A device and method for quickly measuring water content of nanoscale particles

Abstract

The invention relates to a device for quickly measuring the water content of nanoscale particles and a measuring method thereof. The device includes a clean humid air generation unit, a particle humidity exchange unit, a nanoscale particle number concentration spectrum distribution measurement unit and a dynamic PID humidity feedback adjustment unit. The clean humid air generating unit includes air source, Nafion humidifying tube, Nafion drying tube and three-way solenoid valve. The nanoscale particle number concentration spectrum distribution measuring unit includes a differential electric mobility analyzer and a particle number concentration detector. The dynamic PID humidity feedback adjustment unit includes a first humidity sensor, a second humidity sensor, a third humidity sensor, an ambient atmospheric humidity sensor, a dual selector, a subtractor, an adder, a PID controller and a pulse width modulation driver. The invention can significantly improve the accuracy and time resolution of the water content measurement of the particles, and can be applied to the on-line measurement and real-time inversion of the water content of the nanoscale (3-100 nm) particles in the ambient air, and the time resolution is better than 10 minutes.

Description

technical field [0001] The invention relates to the technical field of aerosol analysis and monitoring, in particular to a device for quickly measuring the water content of nanoscale particles and a measuring method thereof. Background technique [0002] Atmospheric nanoscale particles interact with water vapor to increase the water content of particulate matter, which affects the formation, growth and heterogeneous chemical reactions of atmospheric nanoscale particles, and has direct and indirect effects on atmospheric visibility and cloud climate effects. It belongs to the research field of particulate matter. one of the fundamental issues. The atmospheric lifetime of nanoscale particles is short, and their physical and chemical properties are unstable, resulting in rapid changes in the number concentration spectrum distribution of nanoscale particles in the ambient atmosphere. Moreover, the charging efficiency of particles below 100nm in the atmosphere is low, and the di...

AI Technical Summary

Problems solved by technology

The atmospheric lifetime of nanoscale particles is short and their physical and chemical properties are unstable, resulting in rapid changes in the number concentration spectrum distribution of nanoscale particles in the ambient atmosphere

Moreover, the charging efficiency of particles below 100nm in the atmosphere is low, and the diffusion loss is significant, which increases the difficulty of online measurement of the water content of nano-scale particles

At present, the existing method directly samples and measures the ambient air. For example, Chinese patent CN 105203434A discloses a particle size spectrometer for measuring the water content of aerosol. Due to the influence of humidity changes, it can only reach 80-90% of the actual ambient humidity under high humidity conditions, so there is a certain underestimation of the moisture content of particulate matter; at the same time, the dry-wet conversion equilibrium time of the particle size spectrometer to measure the moisture content of aerosols is relatively short. Long, resulting in low water content measurement time resolution, it is difficult to deal with the characteristics of rapid changes in particle size and number concentration of nano-scale atmospheric particles

Images