Agricultural systems engineering (greenhouse, fish farming, mushroom production)
Zh. Seifi laleh; H. Samimi Akhijahani; P. Salami
Abstract
IntroductionWith increasing the world's population, the demand for supply water resources is also increasing. Nevertheless, climate change has severely impacted the accessibility of fresh water resources. Consequently, researchers have been focusing on producing drinkable water from seas and oceans. ...
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IntroductionWith increasing the world's population, the demand for supply water resources is also increasing. Nevertheless, climate change has severely impacted the accessibility of fresh water resources. Consequently, researchers have been focusing on producing drinkable water from seas and oceans. Iran, with its significant levels of solar radiation and access to open water from the north and south, is an ideal country for fresh water production. Using solar water desalination systems is a reliable and cost-effective solution for producing drinking water from salt water sources. The purpose of this research is to enhance the performance of the solar water desalination system by using the latent heat storage system and a solar tracking system. In this experimental setup for fresh water production, water was used as the working fluid, while a parabolic collector functioned as the source of thermal energy.Materials and MethodsThe solar water desalination system was designed and built on a laboratory scale at the University of Kurdistan, and then the necessary experiments were carried out. The flowing fluid (water) inside the spiral tube in the tank is pumped into the absorber tube of the parabolic collector. Inside the receiver tube, there is a spiral copper tube with a 7 cm pitch, which contains paraffin. The parabolic mirror reflects the sunlight onto the receiver tube, causing the working fluid, water, to heat up. The cooling process is achieved using a specific source located in the upper section of the distillation tank. In this case, the steam droplets in the tank hit the bottom surface of this cooling tank, which has the shape of an inverted funnel, leading to condensation. The study was conducted over four consecutive days, from 10:00 to 14:00, under identical conditions from August 24th to August 27th, 2022. It took place at the Renewable Energy Laboratory, University of Kurdistan in Sanandaj, Iran, and was conducted for three different volume flow rates of fluid: 1.9, 3.1, and 4.2 l.min-1 with phase change materials (PCM) and 4.2 l.min-1 without phase change materials (WOPCM); the pump’s maximum flow rate was 4.2 l.min-1. Variations of outlet temperature, thermal efficiency, desalination efficiency, and produced water were investigated under different conditions.Results and DiscussionThe results reveal that by decreasing the pitch of the spiral tube, there is an increase in the amount of heat captured, due to the increase in the Nusselt number. At the beginning of data collection, a significant amount of the energy that enters the receiver tube is absorbed by both the phase change material and the spiral tube inside the receiver and as a result, the initial air temperature is lowered. The highest temperature of salt water occurs when the fluid is flowing at a rate of 4.2 l.min-1, while the lowest temperature is observed at a flow rate of 1.9 l.min-1. With a flow rate of 4.2 l.min-1, the absorbent tube rapidly transfers the absorbed heat to the salt water chamber through the fluid. The input energy to the tank has increased from 1.53 to 2.83, 1.14 to 2.18, and 0.73 to 1.48 MJ for fluid flow rates of 4.2, 3.1, and 1.9 l.min-1, respectively. At a flow rate of 4.2 l.min-1, the thermal efficiency of the system without phase change materials (3.51%) is lower compared to the case with phase change materials (5.02%). Moreover, using a solar tracking mechanism increased the thermal efficiency of the collector by 9.86% compared to the system using a photocell sensor. Based on the water quality values, it can be stated that the level of dissolved solids in the water sample has been significantly decreased. This indicates that the water can be used for drinking.ConclusionIn this research, the process of thermal changes in a solar water desalination system using PCM was investigated. The obtained results demonstrate that the use of PCM improved the thermal efficiency of the collector and the water obtained from the current system is safe for consumption. Furthermore, by implementing a solar panel tracking system, the efficiency of the solar collector is improved.
Agricultural systems engineering (greenhouse, fish farming, mushroom production)
M. Jalali; A. Banakar; B. Farzaneh; M. Montazeri
Abstract
IntroductionIn the poultry industry, reducing energy consumption is essential for reducing costs. Energy requirements in the poultry industry include heating, cooling, lighting, and power line energy. Identifying factors that increase energy usage is crucial, and providing appropriate solutions to reduce ...
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IntroductionIn the poultry industry, reducing energy consumption is essential for reducing costs. Energy requirements in the poultry industry include heating, cooling, lighting, and power line energy. Identifying factors that increase energy usage is crucial, and providing appropriate solutions to reduce costs and energy consumption is inevitable. One of the major and expensive factors in the poultry industry is the use of fossil fuels, which also causes pollution. Energy costs directly impact the cost of production and increase the per capita cost of production in the meat and egg sectors. In Iran, poultry farms are among the most widely used energy consumers, especially for heating breeding halls, making them a significant subset of the agricultural sector.Materials and MethodsThe problem under study is the thermal simulation of a meat poultry farm located in Ardestan city, Isfahan province. Ardestan city is situated in a desert region in the north of Isfahan province, at a latitude of 33 degrees and 23 minutes north, and a longitude of 52 degrees and 22 minutes east. The dimensions of the poultry hall floor are 5 meters by 8 meters, and it has a capacity of 300 poultry pieces. There are two inlet air vents (windows), each with dimensions of 1.90 by 1.6 meters. The roof has an average height of 2.5 meters and is sloping, made from a combination of plastic carton, fiberglass, and sheet metal.To reduce energy consumption in this poultry farm, a solar heating system is designed and studied in this research. The farm is one of the functions of Isfahan province, with dimensions of 8 meters in length and 5 meters in width. The simulation is performed using TRNSYS software.Results and DiscussionThe results demonstrate that a collector surface area of 26 m2 is necessary to reach the technically optimal point, where the sun's maximum production is achieved with no energy dissipation. Furthermore, the findings indicate that a balance of 16 m2 is required to align the solar system with the auxiliary system.ConclusionBy installing 2 square meters of solar collectors, 5.2% of the total energy demand can be met with solar energy. To fully meet the energy demand using solar energy, a collector area of 30 square meters is required. As the solar fraction increases, the system's ability to extract solar energy also increases. The maximum production of solar energy without any wastage is achievable with a collector area of 26 square meters. Moreover, to maintain a balance between the use of solar energy and the auxiliary system, a collector area of 16 square meters is needed.
M. H. Aghkhani; M. H. Abbaspour-Fard; M. R. Bayati; H. Mortezapour; S. I. Saedi; A. Moghimi
Abstract
Drying is a high energy consuming process. Solar drying is one of the most popular methods for dehydration of agricultural products. In the present study, the performance of a forced convection solar dryer equipped with recycling air system and desiccant chamber was investigated. The solar dryer is comprised ...
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Drying is a high energy consuming process. Solar drying is one of the most popular methods for dehydration of agricultural products. In the present study, the performance of a forced convection solar dryer equipped with recycling air system and desiccant chamber was investigated. The solar dryer is comprised of solar collector, drying chamber, silica jell desiccant chamber, air ducts, fan and measuring and controlling system. Drying rate and energy consumption in three levels of air temperature (40, 45 and 50 oC) and two modes of drying (with recycling air and no-recycling with open duct system) were measured and compared. The results showed that increasing the drying air temperature decreased the drying time and increased the energy consumption in the mode of non-recycling air system. The dryer efficiency and drying rate were better in the mode of recycling air system than open duct system. The highest dryer efficiency was obtained from drying air temperature of 50 oC and the mode of recycling air system. In general, the efficiency of solar collector and the highest efficiency of the dryer were 0.34 and 0.41, respectively.
