Research On Continuous Magnetophoresis Separation And Detection Technology Of Ferromagnetic Wear Debris In Lubricating Oil

Ship oil analysis is an important means to monitor the operation of ship machinery and equipment,and can effectively diagnose and prevent all kinds of ship equipment failure.The existing oil detection method of marine power plant has problems with a single detection,low accuracy,offline monitoring of oil.In recent years,the rapid development of microfluidic technology has advantages of a high degree of integration,rapid analysis and portable,which provides a new means for oil on-line detection.In this paper,a continuous separation and detection system for ferromagnetic particles based on microfluidic chip was designed with the aid of the magnetophoresis separation and photoelectric detection technology,which realized the functions of the on-line continuous counting,separation and size determination.The following research results and conclusions were obtained:(1)The basic theory of magnetophoresis in microchannel was studied,and the numerical model of magnetic separation is established.The magnetic field,the flow field and the trajectories of the magnetic particles was simulated by COMSL.The effects of magnetic field position,particle velocity and size on the separation efficiency was investigated by simulation.The results showed that the microfluidic chip was suitable for micro-magnetic field,such as strong magnetic field,high magnetic field gradient and suitable for miniaturization.The magnetic field position needed to be suitable,otherwise it would cause the particle to adsorb to the separation area or could not complete the separation.In the case of a certain magnetic field,the particle flow rate was slower,the particle size was bigger,and the particle deflection degree was bigger.The size of the chip can be separated the particles from the diameter of<5?m,5?8p?m and>8?m.(2)Based on the theoretical research,a microfluidic magnetic separation platform was set up.The separation of magnetic particles in lubricating oil was studied and the effects of different particle velocities and sizes on separation was investigated.The experimental results show that the increase of velocity increased the effect of flow field force,and the increase of particle size increased the magnetic field force,and the simulation results were basically consistent.It was also proved that the separation chip can successfully sort the ferromagnetic particles with size of 2,5,15?m.(3)The periodic magnetic field generating device using photoresist and related control system is designed to solve the problem of magnetic cohesion in the microchannel.And the detection and separation experiments on iron particles of 15?m and 25?m were carried out to obtain a good detection signal,in which the signal value of 15pm was 0.981V and the signal amplitude was 1.139V.The signal value of 25?m was 1.139V and the signal amplitude was 1.909V.