Contribución a la mejora de la exactitud de los caudalímetros ultrasónicos tipo clamp-on
- Autores: Oliver Millán Blasco
- Directores de la Tesis: Miguel J. García Hernández (dir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2017
- Idioma: español
- Tribunal Calificador de la Tesis: Ramón Montero (presid.), Juan Antonio Chávez Domínguez (secret.), Carlos Fritsch Yusta (voc.)
- Programa de doctorado: Programa de Doctorado en Ingeniería Electrónica por la Universidad de las Illes Balears y la Universidad Politécnica de Catalunya
- Materias:
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- Resumen
This thesis is included in the area of industrial instrumentation. The objective has been to go deeper into the field of Clamp-on ultrasonic flowmeters. The advantage of Clamp-on with regard to insertion is the low cost of maintenance, the non-generation of load losses in the installation and its low economic cost compared to other technologies. One inconvenience is this equipment presents measurement errors superior to the insertion one.
The research developed in this thesis has focused on improving the measurement accuracy of Clamp-on ultrasonic flowmeters, when they are installed on plastic pipes commonly used in the industry. The accuracy of these flowmeters is essentially affected by zero error, which is an additive error and by the lack of linearity in the response associated with multiplicative error.
Regarding the zero error identified, this is due to the dispersion of the material produced by the variation of the propagation velocity as a function of the power of the acoustic signal and by the lack of spatial homogeneity of the dispersive properties of the pipe wall. This phenoma means that the reciprocity criterion is not fulfilled in the system.
On the other hand, the two causes that produce the the lack of linearity in the measurement are identified, studied and modeled. In Chapters 3 and 4, both phenomenon are described. The first one refers to the linearity error produced by the recombination of propagation paths in the reception transducer due to the multiple reflections in the interfaces between materials. The second phenomena is produded by the recombination of propagation paths in the reception transducer due to the split of the ultrasonic beam when it crosses a dispersive material with an oblique angle.
Given the importance of these phenomenon in the measurement and as fundamental contributions to this thesis, the physical phenomena that affects the measurement is analyzed and modeled. The necessary theory is provided and a series of actions are proposed with the aim of minimizing these phenomenon.
Since the beginning of this thesis, as part of the Industrial PhD program of the Generalitat of Catalonia, the proposed approach has been to generate contributions of interest to the industry. As a result of the proposed solutions, the offset error has been reduced from 10.7% to 1.2% and the linearity error has been reduced from 6.4% to 1.8%.
