Inversion for offshore oil-water emulsion concentration based on a six-flux model of laser-induced fluorescence

Oil-water emulsions, as one of the momentous weathering forms of the marine oil-spill, have caused more severe detriment to the marine environment. Laser-induced fluorescence (LIF) is an extremely influential technique for monitoring spilled oil at sea. However, the evaluation of offshore oil-water emulsion concentration based on LIF detection technology has been rarely discussed. Simultaneously, a scientific low-flux model including fluorescence flux has not been established and applied to detect oil spill at sea. In view of this, a six-flux model of laser-induced fluorescence is proposed to invert the concentration of oil-water emulsions at sea. On the cornerstone of laser flux, fluorescence flux is introduced. Utilizing the absorption, scattering, and other characteristics of flux in the medium, differential equations of various flux are established, and the solution framework of the differential equations is afforded. Thereafter, a formula of the fluorescence radiation transfer factor of the oil-water emulsions and their concentration is derived. Furthermore, the validity and availability of the proposed model are proved by experiments. The experimental results reveal that the proposed model has high accuracy in inverting the concentrations for oil-water emulsions, and the average error is within 6%. Meanwhile, this model consumes a short time, not exceeding 60 s at most. Utilizing the model, the concentration of oil-water emulsions can be evaluated in real time.