Numerical Simulation Of Throttling Noise Of Electronic Expansion Valve

Electronic Expansion Valve (EEV) is one of the most important components inInverter air conditioner, whose Frequency compression technology have effectivelysaved the air-conditioning electricity. Not only the EEV for regulating the flow ofrefrigerant, and can affect the air conditioning EER. The noise of EEV has got moreand more attention in air conditioning performance. In this paper, the fluid noise ofEEV were measured under the inverter air conditioner in cooling conditions; andestablishing a three-dimensional model of the EEV, and develop a numericalsimulation of two-phase flow and noise characteristics of the interior, the workingfluid is HFC-410A. The results for the flow channel model of electronic expansionvalve design and improvements can play an important reference value.The numerical simulation of the flow field of electronic expansion valve can beachieved using the k-ε turbulence model; the droplet evaporation and boiling model todescribe and calculate the flash process quality between gas and liquid in valve portand its downstream; using broadband noise model to calculate the flow field noise;discrete equations using finite difference method; using coupled algorithm pressure-velocity coupling flow field.First, create three-dimensional models with different flow channel opening of theelectronic expansion valve, then meshing to them and making the mesh-independentanalysis; through the homogenized to flow field to obtain the flow of the electronicexpansion valve under different opening, and compare them to the experimentalvalues, found the simulation results and the experimental value of the measured trendshave a good agreement within allowable error. In addition, the comparison of pressurecloud and velocity cloud under different opening were found very similar, select0.625mm opening degree (i.e.100pulses) of the flow field were analyzed separately.We found both the corner of the valve port inlet and the valve needle at the end facehave pressure minimum value, which could be found from the flow chart that twovortices stay in the end face of the valve needle, their mutual disturbance, the pressure distribution is formed in the irregular region and the downstream not far from causinga high pressure area. Also on the plane of symmetry through the extraction pressure,velocity and turbulence regions numerical kinetic mainstream line, analysis to obtainthe position within the electronic expansion valve noise generated in the port near thewall at its downstream z=-0.138m.Next, analyzed the noise in the EEV, the dominant noise comes from thequadrupole noise, that is, caused by the great turbulent kinetic energy in the valve,which mainly in the port wall, the valve needle as well as the downstream end face ofa particular area of the pipe.Then, have an experimental study about the noise in EEV, arranging themeasuring points around electronic expansion valve by30centimeters. The Enthalpylab could keep the temperature of environment cabinets, adjust the air conditionerwind speed, get a curve between the opening and sound pressure level, and we findthat sound pressure level and opening have same trends under different windconditions, which reflect that the shape of flow channel has an important impact onthe noise.Finally, according to the results of the foregoing analysis, we change the inletpressure, the flared port angle of up and down stream, length of valve port, andestablish corresponding structure model and numerical simulation. The simulationresults show that the mass flow and the turbulent kinetic energy increases as well aspressure, and representative of the sound power level increases. The numericalsimulation about different flared angles of EEV show that the upstream flared angleshas a great impact on the noise, and within the selected angular range, the60to70degree of entrance angle has the minimum sound power level; the downstream flaringangle can effectively reduce the presence of sound power inside the tube, but differentflared angles has little disparity on the noise. The simulation results of different lengthshow that the noise cyclical change with the change of the length.