Modeling Analysis Of Air Handling Units In Full Condition

The air handling unit is developed from the building coil duct,which increases the other function in the basic function of the refrigeration and heating.Now,the air handling unit has become the core equipment of the central air-conditioning system.Its main functions include heating,cooling,humidification,dehumidification,filtration,silencing and so on.Traditional Air handling unit selection design relies on manual calculations,which is inefficient and inaccurate.So,the computer simulation technology is used to design the functional sections of the unit,on the basis of which,the digital selection and design platform of the air processing unit is developed,which makes the work efficiency significantly improved.The frame of this paper is established on the following parts:Firstly,putting forward the judgment of three conditions of heat exchanger.Three mathematical models of heat and mass transfer are established.The detailed calculation formula of heat transfer coefficient,pressure drop model and fan model are given.The model lay a solid foundation for the development of the platform.Secondly,three design models and three simulation models of square chilled water coils are built.The simulation model was verified by experiment.Based on this model,the effects of inlet air dry-bulb temperature,water volume,air volume and fin pitch on the heat transfer and flow performance of fin-tube heat exchanger with different water flow structures are investigated.Besides,two simulation models of cylindrical coil are built.Thirdly,the mathematical models of coil heat recovery,plate fin type heat recovery and wheel heat recovery are established on the basis of characteristics of the segment.Discretization of partial differential equations through the finite difference method.Fourthly,based on the above model,the digital selection and design platform of air handling unit is developed.The platform features cover project management,segment design,integrated output,and enthalpy diagram.With the strong support of the Access database,the component parameter information can be summarized and the value of component can be estimated.The platform has practical engineering significance.