| In recent years,the frequent outbreak of haze weather in most cities of our country seriously affects people's health and quality of life,so the particulate matter has been paid more and more attention.The inhalable particles PM10(aerodynamic diameter less than or equal to 10um)and PM2.5 have great influence on human health,especially PM2.5.Because the aerodynamic diameter is less than or equal to 10 um particles can enter the body,deposited in the respiratory tract,alveolar and other parts causing disease.The smaller the particle size into the part of the body is more deep,the greater the harm to human body.Nowadays,the central air-conditioning system requirements are also getting higher and higher,not only to meet the indoor temperature and humidity control,indoor particulate matter concentration must also meet the state standards or design values.Therefore,the analysis of the characteristics of indoor particulate matter and concentration control is a very important topic in the field of HVAC.Indoor particle concentration is influenced by many factors,such as the concentration of outdoor air particulate matter,the filtration efficiency of air conditioning filter,the amount of dust in the room,the number of air exchange and so on.Therefore,it is very important to study the influence of various factors on the concentration of indoor particles,especially the control of PM10 and PM2.5.In this paper,for the inhalable particulate matter PM10,through theoretical analysis and practical discussion the influence of indoor residual heat,wet load,outdoor particulate matter concentration and other factors on the concentration of indoor particulate matter in non steady state conditions.According to the principle of controlling the particle concentration in the control room,a design calculation method is put forward for the selection of the filter of the air conditioner.The design and selection of the central air system of the residential building is calculated theoretically.The difference between the fresh air system and the air conditioning system and the necessity of the installation of the central fresh air system are expounded.In addition,through the theoretical analysis and calculation of the model,the effect of air conditioning condensation heat by cooling tower discharge on the surrounding hot and humid environment is studied.The main research contents and methods are as follows:(1)Selected a typical air conditioning room,non steady state model of mass conservation was established based on indoor particles,and the theoretical formulas of the supply air volume in accordance with the elimination of residual heat and moisture are derived respectively.Finally,the parameters in the formula are determined.Using the formula to draw the image of the indoor particle concentration with time under different conditions,and according to the image analysis and discussion of the influence of various factors on the indoor particle concentration.(2)The design concentration of outdoor particulate matter is determined based on the conditions of the non guaranteed rate.The design values of indoor particulate matter concentrations are determined according to the national standard.According to the law of conservation of mass,the increasing amounts of indoor particles in unit time is equal to the air conditioning filter removal,the formula of the filter efficiency is derived,and then the filter efficiency can be calculated and the model of the filter can be determined.In addition,according to the different outdoor conditions to determine the particle control of energy-saving operation scheme.(3)Determination of indoor particulate matter in residential building is based on the assumption that the indoor air mixture and particle concentration are uniform.From the point of view of particle mass balance,the indoor particle concentration equation is established.The traditional residential air conditioning system is only adjusting the indoor temperature and humidity,fresh air system is the main method to reduce indoor particulate matter to ensure air quality.(4)According to the energy balance principle,derived the theoretical formula of cooling tower heat emission,and in accordance with the formula to draw the image around the cooling air temperature and humidity changes with time,analysis and discussion of various factors on the temperature and humidity of the surrounding air cooling tower. |
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