عنوان مقاله [English]
نویسندگان [English]چکیده [English]
On the one hand, the limited energy resources and on the other hand increasing energy demand are the factors that enhance the importance of energy management in micro and macro programs, in developed and developing countries. The head loss in different parts of pipelines causes an increase in the amount of energy consumed by the pumps. Therefore, reducing it is critical. One of the most important and easiest ways to reduce energy consumption during fluid supply is using friction-reducing materials in the flow.
In this study, a setup was conducted to find out the effect of adding a small dose of three different polymers (Karaakryl30, Karaakryl58 and Sodium carboxymethyl cellulose) on changing friction losses and its effect on the spray radius of sprinklers in a pressurized irrigation system; in which three Hunter type sprinklers were used. To investigate the effects of these three polymers, the irrigation system consisted of a galvanized tank, a valve to control the flow rate at the beginning of the pipeline, polyethylene pipes with a diameter of 20 mm and a length of 40 meters, three Hunter sprinklers. And two amount of pressure were used. In the first stage, pure water was used to measure the flow rate and the head loss. In the first stage, the experiments were related to the control treatments in which pure water was used to measure the flow rate and energy loss. First, the tank was filled with water. Then, the initial and final sprinklers' output were closed. The sprinkler's nozzle at the end of the path was opened to measure the discharges. And then the control valve fully opened. By switching the pump, water from the sprinkler's output flowed out. After this stage, the discharge valve fully opened and the head loss was measured. Then, by adjusting the control valve (reducing the flow), the amount of flow and pressure were measured again. Adjusting the control valve was performed in 5 different conditions with pure water. The polymer Karaakryl30 was tested with the concentration of 100 mg per liter which was once dissolved in water and then stirred after half an hour again. After that, the pump started immediately. In the same way of the pure water measuring, the pressure and flow rate were measured. Then the Pump was turned off and all three sprinklers were installed, adjusted and fasten to fulcrums in the given situations. After pump working, the radius of spraying was measured. In the next stage, without any changes to the system compared to its previous state, the tank was filled with water again and the pump was turned on. After pumping all the water in the tank, the spraying radius was measured and compared with a spraying radius of Karaakryl30 solution (100 mg per liter). All the above steps for each of the three materials were tested at three concentrations. By fitting a curve for discharge and head loss data, the relationship between them was obtained, for pure water and the three polymers in three concentrations. Using these relationships, the head loss values were obtained in the same discharges. Considering that friction-reducing material reduces head loss in the pipeline, it increases the pressure in sprinkler nozzles and as a result increases the spraying radius. In this aspect, the effect of adding the polymers on spraying radius was studied, in three concentrations.
The results showed that Karaakryl30 and Sodium carboxymethyl cellulose had the better effect on reducing the head loss and increasing the spraying radius, comparing to the Karaakryl58. The amount of head loss in the discharge of 0.423 lit/s for pure water, Karaakryl30, Karaakryl58 with the concentration of 1000 ppm and Sodium carboxymethyl cellulose with the concentration of 150 ppm was 20.04, 12.8, 16.09 and 12.39 meter, respectively, at the pipe length of 40m and diameter of 20mm. Karaakryl30 with 1000 ppm concentration led to maximum reduction of friction (36.1%) in pipelines and maximum increase in sprinkler spray radius (11.6%), comparing to pure water. Using polymer Karaakryl58 at the same level of concentration increased the same parameters 19.6 and 5.9 percent, respectively. Sodium carboxymethyl cellulose (150 ppm) increased the same measured parameters to 38.1 and 15.6 percent, respectively.
Thus, Karaakryl30 and Sodium carboxymethyl cellulose could be recommended to use in sprinkler systems in short-time and emergency situations such as high evapotranspiration for which it is not economical to consider the pipes with larger diameters in design.