Nano-level particulate matter supersaturated growth device and control method

Abstract

The invention relates to a nano-level particulate matter supersaturated growth device and a control method. The device comprises a particulate matter sample gas channel, a sheath gas channel, saturated water vapor channels, a deionized water channel, a gas flow proportion control device and a temperature gradient control device. According to the nano-level particulate matter supersaturated growth device and the control method, based on a water vapor coagulation theory, sample gas which is wrapped with the clean sheath gas and carries atmospheric particulate matters passes through the saturated water vapor channels; a semiconductor refrigerator and a flexible heater are used for controlling the temperature of the two stages of saturated water vapor channels, so as to generate a temperature gradient; and by the use of the characteristic that the water vapor dispersion rate is higher than the gas heat transfer rate, water vapors around particulate matters are oversaturated, so that the water vapors can be condensed on the surfaces of the particulate matters to promote increase of the particle size of the particulate matters. By control of the flow proportion of the sample gas and the sheath gas, or control of a temperature difference between the two stages of the saturated water vapor channel, the degree of supersaturation of the water vapors is adjusted, and dynamic control of the particle size of the particulate matters subjected to supersaturated growth is realized.

Description

technical field [0001] The invention relates to the technical field of aerosol monitoring, in particular to a device and a control method for promoting the supersaturated growth of nano-scale particles by using water vapor condensation. Background technique [0002] The condensation and growth of particulate matter in a supersaturated environment to reach the measurable particle size range by optical methods is the main means of measuring atmospheric ultrafine particulate matter (particle size less than 100nm). The condensation of water vapor molecules on the surface of particles can promote the growth of particle size. The particle size after supersaturated growth of particles is directly related to the supersaturation of water vapor. The particle growth under different water vapor supersaturation conditions can be obtained The final particle size information is helpful to analyze the chemical composition and condensation growth characteristics of atmospheric particulate ma...

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Problems solved by technology

Chinese patent CN104297118A mentions a device that utilizes the supersaturation of n-butanol vapor to promote the condensation and growth of particles to measure the number concentration of 3nm-5μm particles. The wall temperature of the device and condensing device (39°C and 10°C), and the supersaturation of n-butanol vapor around the particles remain unchanged, which cannot meet the control requirements for the particle size of the particles after condensation growth

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