Study On Structure Optimization Of Marine VAV Terminal Device

Ship air conditioning load changes greatly.Compared with the traditional CAV air conditioning system,VAV air conditioning system has the advantage of saving system energy consumption and reducing installed capacity and thus saving ship space.And the terminal device is one of the most critical equipment in the variable air volume system.The air volume sensing characteristic,that is,the accuracy of the air volume measurement is directly related to the variable air volume air conditioning system can whether accurately adjust the air volume,thus affecting the room temperature control accuracy and energy efficiency and economy of the air conditioning system.The significance of this thesis is to optimized design the marine VAV box to get the goal of reasonable duct structure,uniform outflow and high measuring accuracy of air volume.This thesis provides a reference for the design and reconstruction of marine variable air volume terminal devices.The numerical simulation and experimental tests are carried out for the flow field distribution of the terminal device.Comparison of these two results shows the reliability of the numerical simulation results,and provides a reference for setting up boundary condition of the terminal device numerical simulation.This thesis study the flow field distribution of the terminal when using angle air valve and displacement air valve under the condition of two different air valve opening degree and three different inlet airflow(150 m3/h,200 m3/h and 270 m3/h).It is found that the flow field is more distributed when the displacement device is used in the terminal device,and it is more advantageous to improve the air volume sensing characteristic of the terminal device.The numerical simulation of the terminal device with eight kinds of deflector angles is carried out to optimize the design of the deflector angle of the end device.It is found that the uniformity of the flow field distribution of the end device is the best when the baffle angle is 30 degree.This thesis discusses the effect of the optimization of the terminal device structure on the accuracy of the air flow measurement,and further improves the accuracy of the air volume measurement by optimizing the air volume sensor installation position.In order to solve the problem of the nonuniformity of the terminal device outflow,the optimal design of the terminal device outlet duct is designed by increasing the length of the air duct and installing the rectifier board.In this thesis,numerical simulation is used to optimize the air duct structure,air outlet tube and installation position of the air volume sensor of the terminal device.The air volume measurement error is reduced from 24% of the original structure to 1.8% of the optimal structure.This thesis solves the problem that the air volume measurement error is large and the outflow is not uniform in the terminal device.The conclusion of this thesis can provide reference for the design and transformation of the ship’s variable air volume terminal device.