Abstract
The vacuum-blowing cleaning system, utilizing positive and negative pressure mixed-delivery theory, has been adopted for the road sweeper vehicle. To enhance the solid particle separation performance and to evaluate the motion characteristics of inhaled particles under different structural parameters, the gas-solid flow in the vacuum-blowing cleaning system was investigated by using computational fluid dynamics (CFD) technology. The influence of the main structural parameters on the grade dust collection efficiency and average detention time of the inhaled particles was determined, such as suction-inlet diameter, suction-inlet inclination angle, and front baffle inclination angle. And the interplay between them was also investigated. In addition, a dust collection efficiency model was built, based on uniform design (UD) and multiple regression analysis (MRA), and subsequently verified via experiments. The results revealed that the structural parameters have significant influence on the dust collection performance. The suction-inlet diameter, front baffle inclination angle, and suction-inlet inclination angle exerted the highest, second-highest, and lowest influence, respectively. Furthermore, the interaction among structural parameters also influenced the collection performance. The highest, second-highest, and lowest levels of influence were determined for the inlet diameter/baffle inclination angle, inlet inclination angle/baffle inclination angle, and inlet diameter/inlet inclination interactions, respectively. The highest dust collection efficiency (i.e., 96.10%) and a short average detention time of particles in the chamber were realized under the following conditions: suction-inlet diameter and inclination angle: 200 mm and 110°, respectively, and front baffle inclination angle: 105°.
Highlights
In recent years, particulate pollution has become increasingly severe, and has attracted considerable attention [1]
To simplify the working process of dust collection during mobile operation of the vacuum-blowing cleaning system, the simulation model is simplified as follows: (i) The cleaning operation occurs without heat exchange between the air in the vacuum-blowing cleaning system and external air; (ii) The airflow in the dust collection system is incompressible and undergoes stable-state flow, and boundary conditions remain unchanged with the time; (iii) The expansion area is designated as the region surrounding the vacuum-blowing cleaning system, and the inlet pressure is set to standard atmospheric pressure; (iv) The vacuum-blowing cleaning system moves at a constant speed during operation, and dust particles are static unless being inhaled via the front inlet surface
The most significant drop occurs for diameters ranging from 45 to 152 mm, and a given inclination angle of 60°. This results from the fact that, similar to the suction-inlet inclination angle, a suitable baffle inclination angle contributes to the smoothness of air flow and improvement of the dust collection efficiency
Summary
Particulate pollution has become increasingly severe, and has attracted considerable attention [1]. Using a parameter design method, Yang et al [19] assessed the width, diameter, and inclination angle of the dust collection system, and determined the optimal combination of structural parameters. The aforementioned studies are all based on the analysis of single gas-phase flow, thereby providing theoretical support for the structural design and simulation computation of a dust collection system. Using a gas-solid two-phase liquid computing method, Wu [22] determined the running speed and system pressure drop of a dust collection system, and proposed an optimum operation-condition range. The structural parameters required for the modeling of a vacuum-blowing cleaning system are investigated from the viewpoint of their influence on the dust collection efficiency. The motion characteristics of inhaled particulates are evaluated using a computing method where a gas-solid two-phase liquid is considered. The optimal structure is determined based on uniform experiments and regression analysis considering the structural interplay, and the rationality of the numerical simulation is verified via experiments
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