1,721,043 research outputs found
Investigation of a 5 kW micro-CHP PEM fuel cell based system integrated with membrane reactor under diverse EU natural gas quality
Full text linkThis work investigates the techno-economic assessment of a 5 kW micro-cogeneration system based on membrane reactor and PEM fuel cell flexible towards different natural gas qualities. The flexibility of the system is evaluated for four typical natural gas compositions from different European countries featuring an average condition and three extreme cases. The optimal system design conditions are determined together with performance variation as function of NG composition and load. The sweep gas and vacuum pump are explored as options to reduce the membrane surface area, outlining the efficiency advantages of the former (41.21% vs. 39.24%). Simulations at partial load show that the electric efficiency increases until 60â70% of the load in both cases, then quickly drops. Micro-CHP performance are used as input to determine the specific system target cost (â¬/kW) based on a yearly energy and economic analysis. The first reveals that the primary energy savings is always positive outlining the environmental benefit of FERRET system application respect to the reference separated production. The target cost considering its application to two dwellings is around 2000 â¬/kW
On the Design of Recuperator for Transcritical Cycle Adopting CO2‐Based Mixture as Working Fluid: A Focus on Transport Properties Prediction
Full text linkTranscritical cycles working with CO2-based mixtures gain considerable attention due to thermodynamic efficiency gain compared to pure sCO(2) in hot environments. Previous literature works prove that the adoption of CO2 mixtures provides a reduction of the levelized cost of electricity in concentrated solar power applications and medium-high temperature heat recovery. However, for techno-economic analysis and heat exchanger design, proper evaluation of transport properties of the CO2-based mixtures in power cycle conditions is necessary. Herein, it deals with the analysis of the proper transport properties models for CO2 mixtures to assess their actual thermal behavior. A literature review on transport properties models, and their validation with available experimental data, proves that the friction theory is suitable for CO2 blended with dopants having high molecular complexity. The impact of the different model selection on the recuperator sizing, considering optimized power cycle conditions, is assessed on the CO2 mixtures with hexafluorobenzene and decane: The TRAPP and Chung-Lee-Starling models are imported from Aspen Plus, while the friction theory model is implemented and calibrated in an in-house MATLAB code. The optimal design of the recuperator for the CO2 + C6F6 mixture in a 100 MWel power block coupled with a solar power plant located in Sevilla is carried out
Technical assessment of a micro-cogeneration system based on polymer electrolyte membrane fuel cell and fluidized bed autothermal reformer
No full text
Fixed bed membrane reactor for hydrogen production from steam methane reforming: Experimental and modeling approach
Full text linkHigh-temperature electrolysis integrated with advanced power cycles for the combined production of green hydrogen, heat and power
No full textAn Overview of Real Gas Brayton Power Cycles: Working Fluids Selection and Thermodynamic Implications
Full text linkThis paper discusses and reviews the main real gas effects on the thermodynamic performance of closed Brayton cycles. Cycles with carbon dioxide as working fluids are taken as a reference and a comparison of the thermodynamic cycle efficiencies that are made with other possible working fluids (pure fluids and fluid mixtures). We fixed the reduced operating conditions, in optimal conditions, so that all working fluids had the same thermodynamic global performances. Therefore, the choice of the working fluid becomes important for adapting the cycle to the different technological requirements. The positive effects of the real gas properties in supercritical cycles were approximately maximal at reduced minimum cycle temperatures of about 1.01 to 1.05, with maximum to minimum cycle temperatures of about 2.2. The use of mixtures furthers widens the application of the field of closed Brayton cycles, thereby allowing a continuous variation in the critical temperature of the resulting working fluid and, in some cases, also making it possible to take the condensation with a significant further increase in the thermodynamic cycle efficiency. The paper also demonstrates the thermodynamic convenience of resorting to mixtures of carbon dioxide and inert gases. Extensive measurements of vapour–liquid equilibria and analysis of the thermal stability and material compatibility are essential for a practical and full use of the real gas Brayton cycles
- …
