Analysis And Optimization Of Airflow Organization In A Large Space Under Unilateral Air Supply Method Of Layered Air Conditioning

Among China’s total energy consumption in the society,building energy consumption accounts for a considerable proportion.Among building energy consumption,the energy consumption of air conditioning in large spaces accounts for a large proportion and should be given sufficient attention.For such a building,how to use air conditioning for air supply,so that the working area obtains reasonable airflow organization distribution,is a problem that researchers have been paying attention to.The air-conditioning system of a large space has special characteristics,of which layered air-conditioning is a typical airflow organization form.In this paper,under the premise of single-sided air supply method of layered air conditioning,the airflow organization in large space building is studied.Starting from reducing the building energy consumption and obtaining the ideal airflow organization effect,a certain scheme design and optimization study are carried out,which has been experted to have certain reference significance for future projects.First of all,in order to grasp the current research status of air supply using air conditioning,airflow analysis methods and evaluation indicators of large space buildings,a data and literature investigation was carried out.Based on previous research work,the analysis and research methods adopted in this paper are determined:scale model experiment and CFD numerical simulation,and the two analysis methods are introduced.Then,based on the Archimedes number(Ar)related criteria,a scale model experiment is established,and experimental data are obtained.Meanwhile,a simulation of air-supply conditions was performed using CFD numerical simulation and the results of the simulation and the scale model experiment were dimensionally compared with the results of the speed and temperature to verify the accuracy of the CFD model.Finally,the study on the optimization of the airflow organization under unilateral air supply method of layered air conditioning in the large space is carried out,and the Box-Benhken central combined test design method is used to design a total of 29 different working conditions about three levels of the four air supply parameters:the air supply temperature,the air supply speed,the air supply angle and the air supply position.The CFD numerical simulation was used to obtain the average temperature of working area,average wind speed of working area,velocity non-uniformity coefficient of working area,and the heat distribution coefficient under different working conditions.The four air supply parameters are dimensionlessly transformed into Archimedes number,Reynolds number,dimensionless angle θ~* and dimensionless height h~*,about which the regression model for evaluation indexes such as wind speed,speed unevenness coefficient,and heat distribution coefficient was established to obtain the optimal air supply combination.Meanwhile,the flow field analysis of the vertical plane and the working plane in different working conditions is analyzed to verify the accuracy of the model for evaluation indexes.Finally,the optimal air supply combination is obtained.In order to making the average wind speed in the working area to meet the requirements,the uneven coefficient of air flow organization in the working area to be the smallest,and the ventilation effect of the air conditioning system to be the best,Ar is determined to be 0.000851,Re is determined to be 35481.34,the air supply angle is determined to be 5.4°,and the air supply height is determined to be 6.55 m from the ground.