论文和技术资料

Europeans spend between 80% to 90% of their time indoors, for example at home, school, office, and other public buildings. Besides, due to energy-saving measures in buildings, natural ventilation is reduced leading to the accumulation of indoor air pollutants. Consequently, indoor air quality plays a significant role in human health. To combat indoor air pollution effectively, integrating air purification devices into continuous flow systems such as HVAC (Heating, Ventilation, and Air Conditioning) equipment is an interesting approach. One viable technology for this purpose is electrostatic precipitation (ESP), a widely used and efficient technique for removing particulate matter (PM) from the air. ESP devices consist of an ionisation section where a strong electric field is generated between two electrodes. This leads to corona discharge of the air passing through, causing the particles to become charged. Subsequently, in the collector section, the charged particles are electrostatically attracted to a collecting surface and removed from the air. In this work, a simplified two-stage ESP device for indoor air treatment was investigated using the COMSOL Multiphysics® software. In contrast to the single-stage electrostatic precipitator model found in the Application Libraries, this device consisted of a separate ionisation and collector section, which were initially treated in two separate models (2D). Firstly, steady-state airflow was implemented in both sections using the k-ω turbulence model (CFD Module). To account for the secondary electro-hydrodynamic flow, a volume force feature was incorporated into the model in a later stage. In the collector section, the static electric field was implemented using Poisson's equation (Electrostatics). Particle motion throughout both sections was simulated using a Lagrangian approach, tracking the trajectory of a number of representative particles. The dominant forces affecting particle trajectories in ESPs are the drag force caused by the airflow and the Coulomb force resulting from the electric field (Particle Tracing for Fluid Flow). It was assumed that a particle adhered to the collector plate once its trajectory intersected with it, leading to the accumulation of charged PM. An essential aspect of ESP operation is the corona discharge, which charges the particles passing through the device. To simplify the model, a simplified corona model was employed, omitting detailed simulation of all plasma processes. Mathematically, corona discharge can be described using Maxwell's equations, assuming steady-state conditions and the absence of a changing magnetic field. This results in two coupled equations representing the electric potential and electric charge density distribution, solvable with appropriate boundary conditions (Plasma Module). The ionisation section was initially modelled in 2D and will be extended to 3D. Subsequently, it will be coupled with the collector section model. Experiments still need to be conducted using the simplified device connected to a climate chamber, along with PM generation and detection equipment. Once validated with these experimental results, the model will be used to determine the effects of particle size distribution, concentration, the strength of the electric field in the collector section, and the distance between the collector plates.