Numerical evaluation of contaminants mixing uniformity in a full-scale test chamber with mixing fan

Abstract

Most existing models and standards for volatile organic compounds emission assume that contaminants are uniform in the testing devices. In this study, a three-dimensional transient numerical model was proposed to simulate the mass transport process based on a full-scale test chamber with a mixing fan, and the airflow field and contaminants concentration distribution were obtained within the chamber under airtight and ventilated conditions. The model was validated by comparing the numerical results with experimental data. The numerical results show that the contaminant source position and the airflow field characteristics have significant impact on the contaminant mixing, and the fan rotation has an important role in accelerating mixing. In the initial mixing stage, the concentration distribution is obviously uneven; as the mixing progresses, it gradually reaches acceptable uniformity except for some sensitive regions, such as high concentration region at the injection point of the contaminants and low concentration region at the air inlet. To ensure test accuracy, the monitor should avoid above sensitive regions; and some special regions are recommended where contaminant concentration uniformity can be reached sooner. The ventilated chamber results indicate that the mixture of contaminants in the chamber is actually better than the results shown by conventional test method.

Application of polyhedral meshing strategy in indoor environment simulation: Model accuracy and computing time

“…From the available literature, many studies had been conducted to develop optimal CFD strategy for indoor environment simulations, 9 such as turbulence model choice, 10–12 airborne pollutant models, 13–15 parameters/variables of various indoor air conditioning systems and different meshing strategies. 16–19 The meshing strategy is how to determine mesh type and grid number/distribution in numerical simulations.…”