An axial flow cyclone with an inner diameter of was designed and tested to remove fine particles at low pressure (6–) and low flow rate (0.455 and ) conditions. Pressure inside the cyclone was found to have a considerable effect on the particle collection efficiency. At lower pressure, the particle collection efficiency was also found to be higher. The cyclone with higher pressure drop has higher collection efficiency. At a fixed inlet pressure, higher pressure drop of design 1 with one 3-turn vane was found to have a higher collection efficiency than design 2 with three half-turn vanes. At lowest achievable pressure of at the flow rate of in this study, the axial flow cyclone of design 2 is able to remove particles below efficiently, and the cutoff aerodynamic diameter is .
Theoretical prediction of cutoff aerodynamic diameter was found to agree with published experimental data in the literature at ambient conditions. However, at vacuum and low flow rate conditions, experimental collection efficiency was found to be much lower than theoretical efficiency. Based on the experimental data, a semi-empirical equation incorporating the flow Reynolds number was developed to predict the cutoff aerodynamic diameter with good accuracy at different inlet pressures, flow rates and cyclone designs.
This low flow rate axial flow cyclone is applicable for fine particle removal in the low pressure exhaust gas of reaction chambers, such as in the semiconductor and optoelectronic industries. In the future, it is worthwhile to study the effect of particle loading in the cyclone and particle material on the particle collection efficiency.