| Since the late 1970s,due to the consideration of building energy conservation,measures have been taken to reduce the fresh air volume of the air conditioning system,but the harmful pollutants generated can not be completely discharged,and the human body has appeared"sick building syndrome".It is mainly due to the high indoor PM2.5 particle concentration,and the best way to control indoor PM2.5 particle concentration is to use air purifier,but the purification effect of air purifier is affected by purification technology,installation method,room geometry,air flow organization form and intelligent design of purifier.Moreover,because the air purifier has a return air outlet and is a power source,the change of air supply parameters has a significant impact on indoor PM2.5 particle concentration,and the action area and purification effect of the air purifier clean air flow are closely related to the air supply parameters.However,the user lacks reasonable guidance on how to match the air supply speed and the angle of elevation of the air supply,and cannot effectively use its purification effect.In this paper,the methods of experiment and simulation are used to study the air purifier in the office.By changing the air supply elevation angle and air supply speed of the air purifier,the influence of the air supply elevation angle change on the indoor purification time in different areas when the air purifier is running at different air supply speeds is explored.Furthermore,what kind of air supply is used when the air purifier is distributed in different areas of the room The air elevation angle and the air supply speed match,making the air purification effect optimal,giving reference suggestions,providing the operation guide for the optimal use of air purifier.According to the GB/T 18801-2015,built a large volume environmental test cabin,designed its air conditioning system,air purification system,pollution source generation device,and selected the equipments.The air purifier operation experiment was carried out in it,and the change rule of PM2.5 particle concentration with time was obtained.On this basis,the numerical model of the environmental test cabin and the air purifier was established by using ICEM software,and the preliminary simulation was carried out.The results showed that the average error at the two measuring points 3m and 6m away from the air purifier is 5.97%and 5.39%respectively,and the average error is small.It is considered that the air purifier model is more accurate and can be used in the actual room for expansion simulation.The above air purifier model is applied to a 72m~2 real room.The elevation angle of the air supply is set to 35°,55°,90°,and the air supply speed is also set to 25%,50%,100%.A total of 9 simulated working conditions are set,and the purification time is defined,that is,the time for indoor PM2.5 particle concentration to reduce from 150?g/m3to15?g/m3,so as to evaluate the PM2.5 particle purification.The simulation results show that:(1)When the air purifier operates in different air supply modes,the concentration distribution of PM2.5 particles in different positions of the room is different.Based on this,the room area is divided into seven areas according to the purification time,the purification effect of each working condition on different areas is evaluated;(2)When the air supply speed is 100%and the angle of elevation of the air supply is 55°,the purification time of each area in the room is longer than that of other angles,and the air flow short circuit is easy to occur at the return air port B2,so the overall purification time is longer;(3)When the air velocity is 100%,the purification time at the back of the room decreases and the purification time at the front and middle of the room increases with the elevation angle increasing.Therefore,no matter which area the personnel are distributed in,it is not recommended to use 55°elevation angle of air supply;when the personnel are mainly distributed in the rear of the room,the elevation angle of air supply is set as 35°,which can reduce the purification time by up to 6%compared with other angles;when the personnel are distributed in the front and middle of the room,it is recommended to set the elevation angle of air supply as 0°,which can reduce the purification time by up to 8%;(4)When the air velocity is 50%and the air elevation angle is set to 55°,the attenuation constant of PM2.5 particles in each area is relatively close,so the purification time in each area of the room is approximately the same,and the maximum deviation is only 1.25%.Reducing the angle of elevation of air supply can increase the purification time of each area in the room;when the recommended air supply speed is 50%,no matter which area the personnel are distributed in,it is recommended to set the angle of elevation of air supply to 55°,which can reduce the purification time by up to 21%;It is recommended to set the purifier to swing mode when the personnel are separately distributed in the front side area of the room;(5)When the air supply speed is 25%,increasing the angle of elevation of air supply can reduce the purification time of the middle and rear areas of the room,but will extend the front area of the room purification time in the room;when the personnel are in the front area of the room,it is recommended to set the elevation angle of air supply to 0°,which can reduce the purification time by up to 4%compared with other angles;when the personnel are in the middle and back of the room,it is recommended to use the elevation angle of 55°air supply,which can reduce the purification time by up to9%;When the indoor personnel are separately distributed in the side area of the middle part of the room,the purification time difference between the indoor personnel and the middle part of the room is 1.27min,which is quite different.It is recommended to set the purifier in swing mode to reduce the purification time of the area;(6)When the air supply speed changes,setting different air supply angles will affect the room in the width direction,the purification time of each area has an impact,but the overall trend of the purification time of each area is the same,so the setting of the elevation angle of the air supply mainly depends on the depth of the room under different air supply speeds.In this paper,experimental and simulation methods are used to study the purification time of different areas of the room when the air purifier is running in different air supply modes,summarizes the change rule of purification time in different areas,explains the reasons,and further proposes the best air supply mode of air purifier according to the different areas of indoor personnel.The research results of this paper can provide guidance for users to reasonably and effectively match the elevation angle and velocity of air supply,improve the use guide of relevant products,and also provide theoretical basis for the intelligent design of air purifier production enterprises,such as the setting of air supply mode and so on,according to the different areas of personnel. |
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