Numerical Study On The Interior Environment Of The Waiting Hall With Large Space

Recently,with the construction of large exhibition halls,conference centers and transportation hub stations,many large space buildings have appeared.On account of these characteristics of large space and heat sources laid in lower space,with lower space as work area,stratified air-conditioning technology has become one of the best options,in order to save cooling load,the initial investment and operation energy consumption.With reasonable air distribution taken advantage of by stratified air-conditioning technology,air-conditioning is only carried out for work area in lower part of the large space building,and no air-conditioning or only ventilation for upper part.Compared with entire air-conditioning scheme,stratified air-conditioning technology has significant advantages in energy saving and consumption reduction.The existing research on stratified air-conditioning technology for interior environment of tall and large building has explored the influence of various factors on the interior environment of large-space building,and the rationality of stratified air-conditioning technology has been verified for improving the interior environment of tall and large building.However,the research on the application of stratified air-conditioning technology to the air distribution of interior environment in waiting hall of railway station and the influence of various factors has not been thorough and comprehensive.The waiting hall of a railway station is selected as the study object,the geometric and mathematical models were established,and the appropriate turbulence model was chosen to simulate the air-conditioned air distribution in the waiting hall under design condition to verify the rationality of air distribution under design condition.The results show that the velocity range of work area in interior environment of waiting hall is about-0.2-0.37m/s,the temperature in work area is a little lower than design temperature 26℃,the PMV is about-0.5-0.5,the PPD is less than 7%,and the air distribution satisfies requirements of design specification.It shows that air distribution is reasonable under design condition,the interior environment of waiting hall is ideal,and most of passengers are satisfied.In order to study the influence of various factors on air distribution of interior environment in waiting hall with large space,the numerical simulation analysis was performed on air distribution under different air supply temperature,air supply velocity,air supply angle,air supply height,and air supply vent conditions.The results show that:with increase of air supply temperatures,the temperature of flow field in the interior environment of waiting hall increases,and then decreases,both PMV and PPD decrease first,and then increase,the influence of air supply temperature on flow field is prominent.With increase of air supply velocities,the velocity of flow field in work area increases,the temperature decreases,the PMV decreases,the PPD decreases first,and then increases,the influence of air supply velocity on flow field is prominent.With increase of air supply angles,the velocity of work area increases first,and then decreases,the temperature decreases first,and then increases,the PMV increases,the PPD increases,the influence of air supply angles on flow field is prominent.With the increase of air supply heights,the velocity of work area increases a bit,the temperature decreases a bit,the PMV increases a bit,the PPD increases.The air supply height has a certain effect on flow field of work area.With the change of air supply vent types(enlargement of air supply vent area),the velocity of work area increases a bit,the temperature increases a bit,the PMV increases,and the PPD decreases first,and then increases.The type of air supply vent has a certain effect on velocity,temperature,PMV,PPD distribution in work area.In order to check unsteady characteristics of air distribution in waiting hall,the change characteristics of air distribution with time in 20s after the start of air supply were observed.Comparing steady and unsteady results,these conclusions were made:With time going by,the velocity of interior environment with large space increases from both sides to center gradually,and the final velocity is more than steady value;The temperature of interior environment decreases from both sides to the center gradually,the final temperature is higher than the steady value;The PMV and PPD of interior environment decrease from both sides to the center gradually,the final values are higher than steady ones.The unsteady simulation can achieve a finer air distribution than the steady one.