Fluid Dynamics Of Room Moist Air Movements Subject To Thermal Buoyancy Driven Natural Ventilation

With the rapid development of urban construction and economy,and large population of urban in hot and humid area in the south of China,high-rise buildings springing up,the demand of air-conditioning cooling and dehumidification in summer is huge.The key to adjust properly the indoor thermal and humidity environment and how to choose the right floor to live and work are the deep understand of heat and moisture transfer mechanism indoor.The method of computer numerical simulation has advantage of rich information and short research cycle,and so on.The paper is mainly using computational fluid dynamics methods to explore building indoor humidity environment flow characteristics by natural ventilation.This dissertation,firstly through establishing the numerical simulation of natural convection laminar physical model in enclosure,simulates and analyzes the effect of position and length of the partition and thermal Rayleigh number on heat and moisture transfer on natural convection.The results show that the overall heat and moisture transfer in the system,with the increase of length of vertical partition,convection plays a more and more important role.At the low Rayleigh number case,position and length of partition of less influence on the heat and mass transfer of the whole system;With the increase of Rayleigh number,heat and moisture transfer rate isn't sensitive to location of vertical partition.Vertical baffle dominance in inhibiting heat and moisture transfer.Horizontal partitioning position in the heat and mass transfer inhibition also plays an important role.Then adopts model experiment and numerical simulation to study the effect of vertical partition the length and the position and temperature difference between indoor and outdoor on indoor wall temperature distribution.The research shows that layered structure and indoor vertical baffle position correlation is very small;A long vertical baffle more effective interference flow field and a greater influence on indoor convective heat transfer.The bigger the temperature difference between indoor and outdoor,the effect of natural ventilation effect is more obvious.The experimental results and numerical simulation results are basically identical.Moreover,analyzing the effect of length and position of partition on indoor heat and moisture transfer in the Multistory buildings thermal buoyancy natural ventilation with with unilateral middle opening.It is concluded that vertical baffle is far away from the opening,indoor moist air convection more stronger.Improve the heat and moisture transfer rate,the position of vertical partition is the most important factor.When Vertical partition is located in the mid-plane,the indoor wet air convection effect is the worst.For different floors,length of vertical partition influence on the indoor relative humidity is different,in the mid-plane,length of vertical partition have little impact on relative humidity.Vertical baffle near the mid-plane,indoor relative humidity of the first and second floor is minimum.For the horizontal baffle,baffle closer to the top,each layer heat transfer rate is less affected by the length of the partition.For the first and second floor,With the increase of the length of horizontal baffle(LH < 0.75),the existence of the baffle is hardly affect the moisture transfer rate.For the third floor,when location of horizontal baffle Dy?0.4,shorter horizontal baffle could enhance the wet air diffusion;Relative humidity distribution isn't sensitive to horizontal baffle position.The last,discussing the effect of length and position of partition and strategy of opening on indoor heat and moisture transfer in the high-rise buildings thermal buoyancy natural ventilation.The study found that regardless of length and position of baffle in the higher floors,indoor moist air convection more severe;No matter which floor,a long vertical baffle greatly effect on indoor convective heat transfer.With the increase of floor,relative humidity is less affected directly by the length of vertical baffle;For vertical partition,indoor relative humidity were similar between adjacent floors with the higher floor;When building storey below six floors,vertical baffle near the mid-plane,the effect of mass transfer is the worst.Relative humidity is not sensitive to the position of vertical baffle.When indoor exist a short horizontal baffle,mass transfer effect is best;With the increase of floor,relative humidity distribution isgreater affected directly by length and position of horizontal baffle.For below six-story buildings,longer horizontal baffle is greater influence on the indoor wet air convection,while baffle position almost does not affect the indoor moisture transfer rate;When building floor number not less than six floors,horizontal baffle is closer to the bottom,the region of relative humidity distribution affected directly by moist air outdoor narrows continuously.With double openings,indoor wet air convection heat transfer effect is better;In addition,with the increase of floor,indoor convective heat transfer effect in double opening strategy is more obvious;For below the seven-story building,adopt double opening way of ventilation,indoor and outdoor water transfer enhancement;On the contrary,when building floor number not less than seven layers,with one open ventilation way,indoor and outdoor water transfer enhancement;When building floors above six floors,with the increase of floor,the openning strategy to the influence of moisture transfer rate smaller with horizontal partitions.Research on flow mechanism for building humidity environment by natural ventilation in hot and humid area,laids the foundation for understanding the mechanism of coupled heat and moisture transfer by natural convection,it is suggested that the interior decoration,furniture,partition wall and other obstacles should be arranged properly,and choose the right floor to live and work,it provide the guidance and help to optimization of the building ventilation environment and some reference basis for people to choose floor and indoor installation.This paper explores to keep suitable thermal and humidity indoor environment by natural ventilation via probing the heat and moisture transfer mechanism under natural ventilation.