Research On Aerodynamic Noise And Noise Reduction Of Air-Conditioner Electronic Expansion Valve

The fluid noise of electronic expansion valve is measured under rated refrigeration condition of variable frequency air conditioning.At the same time,the3 d model of the electronic expansion valve is established,and the flow and noise characteristics of the valve are simulated numerically by using R22 as the working medium.The calculated results have important reference value for the study of air conditioning noise.In this paper,the electronic expansion valve flow field numerical simulation using Reliable turbulence model,evaporation and boiling model is used to describe the calculation in the process of flash and downstream of the valve port and quality between gas and liquid two phase transformation;The convection field noise is calculated by using broadband noise model.The control equation discrete by finite difference method.The Coupled algorithm is used to solve the combined flow field of pressure and velocity.Firstly,the 3d flow path model of electronic expansion valve with different opening degrees was established,and the meshing was divided and the meshing independence was analyzed.The flow rate of the electronic expansion valve with different opening degrees is obtained by time-homogenizing the flow field of the electronic expansion valve.In addition,the pressure cloud map and velocity cloud map of the flow field with different opening degrees were compared,and the distribution was very similar.The flow field with a width of 1.875 mm was selected for separate analysis.The corner and the entrance of the valve port valve needle is found to exist under the end surface of the minimum pressure valve needles were found in the flow chart were two vortex,they mutual interference,formed the irregular distribution of pressure.In addition by extracting symmetry plane pressure,velocity and turbulence kinetic energy online mainstream areas,analysis for electronic expansion valve in the location of the noise produced in the valve port near the wall and its middle and lower reaches.Then,the cause of electronic expansion valve noise is analyzed and theexperimental results are compared,and the simulation results are verified.Electronic expansion valve's main source of noise is quad pole noise,namely the produced fluid in the valve has no regulation motion larger turbulent kinetic energy,mainly distributed in the valve opening under the wall,needle valve end face,and a particular area of the downstream piping.The relationship between compression ratio,noise and mass flow is introduced,and the importance of compression ratio is analyzed.Finally,on the basis of compression ratio,the scheme of connecting a capillary before the expansion valve to reduce the noise of the valve is designed and verified by simulation.To get the results of numerical simulation and the simulation results of the comparison of a single valve,found that the optimal scheme of fluid into the valve pressure really had a good control of the speed of the fluid within the valve compared with a single valve also reduced a lot.The noise at the valve and the middle and lower reaches of the valve are well controlled.