Performance analysis of multiple structural parameters of injectors for hydrogen-mixed natural gas using orthogonal experimental methods

Hydrogen is a clean energy source with high combustion calorific value and nonpolluting products. However, the high transportation costs hinder the development of hydrogen energy. A high flow rate, long-distance, and high-efficiency delivery can be realized by mixing natural gas with hydrogen, which significantly reduces the transportation cost. However, high concentrations of hydrogen aggregates risks hydrogen embrittlement in the natural-gas pipeline network and leakage. An injector is a highly efficient gas-blending device. Therefore, analyzing and optimizing the multiple structural parameters of the injector are necessary for improving the mixing efficiency and homogeneity of hydrogen and natural gas. First, eight structural parameters of the injector were selected and four levels were considered for each parameter. Subsequently, an orthogonal experiment table was constructed using the orthogonal experimental method. Finally, a modeling simulation was performed using Fluent simulation software. The results showed that the injectors can significantly shorten the distance of mixing uniformity and achieve faster mixing uniformity. The diameter of the mixing pipe was found to be the main factor affecting the overall score. Computational Fluid Dynamic-20 (CFD-20) had the highest overall score. The LCOV10% for CFD-20 improved by 21.5% over that of the initial model, and the composite score improved from 0.93 to 0.98. The results can provide a reference for the design of injector parameters and installation of metering equipment.