A thermal process control laboratory

Thermal systems are an important segment of engineering design, but practical, realistic laboratory models are not plentiful. There are some educational oriented systems models, but these are expensive and typically the design details of the machine are not furnished with the purchase of the equipment, making deviation from the original intent of the equipment difficult. This paper describes the development of a small, portable, and inexpensive system that allows students a wide range of educational experiences. Students may study the overall design and construction of the system, selection and cost of components, and the effect of different control schemes. The laboratory apparatus is built around an industry standard, low cost PLC. The control scheme may be changed from a simple OFF-ON control to a PID loop by a software routine on the PLC. Heating and sensing devices are those used typically in plastics manufacturing equipment and the controlled device may be varied to simulate the effect of process conditions and raw material on the thermal control system. Data logging is available to allow students to record and observe the system effect of process changes. The apparatus may be fabricated at a low cost (under $500), is small in size and portable, and may be powered from available single phase AC voltage. This has important implications in programs where lab space or funding is an issue, and also may be integrated into distance education programs. Examples of integration into courses are addressed.