| Resumo: |
Contamination of surfaces occurs in a variety of systems that interfere both with health and with the efficiency of industrial operations. Among many others, two illustrative examples can be given: i) the development of biofilms on drinking water distribution pipes causes water contamination as a result of the detachment of portions of the biological matrix where pathogenic growth may have occurred; ii) the growth of unwanted deposits on heat exchanger surfaces, such as in milk pasteurizers, increases energy consumption and environmental costs (the latter due to the periodic use of chemical agents to clean the equipment). In order to detect the onset of surface contamination and the properties of the attached layers, and to immediately assess the efficiency of the immediate actions taken to remove the deposits, reliable on-line monitoring systems are needed.
The goal of this project is to develop a new methodology that is capable not only to accurately detect the formation of an attached deposit, but also to identify the general characteristics of its structure (such as determining whether it is a biological or an non-biological layer, and its consistency), in order to enable proper countermeasures to be taken in real time. The methodology proposed, is based on the analysis of the vibration response of the contaminated surfaces in reaction to mechanically induced nano-vibrations. Both, the excitation and the response signal are read by piezoelectric elements. This response depends on the amount and on the physico-chemical properties (including density and elasticity) which are characteristic of the attached deposits. The establishment of mathematical relations between response signal and deposit properties is sought, so that each signal can be associated to a given type and amount of contamination.
Since the mechanical response of the surface to be sensed is of major importance for the quality of the signal, a detailed analysis and simulation of the vibration  |
Resumo
Contamination of surfaces occurs in a variety of systems that interfere both with health and with the efficiency of industrial operations. Among many others, two illustrative examples can be given: i) the development of biofilms on drinking water distribution pipes causes water contamination as a result of the detachment of portions of the biological matrix where pathogenic growth may have occurred; ii) the growth of unwanted deposits on heat exchanger surfaces, such as in milk pasteurizers, increases energy consumption and environmental costs (the latter due to the periodic use of chemical agents to clean the equipment). In order to detect the onset of surface contamination and the properties of the attached layers, and to immediately assess the efficiency of the immediate actions taken to remove the deposits, reliable on-line monitoring systems are needed.
The goal of this project is to develop a new methodology that is capable not only to accurately detect the formation of an attached deposit, but also to identify the general characteristics of its structure (such as determining whether it is a biological or an non-biological layer, and its consistency), in order to enable proper countermeasures to be taken in real time. The methodology proposed, is based on the analysis of the vibration response of the contaminated surfaces in reaction to mechanically induced nano-vibrations. Both, the excitation and the response signal are read by piezoelectric elements. This response depends on the amount and on the physico-chemical properties (including density and elasticity) which are characteristic of the attached deposits. The establishment of mathematical relations between response signal and deposit properties is sought, so that each signal can be associated to a given type and amount of contamination.
Since the mechanical response of the surface to be sensed is of major importance for the quality of the signal, a detailed analysis and simulation of the vibrations induced, as well as the optimization of the surface dimensions and materials has to be done. Complementarily, the study of the best-fit piezo elements (ceramics, polymers, quartz), shape, size, location to be placed, procedure to fix them and also the excitation signal (frequency, wave type, amplitude) are some of the parameters to be studied. |