Research And Improvement On The Current Standards Of Household Air Cleaners And Fresh Air Ventilators In China

Fine particular matter (PM2.5) and Volatile organic compounds (VOCs) are majorconcerns causing indoor air quality (IAQ) problems in China nowadays. Facing suchsevere health risks, more and more families use air cleaners or fresh air ventilators toimprove indoor air quality. However, there are some shortcomings in currentChinese standards regarding both air cleaners and fresh air ventilators, resultingin some products sold in Chinese market with bad qualities and confusions forcustomers when choosing and using these products. There is a lack of suggestedroom size and feasible test method for assessing the lifespan of air cleaners. Andtest methods for assessing cross-contamination and air leakage of fresh airventilators are also needed. This paper focused on these problems and the mainacademic contributions are as follows:1. A new correlation of suggested room size and clean air delivery rate (CADR)suitable for China was obtained by analyzing the mass balance equation ofpollutants in a room with air cleaner. In steady state, the suggested room sizeis in direct proportion to the CADR of air cleaner, whose proportionallycoefficient is defined as suggested room size coefficient. According toindoor air quality in China, the suggested room size coefficient for PM2.5andformaldehyde are0.15h/m and0.21h/m respectively. This method is atheoretical basis for customers to choose air cleaners based on room size andis suitable for all kinds of indoor air pollutants.2. The suggested room size working condition was defined to estimate the totalamount of pollutant removed by air cleaner after a period of time. TheCADR decay ratio was defined and a corresponding test method wasdeveloped. The CADR decay ratio test consists of an accelerated aging testand a CADR test before and after it respectively. In the accelerated agingtest, the amount of pollutant removed by air cleaner is the same as realworking condition. The lifespan of air cleaners can be estimated with CADRdecay ratio test and suggested room size working condtion.3. The cross-contamination in fresh air ventilators are caused by air leakage and permeation of pollutants through the heat exchange membrane. The testcondition of air leakage in current standard is far from real workingcondition, overestimating the air leakage ratio. A test method using fineparticle matter as tracer gas was developed to test the air leakage ratio offresh air ventilators in real working condtion. A test method using toluene astracer gas was developed to test the cross-contamination ratio of fresh airventilators. By these methods, the cross-contamination ratio and theproportion of it caused by air leakage can be tested respectively. A fresh airventilator was tested as an example, of which the cross-contamination ratioincreased from19%to32%with the increase of toluene concentrationdifference between exhaust air and fresh air and the air leakage ratio was19%.