Investigation On The Performance Of An Air Volume Distributor In Mini-type Ventilation Systems

With the development of society, people's concern over indoor thermal environment and indoor air quality (IAQ) has led to the emergence of mini-type ventilation system, which brings healthy and comfortable environment to freestanding residential buildings and small offices.Mini-type ventilation system is usually applied to those buildings with low headroom and small compartments, as a consequence, there is usually no room for components like reducers or T-fitting to adjust the distributing of air volume, and flexible ducts with diameter from 100 to 200 mm are adopted to simplify the installation and reduce the length of ducts. One of the critical factors which is responsible for indoor air quality and indoor thermal environment is the distribution of air volume, which is realized by adjusting the cross sections of reducers, fittings and local plenum chambers in large-sized air conditioning systems. In view of the characteristics of mini-type ventilation system, it's difficult to take the advantage of the research fruits of large-sized systems, and research work on new air distribution methods special for mini-type ventilation system must be done according to actual situations.Considering the characteristics of mini-type ventilation system and freestanding resident buildings, the mathematical and physical models of mini-type ventilation system are established in this paper. The core component of mini-type ventilation system is air distributor which has crucial influence on the performance of the whole system, that's why air volume distributor is chosen as the emphasis of this research.According to ventilation code and the principle that the guide vane equipment should be simple and can adjust the air volume distribution coefficient effectively, mathematic and physical model of air volume distributor is set and three types of air volume distributors of different size are researched by means of numerical simulation.According to the consequence of physical and numerical simulation, one of the air volume distributors is confirmed to be optimized model among these three models, the variety of air distributing curve and resistance for three different air volume ranges are achieved By more detailed research on the optimized model , Furthermore, the reliability of the result of mathematic simulation is verified by experiment so that it is possible to offer a reference for the choosing and designing of mini-type ventilation system.In practical cases, the resistance in different branches is not always similar, pilot study on the influence of resistance on air distributing has been done, which shows that that the volume distribution coefficient is not influenced by the magnitude of the residences with the precondition that all the residence in different branches are the same;volume distribution characteristic will be different when the residences of face and side are different, but it is only related to the difference of residence between frontal and side face.Furthermore, the scheme of air volume distributing methods in 2 mini-type ventilation system for two practical buildings is confirmed according as the conclusion of this paper.