The Eddy Dissipation Concept (EDC) is common in modeling turbulent combustion. Several model improvements have been proposed in literature; recent modifications aim to extend its validity to Moderate or Intense Low oxygen Dilution (MILD) conditions. In general, the EDC divides a fluid into a reacting and a non-reacting part. The reacting part is modeled as perfectly stirred reactor (PSR) or plug flow reactor (PFR). EDC theory suggests PSR treatment, while PFR treatment provides numerical advantages. Literature lacks a thorough evaluation of the consequences of employing the PFR fine structure treatment. Therefore, these consequences were evaluated by employing tests to isolate the effects of the EDC variations and fine structure treatment and by conducting a Sandia Flame D modeling study. Species concentration as well as EDC species consumption/production rates were evaluated. The isolated tests revealed an influence of the EDC improvements on the EDC rates, which is prominent at low shares of the reacting fluid. In contrast, PSR and PFR differences increase at large fine fraction shares. The modeling study revealed significant differences in the EDC rates of intermediate species. Summarizing, the PFR fine structure treatment might be chosen for schematic investigations, but for detailed investigations a careful evaluation is necessary.

Hydrogen storage in a depleted gas field is a promising solution to the seasonal storage of renewable energy, a key question in Europe’s green transition. The gas composition and pressure in the month-long storage and recovery phase can vary substantially; meanwhile, the recovered H₂ has to be pure, especially for fuel cell applications. Pressure swing adsorption can be used for the purification of the recovered gas. A lab-scale, four-bed PSA unit was built to investigate its applicability by separating different H₂-CH₄ mixtures. The feed parameters in the experiments are based on a depleted gas reservoir with a pressure range of 25–60 bar and methane contamination between 0 and 35%. The change in the feed properties is modeled by four distinct stages and the twelve-step cycle is tailored to each stage. The high pressure did not have any irreversible effects on the process. A hydrogen purity of 99.95% was achieved in all stages with the average hydrogen recovery ranging from 60 to 80%. The experiments revealed the challenges of a cycle design when the feed parameters are not constant, but an adequate separation performance was shown, which supports the applicability of the PSA in seasonal storage and confirms the need for further investigation with multicomponent contaminants and large-scale projects.

Energy crisis and solid waste management have remained challenging issues for authorities in Pakistan. These issues tend to rise with increasing population and economic growth of the society. Therefore, environmentally sustainable waste‐to‐energy program must be part of the waste management system since they may substitute fossil fuels with renewable energy sources by enabling energy recovery instead of landfill of solid wastes. In this work, the combustion characteristics of fossil fuel (coal) and solid wastes such as municipal solid waste (MSW) and refuse‐derived fuel (RDF) were investigated by thermogravimetric analysis (TGA) to compare their thermal decomposition behavior. Furthermore, proximate and ultimate analyses of these samples were carried out along with their heating values. The TGA profiles of samples indicate low reactivity of coal, whereas solid wastes present greater reaction rate reflecting their low ash and high volatile contents. It was found that the heating value of RDF sample was close to that of coal. The obtained thermal data were used to calculate the kinetic parameters using Arrhenius and Coats‐Redfern models with different reaction mechanisms. According to these models, the fuels could be arranged in order of activation energy as coal > RDF > MSW. The percentage difference between activation energy values found from Arrhenius and Coats‐Redfern models was in the range of 4.1%‐26.5%. However, the Coats‐Redfern model exhibited consistency in activation energy values, followed by a high value of R². These results of the TGA could be very helpful to predict the combustion dynamics and confirm that MSW and RDF may be used as sustainable fuels, to meet the prevailing challenges of the energy crisis and solid waste management.

This paper aims to describe the capability of the system boric acid–boron oxide for thermochemical energy storage. As part of the systematic research and in-depth analysis of potential solid/gas reaction systems, performed during the last years, this reaction system appears to be highly promising for the future of worldwide sustainable energy supply. The analysis of the reaction heat, by means of thermogravimetric and macroscopic investigations, not only showed a significantly higher energy density of 2.2 GJ/m³, compared to sensible- and latent energy storages, but the reaction kinetic further demonstrated the reactions’ suitability to store energy from renewable energy and waste heat sources. This paper, therefore, shows a new approach regarding the application of the boric acid–boron oxide reaction system and elaborates on the advantages and challenges for its use as energy storage.

Metal oxides are promising potential candidates for thermochemical energy storage in concentrated solar power plants. In particular, the Cu₂O/CuO system is suitable because of its high energy density, applied temperature interval, and reduced cost compared to the CoO/Co₃O₄ system. In heterogenous gas-solid reactions, the pressure affects the kinetics significantly. To quantify this effect for oxidation of Cu₂O to CuO, isothermal runs between 800 °C and 930 °C at different oxygen partial pressures (0.1, 0.2, 0.5, and 1.0 bar) were conducted with thermogravimetric analysis (TGA). Defined fractions of CuO samples (1–100 µm) were analyzed with X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, and scanning electron microscopy (SEM) analysis. The kinetic analyses were performed with extended non-parametric kinetics (NPK), which is applied for the first time to consider the pressure term in the general kinetic equation in addition to the conversion and the temperature term. The results show how the oxygen partial pressure impacts the kinetics and how reparameterization of the pressure term affects the kinetic analysis of the oxidation reaction of Cu₂O to CuO. The best conversion model is a two-dimensional Avrami-Erofeev model with an activation energy of 233 kJ/mol. The kinetic models for conversion, temperature, and pressure presented in this work provide one of the most important requirements for reactor designs.

The increasing demand for high-performance activated carbon necessitates applying sustainable and cost-effective production methods. This study explores the use of biochar derived from renewable biomass. The primary feedstock for biochar consisted of woody residues from composting, along with pre-dried sunflower seed shells that had a moisture content of around 10% as a precursor for the production of activated carbon. The process started with carbonization followed by potassium hydroxide (KOH) activation. Key parameters such as the impregnation ratio, temperature, and activation time were optimized to enhance the physicochemical properties of the activated carbon. Under optimized conditions, namely a KOH-to-biochar impregnation ratio of 3:1, an activation temperature of 800 °C, and an activation duration of 5 h, the yield of activated carbon was 58% and the specific surface area was 498 m²/g. A significant enhancement in surface area, with a maximum value of 709 m²/g, was achieved after increasing the time to 24 h of activation. Differential Scanning Calorimetry (DSC) analysis was applied to evaluate the CO₂ adsorption performance of both biochar and activated biochar at 30 °C, demonstrating a 30% improvement in adsorption efficiency following activation. This study underscores the potential of biochar as a renewable and sustainable precursor for the production of high-performance activated carbon. This study underscores the potential of biochar derived from agro residue as a source for the production of high-performance activated carbon. The findings contribute to the advancement of environmentally friendly production technologies and highlight the potential applicability of biochar-derived activated carbon in gas adsorption and environmental remediation.