Research On Air Conditioner Piping Vibration And Stress Based On ANSYS Workbench

Piping design is the core of air conditioner structural design and it plays an important partin maintaining the working stability and reliability of the air conditioner. Traditional pipingdesign depends on repeated trial production and tests of prototypes, which often costs a lotof manpower and financial resources. In this thesis, the finite element method(FEM) is usedto study the dynamic characteristics of an original prototype of air conditioner by usingANSYS software, with focusing on modal analysis, harmonic response analysis, fluid-structure coupling analysis and static structure analysis in order to investigate the states ofpipe’s vibration and stress. The results and findings of this thesis help deeply understand thepipe failure mechanism and improve the piping design.Pipe fatigue failure is mainly caused by the following three factors: the vibration of thecompressor, the gas pulsation and impaction and the high pressure of refrigerant in pipe.Firstly, the modal analyses of compressor and pipeline system was conducted. The resultsshow that the frequencies of the 7th(46.43 Hz) and 8th(53.77 Hz) modes are very close tothe working frequency(50 Hz) of air of conditioning system, which may cause the resonance.The resolving of the stimulation from the compressor indicates that it is mainly acompounding of those with 50 Hz, 100 Hz and 150 Hz. The harmonic response analysis alsoshows that the deformation and stress of the U-pipe exceeds the allowance under the 50 Hzstimulation. This phenomenon coincides with the 7th mode and the resonance may happen.Secondly, the force caused by the gas pulsation was calculated and exerted on the modelto realize the harmonic response analysis. The results show that the above mentionedU-pipe has the largest regional deformation, and the maximum stress is located at theinterface between the pipe and the condenser with the value greatly less than that arising fromthe compressor body vibration.Finally, the vent pipe, which has the maximum pressure, was analyzed by usingfluid-solid coupling method in steady state. The results show that the maximum deformationof U-pipe locates at the first elbow. The phenomena of stress concentration are founded on theelbow and the ends of the pipe. The pipe deformation and the stress decrease with increasingthe radii of the transition arcs, meanwhile the influence of the radius on the peak stress is onthe decline. Compared with R10 and R30 elbow pipe, R20 elbow pipe is recommended as itmeets the requirements of the reliability and the economy demands in piping design.