Diffusion characteristics of re-suspended PM2.5 within a radiant floor heating room under various ventilation modes

Abstract

Few studies have revealed the effects of re-suspension of particulate matter deposited by radiant floor heating on indoor environments. The present study utilized Computational Fluid Dynamics (CFD) to investigate the impact of radiant floor heating and ventilation mode on indoor airflow patterns, as well as the dispersion and migration of re-suspended particulate matter, based on a turbulence model validated by an environmental test cabin. The Archimedes number (Ar) was employed to represent the strength of interaction between the thermal buoyancy force generated by floor radiation and the inertial force of the supply airflow. The results indicates that as Ar increases, the supply airflow exhibits a downward deflection, thereby forming a stable vortex below to prevent the diffusion of heat and re-suspended PM2.5 generated from the heated floor. As the Ar increases, the re-suspended PM2.5 deposited on the surrounding walls increased significantly, and the indoor PM2.5 concentration gradually decreased. When the Ar exceeds 6.03, the increase in Ar will no longer affect the indoor re-suspension PM2.5 diffusion, deposition characteristics, and removal efficiency. Therefore, it is recommended the critical Ar (Arcrit) of 6.03 for a radiant floor heating room under various ventilation modes, beyond which the indoor flow structure and distribution characteristics of re-suspended PM2.5 no longer change with increasing Ar. This study is helpful to further understand the diffusion and distribution characteristics of re-suspended particulates in floor heating and ventilation rooms, and provide technical reference for improving indoor air quality.