Measuring Vibration and Noise from a Magnetic Levitation Central Air-Conditioner

Mechanical vibrations and acoustic noise induced by air-conditioners are a widespread cause for concern. The magnetic levitation (maglev) central air-conditioner (CAC) system is a new type of air-conditioner system considered to be able to generate less vibration and noise. The performances of a maglev system and a regular CAC system, under normal operating conditions, were compared experimentally in the same room. For each CAC, the compressor vibrations and floor vibrations were measured and evaluated with reference to the guidelines of the Chinese National Standard GB/T 50355-2005, Standard of Limit and Measurement Method of Vibration in the Room of Residential Buildings. The indoor noise generated by each CAC system was also measured and compared. Results show that (1) in the frequency domain, the compressor vibrations of the maglev CAC are one to two orders of magnitude weaker than those of the regular CAC; (2) the dominant frequencies of the compressor of the maglev CAC are 125, 165, and 350 Hz, but there are no apparent characteristic frequencies for the regular CAC; and (3) the indoor acoustic noise generated by the maglev CAC is significantly weaker than that generated by the regular CAC, with A-weighted sound levels differing by 6.5 dB on average.