Model Experimental Study On Stratified Air Conditioning Of High Ceiling Industrial Plant By 2D PIV: Isothermal Condition

In recent years,high ceiling buildings have been appeared increasingly in the industrial and civil occasions.These buildings have heavy air-conditioning load,as a result,they occupy considerable part of the total building energy consumption.There are many air-conditioning models of the high ceiling buildings,such as stratified air conditioning,down-supply air,displacement ventilation,jet air supply and so on.Of which,Stratified air-conditioning technology is most widely used.Stratified air-conditioning is an air-conditioning way that only functions in the low part of the building,while the upper part of the building is left.Compared with the using of whole room air-conditioning,the stratified air-conditioning can save about 30%of the refrigerating capacity in summer.At present,the research ways of stratified air-conditioning technology mainly have two types,experimental study and numerical simulation.However,there are some limitations for both of them.PIV(Particle Image Velocimetry) technology is the latest flow test method,which grows up by fully absorbing the modern computer technology, optical technology and image analysis technology.It is not only can show the physical form of the flow field,but also can provide the quantitative information of instantaneous flow of the full field,it makes the flow visualization studies have a leap from qualitative to quantitative.In this paper,the model size was supposed to be 1/50 of the real scale,PIV technology was also employed into the experiment to measure the flowing way of different conditions.In this model experiment,the author took 3 kinds of air supplying height(h=90mm,h=130mm,h=160mm) into account to discuss the influence of the changing of air supplying height;This experiment also supposed a interval of velocity(u₀=0.3m/s～2.5m/s) into account to discuss the influence of the changing of air supplying velocity;In succession,the author took the rectangle supply-air outlet(3 kinds of aspect ratio) and circle supply-air outlet in to account to discuss the influence of the changing of that.Besides,the author also set 3 kinds of air distribution method to discuss the influence bring by the changing of the air supply method.Through analysis of those photos and datas from experiment of PIV,we summaried the rules of how the air distribution of stratified air conditioning changes regarding to different kinds of air supplying height,air supplying velocity,the type of supply-air outlet and the air supply method.Finally,we designed a reasonable and effective form of layout of air-conditioning.