Performance Analysis And Structure Design Method Of Active Chilled Beam

Radiant cooling oriented from European,numerous studies have now shown that the energy consumption of the radiant cooling system is lower than that of the VAV conditioning system.Under the background of the energy efficiency,a green building gives priority to the radiant cooling.As a form of radiation cooling technology,active chilled beam is widely used in Europe and North America in the past decade owing to energy-saving,thermal comfortable and low noise,and gradually attracts attention of more and more Asian countries.But active cold beam seldom used in practice due to the research on ACB performance is relatively little.And foreign brand price are relatively high,which also limits it largely promote in China.This paper summarizes the performance research of domestic and overseas scholars on the active cold beam.It can be presented in the following three parts based on the working principle: induced jet,heat exchange coil and the mixing chamber coupling with cooling coil.Firstly,basing on single nozzle free jet theory,two nozzle free jet model was established,and multi-nozzles free jet model was derived.The calculation of nozzle spacing is obtained through making modification on multiple nozzles free jet of ACB,the rationality and reliability of calculation method is verified by experiments.Secondly,the effect of the fin spacing and tube number on the heat resistance and heat transfer rate got by using theoretical formulas,providing reliable evidence in the design of coil parameters.Finally,the induction chamber and the heat exchanger are connected together to form the performance expression pattern of the cold beam through taking the second air as bridge.In addition,this paper also analyzes the influence of the parameters on the performance of the ACB,and establishes a synthesis evaluation system.The results of this article are summarized as follows three aspects.Firstly,based on the free jet model of single nozzle,a modified model of multi-nozzle confined jet is obtained,providing reliable evidence in designing of nozzle spacing.And the reliability of the model verified by experiments.Then,the design values of the other parameters of the mixing chamber are obtained by CFD.Secondly,taking advantage of theoretical calculation,the design parameters of the coil is suggested.The mixing chamber and the heat exchanger are combined together by the second air,forming the performance expression of the ACB.And analyzing the impact of various parameters on the heat exchange through experiment.Finally,establishes a synthesis evaluation system of ACB,pointing out the direction for the performance comparison between different ACB.The studies provide relevant parameters for optimum design of ACB.Taking cooling capacity as design objective,design and manufacture an active cold beam,and its performance is tested.