Experimental and numerical investigation on development of a method for measuring the rate of natural gas leakage

Abstract

Measuring gas leakage flow with conventional flow metric methods is impossible due to the extremely low flow rate, the uncertain flow path of gas emitted into the environment, and the inability to detect the exact location of leakage. However, quantifying the amount of natural gas released into the environment is critical because, in addition to resource depletion, natural gas leakage results in the emission of methane gas, a highly potent greenhouse gas. The purpose of this study is to develop a method for determining the leakage rate of gas from household gas pipes that branch off from natural gas distribution lines and their connections. In this method, through passing a forced airflow over gas leakage pores, a mixture of gas and air is created, and then the gas leakage volumetric flow rate is determined using a relationship between the volumetric flow rate of the gas-air mixture and the gas concentration value in the mixture. The first step involves developing a three-dimensional numerical model of a gas branch based on its actual conditions. Numerical simulations establish the model's overall geometry and various components to accurately predict the leaking gas flow rate from the outlet gas concentration value. A physical model based on the numerical results was constructed to validate the numerical solution's results. A gas leak simulator setup was designed and built to verify the results as well as the device's performance accuracy. Measurements were conducted in four different airflows and nine distinct leakage flows. Volumetric flow rates calculated using the proposed method are extremely close to the actual values. Additionally, the numerical solution produced results within an acceptable range of error compared to the experimental results. The measurement errors of this method were less than ±10% in all cases and less than ±5% in approximately 75% of cases.