Solar Heat Driven Water Circulation and Aeration System for Aquaculture

The proposed design concept of water aeration and updraft circulation in aquaculture is based on the Organic Rankine Cycle (ORC) technology and uses a solar energy absorbed by a floating collector. The pressure required for the aerator is created by evaporating a working fluid and optimized for an average depth of a pond. The working pressure is defined by the maximum achievable temperature of the working fluid. The condensing heat is rejected at a certain depth with the lowest temperature and drives the convective circulation. A prototype is designed by using common materials and off-the-shelf components to ensure maintenance-free and proper capacity to fulfil the needs of an average or a small aquaculture farm: the working fluid in the working chamber evaporates increasing in volume and pumping air out of the vessel as well as the expanded working fluid in the second working chamber. The working fluid is cooled down in the condenser which is submerged into the pond and it is condensed while decreasing in volume. The new design can perform multiple cycles per day increasing the volume of pumped air. In order to make the operation of this unit possible during the night, a heat buffer with a phase changing material (PCM) is used. A parametric study of suitable working fluids and PCMs has been performed in order to select the most appropriate combination for the target applications.

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