风量调节方式对室内污染物浓度的影响分析

Impact of the air volume control modes on indoor pollutant concentration

针对不同室外空气质量条件,利用MATLAB/Simulink分别对新回风比例不变、新风量不变改变回风量、回风量不变改变新风量的变风量空调系统室内PM_(2.5)质量浓度和CO2体积分数进行了模拟分析。模拟结果表明:对于新回风比例不变的系统,室内PM_(2.5)稳定质量浓度与室外PM_(2.5)质量浓度有关,而与回风量和额定回风量的比值R1无关;但室内PM_(2.5)质量浓度下降速度与R1有关。对于新风量不变改变回风量的系统,室内PM_(2.5)质量浓度主要受回风量影响。对于回风量不变改变新风量的系统,室外PM_(2.5)质量浓度和新风量是影响室内PM_(2.5)质量浓度的主要因素。

In order to work out the proper strategies for reducing the indoor PM2.5 mass concentration of a variable air volume（ VAV） system,we have done the simulation test and exploration of the indoor PM2.5 massconcentration,as well as the CO2 volume fraction of VAV system,by using a MATLAB/Simulink model on the condition that the outdoor air qualities are supposed to be quite different. As is known,the VAV system involves three different modes,that is,the constant fraction of the fresh air volume in return air volume,the constant fresh air volume and the varying return air volume,in addition to the constant return air volume and varying fresh air volume,respectively. Based on the above belief,we have studied in this paper the mass concentration of the indoor PM2.5 and the CO2 volume to build up the dynamic condition in a hypothetical building,whereas the input parameters have been worked out on the basis of the real-world data. Thus,the results of our simulation show that： for the condition with constant ratio between the fresh-air volume and the return-air volume,the static mass concentration of the indoor PM2.5 is related to the outdoor PM2.5 mass concentration,but has nothing to do with R1 which represents the ratio of the actual return-air volume and the rated return-air volume,though the decreased speed of the indoor PM2.5 mass concentration is in fact related to R1.Therefore,it is recommended to deduce the amount of the outdoor air delivered indoors and to increase the amount of the return air.For condition with constant fresh-air volume and varying return-air volume,the indoor PM2.5 mass concentration is mainly affected by the return air volume. Therefore,it is recommended that the return-air be delivered indoors so as to increase the amount of the fresh air therein,which is aimed to make up for the quantification of the necessary reduced level through our simulation. And,for the condition with the constant return-air volume and varying fresh-air volume,the outdoor PM2.5 mass concentration and the fresh air volume can be the greatest dominant parameters,influencing the evolution of PM2.5 mass concentrations indoors. Therefore,it is recommended to reduce the amount of the outdoor fresh air,but,at the same time,it is necessary to notice the increase of CO2 volume fraction.