Study On Optimization Simulation Of Large-space Airflow Of Winter And Summer In Severe-cold Region

With the improvement of people's modern living standard in our country,people tend to seek higher-level spiritual life.So large-space buildings,which serve people's demand of culture exchange constantly,emerge like theatres,cinemas and lecture halls.The features of this sort of large-space buildings are that it has large density of people and people in it always keep seated for long time.As a result,the inner space need to have uniform distribution of temperature and humidity and high-quality air.The air-condition system can regulate the indoor environment to meet people's demand.However,airflow organization design plays an important role in effect of air conditioning.The air conditioning system serves the audience area primarily,where people assemble.Because of the complication of inner large space and large amount of people,how to choose the reasonable airflow still exist on airflow organization design.Common jet formula based on semiempirical formula,which has certain limitation on application,give the designer lumped parameters rather than detailed information about design.Emerging as a method of predicting the indoor airflow,CFD is effective and economical,which has been proved to be accurate widely.In this paper,firstly we took a classroom of certain college in Changchun for example which is heated by ground-source heat pump system.Then,we compared the testing data with the numerical simulation.At last,we verified the reliability of the numerical simulation method used in this paper,and expand the method to the subsequent work.The main purpose of this paper is to discuss the year-round air conditioning system.We took certain lecture hall in Changchun for example and studied two kind of ventilation,including mixing ventilation and displacement ventilation.We picked out two airflow modes from the mixing ventilation.They were separately the up-supply and dowm-return mode and sidewall supply and bottom return mode.We simulated the design condition of summer and winter with Airpak,one out of CFD,analyzed the distribution of indoor temperature,humidity and speed,evaluated the different design conditions with thermalcomfort index PMV-PPD.At last,we put emphasis on the comparison of ventilation efficiency between mixing ventilation and displacement ventilation and compared the energy consumption in term of theory as a result of difference of the supply air processing of summer design conditions.Due to vertical and horizontal temperature gradient arising from heating load we brought up optimization measures of increasing the air-supply angle and air volume of load side,and meanwhile simulated a series of different design conditions to find out the best condition.We can conclude from the result of numerical simulation that the displacement ventilation can provide the best thermal comfort among the three,and that sidewall supply and bottom return mode was better than up-supply and downreturn mode on thermal comfort.In a word,the displacement ventilation have an advantage over the mixing ventilation on ventilation efficiency and mean age of air.In term of energy consumption of this case,the displacement ventilation consumed 15.9% more refrigeration energy consumption counteracted by reheating,which led the temperature of audience area to decrease by 2~3? and promoted thermal comfort of indoor people dramatically.