Renewable Energy Resources and Technologies
Ahmad Naderi Nobandegani; Mohammad Ahmadzadehtalatapeh
Abstract
In the present study, the performance of a Desiccant Evaporative Cooling System (DECS) under eight different designs to provide the desired indoor air conditions for administration buildings was explored via TRNSYS software. An administration building in Chabahar, Iran as a region with a high cooling ...
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In the present study, the performance of a Desiccant Evaporative Cooling System (DECS) under eight different designs to provide the desired indoor air conditions for administration buildings was explored via TRNSYS software. An administration building in Chabahar, Iran as a region with a high cooling load demand was considered for the study. The simulation results indicated that the two-stage desiccant cooling system (Des. H) was the most suitable design, and it enjoyed the potential to keep the indoor air conditions within the standard recommendations. It was also shown that Des. H is the superior design in terms of energy performance and can meet the space cooling load requirements. The study showed that Des. H had the highest COP value with 2.83. The possible application of solar energy to the regeneration process of the Des. H was also studied. The simulations revealed that Des. H with and without the solar panels had less energy consumption than the existing system. The study showed that the application of Des. H could ensure 26.97 % saving in power per year in comparison to the existing system. Moreover, it was demonstrated that the addition of PVT panels to Des. H could increase the rate of annual power saving to about 68.03 %.
Environmental Impacts and Sustainability
Bahram Hosseinzadeh Samani; Marziyeh Ansari Samani; Rahim Ebrahimi; Zahra Esmaeili; Ali Ansari Ardali
Abstract
Due to limited oil reserves, the rising world fuel prices and environmental problems caused by the use of fossil fuels increase the tendency to use alternative fuels such as biodiesel and bioethanol. In this study, the evaluation of energy and exergy flow from seed planting to final production of biodiesel ...
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Due to limited oil reserves, the rising world fuel prices and environmental problems caused by the use of fossil fuels increase the tendency to use alternative fuels such as biodiesel and bioethanol. In this study, the evaluation of energy and exergy flow from seed planting to final production of biodiesel from rapeseed oil was carried out. Biodiesel production from rapeseed was made in three main phases: farm, oil extraction, and industrial biodiesel production. Initially, the input and output variables for rapeseed production were collected through questionnaires from 30 rapeseed farms in Khuzestan province, Iran. Thus, the amount of energy input and output to the field for rapeseed was estimated to be 12826.98 and 22195 MJ/ha, respectively. The highest energy consumption is related to chemical fertilizers with 65 % share of other inputs. Input and output exergy rates were obtained as 3933.494 and 22603.39 MJ/ha, respectively, and the highest exergy consumption related to diesel fuel with 58 % share of other inputs. At the biodiesel production stage, the input energy and output energy were 156.95 MJ and 41.88 MJ, respectively, and the highest amount of electricity consumed was 91.02 MJ. The total amount of exergy in the production of biodiesel and the output exergy was 48.412 MJ and 64.568 MJ, respectively. In this study, the effects of alcohol-to-oil molar ratio, ultrasound power (W), catalyst concentration (w/w %), and the reaction time (min) on methyl ester yield using response surface methodology based on Box Behnken experimental design in the Design Expert software were investigated. Finally, gas emissions were studied at the planting and biodiesel production stages, and the resultsshowed that the highest greenhouse gas emissions at the planting stage were related to chemical fertilizers and alcohol production.
Renewable Energy Resources and Technologies
Hadi Farzan
Abstract
The present study investigates the effectiveness of thermostat control strategy in cooling energy consumption in residential buildings. To evaluate the energy consumption, two scenarios including a residential zone with and without the thermostat control system are assumed. The TRNSYS software provides ...
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The present study investigates the effectiveness of thermostat control strategy in cooling energy consumption in residential buildings. To evaluate the energy consumption, two scenarios including a residential zone with and without the thermostat control system are assumed. The TRNSYS software provides an efficient numerical tool to model and evaluate a cooling system. Furthermore, since solar-powered cooling systems for residential air-conditioning are receiving growing and significant interest, a hot-water fired absorption chiller coupled with evacuated tube collectors is considered as the cooling system. The results reveal that the cooling systems consume a large amount of energy in hot climate zones without employing the thermostatic control. Therefore, cooling energy has great potential for a significant saving in hot climates. It is illustrated that the thermostat strategy has an obvious impact on such energy saving. In the current study, employing the thermostat in 90m2 residential building results in saving energy by up to 36%.
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%.
