Influence of surrounding structures upon the aerodynamic and acoustic performance of the outdoor unit of a split air-conditioner

Abstract

DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structures upon the aerodynamic and acoustic performance, however they are only limited to the influence of a few parameters on the performance, and practical design of the unit requires more detailed parametric analysis. Three-dimensional computational fluid dynamics(CFD) and computational aerodynamic acoustics(CAA) simulation based on FLUENT solver is used to study the influence of surrounding structures upon the aforementioned properties of the unit. The flow rate and sound pressure level are predicted for different rotating speed, and agree well with the experimental results. The parametric influence of three main surrounding structures(i.e. the heat sink, the bell-mouth type shroud and the outlet grille) upon the aerodynamic performance of the unit is analyzed thoroughly. The results demonstrate that the tip vortex plays a major role in the flow fields near the blade tip and has a great effect on the flow field of the unit. The inlet ring's size and throat's depth of the bell-mouth type shroud, and the through-flow area and configuration of upwind and downwind sections of the outlet grille are the most important factors that affect the aerodynamic performance of the unit. Furthermore, two improved schemes against the existing prototype of the unit are developed, which both can significantly increase the flow rate more than 6 %(i.e. 100 m 3 ·h −1 ) at given rotating speeds. The inevitable increase of flow noise level when flow rate is increased and the advantage of keeping a lower rotating speed are also discussed. The presented work could be a useful guideline in designing the aerodynamic and acoustic performance of the split air-conditioner in engineering practice.

An Investigation of the Acoustic Enclosure of an Air Conditioning Compressor Using Response Surface Analysis and Topological Rigidity Optimization

“…Mao et al [5] investigated the noise characteristics of two-stage centrifugal compressors using a multilayer microperforated panel absorber designed to reduce tonal noise, particularly at the outlet pipe, and experimentally confrmed the noise reduction. Wu et al [6] applied a combined approach of dynamic vibration absorption, sound absorption, and damping technologies to the outdoor unit of split-type air conditioners, achieving a 10 dB reduction in sound pressure levels.…”

Investigation of aerodynamic performance of small axial flow fan coupled with deflecting ring

“…For the bigger axial fan, the inlet ring’s size and throat’s depth of the bell-mouth type shroud, and the through-flow area and configuration of upwind and downwind sections of the outlet grille are the most important factors that affect the aerodynamic performance of the unit. 22 Shroud parameters optimized by experiments can improve the efficiency of the axial fan, and proper deflecting ring length can help to reduce the noise level of the axial fan. 23,24 However, the global performances of the fan coupled with the deflecting rings featuring different lengths need to be compared and investigated further.…”