Design, Development and Testing of an Aquaculture Research Temperature Control System

Abstract

A feedback based variable temperature-control system was developed for facilitating indoor aquaculture research. The system included sixteen independent tanks controlled by a personal computer using T-type thermocouples, a 32-channel multiplexer, two 8-channel analog to digital converter boards, and a set of 32 relays.  Electric immersion heaters were used to increase water temperature, while a chiller and heat exchanger was used for cooling. Five centimeter PVC airlifts allowed for aeration and circulation of water. The system was initially used to simulate fixed and diurnal temperatures, but can be programmed to hold or varying temperatures from 5°C to 34°C in each tank independently. In one set of experiments, tanks were held at 10°C, 15°C and 20°C. Initial results indicated that the system was capable of maintaining and controlling water temperatures within ± 0.4°C. In a different set of experiments, diurnal temperatures (10 ± 5°C, 15 ± 5°C, 15 ± 10°C, 20 ± 5°C) were simulated. Results indicated that the control system was effective in heating the water to the desired temperatures but requires an additional chiller to cool the water. Use of variable temperature control, coupled with the independence of each tank, allows aquacultural researchers to simultaneously simulate a variety of seasonal temperatures inside their laboratories.