Design and test of electrolytic water oxygen increasing device for small transport box of living aquatic products

Abstract: Fresh aquatic products are more and more favored by the market, with the continuous expansion of aquatic trade, living aquatic transportation becomes more and more important. How to improve the survival rate of living aquatic transportation and reduce the cost of living aquatic transportation is an urgent problem to be solved. To ensure the survival of aquatic transport process, it is necessary to maintain the original aquatic survival environment, such as pressure, water quality, dissolved oxygen degree and so on. The dissolved oxygen degree is the key parameter for the survival of aquatic products, then the oxygen increasing device becomes the key technology for small transport box. In order to develop a transportation device for living aquatic products that can continuously increase oxygen, consume less power, have small size, use flexibly and conveniently, a electrolytic water oxygen increasing device was designed for small living aquatic products transportation box. Firstly, a stable constant flow field needed to be created between positive and negative electrodes in the pipeline. Therefore, the structure of transport box and oxygen increasing device were designed, and the structure in the electrolytic water oxygen increasing device which can generate steady and uniform flow field was designed by computational fluid dynamics simulation software. The structural parameters of the flow straightening unit were design with different variables. The control variable method was used to determine range of the parameter, that is, the three variables were respectively controlled unchanged and the other variable was adjusted from small to large for the simulation test. The parameters selection via simulation results was convenient for efficient exchange of water and oxygen. Then, hypoxic water was prepared and the initial oxygen-solubility of hypoxic water was tested by a dissolved oxygen meter. The concrete experimental method was that the electrolytic water oxygen increasing device was placed at the bottom of the sealed box and seal the box body, then adjusting the electrolytic voltage and circulating pump flow rate and recording the dissolved oxygen degree, electrolytic voltage and electrolytic current every 5 minutes until the dissolved oxygen degree of the water reaches 100%. Surface of the relation between oxygen increasing rate and electrolytic voltage under different flow rate were drawn, and the influences of the bivariate of electrolytic voltage and water exchange flow rate were explored. The test results indicated that the lowest total energy consumption was 39.39 kJ when the electrolytic voltage was 37 V and the water exchange flow rate was 6.97×10-5 m3/s for the box volume of 8×10-3 m3 using direct current electrolysis. In the process of ensuring continuous oxygen increasing, three working modes as follows could be realized through controlling the electrolytic voltage and water exchange flow rate. Maximum water exchange flow rate and electrolytic voltage could realize rapid oxygen increasing mode of large amount of oxygen bubble overflow; The local saturation oxygen increasing rate state parameter was adopted to realize the bubble-free oxygen increasing mode; When there was only a small amount of aquatic products or standby, the lowest combined parameter of energy consumption was adopted to realize the low energy consumption mode. The design method and test results for the electrolytic water oxygen increasing device in this study can provide a basis for the application of electrolytic water oxygen increasing method in living aquatic transportation and aquaculture.