Numerical simulation and application of micro-nano bubble releaser for irrigation

Abstract

In oxygenated irrigation, there are problems of large oxygenated bubble particles, low oxygen concentration in water, and mismatch with current irrigation systems. In this paper, numerical simulation of micro-nano bubble releaser was carried out and the development of oxygenated irrigation equipment was studied. The release method of dissolved gas was selected to generate micro-nano bubbles after comparing different micro-nano bubble generation methods. The basic structure of the core-component releaser of generating micro-nano bubbles was initially determined. Effects of different structures of the release device on water aeration performance were studied by CFD analysis method. An optimal structure of the releaser was determined with orthogonal experiments based on a single factor experiment. The structural parameters included a throat of a 3 mm diameter, a 2 mm thick turbulent cavity, a six-degree exit angle, and two outlets. Optimal inlet and outlet pressure difference of the release device was 0.3 MPa. The bubble had an average particle size of 373.1 nm as measured. The release device was fabricated by 3D printing technology and the micro-nano bubble aeration irrigation device was developed. The system function test was carried out. Under the standard state, the performance parameters of the micro-nano bubble aerator included the maximum oxygen concentration of 11.4 mg/L, a total oxygen transfer coefficient of 0.4139 min-1, 0.0114 kg/h oxygenation capacity, and 60.81% oxygen utilization rate. The device had advantages of a high oxygen-increasing efficiency and a small volume, making it quite prospective in the field of oxygenated irrigation.