In industrial buildings, the presence of overhead cranes severely affects roof exhaust ventilation systems when capturing and discharging fumes, resulting in severe deterioration of the indoor plant environment. In this study, an overhead crane-based ventilation auxiliary device, called overhead crane fume-collecting hood (CFCH), is proposed to guide pollutants blocked by the overhead crane back to the roof exhaust hood. The airflow characteristics and pollutant distribution under the three modes of no overhead crane, overhead crane, and overhead crane + CFCH were compared using numerical simulations. Subsequently, the effects of the CFCH length (a), width (b), and height (h) on the pollutant capture performance were determined through orthogonal experiments and computational fluid dynamics. Finally, the pollutant capture efficiency (PCE) of the optimal CFCH was investigated considering different exhaust airflow rates. The results showed that the pollutants captured by the CFCH can be classified into directly and secondary captured pollutants, with the directly captured pollutants dominating. In addition, with the introduction of different sizes of CFCH around the overhead crane girders, the PCE significantly improved by 49.9%–74.6%. The length, width, and height of the CFCH on the PCE were statistically significant, and the priority of the three factors was as follows: h > b > a. The PCE decreased with increasing a, initially increased and then decreased with increasing b, and increased with h. Subsequently, when the optimal CFCH was used, the excessive exhaust air rate had no evident PCE improvement. This provides a new concept for the control of pollutants in industrial buildings and provides a theoretical basis for the design of CFCHs.

Energy consumption of industrial buildings has remained continuously high, and the environmental quality requirements are also constantly improving. Only by improving industrial environmental control technology based on the transport mechanism of the pollution, can the energy consumption of industrial building environmental control be further reduced, and the environmental quality of industrial buildings can be improved as well. Therefore, after verifying the numerical simulation by experiments, this study uses a self-label method to investigate the spatio-temporal distribution of gaseous pollutants from multiple time-series sources in industrial plants with different length-span ratios. The results show that, the polluted flow in plants with different aspect ratios have different flow patterns: (i) the "Back-mixing" flow pattern occurs when the ratio of ventilation rate G and polluted flow rate at the exhaust height L_P is less than 1, i.e., G/L_P < 1, and (ii) the "One-way" flow pattern occurs when G/L_P > 1. For plants with the "Back-mixing" pattern, the following source pollutants enter a density stratified environment induced by the retained pre-source pollutants. The flow of following source pollutants released at the same intensity as the precursor source can reach the roof, while those with low velocity and density difference may be blocked during the ascending process. The maximum height z_m of the flow of the following source is related to both the initial Froude number Fr₀ of the following source and the unsteady vertical density gradient of the fluid in the indoor environment dρ_a/dz. For plants with the "One-way" pattern, the flow from the following source enters into an environment with approximately uniform density. Under the condition of positive buoyancy, design parameters of ventilation corresponding to the vicinity of G/L_P = 1 may be the optimal solution for safety and energy conservation.