Walnut is one of the high yielding crops in horticultural production, and establishment of walnut orchards is growing. Yet despite Iran’s being the second largest producer of walnuts in the world, this country does not play a significant role in walnut export. This gap is most affected by the need to mechanize the harvesting process. This case is more understandable when can construct a new device with greater efficiency in comparison of the existing mechanical systems. In this article, a walnut huller built on the Abouraihan campus of the University of Tehran is evaluated, with Rotational speed, time and brush distance being optimized to make the best quality of hulling process. The results indicate that increasing the rotational speed, increases the amount of walnuts hulled but that the percentage of damaged nuts also increases. If, at a constant rotational speed, the distance between abrasive brushes is reduced, the amounts of nuts hulled and damaged are raised but the degree of hulling is greater than degree of injury. Also, if the distance between abrasive brushes and the rotational speed are decreased, the peeling rate is increased while the damage rate is decreased.
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