Technological Research Of Silicon Nitride Heater Surface Anti-scaling

Silicon nitride heater is a new type of water boiler. Problem of surface of silicon nitrideheater fouling makes it part. The problem makes the quality of water boiler low and restrictsits development. To solve this problem, we do some experiments and numerical simulations.Firstly, through comparison experiment, we find out ultrasonic or magnetic field hasperfect effect of anti-scaling on wall of water boiler.Secondly, through ultrasonic or magnetic field scaling experiments, we find thatultrasonic or magnetic field increases the scale weight on heater. The scale weight treatingwith ultrasonic is41.21%more than the BLA one. The magnetic field is more than158.71%.Ultrasonic or magnetic field can reduce the compactness of scale. Magnetic field can reducemore. Ultrasonic can increase the firmness between scale and heater and magnetic fielddecreases the firmness. Area percentage about scale and heater treating with magnetic field is12.31%less than the BLA. Ultrasonic decreases the thermal efficiency of heater and themagnetic field increases it. The heating speed of heater is2.20kg/min, which5.19%morethan the BLA. With treatment of magnetic field, quality of hot water will be developed. Underoverall consideration, magnetic field can be used to solve the problem of scale on heater andmaking the heater part. We find out the scaling mechanism with ultrasonic or magnetic field.Because all the techniques can decrease the time of scale crystal nucleus taking shape. Littlecrystal nucleus takes shape quickly and the little crystal nucleus has larger specific surfaceenergy. So it likes to stick to the heater and grow up on, than it exacerbates the scale takingshape on heater. For magnetic field, little crystal arrangement is directional. So thecompactness and firmness are low.Finally, through numerical simulation, we optimize the parameter of Silicon nitrideheater and reduce the temperature on silicon nitride heater surface for anti-scaling. The mostsuitable parameter is that the setting angle of two top silicon nitride heater is90o, the rest of is45o, by using this parameter, temperature of on silicon nitride heater surface can be2.14%lower. After numerical simulation, we design the experiment to examine result. The heatingspeed of the new design is1.90%more than the old one. The heat transfer coefficient of thenew design is bigger. The new design can reduce the temperature of heater and the accuracyof numerical simulation is good.All in all, with treatment of magnetic field and new heater design, problem of heaterapart will be solved and quality of hot water will be developed.