The lack of potable water poses a big problem in Syria. The underground water, where exists, is usually brackish and cannot be used as it is for drinking purposes. Syria lies in high solar isolation band and the vast ...The lack of potable water poses a big problem in Syria. The underground water, where exists, is usually brackish and cannot be used as it is for drinking purposes. Syria lies in high solar isolation band and the vast solar potential can be exploited to convert saline water to potable water. The most economical and easy way to accomplish this objective is using solar still. The purpose of the project is to evaluate the potential of using a solar still basin. To implement this goal three similarly solar still basins have been designed, manufactured and tested in selected day for saline water in month of November, 2010. Each solar still consists of insulated metal box with channels. Pyramidal glass covers attached to the basin at an angle (α = 45°). The three basins have divided into three models (M1, M2 and M3). Before taking the measurement of the distilled water three different amount of water used, so for the (model M1) 3 liter of water, (model M2) 6 liter and (model M3) 9 liter, to study and evaluate the effect of water depth in the basin. The average daily output was found to be (3.924) liters/day for model (M1), (3.116) liters/day for model (M2) and 2.408 liters/day for model (M3) for basin area of 1 m2 based on data of selected day.展开更多
Solar energy is very useful in the process of desalination especially for areas that suffer from a lack of clean water resources. In recent years, many people have been using solar still. Therefore the raising of the ...Solar energy is very useful in the process of desalination especially for areas that suffer from a lack of clean water resources. In recent years, many people have been using solar still. Therefore the raising of the productivity and efficiency of solar still represents the most important problems that need further research. The present work aims to study the effect of preheating the water entering to still and the effect of reducing pressure inside the still on the productivity of the solar still. Therefore in present work two identical single basin typical double slope solar stills of the inner basin dimensions for each still 2 m × 1 m × 0.08 m, have been designed and fabricated with mild steel plate. One of them is conventional solar still and the other is modified with flat plate collector and vacuum pump to study the effect of preheating and vacuum on the performance of solar still. The experimental measurements are made to enhance the solar still productivity by firstly preheating the water entering the still using flat plate collector and secondly by integrating the still basin with vacuum pump. The results show that preheating the water entering the still increases the water productivity by amount about 27.7% - 29.3%. The results also show that decreasing pressure inside the still using vacuum pump improves the solar still water productivety by amount about 21.8% - 23.9%.展开更多
3-D numerical simulation was carried out for the water flow in a stilling basin with multi-horizontal submerged jets by using two different turbulence models, namely, the VOF RNG k-ε and Mixture RNG k-ε turbulence m...3-D numerical simulation was carried out for the water flow in a stilling basin with multi-horizontal submerged jets by using two different turbulence models, namely, the VOF RNG k-ε and Mixture RNG k-ε turbulence models. The calculated water depth, velocity profile and pressure distribution are in good agreement with the data obtained in experiments. It indicates that the numerical simulation can effectively be used to study the water flow movement and the energy dissipation mechanism. The numerical simulation results show that the turbulent kinetic energy distribution obtained by using the Mixture turbulence model covers a region about 18% larger than that calculated by using the VOF turbulence model, and is in better agreement with the actual situation. Furthermore, the Mixture turbulence model is better than the VOF turbulence model in calculating the air entrainment.展开更多
Measurements of turbulent flow fields in a stilling basin of multi-horizontal submerged jets were made with the single- camera Particle Image Velocimetry （PIV）. The particle images were captured, processed, and subs...Measurements of turbulent flow fields in a stilling basin of multi-horizontal submerged jets were made with the single- camera Particle Image Velocimetry （PIV）. The particle images were captured, processed, and subsequently used to characterize the flow in terms of the 2-D velocity and vorticity distributions. This study shows that the maximum close-to-bed velocity in the stilling basin is approximately reduced by 60%, comparing to the jet velocity at the outlet of orifices. The jet velocity is distributed evenly at the latter half of the stilling basin and the time-averaged velocity of the cross section is reduced by 77%-85%, comparing to the jet velocity at the outlet of orifices. These results show that the vortices with horizontal axes are continuously repeated during the form-merge-split-disappear process. The vertical vortices are continuously formed and disappeared, they appear randomly near the slab and intermittently reach the slab of the stilling basin. The range of these vortices is small. Vortices with horizontal axes and ver- tical vortices do not coincide in space and the vortices with horizontal axes only affect the position of the tail of the vertical vortices attached to the slab of the stilling basin.展开更多
Energy dissipations induced by the hydraulic jump and the trajectory jet are the most widely known as the two dissipation modes at the downstream of flood discharging structures, which are often considered quite diffe...Energy dissipations induced by the hydraulic jump and the trajectory jet are the most widely known as the two dissipation modes at the downstream of flood discharging structures, which are often considered quite different even contradictory. However, such two energy dissipators can be used jointly and harmonically. In this paper, a new type of stilling basin with a shallow-water cushion and a triangular bottom deflector is proposed based on two different scale physical model tests of the flood discharging tunnel No.2 of Luding hydropower project. The experimental results show that the flow regime of the hydraulic jump in the presented stilling basin with bottom deflector enjoys a good and stable performance within a large range of flow rates and the energy dissipation rate is considerably high as compared to the conventional stilling basin even at a low Froude number. The results also indicate that the stilling basin with triangular bottom deflector has a better performance in improving the potential cavitation erosion according to the analysis of the pressure and the cavitation number compared to the trapezoidal one. The proposed new type of shallow-cushion stilling basin with a shallow-water cushion can be applied in similar energy dissipation projects with low Froude number and large range of flow rates.展开更多
Experiments were conducted to characterize forced hydraulic jumps in stilling basins for enforced cases due to tail water level or dam site arrangement and construction. The case with a single tall sill was simulated ...Experiments were conducted to characterize forced hydraulic jumps in stilling basins for enforced cases due to tail water level or dam site arrangement and construction. The case with a single tall sill was simulated in a horizontal flume downstream of a sluice gate. Results of experiments are compared with the classical hydraulic jump, and significant effect of tall sill on dissipation of energy in shorter distance was confirmed. Furthermore, the generated jumps were classified based on the ratio of sill height to basin length, and a simple design criterion was proposed to estimate the basin length for a desired jump and particular inflow.展开更多
文摘The lack of potable water poses a big problem in Syria. The underground water, where exists, is usually brackish and cannot be used as it is for drinking purposes. Syria lies in high solar isolation band and the vast solar potential can be exploited to convert saline water to potable water. The most economical and easy way to accomplish this objective is using solar still. The purpose of the project is to evaluate the potential of using a solar still basin. To implement this goal three similarly solar still basins have been designed, manufactured and tested in selected day for saline water in month of November, 2010. Each solar still consists of insulated metal box with channels. Pyramidal glass covers attached to the basin at an angle (α = 45°). The three basins have divided into three models (M1, M2 and M3). Before taking the measurement of the distilled water three different amount of water used, so for the (model M1) 3 liter of water, (model M2) 6 liter and (model M3) 9 liter, to study and evaluate the effect of water depth in the basin. The average daily output was found to be (3.924) liters/day for model (M1), (3.116) liters/day for model (M2) and 2.408 liters/day for model (M3) for basin area of 1 m2 based on data of selected day.
文摘Solar energy is very useful in the process of desalination especially for areas that suffer from a lack of clean water resources. In recent years, many people have been using solar still. Therefore the raising of the productivity and efficiency of solar still represents the most important problems that need further research. The present work aims to study the effect of preheating the water entering to still and the effect of reducing pressure inside the still on the productivity of the solar still. Therefore in present work two identical single basin typical double slope solar stills of the inner basin dimensions for each still 2 m × 1 m × 0.08 m, have been designed and fabricated with mild steel plate. One of them is conventional solar still and the other is modified with flat plate collector and vacuum pump to study the effect of preheating and vacuum on the performance of solar still. The experimental measurements are made to enhance the solar still productivity by firstly preheating the water entering the still using flat plate collector and secondly by integrating the still basin with vacuum pump. The results show that preheating the water entering the still increases the water productivity by amount about 27.7% - 29.3%. The results also show that decreasing pressure inside the still using vacuum pump improves the solar still water productivety by amount about 21.8% - 23.9%.
基金Project supported by the National Key Basic Research Program of China (973 Program, Grant No. 2007CB714105)the Science Foundation of Ministry of Education of China (Grant No. 2008108111)the Program for New Century Excellent Talents in University (Grant No. NCET-08-0378)
文摘3-D numerical simulation was carried out for the water flow in a stilling basin with multi-horizontal submerged jets by using two different turbulence models, namely, the VOF RNG k-ε and Mixture RNG k-ε turbulence models. The calculated water depth, velocity profile and pressure distribution are in good agreement with the data obtained in experiments. It indicates that the numerical simulation can effectively be used to study the water flow movement and the energy dissipation mechanism. The numerical simulation results show that the turbulent kinetic energy distribution obtained by using the Mixture turbulence model covers a region about 18% larger than that calculated by using the VOF turbulence model, and is in better agreement with the actual situation. Furthermore, the Mixture turbulence model is better than the VOF turbulence model in calculating the air entrainment.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 51279118, 50479062)the Key Projects in the National Science and Technology Pillar Program (Grant No. 2008BAB29B04)
文摘Measurements of turbulent flow fields in a stilling basin of multi-horizontal submerged jets were made with the single- camera Particle Image Velocimetry （PIV）. The particle images were captured, processed, and subsequently used to characterize the flow in terms of the 2-D velocity and vorticity distributions. This study shows that the maximum close-to-bed velocity in the stilling basin is approximately reduced by 60%, comparing to the jet velocity at the outlet of orifices. The jet velocity is distributed evenly at the latter half of the stilling basin and the time-averaged velocity of the cross section is reduced by 77%-85%, comparing to the jet velocity at the outlet of orifices. These results show that the vortices with horizontal axes are continuously repeated during the form-merge-split-disappear process. The vertical vortices are continuously formed and disappeared, they appear randomly near the slab and intermittently reach the slab of the stilling basin. The range of these vortices is small. Vortices with horizontal axes and ver- tical vortices do not coincide in space and the vortices with horizontal axes only affect the position of the tail of the vertical vortices attached to the slab of the stilling basin.
基金Project supported by the National Science Foundation of China(Grand Nos.51079091,51209154)
文摘Energy dissipations induced by the hydraulic jump and the trajectory jet are the most widely known as the two dissipation modes at the downstream of flood discharging structures, which are often considered quite different even contradictory. However, such two energy dissipators can be used jointly and harmonically. In this paper, a new type of stilling basin with a shallow-water cushion and a triangular bottom deflector is proposed based on two different scale physical model tests of the flood discharging tunnel No.2 of Luding hydropower project. The experimental results show that the flow regime of the hydraulic jump in the presented stilling basin with bottom deflector enjoys a good and stable performance within a large range of flow rates and the energy dissipation rate is considerably high as compared to the conventional stilling basin even at a low Froude number. The results also indicate that the stilling basin with triangular bottom deflector has a better performance in improving the potential cavitation erosion according to the analysis of the pressure and the cavitation number compared to the trapezoidal one. The proposed new type of shallow-cushion stilling basin with a shallow-water cushion can be applied in similar energy dissipation projects with low Froude number and large range of flow rates.
基金the Chamran University of Ahwaz,Jundishapur University of Technology,and the Centre of Shahid Excellence on Operation Management of Irrigation and Drainage Networks for financial support and facilitation of the experiments
文摘Experiments were conducted to characterize forced hydraulic jumps in stilling basins for enforced cases due to tail water level or dam site arrangement and construction. The case with a single tall sill was simulated in a horizontal flume downstream of a sluice gate. Results of experiments are compared with the classical hydraulic jump, and significant effect of tall sill on dissipation of energy in shorter distance was confirmed. Furthermore, the generated jumps were classified based on the ratio of sill height to basin length, and a simple design criterion was proposed to estimate the basin length for a desired jump and particular inflow.
