Development of a miniature cyclone separator operating at low Reynolds numbers as a pre-separator for portable black carbon monitors

• A cyclone separator operating at Re less than 1000 was developed in this study. • Cyclone separators with a cut-off size of 2.5 μm were designed for three flow rates. • The flow rates were 100 mL/min, 150 mL/min, and 200 mL/min. • The cyclone separator can be used as a sampling inlet for portable BC monitors. In this study, a cyclone separator that can be used as a sampling inlet for portable black carbon (BC) monitors operating at a flow rate of less than 200 mL/min was developed. A prototype was fabricated to evaluate its performance by experiments, and the cut-off size of the cyclone separator was predicted through numerical analysis by applying various turbulence models. The RNG k–ε model was found to be suitable for the analysis of the cyclone separator operating at Reynolds numbers of less than 1000. Cyclone separators were designed through simulation and fabricated for each operating flow rate (50, 100, 150, and 200 mL/min) of a BC monitor, and their performances were experimentally verified. Meanwhile, when the non-dimensional analysis method of the previous study conducted at Reynolds numbers of 1000 or higher was used, the cyclone separator operating at Reynolds numbers of less than 1000 also exhibited a similar linear tendency.