Abstract: An airflow feedback control method and apparatus for fan filter unit (FFU) is proposed, which is designed for use with a fan filter unit that is widely used in semiconductor fabrication factories for dust-clearing purpose, for controlling the fan filter unit to generate a constant amount of airflow equal to a preset desired amount. The proposed FFU airflow feedback control method and apparatus is characterized by that it utilizes bell inlet as an airflow measuring nozzle and that airflow is used as feedback parameter to control the FFU, rather than utilizing motor speed as feedback parameter by prior art. This feature allows the fan filter unit to continuously generate a fixed amount of airflow equal to the preset desired amount even if there is a pressure change at the site of installation, thus lessening the problems of insufficient air change rate and sideward-going airflows.

Abstract: A multi-stage thermoacoustic device includes a resonance tube mounted therein a plurality of stacks and a plurality of heat exchangers interlaid with each other adjacent to a second end of the resonance tube. A working fluid is filled in the resonance tube. A driver mounted on a first end of the resonance tube drives the working fluid oscillate in the resonance tube, the working fluid is compressed and expanded and causes temperature oscillation and thermal energy flowing from one end of the stack to the other end. The thermal energy, such as cooling capacity, is finally transferred outward through the heat exchangers on sides of the stacks. The multiple stacks and heat exchangers perform a multiple stage temperature gradient. More thermal energy is transferred, and the working efficiency is improved.

Abstract: An airflow feedback control method and apparatus for fan filter unit (FFU) is proposed, which is designed for use with a fan filter unit that is widely used in semiconductor fabrication factories for dust-clearing purpose, for controlling the fan filter unit to generate a constant amount of airflow equal to a preset desired amount. The proposed FFU airflow feedback control method and apparatus is characterized by that it utilizes bell inlet as an airflow measuring nozzle and that airflow is used as feedback parameter to control the FFU, rather than utilizing motor speed as feedback parameter by prior art. This feature allows the fan filter unit to continuously generate a fixed amount of airflow equal to the preset desired amount even if there is a pressure change at the site of installation, thus lessening the problems of insufficient air change rate and sideward-going airflows.

Abstract: A fan filter unit includes a housing having a side wall and a top wall with a bell mouth serving as an air inlet and an open bottom to which a filtering net is attached to serve as an air outlet. A centrifugal fan is arranged in the housing to drive the air from inlet. The fan assembly has an output port for driving an air flow toward the air outlet. A guide plate is arranged in the housing for guiding the air flow along the path from the fan assembly to the air outlet. A sound-absorbing structure including a plurality of wedge-shaped elements made of a sound-absorbing material is attached to the side wall. The wedge-shaped elements are arranged in a line for effectively reducing noise level caused by the operation of the fan assembly. A second line of wedge-shaped elements is optionally attached to the side wall with the wedge-shaped elements of the two lines alternating each other.

Abstract: A fan filter unit includes a housing having a side wall and a top wall with a bell mouth serving as an air inlet and an open bottom to which a filtering net is attached to serve as an air outlet. A centrifugal fan is arranged in the housing to drive the air from inlet. The fan assembly has an output port for driving an air flow toward the air outlet. A guide plate is arranged in the housing for guiding the air flow along the path from the fan assembly to the air outlet. A sound-absorbing structure including a plurality of wedge-shaped elements made of a sound-absorbing material is attached to the side wall. The wedge-shaped elements are arranged in a line for effectively reducing noise level caused by the operation of the fan assembly. A second line of wedge-shaped elements is optionally attached to the side wall with the wedge-shaped elements of the two lines alternating each other.

Abstract: A low-noise fan-filter unit for providing filtered airflow is disclosed. The fan-filter unit includes a housing having at least an air inlet and a coaxial air outlet; a centrifugal fan installed in the housing for drawing air into the housing and propelling it out of the air outlet; a filter installed between the fan and the air outlet for removing impurities from the air; and a noise reduction arrangement installed between the fan and the filter for reducing noise. The noise reduction arrangements includes three parting plates incorporating with the housing to form a tortuous air passageway which U-turns the airflow at least two times. The tortuous and extended air passageway, and some sound-absorbing materials furnished along the air passageway increase the contact area between the airflow and the sound-absorbing materials, and enhance the effect of noise absorption.