Experimental study on design and operational performance of solar-powered venturi aeration system developed for aquaculture-A semi-floating prototype

Venturi-type injectors have been used usually due to the practical use and modular design that allows for quick configuration, ready-to-use, and low-cost solutions in the last years. This study aims to design a solar-powered venturi aeration system (SVAS) and determine its flow characteristics, standard, and real-time operational performance parameters. SVAS has a design providing the maximum vacuum and air velocity at air inlets and allowing for all technical measurements. Moreover, a solar-powered experimental apparatus having a weather station, a pool station, and a data logger station was constructed. Experiments were carried out using a plastic pool with a capacity of 4000 L, a diameter of 3 m and a depth of 0.75 m, four venturi injectors, and a submersible pump of 0.3 kW operated at the constant water flow regime of 4.1 m3 h-1. According to flow tests, the oxygen mass flow rates ranged from 2.77 to 2.84 kg h-1. The specific energy consumption values are 263.2 kJ per cubic meter for water flow and 380 kJ per kg for oxygen transfer.Standard performance experiments were repeated four times. The maximum overall oxygen mass transfer coefficient obtained during the experiments was 5.58 h-1. The maximum values of standard oxygen transfer rate (SOTR), standard aeration efficiency (SAE), and standard oxygen transfer efficiency (SOTE) were 0.206 kgO2 h-1, 0.681 kgO2 kWh-1, and 7.32%, respectively. The pool conditions were simulated using de-oxygenation and mixing systems to determine the operational performance. For simulation experiments, six procedures and two processes were applied. Throughout operational experiments of four days, real-time dissolved oxygen levels fluctuated between 1.05 mg L-1 and 6.65 mg L-1. The maximum performance values were 0.143 kgO2 h-1 for the actual oxygen-transfer rate, 0.474 kgO2 kWh-1 for aeration efficiency, and 5.1% for oxygen transfer efficiency.