Experimental and numerical simulation of horizontal piston flow ductless ventilation system in large space of underground sewage treatment plants

The operating layer of the underground sewage treatment plant is the main area of staff activity, and the mechanical ventilation is required to ensure air quality. The commonly used air duct ventilation system has many shortcomings such as complex design, high cost, and ceiling duct system increasing the overall burial depth of the operating layer. In this paper, a new type of ductless ventilation system based on horizontal piston flow is proposed for the operating layer of an underground sewage treatment plant. The shrinkage experiment and CFD simulation are used to verify the feasibility of the ductless ventilation system applied to the large space of the operating layer of the underground sewage treatment plant, and its airflow organization and pollutant removal ability are studied. The results show that the ductless ventilation system can form a horizontal piston flow inside the flat large space of the operating layer of the underground sewage treatment plant, and efficiently guide the pollutants to be discharged from the exhaust outlet nearest to the pollutants, thereby effectively improving the air quality. Compared with the duct ventilation system, the ventilation efficiency of the ductless system is higher, which has obvious advantages in ventilation performance, and can effectively reduce the burial depth of the underground sewage treatment plant and reduce the difficulty of construction.