Experimental Validation of a Low-Energy-Consumption Heating Model for Recirculating Aquaponic Systems

Electrical energy is the highest energetic cost in recirculation aquaponic systems (RASs), especially for fish-tank water. Therefore, reducing energy consumption is one of the challenges in developing RAS models. In this study, eleven experimental setups, based on numerical models from an earlier investigator, were built to investigate. Among them, three additional cases (cases 9-11) investigated the transient discharging energy efficiency of thermal energy storage (TES). Cases 9-11 considered three temperature levels, namely, 65-75 degrees C, 71-81 degrees C, and 81-87 degrees C, with a mass flow rate of 0.166 kg/s. The results show that when heating 3.4 m(3) of fish tank water from 24.5 degrees C to 28 degrees C, the average temperature error of the tank water was between 1.2% and 3.4%. The difference in the heat transfer rate was within +/- 4.2%. The error in the thermal efficiency was below 8.0%. The error range of the total required thermal energy was from 6.4% to 11.5%. Cases 9-11 used 5.6%, 6.4%, and 7.2% of the thermal energy of the TES tank, respectively. The electrical energy consumption was low compared to the thermal energy of the fish tank water received from the TES unit. Therefore, the proposed low-energy-consumption heating method can replace electric heaters.