Combustion in large dilutions of carbon dioxide (CO2) has the potential to enable fossil fuel combustion with 100 % inherent carbon capture by simplifying the post-combustion carbon capture process into the facile separation of CO2 and water. Emerging technologies that employ CO2 as a bath gas, exemplified by the Allam-Fetvedt cycle, are gaining widespread international attention, evidenced by ongoing plant developments in both the United Kingdom and the United States. This study presents new ignition delay time datasets (IDTs) for the combustion of methane and methane/hydrogen blends at 20 and 40 bar. The chemical kinetics governing these distinct conditions are investigated by utilizing two distinct chemical kinetic mechanisms, namely UoS sCO2 2.0 and NUIGMech1.1. Ignition delay datasets of methane/hydrogen blends are presented alongside a detailed discussion of the effect CO2, in contrast to N2, on the combustion mechanism. The differences in kinetics of pure methane and pure hydrogen are also discussed with regards to key reactions and the radical pool. This study aims to elucidate the intricate interplay of factors shaping ignition dynamics in CO2– enriched environments.

We show in this paper that maximal Lq-regularity for time-dependent viscous Hamilton-Jacobi equations with unbounded right-hand side and superquadratic γ-growth in the gradient holds in the full range q>(N+2)[Formula presented]. Our approach is based on new [Formula presented]-Hölder estimates, which are consequence of the decay at small scales of suitable nonlinear space and time Hölder quotients. This is obtained by proving suitable oscillation estimates, that also give in turn some Liouville type results for entire solutions.

Porous liquids represent a category of materials that combine the porosity of solid structures with the fluidity of liquids, drawing substantial research interest. In this work, we synthesized a novel class of porous carbon liquids, termed H-PLs, which exhibit stable flow at room temperature. This stability is achieved through cation-π interactions between an imidazolium-based polymeric ionic liquid ([EMIM][TF2N]) and a porous carbon network. Notably, the CO2 adsorption capacity of H-PLs reached 3.73 wt% at 298 K and 8 bar, significantly outperforming parent [EMIM][TF2N] ionic liquid and demonstrating a CO2 solubility approximately 37 times greater than that of N2 under identical conditions. These findings reveal the potential of H-PLs for selective gas adsorption, and suggest that electrostatic-assisted synthesis method offers a rapid, efficient and scalable pathway for future production of porous liquids.

Mantle plumes are responsible for the Earth’s largest volcanic provinces. In the prevailing paradigm, the deep mantle is less degassed than convecting shallow mantle, implying that plume-derived lavas have higher concentrations of primordial volatiles such as helium (He). Demonstrating this has led to explanations that question the established Earth model. Here, we show that the 3He/4He of basalts from the Red Sea display coherent relationships with trace elements, allowing the helium concentration of the Afar plume to be calculated. Contrary to the prevailing model it appears the helium concentration of the Afar plume is 10-25% of the upper mantle. This contradiction is resolved if the plume material itself is a mixture of helium-rich high-3He/4He deep mantle with helium-depleted low-3He/4He recently subducted oceanic crust. This implies that helium-depleted domains may exist in convecting mantle and that moderately high 3He/4He plumes likely do not contain a notable contribution of the deep mantle.

This study investigates the response of a laminar methane-air flame to Nanosecond Repetitively Pulsed (NRP) discharges in a canonical wall-stabilized burner using a combined experimental and numerical approach. The flow and flame behaviors were modeled using Direct Numerical Simulation (DNS) with an Analytically Reduced Chemistry for a precise chemical description. A phenomenological model incorporating detailed plasma kinetics and experimental observations was developed to simulate plasma effects. Zero-dimensional plasma reactor simulations were used to build up a reduced-order model describing discharge energy distribution in the specific conditions studied. Experimental measurements of electrical profiles identified two discharge regimes: a low-energy Corona discharge and a higher-energy Glow discharge, characterized by distinct spatial energy distributions. Experimental flame response analysis revealed three major phases: marginal response up to 100 pulses, a downstream shift of the flame tip, and stabilization after 400 pulses. Numerical simulations indicated that the Corona regime is crucial for explaining initial flame responses, while the Glow regime influences later stages. Adjustments in the Vibrational–Translational (VT) energy relaxation time and energy deposition ratios between fresh and burnt gases were necessary to match experimental observations. Additionally, an accurate modeling of the transient and steady-state flame responses requires integrating both the specificity of the Corona and the Glow discharge regimes. Future work should focus on measuring or theoretically calculating N2(v) relaxation times in CH4-H2O-CO2 mixtures and analyzing the spatial energy distribution of discharges interacting with flames to enhance plasma-combustion coupled models. Novelty and significance In this work, a phenomenological plasma-assisted combustion model has been developed, to investigate a laminar premixed stagnation plate burner, focusing on VT energy relaxation time and spatio-temporal energy distribution modeling. For the first time, not only O2, N2 and O but also the fuel and combustion intermediates and products have been considered in the VT relaxation model. It revealed their strong influence on the overall flame response in a case where the discharge crosses a flame front, highlighting the strong beneficial effect of energy deposited in vibrational form. The study questions and investigates the energy distribution from fresh to burnt gases, challenging the conventional uniform energy distribution assumption. The experimental identification of two specific plasma regimes was necessary to predict the transient flame response. Additionally, energy deposited downstream of the flame, in fresh gases, was found to more efficient than in hot gases to enhance combustion.