Design And Verification Of Water Pushing Microporous Oxygen Increasing Device

As a new mode of freshwater aquaculture,’ zero emission ’ recirculating aquaculture has the characteristics of green,high efficiency and high yield.However,high-density farming also brings problems such as high dissolved oxygen demand.Especially in hot summer,high temperature and low pressure environment will reduce the dissolved oxygen concentration in water,which can lead to fish death in severe cases.Therefore,in view of the energy consumption and efficiency of oxygen enrichment and automation requirements in high-density farming mode,this paper proposes a design scheme of water pushing microporous aeration oxygen enrichment device based on Internet of Things technology,sensing technology and automatic control technology.The main contents are described from the following four aspects.(1)An efficient and energy-saving oxygen enrichment scheme is proposed.In this scheme,high-pressure pure oxygen is used as the gas source,and oxygen is divided into bubbles with a diameter of 0.1 – 0.5 mm through pneumatic components such as pressure reducing valve and solenoid valve,and then nano-sized alumina ceramic is used as an aerator.At the same time,the underwater motor propeller is started to form water flow,and the oxygen bubble and water are fully mixed and pushed out to achieve rapid,efficient and uniform oxygenation.(2)Based on the Internet of Things technology,the overall hardware circuit of the oxygen enrichment device is designed to realize the collection,wireless transmission and automatic control of the main parameters such as dissolved oxygen concentration,water temperature,air pressure and environmental temperature and humidity.The circuit includes the core board and the expansion board.The CC3200 MODA with WiFi communication processor is selected as the main controller in the core board,and the external hardware watchdog max637 is added to improve the working reliability.The expansion board includes sensing detection units such as dissolved oxygen concentration,air temperature,humidity and pressure,PWM speed regulation and control circuit of underwater motor,control circuit of solenoid valve and power supply unit.After drawing schematic diagram and PCB diagram,the board is made,assembled and debugged.(3)The embedded software driver and Internet of Things communication protocol are designed.The overall framework of the program includes WiFi network configuration,temperature and humidity sensor SHT35 and pneumatic sensor BME680 driver module,UART dissolved oxygen sensor driver module and oxygen control module.In addition,the message structure based on message queue transmission protocol is designed for the captivity bucket farming mode.At the same time,in order to ensure the safety of agricultural data transmission,SSL encryption algorithm is used to encrypt the information.After the joint debugging,the functions of information collection,oxygen enrichment mechanism control and data transmission can be realized.(4)Optimization and performance test of oxygen enrichment device.The influence of the distance d between the motor and the aerator and the speed of the motor on the oxygen increase effect was tested.The results show that the oxygen increase effect is the best when d is 14 cm and the duty ratio of the motor speed is set to 60 %.The performance test results showed that the oxygen enrichment capacity of the device was 0.0748 kg / h,and the oxygen utilization rate was 43.7 %,which basically met the oxygen enrichment requirements of high-density farming.It shows that the oxygen enrichment scheme proposed in this paper is reasonable and feasible,and has a certain reference value for the development of high-density enclosure mode of aquaculture.