VEPZO ― Velocity propagating zonal model for the estimation of the airflow pattern and temperature distribution in a confined space

The goal of this paper is to build a locally refined non-isothermal airflow model. This model should not need prior knowledge of the expected airflow pattern to allow the evaluation of many different configurations. For this a new zonal model, the VEPZO (VElocity Propagating ZOnal) model has been developed including the airflow velocity as a property of a zone and a viscous loss model to compute the airflow between the zones. The velocity information from a zone is passed to the flow models and is therefore propagated into the room. Instead of using the power law equation or specialized jet or plume correlations to model the airflow between two zones, an equation derived from the forces acting on a flow path is used. These forces generate an acceleration or deceleration of the airflow. Losses are modelled by viscous dissipation. Two other models, the singular loss and the buoyant singular loss model are presented too. These models can be used to model flow paths through e.g. windows or doors. Results using the VEPZO model are compared with data from two case studies used to validate other zonal models. Airflow and temperature distributions are comparable to the results calculated by other zonal models. Furthermore, the VEPZO model is compared to an experimental setup with several interacting heat sources, showing the strength of the approach not needing specialized correlations for these elements. The VEPZO model is implemented in the equation-based and object-oriented language Modelica and can therefore be interfaced to other physical models.