Noise Prediction of Outdoor Unit of Air Conditioning with Different Sizes Based on CFD

G1 - Installation Effect

Recently, the market shows a demanding of quieter outdoor air conditioning unit. The stringent noise radiation requirement from the air conditioning has driven us to investigate the noise source and noise radiation regulations of the outdoor unit experimentally and numerically, and to develop an effective method in predicting aerodynamic noise of the outdoor unit. In this investigations, the noise of two types of residential air conditioners, up side blow-out outdoor units and front side blow-out outdoor units are presented, Totally fourteen different sizes are investigated in this study. Heat exchanger and associated rotor are the main parts of the studies. Aerodynamic performance is measured to evaluate the effect of changing structure size upon the flow rate and the results are used as the boundary condition for CFD simulation. Based on noise generation mechanism, a corrected program has been developed based on Fukano’s vortex shedding noise model to predict the broadband noise level using CFD results as the input. With correctional of stagger angle, as well as A-weighted SPL has been used in this program. The noise prediction accuracy of two types of outdoor units is quite well. Through the predict results, the effect of the structure size of outdoor unit to the noise level is obvious. The size of outdoor unit will affect the flow rate, noise radiation. For the up side blow-out outdoor unit, the decrease of height of heat exchanger could increase noise level and decrease flow rate. The distance from side board to the rotor tip must be suitable; a well-designed distance could make the noise level down. For the front side blow-out outdoor unit, the thickness of heat exchanger has great effect to the flow rate and noise radiation. The distance from side board to the rotor tip must not be too short, otherwise the internal space could become small and the flow field could become complex. The program demonstrates of meeting the demand of engineering application for design the size of outdoor unit quickly.