Implementing an emissions-rate model in computational fluid dynamics simulations of contaminant diffusion processes: A case study with xylene in painting workshops

摘要

Organic solvents frequently lead to substantial occupational health issues in secondary industries. This study examined the xylene diffusion process in painting workshops as a case study to develop a control of indoor air quality in manufacturing workshops. Three-dimensional simulations of xylene emission were built based on a ventilated chamber test to provide the source term for the mathematical model. An exponential relationship was established between xylene emissions rates and time. Numerical results obtained using the emissions rate model were more consistent with experimental data than those from constant emission rate. Owing to the property that is denser than air; therefore, given the coupled influence of molecular diffusion, gravity and environmental turbulence, the xylene concentration at a height of 0.75–2.5 m is high, and it could possibly exceed the Chinese standard, GBZ 2.1–2019 permissible concentration time weighted average (PC-TWA) of 50 mg/m~(3)in human-occupied zones. At the height of the human breathing zone (1.1 m), the aggregated concentration may even exceed the PC-TWA at 450 s by 100 times. Considering that the diffusion of xylene in a painting workshop represents heavy-gas pollutant diffusion problems, this study can be extended to predict pollutant concentration distributions in other secondary industrial workshops.