Abstract:Aerated drip irrigation can effectively improve crop production efficiency and crop yield. The formation of a large number of uniform smaller micro-bubbles in the aerated system and the improvement of dissolved oxygen concentration in irrigation water are the key to the long distance uniform water and air transport of aerated drip irrigation. The working conditions of a micro- and nano-bubble generator designed was optimized based on the principle of cyclonic shear fragmentation. Through one-way test analysis, high-speed photography and dissolved oxygen meter, the influence of system operating pressure and air inlet on bubble characteristics ( count, diameter and uniformity) and dissolved oxygen was studied. Finally, combined with the response surface RSM optimization test, the combination of operating pressure and air inlet under the optimal aerating effect of the device was determined. The results showed that the generation of bubbles and dissolved oxygen effect were better when the pressure was controlled within 300 ~ 400 kPa. In the range of 1% ~ 5% of air inlet, the best diameter distribution and the smallest average diameter were obtained with 1% of air inlet, while the rate of bubble generation was higher with 5% of air inlet. Meanwhile, the dissolved oxygen test showed that increasing the air intake significantly increased the dissolved oxygen efficiency as well as the final oxygen content. Through the response optimization solution, it was concluded that the plant could operate at a pressure of 350 kPa and an air intake of 2% with the lowest energy consumption. Under this condition, the final diameter of the small bubbles generated by the device was 68.6 μm, the rate of oxygen enhancement was about 0.81 mg / (L·min), the net increase in dissolved oxygen after stabilization was 1.08 mg / L, and the bubble dissipation time was up to 323 s.
