Design Of Circumvolute Variable Frequency Pulse Water Processor And Experimental Study On Its Anti-scaling Effect

With the development of modern society and economy,water plays an indispensable role in people’s daily life and in all walks of life.However,the scale,an inevitable by-product,not only accelerates the aging of the equipment,but also increases the risks of citizen health.In China,the loss of heat transfer efficiency caused by scaling of heat exchanger accounts for more than 10 billion yuan per year.At the same time,drinking high hardness water in the long term is very likely to cause serious health problems.Therefore,it is particularly important to carry out the scale inhibition.Although the common-used scale inhibitors such as chemical methods act well,they inevitably bring out water pollution.Therefore,more and more attention nowadays has been paid to the variable frequency electromagnetic water treatment technology and other physical methods.In this paper,the work principle of the wound-type electric pulse water processor is analyzed.The theoretical calculation shows that the magnitude order of the axial magnetic induction intensity of the solenoid is as tiny as Gauss order.Therefore,this paper assumes that the induced electric field in the water pipe dominant the effect on the hard water solution.This paper establishes the analytic model of the induced current in the solution to deduce the expression of induced current in the solution.Then this paper uses the average power of the induced current to measure the scale inhibition efficiency of the water treatment.Thus,the relationship between the average power,the excitation signal and the coil structure.Through setting the key parameters of the wound coil electric pulse water treatment system,the optimization of the scale inhibition can be realized.Finally,the correctness of the magnetic field calculation and the accuracy of the analytical expression of induced current under the excitation signal are verified by COMSOL simulation.In this paper,a winding type variable frequency electric pulse water treatment system is designed.The system takes the STM32F103 as the microcontrol core,and the signal conditioning circuit composed of CD4046 chip and IR2111 half bridge driving circuit generates the complementary PWM signal with adjustable frequency.It controls the on and off states of the MOSFET devices in the H-bridge power amplifier circuit.Finally,the electric pulse signal with fixed frequency or swept frequency is applied to the multi-turn coil.The frequency range of the signal is 100Hz~20kHz,and the voltage amplitude and frequency can be continuously adjusted.Finally,this paper builds up the scale inhibition experiment platform with the variable frequency electric pulse generator,processing chamber and measuring instruments.The feasibility of the scale inhibition experiment and the reproducibility of the scale inhibition experiment are verified by pre-experiment.The results of the multiple scale inhibition experiments show that the wound coil electric pulse water treatment has good effect on the scale inhibition.The core frequency is 1.5 kHz for the scale inhibition of the drinking fountains,at which the scale inhibition ratio is the best as 46.7% only if the coil length and tank diameter are equal.When the excitation signal frequency,amplitude and coil radius are fixed.The scale inhibition ratio will decrease if one of signal frequency or amplitude and coil radius are changed.The correctness and validity of the relationship between the scale inhibition effect,the signal frequency and the number of turns are proved by both theoretical calculation and experiments.