Uma investigação sobre a eficácia de acelerômetros piezoelétricos e MEMS na detecção de vazamentos em tubulações de água
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Data
2022-04-25
Autores
Girardi, Vitor Franco
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Universidade Estadual Paulista (Unesp)
Resumo
Vazamentos em tubulações de água são uns dos principais problemas enfrentados por grandes centros urbanos em função das longas distâncias de fontes hídricas externas e da escassez de água provocada por mudanças climáticas. Para lidar com esse problema, companhias de água utilizam dispositivos vibroacústicos para localizar vazamentos em sua rede de distribuição, utilizando frequentemente equipamentos com sensores de vibração para leitura do sinal. Outra maneira de mitigar essa situação, que vai de encontro com o conceito de Cidades inteligentes, é a incorporação de sensores de vibração (acelerômetros) em hidrômetros residenciais ou em pontos estratégicos da rede, possibilitando a coleta de sinais de vibração relacionados a presença de vazamentos nas tubulações instrumentadas. Como a maioria dos acelerômetros utilizados em problemas de detecção de vazamentos são piezoelétricos, uma alternativa seria a utilização de acelerômetros fabricados pela técnica MEMS (Micro-Electro-Mechanical Systems ou Sistemas Microeletromecânicos em português), os quais possivelmente seriam mais acessíveis considerando o aumento crescente do potencial dessa tecnologia na redução de custos. Dessa forma, o presente trabalho busca investigar a eficácia de acelerômetros piezoelétricos e MEMS aplicados na detecção de vazamentos em tubulações de água, utilizando modelagens analíticas e testes controlados. Portanto, modelos eletromecânicos foram desenvolvidos para investigar os parâmetros que influenciam a sensibilidade e a faixa de frequência desses transdutores. Experimentos em laboratório foram realizados em conjunto com experimentos em campo para avaliar os acelerômetros na detecção de sinais de vazamentos utilizando técnicas clássicas vibroacústicas. Foi observado que apesar dos acelerômetros MEMS capacitivos utilizados nesse trabalho conseguirem detectar vazamentos, os sensores piezoelétricos de alta sensibilidade e com baixo ruído gerado apresentaram melhor desempenho. Três acelerômetros aptos a medirem sinais de vazamentos pequenos e a distancias maiores foram destacados, sendo um piezoelétrico importado, um MEMS capacitivo importado e um piezoelétrico produzido no Brasil, de melhor custo-benefício entre os sensores testados.
Leaks in water pipes are one of the main problems faced by large urban centers due to the long distances from external water sources and the scarcity of water caused by climate change. To deal with this problem, water companies use vibroacoustic devices to locate leaks in their distribution network, often using equipment with vibration sensors to read the signal. Another way to mitigate this situation, which is in line with the concept of Smart cities, is the incorporation of vibration sensors (accelerometers) in residential water meters or at strategic points in the network, enabling the collection of vibration signals related to the presence of leaks in instrumented pipes. As most of the accelerometers used in leak detection problems are piezoelectric, an alternative would be the use of accelerometers manufactured by the MEMS technique (Micro-Electro-Mechanical Systems), which would possibly be more accessible considering the increasing the potential of this technology to reduce costs. Thus, the present work seeks to investigate the effectiveness of piezoelectric accelerometers and MEMS applied in the detection of leaks in water pipes, using analytical modelling and controlled tests. Therefore, electromechanical models were developed to investigate the parameters that influence the sensitivity and frequency range of these transducers. Laboratory experiments were carried out in conjunction with field experiments to evaluate accelerometers in detecting leak signals using classical vibroacoustic techniques. It was observed that although the capacitive MEMS accelerometers used in this work were able to detect leaks, the high sensitivity piezoelectric sensors with low generated noise presented better performance. Three accelerometers capable of measuring small leak signals and at greater distances were highlighted, being an imported piezoelectric, an imported capacitive MEMS and a piezoelectric produced in Brazil, with the best cost-benefit among the tested sensors.
Leaks in water pipes are one of the main problems faced by large urban centers due to the long distances from external water sources and the scarcity of water caused by climate change. To deal with this problem, water companies use vibroacoustic devices to locate leaks in their distribution network, often using equipment with vibration sensors to read the signal. Another way to mitigate this situation, which is in line with the concept of Smart cities, is the incorporation of vibration sensors (accelerometers) in residential water meters or at strategic points in the network, enabling the collection of vibration signals related to the presence of leaks in instrumented pipes. As most of the accelerometers used in leak detection problems are piezoelectric, an alternative would be the use of accelerometers manufactured by the MEMS technique (Micro-Electro-Mechanical Systems), which would possibly be more accessible considering the increasing the potential of this technology to reduce costs. Thus, the present work seeks to investigate the effectiveness of piezoelectric accelerometers and MEMS applied in the detection of leaks in water pipes, using analytical modelling and controlled tests. Therefore, electromechanical models were developed to investigate the parameters that influence the sensitivity and frequency range of these transducers. Laboratory experiments were carried out in conjunction with field experiments to evaluate accelerometers in detecting leak signals using classical vibroacoustic techniques. It was observed that although the capacitive MEMS accelerometers used in this work were able to detect leaks, the high sensitivity piezoelectric sensors with low generated noise presented better performance. Three accelerometers capable of measuring small leak signals and at greater distances were highlighted, being an imported piezoelectric, an imported capacitive MEMS and a piezoelectric produced in Brazil, with the best cost-benefit among the tested sensors.
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Palavras-chave
Acelerômetros piezoelétricos, Acelerômetros MEMS, Detecção de vazamentos, Técnicas vibroacústicas, Correlação cruzada, Piezoelectric accelerometers, MEMS accelerometers, Leak detection, Vibroacoustic techniques, Cross correlation