The acoustic characteristics, in this doctoral thesis, are investigated by operating the conventional heat recovery ventilator in an anechoic chamber, and the problems are identified and analyzed by examining the acoustic characteristics according to the airflow rate in the heat recovery ventilators...
The acoustic characteristics, in this doctoral thesis, are investigated by operating the conventional heat recovery ventilator in an anechoic chamber, and the problems are identified and analyzed by examining the acoustic characteristics according to the airflow rate in the heat recovery ventilators installed actually at school and elderly welfare facilities. As a way to reduce the noise of the ventilator based on problems found through these works, the effects of reduced noise are surveyed by inserting various sound-absorbing materials at the inside of a ventilator and attaching duct silencers at the outside path of a ventilator.
Moreover, as an effort to reduce noise in consideration of indoor people’s auditory characteristics in the state of different environments, this study conducted the auditory experiment for sound sources in an apartment that could shield the noises from heat recovery ventilator, and surveyed a questionnaire in a variety of auditory environment. In addition, the noise reduction strategies are suggested through acoustic simulation for indoor noise that might happen when the most efficient equipment in reducing the noise inside and on the path of a heat recovery ventilator is applied in various cases of actual construction. The outline and purposes of research conducted in this study are summarized as follows.
The first research, in order to find acoustic problems for the conventional heat recovery ventilator and to suggest methods of reducing noise from heat recovery ventilator by space, measured and discussed the noise as parameters the size and airflow rate of heat recovery ventilator based on domestic and foreign standard specifications. In addition, the noise level was measured, compared, and analyzed according to the length of sound?absorbing duct in order to assess the noise reduction effect when a sound?absorbing duct is connected to a heat recovery ventilator. It is found, as a result, that the noise from a heat recovery ventilator in the anechoic chamber was somewhat higher than noise standard 50 dB(A) at the respective airflow rate, and the noise level went down when a sound?absorbing duct is installed.
The second research, in order to assess the noises from heat recovery ventilators installed at school and elderly welfare facilities, measured, compared and analyzed indoor noise from the capacity of heat recovery ventilators according to the volume size of classroom, teachers’ room and computer room among school facilities, and according to the capacity of different size including two program rooms, reception room for women, cafeteria and table tennis room among elderly welfare facilities. It is found, as a result, that the indoor noise level was higher at the bottom of the supply than at the return side of heat recovery ventilator, and even among heat recovery ventilator of the same capacity, the deviation in indoor noise level was large according to the position of the diffuser.
The third research, in order to reduce noise in conventional heat recovery ventilators, compared and analyzed the noise reduction effect observed inside the heat exchange ventilation systems after preparing various sound-absorbing materials, inserting them inside the systems, and examining acoustic characteristics according to airflow rate. In order to reduce noise on the path, furthermore, silencers were attached to the duct outside heat recovery ventilators and acoustic characteristics were examined according to the length and form of the silencers. It is found, as a result, that the noise reduction effect was 0.4 ∼ 2.3 dB(A) when sound-absorbing materials were inserted, depending on airflow rate compared to conventional heat recovery ventilators, and 6.5 ∼ 9.1 dB(A) when silencers were attached.
The fourth research, in order to predict and analyze the sound pressure distribution and acoustic factors in low noise heat recovery ventilators, conducted an experiment on the loudness, noisiness and annoyance of noise sources, and the auditory responses to noise?related life feelings for conventional and low?noise heat recovery ventilators under the various background noises of apartment using 3D computer simulation by the raytracing method and the mirror image model method. It is found, as a result, that the noise in each room of the apartment was reduced by about 2.6 dB(A) when sound-absorbing materials were inserted, about 8.0 dB(A) when silencers were attached, and about 9.6 dB(A) when sound-absorbing materials were inserted inside the heat recovery ventilator and silencers were attached outside.
The acoustic characteristics, in this doctoral thesis, are investigated by operating the conventional heat recovery ventilator in an anechoic chamber, and the problems are identified and analyzed by examining the acoustic characteristics according to the airflow rate in the heat recovery ventilators installed actually at school and elderly welfare facilities. As a way to reduce the noise of the ventilator based on problems found through these works, the effects of reduced noise are surveyed by inserting various sound-absorbing materials at the inside of a ventilator and attaching duct silencers at the outside path of a ventilator.
Moreover, as an effort to reduce noise in consideration of indoor people’s auditory characteristics in the state of different environments, this study conducted the auditory experiment for sound sources in an apartment that could shield the noises from heat recovery ventilator, and surveyed a questionnaire in a variety of auditory environment. In addition, the noise reduction strategies are suggested through acoustic simulation for indoor noise that might happen when the most efficient equipment in reducing the noise inside and on the path of a heat recovery ventilator is applied in various cases of actual construction. The outline and purposes of research conducted in this study are summarized as follows.
The first research, in order to find acoustic problems for the conventional heat recovery ventilator and to suggest methods of reducing noise from heat recovery ventilator by space, measured and discussed the noise as parameters the size and airflow rate of heat recovery ventilator based on domestic and foreign standard specifications. In addition, the noise level was measured, compared, and analyzed according to the length of sound?absorbing duct in order to assess the noise reduction effect when a sound?absorbing duct is connected to a heat recovery ventilator. It is found, as a result, that the noise from a heat recovery ventilator in the anechoic chamber was somewhat higher than noise standard 50 dB(A) at the respective airflow rate, and the noise level went down when a sound?absorbing duct is installed.
The second research, in order to assess the noises from heat recovery ventilators installed at school and elderly welfare facilities, measured, compared and analyzed indoor noise from the capacity of heat recovery ventilators according to the volume size of classroom, teachers’ room and computer room among school facilities, and according to the capacity of different size including two program rooms, reception room for women, cafeteria and table tennis room among elderly welfare facilities. It is found, as a result, that the indoor noise level was higher at the bottom of the supply than at the return side of heat recovery ventilator, and even among heat recovery ventilator of the same capacity, the deviation in indoor noise level was large according to the position of the diffuser.
The third research, in order to reduce noise in conventional heat recovery ventilators, compared and analyzed the noise reduction effect observed inside the heat exchange ventilation systems after preparing various sound-absorbing materials, inserting them inside the systems, and examining acoustic characteristics according to airflow rate. In order to reduce noise on the path, furthermore, silencers were attached to the duct outside heat recovery ventilators and acoustic characteristics were examined according to the length and form of the silencers. It is found, as a result, that the noise reduction effect was 0.4 ∼ 2.3 dB(A) when sound-absorbing materials were inserted, depending on airflow rate compared to conventional heat recovery ventilators, and 6.5 ∼ 9.1 dB(A) when silencers were attached.
The fourth research, in order to predict and analyze the sound pressure distribution and acoustic factors in low noise heat recovery ventilators, conducted an experiment on the loudness, noisiness and annoyance of noise sources, and the auditory responses to noise?related life feelings for conventional and low?noise heat recovery ventilators under the various background noises of apartment using 3D computer simulation by the raytracing method and the mirror image model method. It is found, as a result, that the noise in each room of the apartment was reduced by about 2.6 dB(A) when sound-absorbing materials were inserted, about 8.0 dB(A) when silencers were attached, and about 9.6 dB(A) when sound-absorbing materials were inserted inside the heat recovery ventilator and silencers were attached outside.
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