Numerical and experimental study on airborne disinfection by negative ions in air duct flow

Abstract

In this paper, we develop a mathematical model that aims (1) to predict the distribution of negative ions generated by an air ionizer installed in a ventilation duct and (2) to predict the efficiency with which it inactivates bacteria. The transportation equation for the negative ions was resolved combined with the bulk air velocity and the electric field.The bacteria distribution was solved numerically by integrating the susceptibility constant, which was acquired from the experiments. Two types of bacteria (Serratia marcescens, Staphylococcus epidermidis) were aerosolized and released into a 9-m ventilation duct system. Inactivation efficiencies were calculated for inlet velocities from 2 to 6.5 m/s and for various ion intensities. The efficiencies for S. marcescens and S. epidermidis were 31.53% (SD, 11.4%) and 12.17% (SD, 0.43%), respectively, with susceptibility constants of 8.67 × 10 −11 Colony-Forming Units (CFU)/ions and 2.72 × 10 −11 CFU/ions, respectively. The modeling results matched those of the experiments well. The pressure penalty at the maximum velocity (6.5 m/s) was only 9 Pa. The results show that the use of negative ions has great potential to enhance indoor air quality by reducing airborne microorganisms in ventilation systems.

Negative Air Ions and Their Effects on Human Health and Air Quality Improvement

“…There are many references to report the possible biological effects [ 24 , 32 , 33 , 35 , 38 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 116 , 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 ]. And some of them were listed in Table S2 .…”

Disinfection by in‐duct ultraviolet lamps under different environmental conditions in turbulent airflows

“…Consequently, their findings on the inactivation effectiveness of UV lamps and susceptibility (Z value) of bacteria to UV may have limited applicability for in-duct UV lamps in real ventilation ducts, where turbulent airflows and various environmental conditions are commonly involved. 19,20 Temperature may also play a critical role in influencing the effectiveness of sterilization by in-duct UVC lamps. UV output is highly dependent on the mercury vapor pressure of the UV lamp.…”

Generating Negative Air Ions in Construction Waterscapes at a Garden Scale

“…This NAI concentration is between the NAI concentration produced in forests and that produced in waterfalls, indicating its favorable healing and recovery effects [52]. Zhou et al [53] have demonstrated that NAIs also have great potential for enhancing indoor air quality by reducing airborne microorganisms in ventilation systems. Wu [2] also demonstrated that NAIs can eradicate particulate matter.…”