Generalized algorithm for simulating contaminant distribution in complex ventilation systems with recirculation

摘要

In complex ventilation systems with air recirculation, the contaminant concentration at the supply inlets is generally unknown, which limits the application of computational fluid dynamics (CFD) tools to simulate the indoor contaminant distribution. In this article, we develop a new algorithm that can deal with different ventilation scenarios while it requires minimum computing time. This algorithm divides indoor contaminant distribution into two parts: the contribution from inlets and the contribution from sources. The former can be obtained with the concentrations at inlets and volume fraction for each inlet, which is defined as the relative concentration when the boundary concentrations are 1 for the inlet and 0 for other inlets. The latter is calculated by setting the concentrations at all inlets as 0. By combining the contaminant transportation characteristics in rooms and system ducts, the algorithm does not require iteration to solve the contaminant distribution in actual ventilation systems. The demonstration results of two case studies show the great influence of duct configuration on indoor contaminant distribution.