An Air Velocity Monitor for Coal Mine Ventilation Based on Vortex-Induced Triboelectric Nanogenerator

Abstract

Air velocity of coal mine ventilation is an important consideration that may cause serious damage. This paper proposes a simple, low cost and effective air velocity monitor (AVM) for coal mine ventilation. The AVM uses the lock-in characteristic of vortex-induced vibration (VIV) to sense the air velocity. Amplitude of the VIV is converted into frequency signal of a vortex-induced triboelectric nanogenerator (VI-TENG) to improve the durability. Structure of the AVM are designed, and parameters of the AVM are optimized with experiments. For the upper and lower air velocity thresholds of 3.1 and 3.6 m/s, the optimized flexible beam length, slider weight, electrode space and electrode width are 42.5 mm, 0.4 g, 0.2 mm and 0.5 mm, respectively. Experiments also show that the output frequency of the VI-TENG could represent the amplitude of VIV well with the correlation coefficient of 0.93. Durability test demonstrates that the AVM generates stable output frequency in 120,000 cycles. A prototype and its controller are fabricated. Wind tunnel tests of this prototype show that it can give alarm when the gas velocity goes above the upper threshold or below the lower threshold. The proposed AVM could be a good solution for simple and effective coal mine ventilation alarm.

Recent Progress in Flow Energy Harvesting and Sensing Based on Triboelectric Nanogenerators

“…TENGs with the characteristics of small size, distributed, and low noise have been extensively studied for wind energy harvesting due to their ability to convert the kinetic energy of wind into electrical energy. Various designs have been proposed to maximize the efficiency and output of TENG-based wind energy harvesting systems, including rotating wind turbines, [109][110][111][112] vortex-induced vibration (VIV), [113][114][115][116] and fluttering flags. [117][118][119][120][121][122] Each design has unique advantages and challenges, which are briefly described below.…”

“…Energy harvesting from cylindrical VIV using TENGs is an emerging approach that holds great promise for harnessing flow energy from fluid-induced vibrations. [113][114][115][116] As illustrated in Figure 5b, a cylinder is connected to the TENG using a stretched spring, and when the cylinder is subjected to lateral wind flow, it acts as an oscillator, converting wind energy into kinetic energy. [113] The TENG then takes responsibility for transforming the kinetic energy into electrical energy through the periodic contact and separation behavior between the two electrode plates.…”

A Rolling‐Bead Triboelectric Nanogenerator for Harvesting Omnidirectional Wind‐Induced Energy toward Shelter Forests Monitoring

“…Zhang et al [23] proposed a novel cantilever beam TENG for energy harvesting and investigated the coupling between the beams during fluid-induced vibration. Shen et al [24] utilized the locking property of vortex-induced vibration (VIV) to sense airflow velocity and achieve sensing signals at low wind speeds. These flow-induced vibration energy harvesting or sensing devices employ a cantilever structure, confirming the application of fluid-responding structures at low wind speeds.…”

“…Shen et al. [ 24 ] utilized the locking property of vortex‐induced vibration (VIV) to sense airflow velocity and achieve sensing signals at low wind speeds. These flow‐induced vibration energy harvesting or sensing devices employ a cantilever structure, confirming the application of fluid‐responding structures at low wind speeds.…”

Kármán Vortex Street Driven Membrane Triboelectric Nanogenerator for Enhanced Ultra-Low Speed Wind Energy Harvesting and Active Gas Flow Sensing

“…Kármán vortex street, referring to continuous vortex shedding when fluids flow across blunt bodies, is always on the one hand considered as a harmful effect to infrastructures due to corresponding vortex-induced vibrations. On the other hand, it can masterly be applied for effectively energy harvesting, which has been applied in piezoelectric and EMG. , Recently, vortex-induced vibration has also been introduced into TENGs, − which largely improved the wind and underwater energy harvesting performance. However, the interaction between the vortex and TENGs and the enhancement mechanism are still unclear, which are important for guiding the future designs of TENGs because of their varying structures and materials.…”