Solid oxide fuel cell reactor analysis and optimisation through a novel multi-scale modelling strategy

The simulation of a solid oxide fuel cell (SOFC) that incorporates a detailed user-developed model was performed within the commercial flowsheet simulator Aspen Plus. It allows modification of the SOFC's governing equations, as well as the configuration of the cell's fuel-air flow pattern at the flowsheet level. Initially, the dynamic behaviour of single compartment of a cell was examined with a 0D model, which became the building block for more complex SOFC configurations. Secondly, a sensitivity analysis was performed at the channel (1D) scale for different flow patterns. Thirdly, the effect of fuel and air flow rates on the predominant distributed variables of a cell was tested on a 2D assembly. Finally, an optimisation study was carried out on the 2D cell, leading to a robust, optimal air distribution profile that minimises the internal temperature gradient. This work forms the foundation of future stack and system scale studies

Ontology-Based Information Management in Design Processes

Engineering design processes are highly creative and knowledge-intensive tasks that involve extensive information exchange and communication among diverse developers. In such dynamic settings, traditional information management systems fail to provide adequate support due to their inflexible data structures and hard-wired usage procedures, as well as their restricted ability to integrate processes and product information. In this paper, we advocate the idea of Process Data Warehousing as a means to provide an information management and integration platform for such design processes. The key idea behind our approach is a flexible ontology-based schema with formally defined semantics that enables the capture and reuse of design knowledge, supported by advanced computer science methods

High-efficiency low LCOE combined cycles for sour gas oxy-combustion with CO2 capture

The growing concerns over global warming and carbon dioxide emissions have driven extensive research into novel ways of capturing carbon dioxide in power generation plants. In this regard, oxy-fuel combustion has been considered as a promising technology. One unconventional fuel that is considered is sour gas, which is a mixture of methane, hydrogen sulfide and carbon dioxide. In this paper, carbon dioxide is used as the dilution medium in the combustor and different combined cycle configurations were considered and analyzed, each with a different way of dealing with the harmful sulfur products in the working fluid. Out of these options, which included acid resistance, no-condensation and SOx removal cycles, it is found that the cycle using acid resistant materials to have the best efficiency at 45.2%. However the cost of electricity (COE) of the cycle incorporating SOx removal is about 3% lower. Comparing these combined cycles to the sour gas water cycles discussed in our previous paper (Chakroun and Ghoniem, 2015), it is evident that sour gas based oxy-combustion combined cycles generally perform better in terms of both technical and economical performance. Therefore, it is concluded that the best process cycle to use for this sour gas fuel to be the combined cycle with the SOx removal system. This high-efficiency cycle has the lowest COE out of all of the five cycles studied.Siemens CorporationAspen Technology, Inc

Techno-economic assessment of sour gas oxy-combustion water cycles for CO2 capture

Growing energy demand coupled with the threat of global warming call for investigating alternative and unconventional energy sources while reducing CO2 emissions. One of these unconventional fuels is sour gas, which consists of methane, hydrogen sulfide and carbon dioxide. Using this fuel poses many challenges because of the toxic and corrosive nature of its combustion products. A promising technology for utilizing it is oxy-fuel combustion with carbon capture and storage, including the potential of enhanced oil recovery for added economic benefits. Although methane oxy-fuel cycles have been studied in the literature, using sour gas as the fuel has not been investigated or considered. In this paper, water is used as the diluent to control the flame temperature in the combustion process, and the associated cycle type is modeled to examine its performance. As the working fluid condenses, sulfuric acid forms which causes corrosion. Therefore, either expensive acid resistant materials should be used, or a redesign of the cycle is required. These different options are explored. A cost analysis of the proposed systems is also conducted to provide preliminary estimates for the levelized cost of electricity (LCOE). The results show the acid resistance cycle with a 4.5% points increase in net efficiency over the cycle with SO[subscript x] removal. However there is nearly a 9% decrease in the cycle's LCOE for the latter case.Aspen Technology, Inc