This paper presents an effect of general dimensions of a reverse flow mini-cyclone with a tangential inlet on its separation efficiency. Several mini-cyclone design modifications are presented and evaluated for use in the air filtration systems of motor vehicles. Local design improvements of three components of a reverse flow mini-cyclone with a tangential inlet D-40 of an air filter fitted in an all-terrain vehicle engine were introduced. An asymmetric curvilinear shape of an outlet port was used instead of a symmetrical shape. An outlet vortex finder inlet port shape was streamlined, and a cylindrical outlet vortex finder of the cyclone was replaced with a conical one. Experimental evaluation of the effects of the design improvements of mini-cyclone on its separation efficiency and performance as well as flow resistance was carried out. Separation efficiency of the cyclone was determined using the mass method as a product of dust mass retained by the mini-cyclone and supplied to the mini-cyclone in a specified time. Separation performance of the cyclone was determined as the largest dust particle dz =dzmax in a specific test cycle in the cyclone outlet air stream. A polydisperse PTC-D test dust used in Poland, a substitute for AC-fine test dust was used. Dust concentration at the mini-cyclone inlet was kept at 1 g/m3. The size and total number of dust particles in the air stream at the outlet of the original mini-cyclone and at the outlet of the improved mini-cyclone was determined using a particle counter.

The paper presents the experimental study of a novel unsteady-statemembrane gas separation approach for recovery of a slow-permeant component in the membrane module with periodical retentate withdrawals. The case study consisted in the separation of binary test mixtures based on the fast-permeant main component (N2O, C2H2) and the slow-permeant impurity (1%vol. of N2) using a radial countercurrent membrane module. The novel semi-batch withdrawal technique was shown to intensify the separation process and provide up to 40% increase in separation efficiency compared to a steady-state operation of the same productivity.

A comparative analysis of filtration performance of tangential and axial inlet reverse-flow cyclone separators and vortex tube separators is presented. The study showed that vortex tube separators are characterized by a quality factor q several time higher than tangential inlet reverse-flow cyclone separators. The cyclone separators yield low separation efficiency and low filtration performance at low air flow rates at low air volumes aspired by the engine at low speed. One of the well-known and not commonly used methods to improve separation efficiency is to apply electric field. An original design of a vortex tube separator with insulators generating electric field in the area of aerosol flow is presented. High voltage was applied to the cyclone separator housing and its swirl vane. A special method and test conditions were developed for cyclone separators with electric field. Separation efficiency, filtration performance and pressure drop across the cyclone separator in two different variants were determined. The tests were carried out at five inlet velocity of cyclones υ₀  = 1.75; 3.5; 7.0; 10.5; 14 m/s at an extraction rate of m₀  = 10%, and at an average dust concentration in the inlet air of
s = 1 g/m³. Using the electric field in the area of a swirling aerosol stream resulted in an increase (over 12% – φ_c  = 96.3%) in separation efficiency at inlet velocity of cyclone ranging from 1.75 to 3.5 m/s. An increase in separation efficiency at other inlet velocity of cyclone is minor and does not exceed 3‒4%.