Study On Dynamic Characteristics Of Looped Duct In VAV Systems

With rapid progress of national economy and advance of industrial and cities level,evolution on HVAC system and air-conditioning style have been imperious and essential to building containable development for the sake of energy efficiecy,environment protection and equipment automatization. The appearance and development of VAV (Variable Air Volume) system are dominant in modern building energy saving work, of which research work also regarded and carried out gradually.First, this paper review basic theory and latest research work on VAV system and duct supply air according to the existing literatures, and consequently potential value in use and feasibility in projects are suggested on novel air loop ducts which seldom are employed in research work and actual projeces. Secondly, according to the limited initial theory and the existing conditions, dynamic performance model and measurement method are established, and related structures of the experimental platform provides a platform support for in-depth study.Through experiments and analysis, summed up the basic driving force of looped duct systems, and through the tree-shaped duct to do contrast, analysis the dynamic performance and energy consumption of looped duct.The experimental results indicate that supply air volume of multi-branch looped duct is the largest, of tree-shaped duct is the smallest; The resistance of the network is to the contrary, the resistance of tree-shaped duct is the biggest, of multi-branch looped duct is the smallest, efficiency of multi-branch looped duct is the highest, and have the most energy-saving advantages, and energy-saving effect of tree-shaped duct is the worst. At the same time, because of the automatic adjustment of the connecting duct, hydraulic characteristics of multi-branch looped duct and looped duct can be improved, equivalent to an increase of regulation means. If load in the various district have little difference, compared with tree-shpaed duct, looped duct don't have obviously advantage in the hydraulic performance, but in the case of load in the various district having large difference, static pressure distribution of looped duct has more advantage because of the automatic adjustment of the connecting duct.