| There are mainly two ways to measure the existing indoor formaldehyde:sampling detection and real-time monitoring.The traditional sampling and detection methods can not get the timely formaldehyde pollution situation,and due to the high cost of equipment and labor,the generalization of these methods is poor.With the rise of sensor technology,the use of sensors to monitor indoor formaldehyde is becoming a trend.The indoor formaldehyde pollution can be duly and continuously obtained through the sensors arranged in the room.However,the existing standards and researches rarely talk about how to identify the influencing factors of timely indoor formaldehyde monitoring and how to correct these problems by scientific methods.This article will carry on the research to this.In the field experiment,the formaldehyde concentration in different positions under different working conditions was monitored,and the indoor formaldehyde concentration was measured by sampling method.At different locations,there are large errors in the monitoring data,and the threshold of 0.1mg/m~3 as specified in the range.There is a significant difference in the vertical direction of the monitoring data,while there is no obvious rule in the horizontal direction.Through the comparison and statistical analysis of the non-uniformity coefficient k,error range,it was found that in most cases,the sensor monitoring data arranged in the ceiling,side wall and desktop could not effectively reflect the formaldehyde pollution situation.The error can be effectively reduced through the correction of monitoring data.In the process of correction of 4 monitoring locations and9 working conditions,the average error after correction is reduced by 46-71%.Moreover,this correction method has good robustness,and the error probability is only 8%under the change of different input parameters.Comparing the monitoring data with the sampling results,it is find that the difference between detection results and maximum concentration in the room is the smallest.A variety of factors affecting indoor formaldehyde monitoring results were studied by CFD simulation.Through the orthogonal test which contains six factors,it is find that air distribution and pollution sources obviously influence the monitoring results.This is mainly because the relative position of supply air and pollution influence the proliferation of formaldehyde in the indoor,and it has great influence on the monitoring data of different invigilator’positions.When arranging sensors,we should first consider the two factors.According to the location of air distribution and pollution source,the correction method applicable to engineering practice under different conditions is given.In the correction process of 16 working conditions,the stability of the correction method is basically more than 90%(94±6%),and the error is reduced by 61±24%.The above correction method is verified by field measurement,and the error can be reduced effectively under some of the working conditions.Based on the simulation results,an appropriate fitness function was designed with the help of genetic algorithm,the optimal sensor placement location and number were precisely found,and the coefficientλwas proposed to reflect the effectiveness of the monitoring data.Combined with the monitoring efficiency coefficientλand economy,a strategy for optimal sensor placement was developed.This strategy mentions that the monitoring data should be modified to improve the monitoring effectiveness,and the number of sensors should be increased when the monitoring data cannot meet the requirements.In the optimization of the 17 conditions,76%of the conditions require only one sensor and correction to achieve a monitoring efficiency coefficientλof more than80%,while the remaining 24%require two sensors. |
