Modelling experiments with small-scale thermal system used for pig fattener heating

This study presents the ongoing research conducted in the field of thermal systems which are commonly used in agriculture and also in other fields to utilize the solar thermal energy. This paper describes a small-scale physical system that is controlled by hardware-inthe-loop (HIL) method. The solar thermal input is realized by a heating element, which can provide a 60 W power in total. The input energy is controllable via Pulse Width Modulation (PWM) to mimic the stochastic changes in weather. The heat storage unit is a 1 litre in volume isolated tank, which contains also the heat exchanger unit. The working fluid in this system is water which is forced by custom made peristaltic pumps both on the "collector" side and on the output. In this way the mass flow rate of the pump can be controlled on the heat exchanger and on the user side, as well. The user side is modelled by a water-air heat exchanger forcing cooled air by a varying speed fan. The temperatures are measured on several points of the system which are used to control the flow rates. Experiments were performed with various controlling algorithms in order to find an optimal solution to provide heat for a pig fattener. The recent status of the test results is shown in the case of On-Off and PID control methods in contrary.