Method of sensing aerosol characteristic parameter using dual-wavelength scattered signal and application thereof

A method of sensing aerosol characteristic parameters using dual-wavelength light scattered signals, characterized by comprising the following steps:

• step 1, constructing a detector consisting of light emitting devices with shorter and longer wavelengths respectively and two channels of detection signals, wherein an included angle between the optical axis of the first channel of light emitting device with shorter wavelength and the optical axis of a light receiving device is larger than 90°, and an included angle between the optical axis of the second channel of light emitting device with longer wavelength and the optical axis of the light receiving device is smaller than 90°;
• step 2, for received scattered signal of aerosol by the first channel, expressed by shorter-wavelength light scattered light power PS, calculating the corresponding surface area concentration C2 of the aerosol via the formula below:
• C
• 2
• =
• P
• S
• M
• 2
• wherein the unit of C2 is nm2/cm3, the unit of PS is voltage V converted from scattered light power, and M2 is a scattered light surface area concentration conversion coefficient which is a constant corresponding to a given optical structure and electric parameters, of which the numerical range is (1.5-3.5)×10−10, and of which the unit is V/(nm2/cm3) when light power is expressed by voltage;
• step 3, for received scattered signal of aerosol by the second channel, expressed by longer-wavelength light scattered light power PL, calculating the volume concentration C3 of the aerosol according to the formula below:
• C
• 3
• =
• P
• L
• M
• 3
• wherein the unit of C3 is nm3/cm3, the unit of PL is voltage V converted from scattered light power, and M3 is a scattered light volume concentration conversion coefficient which is a constant corresponding to a given optical structure and electric parameters, of which the numerical range is (0.5-2.5)×10−12, and of which the unit is V/(nm3/cm3) when light power is expressed by voltage;
• step 4, calculating the ratio of the volume concentration C3 of aerosol to the surface area concentration C2 of aerosol according to the formula below, so as to obtain the Sauter mean diameter DS of aerosol, of which the unit is nm:
• D
• S
• =
• 6
• 
• C
• 3
• C
• 2
• ,
• and
• step 5, directly outputting the three parameters, including the volume concentration C3, the surface area concentration C2 and the Sauter diameter DS, of aerosol as aerosol characteristics, and simultaneously comparing the three parameters with corresponding set thresholds Vth, Sth and Dth:
• returning to step 1 when the volume concentration C3 and the surface area concentration C2 are lower than the corresponding preset thresholds Vth and Sth respectively;
• and
• judging whether the particle Sauter mean diameter DS is larger than the set threshold Dth when at least one of the volume concentration C3 and the surface area concentration C2 is higher than the corresponding preset threshold Vth or Sth;
• if so, emitting a corresponding non-fire factor interference prompt signal;
• and if not, emitting a corresponding fire alarm signal.