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The objective of this paper was to study the sCO2 cycle as a waste heat recovery system for a 180 kW biogas engine. The research methodology adopted was numerical simulations through two models built in different programs: Aspen HYSYS and GT Suite. The models were used to optimize the design and thermodynamic parameters of a CO2 cycle in terms of system power, system efficiency, expander, and compressor efficiency. Depending on the objective function, the sCO2 cycle could provide additional power ranging from 27.9 to 11.3 kW. Based on the calculation performed, "Recuperated cycle at maximum power" was selected for further investigation. The off-design analysis of the system revealed the optimum operating point. The authors designed the preliminary dimensions of the turbomachinery, i.e., the rotor dimension is 16 mm, which will rotate at 100,000 rpm. [ABSTRACT FROM AUTHOR]

This article deals with a thermal energy storage system in the form of a water tank with a thermocline. The well-known thermocline phenomenon is modeled using computational fluid dynamics (CFD). However, the reservoir model proposed in this article is zero-dimensional. This is due to the fact that the aim of this article is to build a mathematical model that will be more useful in mathematical models of complex energy systems in which a hot water tank is one of many elements of the system. In such a zero-dimensional mathematical model, the hot water tank will be modeled using equations describing heat transfer, and the thermocline itself will be treated as a heat transfer surface with known dimensions and heat transfer coefficient. A novelty of this paper is that it addresses heat loss across the thermocline as defined in this manner. A CFD model of a thermal storage tank is created, validated with available experimental data, and used to obtain the heat transfer coefficient U. The resulting value is then analyzed quantitatively and qualitatively and the changes in the thickness of the thermocline are accounted for in the equation. The results from this groundbreaking work can be used to analyze heat storage in the form of thermocline water tanks at the level of system modeling, e.g., for the purpose of configuring the structure of other devices and control systems. [ABSTRACT FROM AUTHOR]

The paper contains a comprehensive summary of the current state of research on the polymer burnout process in molten carbonate fuel cells (MCFC). Outline information discussing both MCFC fundamentals and the start-up process are given along with references to the literature. The main part of the article presents the result of an on-site experiment regarding polymer burnout performed on an MCFC stack. The outcomes are discussed and conclusions are clearly stated. [ABSTRACT FROM AUTHOR]

This paper presents models of three elements: heat exchanger, compressor and expander dedicated to supercritical CO2 cycles (Brayton). The models are built using Ebsilon software and validated against experimental data from available literature. Radial turbomachinery and thin plate heat exchangers were used to meet the demands of the relatively compact design of the S-CO2 cycle elements. It seems that there are no general relationships for the turbomachinery and real characteristics need to be used for constructing the models. [ABSTRACT FROM AUTHOR]

In this study, two types of high temperature electrolyzers (O=SOE and H+SOE) were investigated for hydrogen generation in relation to nuclear power plant operations. The analysis encompasses the thermal integration of proton and ion conducting solid oxide electrolyzers, which are fed with steam generated in the nuclear plant. Under consideration in the study was the steam turbine cycle of an AP1000 nuclear power plant. The main parameters of electrolysis were tailored to match the typical operating temperature of the electrolyzers, and the water utilization factor was set at the same value for the two technologies under consideration. There are some advantages to applying high temperature electrolysis to the deaerator steam feed: first, there is almost no modification of the nuclear steam turbine cycle; second, flexibility of the nuclear power plant rises by 20% with almost constant thermal load of the nuclear reactor; and third, high pressure hydrogen is obtained for commercial purposes. The analysis concludes that hydrogen can be produced in electrolyzers integrated with nuclear plants at an energy cost of 38.83 and 37.55 kWh kg H2 −1 for protonic and ionic solid oxide electrolyzers, respectively. • Study addressed the coupling of solid oxide electrolysers with nuclear plant. • Oxygen ion and proton conducting solid oxide electrolyzers were modelled. • Analysis of hydrogen generation using high temperature electrolysis was performed. • Electric power demand for producing hydrogen in the cycle was computed. • Values of 38.83 and 37.55 kWh/kg H 2 were found for H+ and O= SOE, respectively. [ABSTRACT FROM AUTHOR]