Experimental Study On Fine Particle Condensation In High Voltage Pulsed Electric Field

The proportion of fine particulate matter PM_2.5 in the air pollutants in the inhalable particulate matter PM₁₀ is 40%⁷0%,which accounts for a relatively high proportion.Because most of the harmful elements and compounds are enriched in fine particles,which has a serious impact on human health and reduces the visibility of the atmosphere,how to remove fine particles in the atmosphere has become the focus of research.Because conventional dust collectors are not effective in removing fine particles,a variety of coalescence technologies have emerged,and electrocoagulation has become the focus of research.Most scholars have studied the applicability of DC electric field,AC electric field,low-voltage pulsed electric field and high-voltage pulsed electric field,but the coagulation principle and experimental research of coagulation of high-voltage pulsed electric field are few.The thesis researches on the coagulation of fine particles by high-voltage pulses through experiments and studies the properties and coagulation efficiency of high-voltage pulsed power supplies.The thesis analyzes the charge mechanism of high-voltage DC electric field and high-voltage pulsed electric field.In the high-voltage DC electric field,the charge mechanism can be divided into two types:electric field charging and diffusion charging.The influence of charge,fine particles with a particle size of less than 0.2?m are mainly affected by diffusion charge.Fine particles with a particle size of 0.2⁰.5?m are difficult to charge;in high-voltage pulsed electric fields,they can be divided into electrons during the pulse discharge period There are two kinds of charge and ion charge outside the pulse discharge period.When the particle size of the fine particles is greater than 0.1?m,the electron charge plays a major role,and when the particle size of the fine particles is less than 0.1?m,the ion charge plays a major role.At the same voltage level,the high-voltage pulsed electric field charges fine particles more easily than the high-voltage DC electric field,and it also saves electricity.A high-voltage pulsed electric field charging test bench for inhalable particles was built.Through experiments,the effects of pulse peak voltage,pulse frequency and pulse duty cycle of high-voltage pulse power on fine particle coagulation were studied,and the pulse peak voltage,pulse frequency and pulse duty were obtained.The air ratio condenses the fine particles.The results show that:high-voltage pulse voltage has little effect on the total coagulation efficiency;the pulse frequency increases,the coagulation efficiency of fine particles decreases linearly,and the coagulation efficiency of small particles is larger than that of large particles;the pulse duty cycle increases,The efficiency of coagulation of fine particles increases linearly,and the effect of coagulation of large particles is better than that of small particles;the effect of negative voltage pulse power supply on the efficiency of coagulation of fine particles is similar to that of positive voltage power supply.Under the working conditions,the positive voltage pulse is better than the negative voltage pulse;under the conditions of DC voltage 15kV,pulse voltage 20kV,pulse frequency 70Hz,pulse duty ratio 50%,average wind speed of section1.6m/s,0.3?m,The coagulation efficiency of 0.5?m and 1.0?m fine particles reached the highest value,respectively 84.1%,84.3%and 86.8%.