Understanding the behaviour of gas–liquid flows in upward and downward pipe configurations in chemical, petroleum, and nuclear industries is vital when optimal design, operation, production, and safety are of paramount concern. Unfortunately, the information concerning the behaviour of such flows in large pipe diameters is rare. This article aims to bridge that gap by reporting air–water upward and downward flows in 127 mm internal diameter pipes using advanced conductance ring probes located at two measurement locations. The liquid and gas flow rates are 0.021 to 0.33 m/s and 3.52 to 16.1 m/s, correspondingly, covering churn and annular flows. To achieve the desired objectives, several parameters, probability density function (PDF), power spectral density (PSD), Slippage Number (S_N), drift velocity (U_gd), and distribution coefficient (C₀) were employed. The flow regimes encountered in the two pipe configurations were distinguished employing a flow regime map available in the literature and statistical analysis. The obtained results were supported by visual inspection. The comparison between the present study against reported studies reveals the same tendency for the measured experimental data. The Root Mean Square Error (RMSE) method within 4% was utilized in recommending the best void fraction prediction correlation for the downward and upward flows.

Dry reforming of methane (DRM) is a promising method for turning two major greenhouse gases, CO₂ and CH₄, into syngas (H₂ + CO). This syngas has the right H₂/CO ratio for making valuable chemicals and liquid fuels. However, there are significant challenges that make it tough to implement commercially. One big issue is that the process requires a lot of energy because it is highly endothermic, needing temperatures over 700 °C. This high heat can quickly deactivate the catalyst due to carbon build-up (coking) and the thermal sintering of metal nanoparticles. Researchers increasingly recognize mechanochemistry—a non-thermal, solid-state technique employing mechanical force to drive chemical transformations—as a sustainable, solvent-free strategy to address these DRM challenges. This mini-review critically assesses the dual role of mechanochemistry in advancing DRM. First, we examine its established role in creating advanced catalysts at lower temperatures. Here, mechanochemical methods help produce well-dispersed nanoparticles, enhance strong interactions between metal and support, and develop bimetallic alloys that resist coke formation and show great stability. Second, we delve into the exciting possibility of using mechanochemistry to directly engage in the DRM reaction at near-ambient temperatures, which marks a major shift from traditional thermocatalysis. Lastly, we discuss the key challenges ahead, like scalability and understanding the mechanisms involved, while also outlining future directions for research to fully harness mechanochemistry for converting greenhouse gases sustainably.