The cyclone is widely used as air cleaning device. Many studies have been made on how to enhance its particle collection efficiency or reduce the airflow resistance, but usually the alteration of only one dimension is discussed, and only the collection efficiency or the airflow resistance is considered. Some studies have compared the 50% cut-off size under the same airflow resistance, or compared the airflow resistance under the same 50% cut-off size to obtain the optimal configuration. Yet steps like this take long time to complete, which makes it difficult to compare the cyclone efficiency comprehensively.
This work adopts the cyclone quality factor as the performance index, and the cyclone designed by Stairmand is adopted as the basic configuration in the present study. With the cyclone body diameter (D) fixed, we vary the cyclone length (H), inlet height (a) and width (b), cyclone length without the cone (hb), cone height (hc), cone bottom diameter (B), and vortex finder length (S). The results show that each of these design parameters has a different impact on the cyclone performance.
Based on the cyclone quality factor, equivalent to the filter quality factor, it is found that the H and S of the Stairmand cyclone are already the optimal conformations. The cyclone performance could be further improved, if further changes could be made to the other conformations, for example, narrowing down the inlet (adjusting a/b from 13/5 to 20/3.2), reducing the cone bottom diameter (adjusting B from 9 mm to 4 mm) and decreasing the vortex finder diameter (adjusting De from 13 mm to 8 mm), The cyclone quality factor appears to be a function of the volumetric flow rate. Results demonstrate that while the air flow is fixed at 15 L/min, the newly improved cyclone could perform 12 times better than the Stairmand cyclone, according to the cyclone quality factor.