مطالعه تجربی درباره میدان جریان و ویژگی های اقتصادی سیستم تهویه
Abstract
1- Introduction
2- Experimental setup
3- Results
4- Discussion
5- Conclusions
Acknowledgements
References
Abstract
Push-pull ventilation systems provide excellent control of contaminants and harmful gases. However, since both a push inlet and a pull outlet are used in the push-pull ventilation system, the flow rate required by the system is large. In that case, the energy consumption of the system is large. The purpose of this paper is to study the flow field and economic characteristics of a parallel push-pull ventilation system by reducing the flow rate of the exhaust outlet, which will be achieved by reducing the size of the exhaust hood. The three commonly used push-pull ventilation systems were analyzed: a high velocity push-pull system with high air supply velocity, a low velocity push-pull system with wide airflow and small velocity, and a parallel push-pull system with wide airflow and uniform air supply velocity. Results showed that the parallel push-pull ventilation system was the only one in which the flow rate of the exhaust outlet could be reduced, reducing the overall energy consumption. Under conditions of the parallel air supply jet, the diffusion range of contaminants in the push-pull flow field was the smallest and reducing the exhaust air flow rate did not affect the capture efficiency of pollutants. These results may be useful in guiding the design of push-pull ventilation system and optimize economic constraints.
Introduction
During different industrial production processes, contaminants such as dust and steam may be produced. In order to effectively protect the working environment of workers, local ventilation can be used [1–۶]. A widely used local ventilation method in industrial applications is the push-pull ventilation system, which has good pollution control [7–۹]. The system is composed of two parts: an air supply inlet and an exhaust outlet, which uses an air supply jet as the power to transport contaminants to the exhaust outlet [10–۱۳]. Depending on the type of air supply used, push-pull ventilation systems can be divided into high velocity push-pull ventilation system, low velocity push-pull ventilation system and parallel push-pull ventilation system. A High velocity pushpull ventilation system uses a high velocity supply jet to mix and transport contaminants [14,15]. A low velocity push-pull ventilation system uses low velocity and wide air flow to control workspace contaminants [16]. A parallel push-pull ventilation system uses a low turbulence intensity, uniform, and wide air flow with good directionality to push the contaminants into the exhaust outlet [13,17,18].
Initial research on push-pull ventilation systems was based on the high velocity system [19,20]. Betta et al. explored the capture of pollutants with different particle sizes [21]. Marzal et al. studied the effect of the geometric size of the air supply on capture efficiency and observed flow field characteristics by using airflow visualization [22,23]. Robinson et al. explored the flow field distribution and developed design recommendations for a push-pull ventilation system [24,25]. Rota et al. tested the impact of different factors on contaminant capture and proposed corresponding design suggestions [26]. Enrique Gonzalez et al. studied the effect of different sizes of exhaust hood on capture efficiency [27].