Peanut Dryer Noise Levels with and without Muffler

Abstract

Harvested peanuts must be dried before being stored to prevent spoilage. Peanuts are dried using forced heated air dryers that produce a great deal of noise while operating. In an effort to abate dryer noise, a cylindrical muffler was designed, fabricated from sheet metal, and tested. The muffler was 1.17 m in diameter, 0.61 m in length and was lined with 0.55 m of R 30 fiberglass batting. Five configurations of the muffler were tested and the most effective was the two inline mufflers attached to the air intake of the dryer. The two inline mufflers were found to reduce noise 4.5m in front of the dryer air intake to the OSHA permissible level of 90 dBA for an eight-hour time period. The inline lined mufflers reduced noise levels at 4.5 m from the side of the dryer to just less than 85 dBA the level above which OSHA recommends employers initiate hearing conservation programs. Sound levels at 23 m in front of the dryer air intake were reduced to 69 dBA which is equivalent to classroom chatter. Though the muffler designed in the study reduced dyer noise to acceptable levels, study results and new technologies suggest that further noise reduction is possible by redesigning the muffler using natural harmonics of the dryer/muffler structure, new tuned noise damping materials, and designing for sound resonance effects.