| Fluid transportation pipelines have made an important contribution to the efficient transportation of energy around the world.In order to ensure the safety and reliability of the transportation pipeline network,the fluid transportation pipeline detection system has formed an all-weather,all-terrain intelligent detection system composed of advanced sensor networks.Although the pipeline detection method has been upgraded,the energy supply problem of the smart sensor network is a new challenge that needs to be faced.The traditional power grid and battery power supply method greatly increase the construction and maintenance costs of the detection network.In recent years,the rapid development of micro-nano energy harvesting devices manufactured by micro-nano processing technology.It has been proven to be an adaptable,efficient and green sustainable energy supply method.And this is undoubtedly an important breakthrough to solve the self-supply problem of fluid transportation pipeline detection.The research of this paper is based on the perspective of self-powered detection of fluid transportation pipelines.First,the energy flow pattern of the fluid medium inside the pipeline is studied.Secondly,based on the theory of triboelectricity and piezoelectricity,we used micro-nano manufacturing technology to manufacture two kinds of micro-nano energy harvesting devices.Finally,the self-supply energy of fluid transportation pipeline detection is realized by using the micro-nano energy harvesting devices to convert the severely destructive water hammer vibration energy in the pipeline into electric energy.The main research contents of this paper are as follows:(1)We studied the influencing factors and basic characteristics of water hammer in fluid transportation pipelines through theoretical analysis and multi-physics finite element simulation.The momentum equation was analysed based on the action mechanism of water hammer and the momentum conservation theorem,and the finite element simulation was carried out.The analysis shows that the vibration period of the water hammer is inversely proportional to the elastic modulus of the pipe wall material and directly proportional to the diameter of the pipe.The speed of the fluid medium does not affect the propagation speed and period of the water hammer.(2)Theoretical analysis and formula derivation of micro-nano energy harvesting devices are carried out,and mathematical models of friction energy harvesting devices and piezoelectric energy harvesting devices are established.We have derived the equation expressions of the output voltage and the amount of transferred charge of the two micro-nano energy harvesting devices.According to model analysis,increasing the area of the dielectric layer and the operating frequency of the device will help increase the output current and output voltage at both ends of the load.(3)A flexible self-recovery friction energy harvesting device enhanced by Ag nano-interconnects was prepared.The study uses COMSOL simulation software to simulate the working principle of friction energy harvesting devices.It tested the output characteristics of the device and its practical application effect in fluid pipelines,and the improvement effect of Ag interconnects on the electrical characteristics of the device was verified.When the working frequency is 4 Hz,the amount of charge transferred by the friction energy harvesting device is 18 n C,and the peak power density reaches 75 m W/m~2.Compared with the friction energy harvesting device without Ag interconnects enhancement,it has improved by 63%.The device can not only provide energy for the microelectronic detection device which from the fluid transportation pipeline detection system,but also can reduce the impact of water hammer on the pipe wall to achieve the effect of protecting the pipeline.(4)A friction-piezoelectric composite energy harvesting device based on PTFE and ZnO nanowires was prepared.The research uses COMSOL simulation software to conduct three-dimensional multi-physics simulation and design optimization of composite energy harvesting devices.And we tested its actual output characteristics.At the operating frequency of 25 Hz,the peak open-circuit voltage and short-circuit current of the composite energy harvesting device reached 450 V and 5.88 u A,respectively,and the peak power density was 2.78 W/m~2.Multiple composite energy harvesting devices can also be combined into an energy harvesting array to meet the requirements of different environments and performance,thereby realizing self-supply energy for fluid transportation pipeline detection. |
