Active control of compressor noise in the machinery room of refrigerators

Ku, Jeong-Mo; Jeong, Weui-Bong; Hong, Chang-Oh

doi:10.3397/1/376730

Cited by 7 publications

(2 citation statements)

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“…In addition, we control the absorption frequency at 230-330 Hz, which covers with the main noise frequencies of household appliances in our daily life. [43][44][45] Therefore, the AAVMA absorber could effectively reduce the noise pollution caused by the high penetration ability of low-frequency sounds. In the future, the demonstrated AAVMA can be developed into stunning applications, such as intelligent window silencers, which not only effectively solves the influence of external noise, but also provides a fresh air and bright working environment.…”

Section: Discussionmentioning

confidence: 99%

Automatically Adaptive Ventilated Metamaterial Absorber for Environment with Varying Noises

Tian

et al. 2021

Adv Materials Technologies

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thickness, health and environment issues, fire resistance, moisture resistance, and durability issues. [1][2][3][4] In the past two decades, varieties of artificial structures, collectively called "acoustic metamaterials," have been designed to manipulate sound waves beyond natural limits. [5][6][7][8][9][10][11][12][13] For example, low-frequency (<500 Hz) sound waves have strong penetration ability, long propagation distance, and low attenuation coefficient, hence it is still a great challenge to deal with low-frequency noises. [1,3,4,14] In the last decade, diverse sound-absorbing metamaterials in subwavelength scales have been designed, which generally increase the density of states at targeted low-frequencies in the metamaterials in order to enhance the dissipation of sound energy. [15][16][17][18][19][20][21][22][23][24][25] However, for most acoustic metamaterials, their targeted frequencies and operating functions can hardly be adjusted after being fabricated. It is hence an intrinsic barrier for their applications in scenarios where the frequencies of noise can change over time.To overcome this stringent barrier, tunable acoustic metamaterial absorbers have been proposed and investigated in recent years. [26,27] Some tunable mechanisms, mainly employing the mechanical deformations, piezoelectric, and/or magnetic effects, have been presented. [28][29][30][31][32][33] However, they generally require rigid backings to impede sound transmissions, which forbid the transmission of fluids, such as air and water. The absorption of a ventilated acoustic metamaterial composed of subwavelength scatters is usually much smaller compared with its reflection. It is a challenge to break the limit and finally achieve a tunable absorber with simultaneously good absorption and ventilation at low frequencies. [33] Besides, their intricate mechanical, electronic, and magnetic structures are inconvenient and may be unstable for daily applications. [34,35] Moreover, previously designed adjustable metamaterial absorbers could not automatically perceive incident sound to realize intelligent adjustment and absorption. [21,[36][37][38][39][40][41][42][43] A simpler, more adjustable, and more automatic scheme is eagerly needed.Here, we demonstrate an automatically adaptive ventilated metamaterial absorber (AAVMA) for low-frequency sound that can achieve high-efficiency (>90%) absorption for onesided incidence with frequency varying in the working range. The ventilated absorber can automatically monitor the environmental noise and intelligently adjust the sound absorption An automatically adaptive metamaterial sound absorber is designed, which can absorb tunable low-frequency (<500 Hz) sounds under ventilated conditions by designing a feedback circuit to actively detect the noise signals and adjust the sliders on the reconfigurable absorbers. The automatically adaptive ventilated absorber provides an intelligent route to adapt for different low frequencies, through adjusting the sound absorption units directly in accordance with the...

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Section: Discussionmentioning

confidence: 99%

Automatically Adaptive Ventilated Metamaterial Absorber for Environment with Varying Noises

Tian

et al. 2021

Adv Materials Technologies

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“…However, there is not enough room for a large loudspeaker which can produce low-frequency noise. In this case, to increase the ANC technique's performance, the filter coefficient's low-frequency component can be filtered out [1]. Moreover, the POCS technique has been implemented to increase the performance of the ANC system [2].…”

Section: Introductionmentioning

confidence: 99%

Active Noise Control of Air Conditioning System Noise

Okcu,

An,

Lee

2023

Proceedings of the 8th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COM

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A HVAC (Heat Ventilation Air Condition) system of passenger seat in autonomous bus is used for heating and cooling of the seat. The compressor of the HVAC system generates the operating noise, and the noise makes passengers annoyance. Frequency spectrum of the compressor noise composes of operating frequency and its harmonics components. Frequency band of operating frequency is low, and that of harmonic frequencies is high. Active noise control (ANC) has been used for reduction of low frequency noise while a passive method using absorption material has been used for attenuation of high frequency harmonic noise. However, some part of harmonic components at low frequency band among harmonic components is not able to reduce by using absorption materials. In this paper, a new ANC method is proposed for the reduction of noise level of low frequency harmonic components based on harmonic flited x-LMS (HFX-LMS) algorithm. The novel method is successfully applied to the noise control of compressor of HVAC system of passenger seat in autonomous bus.

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