Design of a Winnowing Machine for West African Rice Farmers

Project Abstract

<p>                    <b>ABSTRACT&nbsp;</b><br></p><p> Current basket winnowing methods utilized in Lafia, Nigeria are inefficient in cleaning impurities from rice paddy harvested from the field. To address the issue, a design was created which combined the technology of a dual-combine sieve and Chinese winnowing machine with the emphasis of creating the prototype from accessible and recycled materials. The design underwent a series of system developments from theoretical concept to first prototype, leading to the adjustment of key components. Performance of the machine was determined through testing, and future improvements were suggested based off the performance results. The relative cost of the machine and feasibility of implementation was found in relation to Lafia, Nigeria. Ultimately, the first prototype was a successful proof of concept, and shows promise in being an effective solution for improving the efficiency and quality of winnowing. <br></p>

Project Overview

<p><b>1.1 INTRODUCTION&nbsp;</b></p><p> Reducing rice post-harvest losses is a necessary step toward ensuring greater global food security as increased future demand will require increased production efficiency. Winnowing is a process of cleaning chaff from paddy initially harvested from the field, and is conducted by using wind separation to blow lighter chaff and debris from rice paddy mixture dropped from a height. (Okunola and Igbeka, 2009). Currently, developing communities in West Africa utilize antiquated winnowing baskets which depend heavily on natural wind for cleaning; there is a reported 1-5% total global rice loss from cleaning processes alone as winnowing baskets have limited efficiency in separating rice from debris (Ogunlowo &amp; Adesuyi, 1999). Consequently, rice winnowed by this method also has a reported reduction in quality. This is a significant problem; low-quality rice is not only unsuitable for export, local West African consumption and demand is also low (Hall, 1972). The use of winnowing baskets is labor intensive and inefficient, requiring women workers who traditionally winnow rice to input full eight hour work days. Because the performance of winnowing baskets is contingent upon natural wind, the rice output quantity suffers from paddy separation losses and is also low-quality. The previous focus was to conduct a literature review of winnowing technology utilized in industrial processes to adopt that technology in design suitable to Lafia, Nigeria. The objective of this report is twofold: to explore the implementation challenges of creating a design which improves the efficiency and quality of rice winnowing, while simultaneously prioritizing the accessibility and ease of design replication. As such, the prototype developed for this report takes into consideration a number of key constraints and parameters determined for Lafia, Nigeria. There are several constraints which are highly relevant in the prototype of a winnowing machine. Accessibility of parts and the cost of obtaining parts are related; the two constraints highly influence what materials will be used for construction of the prototype. An assumption is that Nigerian women will be operating the winnowing machine as they are traditionally entrusted with the job, a factor which will influence the physical dimensions and direct physical labor inputs needed of the prototype. The local capacity of Nigerians to upkeep a winnowing machine and the availability of local fuel sources are also important constraints in determining the sophistication of the machine, and the source of power used to drive the prototype. Lastly, human health and well-being is of the utmost concern, which influences the overall design when incorporating safety factors and measures undertaken to reduce debris inhalation. Ultimately, the goal is to adequately address the relevant local constraints, in hope that the prototype is wellreceived and adopted. <br></p>