Development and Simulation of a Low Cost Closed Thermal System to Generate Thermal Cycles through PID Control and IoT Applications

The aim of this paper is to present the development of a multi-purpose device that enables the variation of temperature in a closed chamber with known volume. This system will allow students, researchers and engineers to acquire accurate data and process them in different applications where temperature control is relevant, for example bacterial growth, conservation of biological material,dry air sterilization and other laboratory process. The proposed approach applies proportional-integral-derivative (PID) control loop mechanism, which is widely used in laboratory equipment and industrial control systems. The difference with other systems is, that the one presented here, can be customized using inexpensive components including hybrid digital electronic and analogue actuators. These components can be arranged in different configurations according with a specific need or process. A thermal model was developed taking into account losses and disturbances, and the mathematical model was formulated by finding three different transfer functions for three temperature zones. The first zone covers the range from ambient temperature to 60° C with an actuator (Rb), another actuator for the range from 60°C to 200°C (Ra) and the third actuator (Rc) that covers the range from 0 to -13°C. The data is acquired using an Internet Of Things (IoT) platform.