Effects of Operating Parameters on Threshing Efficiency Control the Amount of Threshing Loss

Document Type : Research Paper

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Abstract

Performance of grain harvesters is estimated by Threshing Power, losses fuel consumption. Grain loss is the most important of them. Total grain losses of combine harvesters in Iran is about 20% of production and sometimes higher. One of ways concern to loss reduction is separation of harvesting processes and providing a desire Mathematical Model for them by investing and measuring of important parameters in losses. Threshing is one of these processes which has more effect on combine performance. Threshing efficiency varies in reverse with threshing loss. It is desire to maximize threshing efficiency in threshing mechanism, because it will decrease the threshing losses and the load of separation mechanisms. Height of stem, feed rate, space between threshing drum and concave and rotational speed of threshing drum are operating factors which not only effect threshing efficiency but also combine loss. In order investigate the effect of mentioned parameters on threshing efficiency an experiment was conducted In 4×3×3 factorial pattern with completely randomize blocks design. Independent variables in these experiments were stem height, feed rate, clearance ratio and rotational speed of threshing cylinder. Threshing efficiency was considered as dependent variable. Analysis of variance showed that all variables had significant effect on threshing efficiency but interaction effects of them were not significant (P<0.01).Threshing efficiency increase when stem height, feed rate, and threshing clearance decreased. Also as rotational speed of cylinder increased, threshing efficiency increased. Multiple regression was used to express relation between dependent and independent parameters. The most compatible model for threshing of materials (y1) was as follow: y1=a0 e (a1x1+ a2x2+ a3x3+ a4x4)  Which x1, x2, x3 and x4 were stem height, feed rate, threshing clearance rate and speed of threshing cylinder respectively and a0, a1, a2, a3 and a4 were constants. 

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References

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