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Concentrated solar power (CSP) has gained traction for generating electricity at high capacity and meeting base-load energy demands in the energy mix market in a cost-effective manner. The linear Fresnel reflector (LFR) is valued for its cost-effectiveness, reduced capital and operational expenses, and limited land impact compared to alternatives such as the parabolic trough collector (PTC). To this end, the aim of this study is to optimize the operational parameters, such as the solar multiple (SM), thermal energy storage (TES), and fossil fuel (FF) backup system, in LFR power plants using molten salt as a heat transfer fluid (HTF). A 50 MW LFR power plant in Duba, Saudi Arabia, serves as a case study, with a Direct Normal Irradiance (DNI) above 2500 kWh/m2. About 600 SM-TES configurations are analyzed with the aim of minimizing the levelized cost of electricity (LCOE). The analysis shows that a solar-only plant can achieve a low LCOE of 11.92 ¢/kWh with a capacity factor (CF) up to 36%, generating around 131 GWh/y. By utilizing a TES system, the SM of 3.5 and a 15 h duration TES provides the optimum integration by increasing the annual energy generation (AEG) to 337 GWh, lowering the LCOE to 9.24 ¢/kWh, and boosting the CF to 86%. The techno-economic optimization reveals the superiority of the LFR with substantial TES over solar-only systems, exhibiting a 300% increase in annual energy output and a 20% reduction in LCOE. Additionally, employing the FF backup system at 64% of the turbine's rated capacity boosts AEG by 17%, accompanied by a 5% LCOE reduction. However, this enhancement comes with a trade-off, involving burning a substantial amount of natural gas (503,429 MMBtu), leading to greenhouse gas emissions totaling 14,185 tonnes CO₂ eq. This comprehensive analysis is a first-of-a-kind study and provides insights into the optimal designs of LFR power plants and addresses thermal, economic, and environmental considerations of utilizing molten salt with a large TES system as well as employing natural gas backup. The outcomes of the research address a wide audience including academics, operators, and policy makers. [ABSTRACT FROM AUTHOR]

The development of a compact mechanism has made a great contribution to work on the combustion of hydrocarbon species and facilitates the investigations on chemical kinetics and computational fluid dynamics (CFD) studies. N-propylcyclohexane (NPCH) is one of the important components for jet, diesel, and gasoline fuels which needs a reliable compact reaction kinetics mechanism. This study aims to investigate the construction of a well-validated mechanism for NPCH with a simplified chemical kinetics model that delivers a good prediction ability for the key combustion parameters in a wide range of conditions (temperatures, pressures, and equivalence rates). The NPCH reaction kinetic mechanism was constructed with the aid of a coupling process, simplification process, rate modification, and a combination of standard reduction methods. The model includes a simplified sub-mechanism with 16 species and 58 reactions and a semi-detailed core mechanism with 56 species and 390 reactions. Two key parameters including ignition delay time and laminar flame speed are simulated by the use of ANSYS Chemkin-Pro. The simulation results for these parameters are validated against the available data in the literature, and the results show a good agreement compared to the experimental data over a wide range of conditions covering low to high temperatures at different pressures and equivalence ratios. [ABSTRACT FROM AUTHOR]

This study aims to experimentally evaluate the impact of a double-sided microporous layer coating on gas diffusion layers in terms of their key properties and fuel cell performance, in comparison to conventional single-sided coated gas diffusion layers (GDLs). Vulcan black and Ketjenblack were used as the carbon black materials. This was to investigate the sensitivity of the results with respect to the type of carbon black used. The results showed that the in-plane electrical conductivity is almost insensitive to microporous layer (MPL) loading and carbon black type. Furthermore, the electrical conductivity of all the MPL-coated GDLs are slightly lower than that of the uncoated GDL. The Ketjenblack black MPL samples were found to demonstrate higher gas permeability than the Vulcan black samples. The addition of the MPL resulted in a favourable shift in pore size distribution, with prominent micropores observed in both single- and double-sided MPL-coated GDLs. Contact angle measurements indicated a slight increase in the hydrophobicity with the addition of a microporous layer, but without significant differences between carbon black types or loading levels. Cross-sectional SEM images showed that there was a higher level of MPL penetration into the carbon substrate for the GDLs coated with Vulcan black as compared to a Ketjenblack coating. In situ fuel cell testing demonstrated the superior performance of the double-sided Vulcan black MPL-coated GDL under high humidity conditions, while the single-sided Vulcan black MPL-coated GDL exhibited better performance at low humidity conditions. All the above findings have been thoroughly discussed and justified. [ABSTRACT FROM AUTHOR]

In-situ biomethanation combines conventional biogas production from the anaerobic digestion (AD) of organic matter with the addition of hydrogen to produce a higher quality biomethane gas. However, challenges surrounding its performance and control could hinder its uptake. To investigate this, an automated rig was designed and operated to study in-situ biomethanation with sewage sludge (SS) and food waste (FW) feedstocks. The effects that were experimentally investigated included the biogas recirculation rate, stirring intensity, and organic loading rate (OLR). All the results highlighted the rate-limiting effect of H2 gas–liquid mass transfer (measured kLa in the range of 43–82 day−1), which was implied by a lack of evidence of hydrogen-induced biological inhibition and a high average equilibrium hydrogen content in the biogas (a volume of 7–37%). At an OLR of 2 g VS L−1day−1, increasing biogas recirculation and mechanical stirring rates improved the methane evolution rate up to 0.17 and 0.23 L L−1day−1 and the H2 conversion up to 80 and 66% for sewage sludge and food waste, respectively. A lower OLR of 1 g VS L−1day−1 allowed for increased hydrogen conversion but at a lower level of methane productivity. A process model, validated on experimental data, predicted that improving the kLa to at least 240 day−1 would be required for in-situ biomethanation at OLRs common in AD systems in order to achieve a drop-in quality in terms of the biogas, with further downstream treatment required for certain applications. [ABSTRACT FROM AUTHOR]