Affiliation:
1. INMA Bucharest, No. 6 Ion Ionescu de la Brad Blvd., Bucharest, Romania
Abstract
The ultraviolet (UV) irradiation has been studied and used in the recent decades as a mean to inactivate various potentially harmful microorganisms, being considered an effective treatment that could limit or even avoid the use of chemical disinfectants. Within the wavelength spectrum of UV radiation, the UV-C radiation wavelength ranging between 200 and 280 nm is considered lethal to most types of microorganisms. In this paper it was studied the variation of the distribution of radiation's intensity generated by a matrix of 25 UV-C LEDs (5 x 5), (assimilated to the LED panel above a stationary conveyor), on a spherical surface (assimilated to a berry) positioned in reprezentative locations below the matrix. A fruit located under the irradiation matrix receives the strongest radiation from the LED located at the smallest distance from it, but is influenced, as a result of the superposition principle, to a lesser extent by the other LEDs within the network. It has been found that for a too small distance between the matrix of LEDs and the conveyor, the radiation dose is uneven on the surface of fruit, and by increasing this distance a radiation distribution much more uniform is obtained, but at the expense of a decrease in its intensity and an increase in the time required for irradiation, implicitly leading to an increase in operating costs. In conclusion, for the most efficient operation of the equipment, a compromise solution must be chosen.