Numerical Simulation And Influencing Factors' Analysis Of The Central-station Air Handling Unit Performance

With the development of our national economy, the central-station air handling unit is widely used by all professions and trades, so the performance of central-station air handling unit is the focus of the research work for many professors and scholars.The research of the central-station air handling unit performance is carried out by experiment widely at present. But the experiment research is confined by the experiment conditions and other factors. So it is very important to research the unit performance by numerical simulation.We choose the style of the central-station air handling unit in this paper through public inquiry. The unit is composed of the air mixing section, the filtering section, the heating/cooling section, the dry steam humidifying section, the fan section, the straightener & muffler section and the air delivery section.Firstly, we establish a physical model of this central-station air handling unit based on heat transfer and flowing performance of the air in it. We think the energy transfer of the air in the unit fully. It includes the energy transfer between air and air handling units, the heat transfer through unit cabinet, the energy transfer by air leakage, and the energy transfer by other reasons.Secondly, we establish a mathematical model of this central-station air handling unit based on analysis and simplification. Then, we compile a program by Matlab to solve this model. At last, we draw some useful conclusions by numerical simulation and analysis of this unit performance during the unsteady process and the steady process.We usually establish a mathematical model based on some simplifications because the physical problems are complex, but we must do some experiments to prove the mathematical model and these simplifications. In this paper, we do experiments under six working conditions to prove the mathematical model and simplifications. We compare the results of the experiments and the numerical simulation. Then, we draw conclusions: themathematical model is quite right and these simplifications are quite reasonable.After all, we analyze the influencing factors of the central-station air handling unit performance. They are include the air rate in this unit, the inlet air temperature of this unit and the volume of air leakage. We also solve two questions about the use of this unit. They are include the thickness of insulating layer and the feasibility of a central-station air handling unit without floor.Based on the numerical simulation, we analyze the influencing factors of this unit performance. The simulation calculation shows that the influences of the air rate in this unit, the inlet air temperature of this unit and the volume of air leakage are quite heavy.Some manufacturers want to save the initial cost of unit, so they use a unit without its floor. In this paper, we analyze and prove that the idea is infeasible. It saves the initial cost of unit, but it wastes a lot of operating cost.Generally speaking, we try to establish the numerical analysis on the performance of the air handling unit. Through numerical analysis we can get different running data of the unit more easily, thus we can save invest of experimental research and shorten the time of the R&D of the new product, especially, overcome the uniqueness of experiment.