Moein Mokhtari Sataiy; Houshang Bahrami; MohammdJavad SheikhDavoodi; Davood Momeni; Mohsen Soleymani
Abstract
In this study, technical and economical potential of using solar energy for heating cucumber greenhouses in Jiroft region were studied. For this purpose, the climatic suitability of the region was determined. According to the data and thermal requirement of greenhouse, capacity of a flat panel solar ...
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In this study, technical and economical potential of using solar energy for heating cucumber greenhouses in Jiroft region were studied. For this purpose, the climatic suitability of the region was determined. According to the data and thermal requirement of greenhouse, capacity of a flat panel solar water heater was calculated and was compared with the conventional system, gasoil heater. The results of paired t-test showed that there was no significant difference between the two greenhouses in terms of CO2 content, average temperature and relative humidity, but there were significant differences in terms of chlorophyll content and yield between the two greenhouses, at the probability level of one and five percent, respectively. There was a significant difference, with a higher average of conventional system. The results of data analysis in Kamfar software showed that in terms of economic indicators, the use of solar water heaters for heating greenhouses in this area is justifiable in the fifth year and the return on investment is 5.32 years.
D. Momeni; Ghasem Zarei; Jalal Javadimoghadam
Abstract
Greenhouse cultures include energy-related economic activities in the agricultural sector. Due to the problems in the production, transmission and distribution systems of electricity in conventional systems, development of CHP systems were so attractive in recent years. In this research after determining ...
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Greenhouse cultures include energy-related economic activities in the agricultural sector. Due to the problems in the production, transmission and distribution systems of electricity in conventional systems, development of CHP systems were so attractive in recent years. In this research after determining of advantages and disadvantage of CHP systems for using in greenhouse cultures, technical, economic and environmental assessments of these systems were evaluated. Finally, the role of government policies and supports were investigated. For technical, economic and environmental feasibility of using these systems in the greenhouse, the technical use of the system in the greenhouse, the amount of net present value (NPV), investment income components, cost components of capital, the amount of stored energy and carbon dioxide emissions were calculated. The results showed that because of the low number of technical personnel for installation, maintenance and repair of the system, it would be out of order if a problem occurred. Economically, it can be economically feasible to use government-sponsored sales of electricity to the national grid and the use of free-tariff gas. This reflects the role of government policies and facilities in the economic development of these projects.
Jalal Javadi Moghaddam; sayid Ozlati; Ghasem Zarei; Davood MOMENI; Farzad Azadshahraki
Abstract
Greenhouse structure is one of the most important factors in the greenhouse industry; enhancing its strength and decreasing the cost of its manufacturing have always been among manufacturers consideration. The aims of this study were to design an octagonal greenhouse with square cross-sectional components ...
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Greenhouse structure is one of the most important factors in the greenhouse industry; enhancing its strength and decreasing the cost of its manufacturing have always been among manufacturers consideration. The aims of this study were to design an octagonal greenhouse with square cross-sectional components with enough resistance to standard loads applied by structure stress analysis methods. Design and optimization of this greenhouse involved selecting the minimum thickness of the profiles and columns. In addition, the layout of the trusses is led to minimum weight of structures per square meter. This greenhouse was designed to have nessecary structure standards and could be used in different climate conditions of Iran. In design process, initially the effects of wind load with 120 km/h were determined by using fluid dynamics calculations. Afterward, the main frame of the structure including columns, horizontal beams and trusses, were designed according to wind, snow and pendant loads. The results showed that the wieght of metal to be used to build the structure of greenhouse was less than 8.5 Kg/m2 , very lower than that in similar stuctures (20 kg/m2).
Abstract
The present study evaluated the performance of a novel solar heating system. A linear Fresnel lens was used to concentrate the heat in this system. Pre-experimentation tested the performance of the system at 5 alignment angles and 5 slope angles. The data was used to evaluate the performance of the system ...
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The present study evaluated the performance of a novel solar heating system. A linear Fresnel lens was used to concentrate the heat in this system. Pre-experimentation tested the performance of the system at 5 alignment angles and 5 slope angles. The data was used to evaluate the performance of the system in December 2014 at 6 flow rates (100, 200, 300, 400, 600, and 800 ml.min-1). In these experiments, solar radiation, wind velocity, temperature of fluid in collector, ambient temperature, and ambient relative humidity were recorded. The results demonstrated that the best performance of the system was at a 300 ml.min-1 flow rate, due south orientation, and with monthly adjustment of the slope of the lens. The correlation between the parameters indicated that at different flow rates, the effect of solar radiation on the temperature of the ambient air, heat-absorber pipe, output fluid, and input fluid were 0.91, 0.895, 0.86 and 0.84, respectively.
