Changes in the Operating Conditions of Distribution Gas Networks as a Function of Altitude Conditions and the Proportion of Hydrogen in Transported Natural Gas

The article presents a comparison between the pressure conditions of a real low-pressure gas network and the results of hydraulic calculations obtained using various simulation programs and empirical equations. The calculations were performed using specialized gas network analysis software: STANET (ver 10.0.26), SimNet SSGas 7, and SONET. Additionally, the simulation results were compared with calculations based on the empirical Darcy–Weisbach and Renouard equations. In the first part of the analysis, two calculation models were compared. In one model, the geodetic elevation of individual network nodes was included (elevation-aware model), while in the second, calculations were performed without considering node elevation (flat model). For low-pressure gas networks, accounting for elevation is critical due to the presence of the pressure recovery phenomenon, which does not occur in medium- and high-pressure networks. Furthermore, considering the growing need to increase the share of renewable energy, the study also examined the network’s operating conditions when using natural gas–hydrogen mixtures. The following hydrogen concentrations were considered: 2.5%, 5.0%, 10.0%, 20.0%, and 50.0%. The results confirm the importance of incorporating elevation data in the modeling of low-pressure gas networks. This is supported by the small differences between calculated results and actual pressure measurements taken from the operating network. Moreover, increasing the hydrogen content in the mixture intensifies the pressure recovery effect. The hydraulic results obtained using different computational tools were consistent and showed only minor discrepancies.