| UNDERSTANDING THE EFFECT OF RESONANT FREQUENCY USING ULTRASONIC-ASSISTED MEASUREMENT IN GAS FUEL SYSTEM FOR NATURAL GAS VEHICLE |
| Ho Kil Lee1, Kwon Se Kim2, Seok Yeon Im3 |
1Korea Automotive Technology Institute
2Korea International University in Ferghana
3Tongmyong University |
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| ABSTRACT |
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This work is the experimental study to use the ultrasonic sensor which can seek the optimum sensitivity of pure methane gas used in natural gas vehicle (NGV). This research is to experimentally analyze the acoustic characteristics using an impedance analyzer and three different thicknesses of ultrasonic matching layer (UML). The experiment is composed of 7.0, 7.5, and 8.0 mm of matching layer thickness, 30, 60, 90, and 120 cm of sensor gap in atmospheric air, 20 and 40 cm of sensor gaps between transmission and reception, pure methane of used fuel, 0 ~ 45 % of mixture gas (CH4), 350 and 400 V of input voltage strength, and 295 K for room temperature. The experiment method includes the sensor concept and structure, theory of ultrasonic energy transfer, signal processing, and experimental setups and conditions. As a result, the sensor sensitivity of ML 7.5 mm is well-measured by stages in entire ratios of an air-methane mixture. Namely, it can be noticed that sensitivity of ML 7.5 mm has the most appropriate effect in the measurement of gas fuel comparing with other sensors. Consequently, the sensitivity characteristics in an air-methane mixture ratio and pure gas space (PGS) have a relation of an inverse proportion. Furthermore, the accuracy of methane gas in high-pressure is higher than low-pressure condition because ultrasound is advantageous in high density. |
| Key Words:
Natural gas vehicle (NGV), Methane gas (CH4), Ultrasonic-assisted measurement (USM), Matching layer (ML), Ultrasonic sensor, Longitudinal wave, Acoustic impedance |
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Corresponding Author.
Seok Yeon Im , Email. 
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