Understanding the effect of methane gas sensitivity using ultrasonic sensors and multi-matching layers inside a natural gas vehicle tank

This research paper is the experimental study to investigate the effect of ultrasound sensitivity in the pure methane gas space as the pressure and sensor distance increases. We offer the solution to overcome the low sensitivity characteristics of ultrasonic sensors in the methane gas space. This proposal shows the physical characteristics analyzed with self-induced vibration, beam pattern, amplitude, attenuation, and Gaussian distribution validation in CH₄ gas space. An ultrasonic sensor is designed with PbTio₃ material of an MS-50 PTZ. The signal processing analysis system (APAS) is composed of the mechanical and controlling sections including three mass flow controllers, an air cylinder, safety valves, three pressure regulators, a CVC, ultrasound sensors, and two gas tanks (air and CH₄). The experiment is performed in a wide range of the initial conditions, i.e., supplying voltage of 25 V, current of 0.2 A, pulse rate of 7 Hz, measuring distance of 0.32 to 1.02 m, resonance frequency of 57.3 Hz, ambient temperature of 296 K, and pressure increases of 1, 2, 3 and 4 bar. The ultrasonic sensitivity of a sensor (T: EVA and R: EVA) significantly enhanced the acoustic impedance in a methane gas space as pressure increases. It is verified that the sensitivity effect of an ultrasonic sensor used with ethylene vinyl acetate (EVA) matching layer is higher in the methane gas space than a chemical wood (CW) matching layer. Consequently, the effect of gas sensitivity computed by a GDA including the width (W), area (A), and height (H) is enhanced by an EVA sensor in comparison to other Models.