Design and Implementation of a Temperature Control System for Aquaponic Fish Tanks in Kazakhstan

Sammanfattning

This thesis develops and evaluates a water temperature control system for an aquaponics facility in Kazakhstan, where stable thermal conditions are critical for system performance. The system consists of a closed-loop hydronic heating system using a gas boiler as the heat source to regulate fish tank temperature. Two control strategies, PI control and on–off control, were implemented, tuned and evaluated based on temperature stability and operational performance after deployment. The system successfully maintained the desired water temperature within acceptable limits. While PI control provided marginal performance improvements, on–off control was found preferable due to its lower implementation complexity and comparable performance. In addition, a comparative analysis of energy sources showed that gas heating results in approximately seven times lower operating costs and four times lower CO2 emissions than electric heating under current energy conditions in Kazakhstan. These findings suggest that simple control strategies combined with gas-based heating provide a cost-effective and environmentally favorable solution for aquaponics temperature regulation in coal-dependent energy systems.