As part of the BMBF-funded SAFEFRESH project, food processing and transport processes were investigated for their susceptibility to contamination. Contamination during transport due to the introduction of pathogens and non-compliance with the cold chain was identified as a major risk. The focus of the project is on air disinfection and purification in refrigerated vehicles. For this application, the specific properties of UV LEDs bring special advantages that could not be achieved without them and lead to unique selling points.
The equipment of refrigerated vehicles with mechanically extremely robust UVC-LEDs enables the minimization of microbial contamination of the transported goods, in particular of food or pharmaceutical products, by disinfection of the introduced cooling air as well as cleaning of ambient air pollutants / odors. The additional reduction of odor contamination through photocatalytic oxidation by means of UVA-LEDs of activated titanium dioxide surfaces is a further purification step.
The task of Fraunhofer IOSB-AST in this subproject is, on the one hand, the physical simulation of the radiation propagation as well as the air flow in the planned system and, on the other hand, a determination of the optimal LED arrangement and number and the simulative design of the necessary cooling system. Furthermore, an efficient control of the LEDs as well as their monitoring shall be realized. However, in contrast to the work already carried out in the previous projects in the former water field of work, a possibility of external monitoring of the systems is to be created, which will make it possible to control entire fleets of cooling trailers with regard to the function of their air disinfection systems.
In the project, a combined UVC/UVA photoreactor for flowing air was developed, which combines the microbiological disinfection effect in the UVC range with the photocatalytic cleaning effect of odorous substances in the UVCA range. The device is very compact with dimensions of 30 x 30 x 50cm and can be integrated into any vehicle electronics thanks to the CAN interface. The sophisticated internal air guidance system ensures that the air flowing through is effectively guided over the titanium dioxide layer located in front of the UVC sources, thus achieving a high cleaning performance. The reactor consists of cascadable sub-modules, which are equipped with a UVA output of 500W (365 nm) as well as a UVC output of 3.2 W (270 nm).