiation intensity ...
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This study analyzes the thermal performance of solar thermal energy using double-pass absorber plate in Sanandaj, Iran. To this end, a mathematical model was encoded according to the energy and exergy balance equations and solved by MATLAB software. Given the environmental conditions and radiation intensity of a winter day in Sanandaj, the effects of external parameters such as radiation intensity and internal parameters such as canal’s height, inlet mass flow rate, absorber length as well as some physical parameters on the efficiency of the system were analyzed and the energy and exergy output of the system was studied. To validate the proposed model, the results obtained from numerical simulation were compared with experimental data, which showed an acceptable compatibility. Finally, the ability of the system to supply the thermal load of the building in the given day was examined and the roles of various factors in the area under thermal coverage of this system were analyzed. The obtained findings indicated that a system with an area of 3 m2 and mass rate of 250 kg/hr in radiation intensity of 619 W/m2 and temperature of 3.45° is capable of supplying the thermal load of a space with an approximate area of 14 m2.
Research Article
Mahsa Alimoradi; Mohsen Jahanshahi; Majid Peyravi
Abstract
Treatment of landfill leachate is challenging, due to its characteristics such as age, dumping place, composition and origin of wastes. For this reason, the application of hybrid processes is helpful for complete treatment of contaminants present in the leachates. The addition of membrane operations ...
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Treatment of landfill leachate is challenging, due to its characteristics such as age, dumping place, composition and origin of wastes. For this reason, the application of hybrid processes is helpful for complete treatment of contaminants present in the leachates. The addition of membrane operations to biological treatment technology offers new advantages for this method. For this aim, a bench-scale integrated process based on submerged aerobic MBR has been designed and fabricated. Also, Nanofiltration process as a post-treatment was used to upgrade MBR effluent. The results showed that the submerged UF-MBR system effectively removed biodegradable trace organic compounds with the average removal rate of about 75% at optimum food-to- microorganism (F/M) ratio (BOD basis) of 0.2 gBOD/g.d under a HRT of 24 h. The addition of NF process increased the treatment efficiency up to 98%. The effluent COD was reduced from 3500 mg/l to below 50 mg/l. Further, the effect of PAC addition was studied. NH3 –N, TKN and Heavy metals removal efficiency were obtained 97 ± 2%, 96 ± 2% and 99 ± 2%, respectively.
Research Article
Behzad Aghabarari
Abstract
In this study, Functionalized chitosan with amine groups was synthesized and coated on the surface of carbon black. The hybrid amino functionalized chitosan-carbon support was employed as an efficient, environmentally friendly heterogeneous catalyst for the transesterification reaction of canola oil ...
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In this study, Functionalized chitosan with amine groups was synthesized and coated on the surface of carbon black. The hybrid amino functionalized chitosan-carbon support was employed as an efficient, environmentally friendly heterogeneous catalyst for the transesterification reaction of canola oil and methanol. It was observed that this hybrid was more active than parent polymer at the reaction condition. Furthermore, the reactionparameters, such as reaction temperature, molar ratio, amount of the catalyst and reaction time were studied. It was shown that the conversion of canola oil to methyl esters could reach to 95 % during 3.5 h when the reaction was performed with the molar ratio of methanol to canola oil of 12, a catalyst amount of 5 Wt.%, at the reaction temperature of 60 C. These results can be explained by the inherent basicity of amines groups of amino functionalized chitosan on the surface of carbon support. This novel heterogeneous catalyst offers several attractive advantages such as high catalyst activity, easy recovery and reusability of the catalyst.
Research Article
Shahab Alizadeh; Hamid Reza Haghgou
Abstract
In a 10-ton capacity pilot plant solar liquid desiccant air conditioner (LDAC) developed, dehumidification of the outside air is achieved through a honeycomb packed-bed heat and mass exchanger, using lithium chloride solution as the desiccant. The dry air obtained from the dehumidification process is ...
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In a 10-ton capacity pilot plant solar liquid desiccant air conditioner (LDAC) developed, dehumidification of the outside air is achieved through a honeycomb packed-bed heat and mass exchanger, using lithium chloride solution as the desiccant. The dry air obtained from the dehumidification process is evaporative cooled inside a cooling pad and directed into the conditioned space. The dilute solution thus produced is concentrated in a honeycomb packed-bed scavenger air regenerator using hot water from flat plate solar collectors. Carryover of the desiccant particles has been avoided by using eliminators. The air conditioner was installed on a 250 m2 area of the fluid mechanics laboratory of Babol University of Technology, a hot and humid location in the north on the Caspian Sea. The experimental data obtained were compared with the predicted results of a model developed for the air conditioner based on HYSIS and CARRIER energy soft-wares. The comparison reveals that good agreement exists between the experiments and the model predictions. The above tests further reveal that the unit has a satisfactory performance in independently controlling the air temperature and humidity of the conditioned space. The inaccuracies are well within the measuring errors of the temperature, humidity and the air and solution flow rates. An efficient heat recovery within the air conditioner resulted in a thermal COP of about 1.5 and an electrical COP of 7. A commercialization study reveals that the operating cost of an LDAC is significantly lower than its conventional counterpart. The costs would further reduce if a storage system was used to store the concentrated solution of liquid desiccant. A simple payback of five years was determined for the solar components of the liquid desiccant system in this study.
