Composite panels for reducing noise in air conditioning and ventilation systems

The plate silencer [1] that consists of an expansion chamber with two side-branch cavities covered by a light panel can achieve a desirable noise reduction in broadband theoretically. The concept is similar to drum silencer [Choy YS, Huang L. Experimental studies of drum-like silencer. J Acoust Soc Am 2002;112:2026–35]. To attain optimal noise reduction, either the membrane of the silencer should be of minimal weight while retaining very high tensile strength or the panel should be kept at very high bending stiffness that is dependent on its geometry and mechanical properties. To achieve such goal, various kinds of composite system such as carbon fibres or aluminum were mounted on light core foam to build a noise reflection panel. A design of composite panels which can provide a reduction in panel weight as well as enhance the bending stiffness, is introduced in this paper. Predictions of the new model are to be compared with the normal foam plate in the aspects of noise reflection capability and performance of noise abatement apart from the material properties.