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This work investigates the performance of a supercritical CO2 cycle as the bottoming cycle of a commercial gas turbine with 4.7 MW of electric power output. In detail, the partial heating cycle is the layout chosen for the interesting trade-off between heat recovery and cycle efficiency with a limited number of components. Single-stage radial turbomachines are selected according to the theory of similitude. In particular, the compressor is a troublesome turbomachine as it works near the critical point where significant variations of the CO2 properties occur. Efficiency values for turbomachinery are not fixed at first glance but result from actual size and running conditions, based on flow rates, enthalpy variations as well as rotational speeds. In addition, a limit is set for the machine Mach numbers in order to avoid heavily loaded turbomachinery. The thermodynamic study of the bottoming cycle is carried out by means of the mass and energy balance equations. A parametric analysis is carried out with particular attention to a number of specific parameters. Considering the power output calculated for the supercritical CO2 cycle, economic calculations are also carried out and the related costs compared to those specific of organic Rankine cycles with similar power output.

The application of hydrogen in heavy-duty vehicles or trains has been suggested as a promising solution to decarbonize the transportation sector. In this study, a one-dimensional engine modeling is employed to evaluate the potential of hydrogen as a fuel for railway applications. A turbocharged diesel engine is simulated as the baseline unit, and the results are validated with experimental data. The same engine is converted to become compatible with hydrogen through some modifications in the turbocharger group and the injection and ignition systems to preserve the performance of the baseline configuration. The findings show that the engine traction power is reduced from 600 to 400 kW, indicating an inferior performance for the hydrogen-fueled engine. The energy consumption of the hydrogen-fueled engine on a real train mission profile is almost two times the diesel version. However, our Life Cycle Assessment analysis with a Well-to-Wheel system boundary shows a 56% reduction in equivalent CO2 emissions for the engine fueled with photovoltaic-based green hydrogen. Substituting diesel with low-carbon hydrogen can decrease the train's carbon footprint from 4.27 to even less than 2 kg CO2 eq./km, suggesting that moderately modified engines are a promising solution for decarbonizing non-feasibly electrified railway sections. [ABSTRACT FROM AUTHOR]

The HS3 solvent is an innovative blend for CO2 capture made up of a primary (3-amino-1-propanol, AP) and a tertiary (1-(2-hydroxyethyl) pyrrolidine, PRLD) amine studied in the H2020-funded Realise project. The thermodynamic framework has already been validated using experimental observations. The proposed thermodynamic model has been built into Aspen Plus V11 using the ENTRL (Electrolyte Non-Random Two Liquid) package and, then, finalized by including a mass transfer model and kinetics. The resulting full flowsheet simulation model has been validated using experimental measurements from Tiller semi-industrial pilot plant (Trondheim, Norway). The experimental campaign succeeded in demonstrating lower energy requirement and liquid recirculation compared to conventional monoethanolamine (MEA) at 30% w/w. The present contribution aims at presenting the validation procedure of the developed model over experimental data from the large-scale facility at Tiller and showing that the HS3 solvent is a promising blend to mitigate energy consumption in the CO2 capture process. All KPIs of the CO2 capture plant (CO2 capture rate, CO2 flow released in the stripper and temperature profiles inside the two columns) are predicted with an Absolute Average Relative Deviation (AARD) lower than 5% and with an Average Relative Deviation (ARD) close to zero. This statistical analysis demonstrates that the developed HS3 Aspen model can be used for simulation, energy analysis, and technoeconomic assessment purposes. [ABSTRACT FROM AUTHOR]

Carbon Capture and Storage (CCS) is among the main available options to cut CO2 emissions from the industry and energy production sectors, but the high costs of current CCS technology still limit their large-scale applicability. For this reason, there is increasing interest in alternative absorbents with the potential to lower the energy and environmental impact of carbon capture. The estimation of costs, as well as process design and optimization, require accurate, reliable, and stable thermodynamic models. This article presents the development and testing of an ELECNRTL model in Aspen Plus for the characterization of HS3, an innovative blend made up of a primary (3-amino-1-propanol) and a tertiary (1-(2-hydroxyethyl) pyrrolidine) amine studied in the H2020-funded Realise project. The vapor-liquid equilibrium (VLE) model is fitted to in-house experimental data covering a wide range of loadings and operating temperatures. A plot for the system speciation in the liquid phase is obtained. Moreover, a comparison between the heat of absorption data and model prediction is also included. The proposed VLE model shows good accuracy and numerical stability in the whole temperatures and loading ranges of interest for industrial CO2 capture applications. [ABSTRACT FROM AUTHOR]