Adaptive Design and Performance Evaluation of Compact Acoustic Enclosures Built with GFRP for Portable Mini-generators

Abstract

A simple, portable and effective design for enclosing portable generators to reduce the radiated noise has remained a daunting challenge to noise control advocates in many developing countries. This research aims to use an adaptive design approach to create an enclosure for minimizing portable mini-generator noise. The noise characteristics of the mini-generators was ascertained and construction of a 730 by 640 by 600 mm enclosure was accomplished by using glass fiber reinforced plastic (GFRP) to build a double walled enclosure surfacing and rock wool as the sandwiched absorbing material. The sound pressure level (SPL) around the generator before and after the application of the enclosure was measured and evaluated. The results obtained showed that the acoustic enclosure could achieve an insertion loss of up to 16 dB (A) at a distance of 1.0 m.  Also, the heat transfer characteristic of the enclosure design was put into consideration as well as the requirements of the engine air aspiration and cooling inside of the enclosure. Incorporation of fans in the acoustic enclosure design increased convectional fresh air circulation into, and discharge of the heat generated in, the enclosure, thus maintaining a safe temperature of about 40oC inside of the acoustic enclosure at the generator operating maximum load.