Model-based temperature and humidity control of paint booth HVAC systems

The automation of industrial finishing processes in automotive industry requires accurate control of temperature and humidity of the inlet air to guarantee constant product finish quality. Industrial heating, ventilation and air conditioning (HVAC) control systems are used to maintain the required operating conditions for the finishing process even in presence of changes of the ambient air conditions. Industrial HVAC systems consist of different conditioning modules and a controlling device to control the temperature and humidity at the same time. This paper presents a model-based controller design for a series path air flow arrangement consisting of a heating coil and a spray humidifier. As a first step the governing model equations of the considered HVAC system are derived. Subsequently a disturbance feedforward controller based on the inversion of the derived model is designed. Finally simulation results are presented to validate the proposed controller.