折流式反应器空气净化效果

Degradation performance of formaldehyde in a baffling air purifier

针对建筑环境中的低浓度挥发性有机化合物,利用光催化氧化技术设计了一种折流式反应器,并在密闭环境和开放环境下,选取甲醛为目标污染物,对其降解效果进行实验分析。实验结果表明,对于3种不同初始浓度,环境舱中的甲醛含量均可被降低到国家标准限定值以下;密闭环境中的一次通过效率为6.42%-13.64%;开放环境中的总降解效率为70%-95%,且与循环比呈正相关。流态模拟表明,反应器内无渠道流现象,后半部分的流速受阻力作用而较小。此外,在类似于实际应用条件的开放环境下,建立了降解效率模型,并通过实验验证了模型结果的正确性,根据此模型,可通过循环比来预测反应器的总降解效率。

A novel baffling air purifier coated with TiO2 was designed for the photocatalytic oxidation of volatile organic compounds. The removal efficiency of this air purifier was measured in an environmental chamber operating under two different conditions（ closed and open environments）. The results revealed that using the air purifier could steadily keep the formaldehyde concentration below the National Air Quality Standard. Under closed environment,the single-pass removal efficiency of formaldehyde was 6. 42% - 13. 64% for three different initial formaldehyde concentrations. Under open environment,the global chamber removal efficiency was 70% -95% and it was also a function of the recycle ratio： it increased as the recycle ratio increased. The CFD simulation of the air purifier suggested the uniformity of the air flow,but the air flow rate decreased at the exit section due to the air resistance. Besides,a simple numerical model for open environment was constructed,assuming that the formaldehyde was introduced at a constant rate into chamber air. The model revealed the correlation between the global chamber removal efficiency and the recycle ratio,and it could be used to validate the experimental results and address a better understanding of photocatalytic processes.