Research On Contaminant Detection In Hydraulic Oil Based On Impedance Micro-fluidic Chip

With the continuous development and maturity of hydraulic technology,hydraulic systems are widely used in the field of marine engineering.As the key working fluid of the hydraulic system,the quality and cleanliness of the hydraulic oil will have a direct impact on the safe and stable operation of the hydraulic system.In order to ensure the well operation state with the hydraulic system,the detection of oil in the system has become an indispensable project.Detecting pollutants in the hydraulic oil has a significant meaning in improving the reliability of the hydraulic system,prolonging the service life of the system components and saving the cost.First,this paper introduces the main characteristics of the hydraulic system of the ship,points out the causes,sources and hazards of the pollutants in the hydraulic oil,makes a brief description of the research status of the oil detection technology at home and abroad and elaborates the advantages and disadvantages of each detection method.Second,the distinction detection principle of metal particles,water droplets and air bubbles are analyzed.Finally a micro-fluidic detection chip is designed and fabricated.The experimental study on the detection of various pollutants in hydraulic oil is carried out on the chip.The main contents of this paper are divided into the following parts:(1)Micro-channel position and coil distance of the detection chip are simulated by COMSOL Multiphysics simulation software.Simulation results indicate:the larger detection parameters are achieved when the micro-channel is located at the edge of the coil inner hole and the smaller distance between the two coils.(2)Under the guidance of the simulation results,the micro-fluidic detection chip is fabricated and the detection system is set up.The influence discipline of chip structure parameters(coil turns and enameled wire diameter)and excitation parameters(excitation frequency and excitation voltage)on the detection signal of pollutants are studied.Experimental results indicate:when the coil turns number of the detection chip is 20 and the enameled wire diameter is 0.07mm,the detection signal to noise ratio of the four pollutants is highest.When detecting iron particles,the excitation parameters should be set to 1MHz,2V.When detecting copper particles,the excitation parameters should be set to 2MHz,2V.When detecting water droplets and air bubbles,the excitation parameters should be set to 0.3MHz,2V.Thus the highest detection signal to noise ratio are achieved.(3)Detection experiments of four pollutants are carried out under the optimized chip.Study on the relationship between the detection parameters change and the size of particles.The lower limit of detection for each kind of the pollutants is obtained.Experimental results indicate:In inductive mode,the chip can detect 38?m iron particles and 105?m copper particles in oil.In capacitive mode,the chip can detect 100?m water droplets and 180?m air bubbles in oil.