通风管道内负离子传输的数值模拟及试验验证

为能有效去除通风管道系统内颗粒及气溶胶微生物,解决通风空调系统因长期使用而缺少维护和清洁,造成气溶胶微生物在系统里滋生进而形成对人体有害的生物气溶胶病原体细菌等问题,采用欧拉方法建立模拟通风管道内负离子输运过程及分布的数值模型.通过数值模拟和试验测量VI-2500型负离子发生器安装在0.2 m×0.2 m通风管道内送风速度为3～6 m/s时的负离子浓度,验证数值模型的准确性并分析负离子在通风管道内的分布规律.结果表明,负离子的模拟预测值与试验测量值误差很小.送风速度为3 m/s时,风管内负离子浓度的最低值和平均值分别为9.15×109和2.39×109 ions/m3,送风速度为6 m/s时,相应为2.37×1010和6.83×109 ions/m3.通风管道内负离子浓度随送风速度的增加而升高,送风速度一定时,通风管道内负离子浓度沿风速方向逐渐降低.当送风速度低至3 m/s时,风管内负离子浓度最低或平均值仍然可以达到有效净化细菌的负离子浓度最低数量级的推荐值(108～1010 ions/m3).研究显示,负离子数值模型能准确预测VI-2500型负离子发生器在0.2 m×0.2 m风管中产生的负离子浓度,并且发生器产生的负离子浓度能满足4.5 m长风管的净化要求. 

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.