Numerical Simulation Of Pollutant Diffusion And Ventilation Control In Public Building Toilets

Indoor air quality?IAQ?is closely related to our life all the time.Bad IAQ not only affects the comfort of indoor environment,but also harms our health.As a kind of unique indoor space,the air environment in the toilet has not been paid attention to because of the short stay time.However,according to the statistics of the World Health Organization?WHO?,people will spend about three years in the toilet in their life,so it is very important to ensure a good environment of the toilet.Toilets can be simply divided into two categories,residential toilets and public toilets.In this study,the air environment in the public toilet under different ventilation modes is simulated and analyzed.By referring to the ventilation evaluation indicators,toilet hygiene standards and related literature,this article used pollutant concentration in human breathing area?z=0.9 m and z=1.5 m cross section?and ventilation efficiency EC to evaluate the removal of pollutants and indoor air quality in the toilet.Then,this paper conducted a large number of numerical simulation studies on the air flow field,the concentration of pollutant and the velocity field in the toilet,mainly including the following parts:?1?This paper studies the pollutants and velocity field in the toilet under different air change rate;?2?This paper studies the distribution of pollutant and velocity field in toilet under different door opening position and different exhaust height,and the distribution curve of pollutant concentration under different exhaust height was given.?3?This paper studies the ventilation effect of three ventilation modes in the toilet,and gives the appropriate ventilation scheme of the toilet.The results show that:the concentration of pollution in the toilet of public buildings changes continuously and decreases with the increase of the air exchange rate,but the decline rate tends to be gentle,and the conversion ventilation efficiency also decreases.The optimal air change rate is 15 h^-1.When the air change rate is small(5 h^-1),the door opening side to side?along the length of the toilet?can get less pollution concentration,When the air change rate is large?10 h-1,15 h-1,20 h-1?,The door opening forward?along the width of the bathroom?is better.When the bathroom adopts the ventilation method of side wall mechanical exhaust,the height of the alternating air outlet increases?from 0.1 m to 1.2 m?,and the average concentration of ammonia volume in the breathing zone z=0.9 m increases by 15.4%.The average concentration of hydrogen sulfide increased by 24%,while the average concentration of the scale on the z=1.5 m section of the breathing zone changed relatively little;the efficiency of the reversing ventilation gradually decreased with the height of the exhaust outlet,and the ammonia ventilation efficiency increased from 1.055 Reduced to 1.027,hydrogen sulfide ventilation efficiency reduced from 2.070 to 1.706.The air supply system helps to dilute and remove pollutants in the bathroom.In addition,when the air supply from top and return from bottom,the toilet can discharge air faster and get better air quality.