Simulation of the transport of negative ions in air ventilation ducts and validation by experimentation

This study investigated how to effectively remove particle and aerosol microorganisms in ventilation ducts, and to deal with the problems of aerosol microorganisms, which breed in air conditioning systems over the long term without maintenance and cleaning andconvert to bioaerosol pathogens and threaten people's health. A numerical model of negative ions was established to investigate the transport and distribution of negative ions in ventilation ducts by the Euler method. Negative ions generated by VI-2500 in a 0.2 m×0.2 m air ventilation duct with 3-6 m/s air velocity were simulated and measured to validate the numerical model and investigate the distribution of negative ions. The results showed that negative ions predicted by the numerical model agreed well with the measured values. The lowest negative ions and the average negative ions were about 9.15×10⁹ and 2.39×10⁹ ions/m³, with 3 m/s air velocity, and 2.37×10¹⁰ and 6.83×10⁹ ions/m³ with the air velocity at 6 m/s. The negative ions level increased with increasing air velocity and decreased downstream along the duct under constant air velocity. The lowest or average negative ions could still satisfy the lowest negative ions amount (10⁸-10¹⁰ ions/m³) suggested by reference for effective purification when the air velocity was 3 m/s. The numerical model of negative ions could accurately predict the negative ions generated by VI-2500 in 0.2 m×0.2 m ventilation duct, and the negative ions met the purification demand of the 4.5 m ventilation duct.