Research On The Effect Of Humidity And Air Supply Velocity On Human Overall Comfort

With the high degree of urbanization,the per-capita public construction area is getting smaller and smaller.The rooms which is small and crowed is very common in the construction environment,romms,such as office,classroom,and even the bus,or the subway,can be seen as a small and crowded space.In such a room,it’s often when the background thermal environment is set to be quite comfortable,but we would still feel the air is stuffy or not comfortable,so that ones often want to open the window or increase the speed of air flow.In today’s society,healthy and comfortable indoor environment is no longer equal to thermal comfort,and research shows that modern people spend more than 85% of their time in the building,and even some people are living in the room for up to 22 ~ 23 hours.To creat a health and comfortable indoor environment needs us to understand every factor that causes the indoor environment to be uncomfortable.And stuffiness in this kind of small and crowded space has been playing an important role in human overall comfort.To study the subjective air evaluation like PAQ,stuffiness and so on,in the way of traditional heat exposure experiment,the increasing speed of airflow can improve both the heat exchange between the body and the thermal environment and between the inhaled air and the nasal respiratory tract mucosa.And whether the improvement in the overall comfort of the body is the result of the improvement of the subjective thermal response or the improvement of the subjective air evaluation,and whether the improvement of the subjective air evaluation is disturbed by the subjective thermal response has been the traditional thermal exposure experiment have been the major problems that exist in the study of subjective air evaluation.This problem is attributed to the experimental method,the key point is the way that the body and air contact each other,because it will directly determine whether the impact of air flow on the subjective air evaluation is independent or not.Therefore,the difficulty of this experiment is how to isolate the air movement of the inhaled air from the given air flow,by which way we can distinguish between the effect of the air movement on the subjective air evaluation which is in the nasal cavity and in the surrounding.In this study,a contrast experiment by the way of breathing mask was used to minimize the effect of air speed on subjective thermal responses,reducing the additional variables which disturb the research on the subjective air evaluation like stuffiness.This is also the highlight in this study.This study explores the extension and intension of stuffiness by means of experimental and theoretical analysis.Sixteen healthy college students were recruited,including eight male and eight female.The experiment was more like a local heat exposure experiment with different air supply velocities,in which use breathing mask to isolate the air movement of inhalation air from outside heat environment(with ambient temperature of 29.5℃,30%,50%,85% three relative humidity,and 0,1,1.4,2 m / s four air supply velocity).And each case is lasting for 45 min,which include 20 min heat exposure with the mask,5min rest,and 20 min without mask.The experiment include the heat exposure experiment under 3 relative humidity without personalized air supply,the heat exposure under 3 relative humidity and 4 air supply velocity,and the contract experiment between wearing breathing mask and without it.In which,the role of subjective air evaluation,the relationship between velocity and subjective air evaluation,and the feeling position of the air freshness is discussed.The study draws the following main conclusions: Human comfort is mainly affected by the thermal sensation,followed by the stuffiness,then the wet feeling,and the wet feeling can only play a relatively unimportant role.The velocity and the subjective evaluation have pretty good linear relationship(R2> 0.9),and when the air supply reaches 2m / s,it can completely compensate the air freshness difference caused by the humidity.For PAQ,odor,one feels them mainly by the nose,but for air freshness,one feel it through both the body and the nose.Changes in velocity around the body,by improving the heat exchange between the body and the surrounding thermal environment,can significantly improve the air freshness,and changes in velocity within the nose can also improve the nasal heat exchange significantly by which it also improves the air freshness.And the air freshness improvement by these two ways both have a good linear relationship with the air supply velocity.