Determination of CO₂ concentration stratification in a ventilated room using a simplified physical model based on CFD simulation

Almost all existing indoor environment control strategies in air conditioning systems consider indoor air well mixed. However, the unevenness always causes poor thermal comfort in the ventilated room, especially the occupied zone. The negligence of indoor air distribution is one of the main reasons for insufficient indoor environment control, which in turn causes frequent complaints against the poor indoor environment. A dynamic model is developed to predict the CO2 concentration response in a space with mechanical ventilation. This model can be used for optimal indoor environment control to overcome shortcomings of perfectly mixed models of indoor air Few researches have been achieved on the development of accurate but computationally efficient dynamic room model for optimal control. In this paper, the CO2 concentration response of different positions in this ventilated room need to be attained for identifying the unknown parameters and order of the model. The CO2 concentrations are calculated using the transient CFD numerical simulation with step up inlet CO2 concentration. An area identification algorithm is presented to identify the model from the CFD simulation results. The model identified can predict the CO2 concentration dynamic response in a ventilated room accurately. The model developed is more competent for prediction of the dynamic CO2 concentration response owing to less computational burden than complicated CFD models. Therefore, it can be used as a tool for online optimal control as well as simulation for developing optimal control strategies in order to achieve better indoor environment quality.