Design With Optimization of a Magnetic Separator for Turbulent Flowing Liquid Purifying Applications

In this paper, an open gradient magnetic separator for turbulent flowing water purification has been designed, optimized, and experimentally tested. This device consists of an arrangement of identical electromagnets that operate as capture elements. In the first stage of the optimization, we have identified the optimal size of the elementary capture element and its excitation current that allow the separation of ferromagnetic particles (particle radius R_p <; 3 × 10^-5 m) from a water flow of representative velocity (u_f = 0.5 m/s) in a channel of small diameter D = 2.5 × 10^-2 m. For this, we have minimized an objective function, which is the distance between the capture site of a given separated particle and the central point of the capture element. For such minimization, the Tabu search method has been applied. Second, we have optimized the number and the arrangement of capture elements that permit the separation for a channel of important diameter D = 5 × 10^-2 m and reduced flow velocity u_f = 0.2 m/s. In this case, the optimization is based on the comparison between the capture efficiencies of several proposed configurations of the separator. To validate the obtained results, experiments have been carried out on a turbulent water flow (Reynolds number R_e = 10⁴) containing fine ferromagnetic particles (μ_r = 8) with a concentration C_p = 0.8 g/L. The verification is based on the control of the evolution of the separated particles buildup and the quantifying of the volume of separated particles. For such quantifying, the Hall effect sensing technology has been used.