| The noise of a commercial air conditioner condenser in a catering store exceeds the standard.This paper first tests it and gives a noise reduction treatment scheme.According to the noise measurement standard,the condenser was tested on site with a sound level meter,and the equivalent A-weighted sound pressure value at the outlet of the axial flow fan of the condenser was 78.54 d B,and the average value of the equivalent A-weighted sound pressure level at 1m around the condenser was 72.41 d B,far exceeding the standard value specified for Class II areas in GB3096-2008 National Standard Acoustic Environmental Quality Standard of the People’s Republic of China.The condenser acoustic enclosure is designed to reduce noise.LMS virtual lab software is used to simulate and analyze the sound absorbing material by impedance tube method,and centrifugal glass wool with density of 58kg/m3 and thickness of50 mm is selected as the sound absorbing material;Perforated panels with a hole diameter of 3mm,a perforation rate of 20% and a lining behind the panels are used as sound absorption structures.Through the reverberation room method,the sound insulation characteristics of three kinds of sound insulation materials are analyzed and studied,and 2mm galvanized steel plate is finally selected as the sound insulation material of the sound insulation hood.Air++3109 damping coating is selected as the damping layer of the acoustic enclosure through analysis.In combination with the selected sound absorption and insulation materials,a composite structure is proposed,which is composed of 2mm galvanized steel plate,2mm Air++3109 damping coating,50 mm,58kg/m3 centrifugal glass wool and 2mm,3mm aperture,20% perforation rate,and perforated plate of lining cloth behind the plate.The sound insulation of the proposed composite structure is simulated and analyzed to verify the feasibility of the composite structure;At the same time,select the air inlet louver and outlet muffler.Optimization of the shape and structure of the acoustic enclosure.With the objective of minimizing the quality of the acoustic enclosure and the overall dimension as the design variable,the mathematical model of the acoustic enclosure is established.The optimal dimensions of the acoustic enclosure are 2000 mm in length,1492 mm in width and 2011 mm in height by programming and solving with Matlab.Modal analysis of acoustic enclosure.Rhino 7 is used to establish the threedimensional model of the acoustic enclosure,and the model is imported into the Ansys Workbench for modal analysis.From the modal analysis results,it can be seen that the natural frequency of the acoustic enclosure is 50.356Hz-119.92 Hz,while the fundamental frequency of the condenser noise during operation is 45 Hz.Through comparison,it is found that there is no resonance between the two,which verifies the rationality and correctness of the overall structure optimization.In order to study whether the heat dissipation of the condenser is affected and its sound insulation performance after installing the sound insulation cover,CFD numerical simulation is used to conduct thermal and acoustic simulation research on the internal and surrounding environment of the condenser before and after installing the sound insulation cover.It is concluded that not only the noise reduction effect is obvious after installing the sound insulation cover,but also the impact of its thermal environment change on the equipment is safe and controllable. |
