The main performance indicators of the aerator are specified as aeration capacity and power efficiency. Aeration capacity refers to the amount of oxygen that an aerator adds to the water body per hour, in kilograms/hour; power efficiency refers to the amount of oxygen that an aerator consumes 1 kilowatt-hour of electricity to increase water, and the unit is kg/kWh . For example, a 1.5-kilowatt waterwheel aerator, with a power efficiency of 1.7 kg/kWh, means that the machine consumes 1 kWh of electricity and can add 1.7 kg of oxygen to the water body.
Although the aerator is used more and more widely in aquaculture production, some fishery practitioners still do not understand its working principle, type and function, and it is blind and random in actual operation. It is necessary to understand how it works first, so that you can master its use in practice. As we all know, the purpose of using aerators is to add dissolved oxygen to the water body, which involves the solubility and dissolution rate of oxygen. Solubility includes three factors: water temperature, water salt content, and oxygen partial pressure; dissolution rate includes three factors, namely, the degree of unsaturation of dissolved oxygen, the contact area and method of water-gas, and the movement of water. Among them, the water temperature and the salt content of the water are a kind of stable state of the water body, and generally cannot be changed. The degree of unsaturation of dissolved oxygen is the factor that we want to change, and it is also a current state of the water body. Therefore, in order to increase oxygen to the water body, it is necessary to directly or indirectly change the three factors of oxygen partial pressure, water-gas contact area and method, and water movement status. In view of this situation, the measures taken when designing the aerator are as follows:
1) Use mechanical parts to agitate the water body to promote convection exchange and interface renewal;
2) Disperse the water into fine mist droplets and spray them into the gas phase to increase the contact area of water and gas;
3) Inhale through negative pressure to disperse the gas into micro-bubbles and press them into the water.
Various types of aerators are designed and manufactured based on these principles. They either take one measure to promote oxygen dissolution, or take two or more measures.