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URI permanente para esta coleçãohttps://repositorio.fei.edu.br/handle/FEI/5123
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Artigo de evento 1 Citação(ões) na Scopus Thermal performance and pressure drop in a ceramic heat exchanger evaluated using CFD simulations(2011-07-07) MONTEIRO, D. B.; Paulo de MelloThere is one potential demand for heat exchangers capable of supporting high temperatures, typically higher than 800°C, for use in thermal power plants. These heat exchangers could be used in the implementation of EFGT (Externally Fired Gas Turbines) cycles. To support these working conditions the heat exchanger must be constructed with ceramics. This work presents the results obtained with CFD simulations of one plate-fin ceramic heat exchanger. Correlations for the Colburn and friction factors, for a range of Reynolds number between 500 and 1500, are evaluated from the numerical results obtained with CFD. These correlations may be used for the thermal design of ceramic heat exchangers. One validation procedure is conducted comparing the simulation results with experimental data for a compact heat exchanger of similar configuration.Artigo de evento 7 Citação(ões) na Scopus Thermodynamic study of an EFGT (Externally Fired Gas Turbine) cycle with one detailed model for the ceramic heat exchanger(2011-07-07) Paulo de Mello; MONTEIRO, D. B.The EFGT cycle has been considered as an option to burn biomass in gas turbines. One key element on the implementation of one EFGT cycle is the ceramic heat exchanger necessary to support the high temperatures of operation. The performance of the ceramic heat exchanger, its effectiveness and pressure drop imposed to the gas flow, may have significant influence over the thermal efficiency of the EFGT cycle. The simulations of the EFGT cycle presented herein use correlations for the pressure drop and heat transfer of one ceramic heat exchanger of the plate and fin type, evaluated numerically. The results obtained show that the type of ceramic heat exchanger simulated presents adequate performance to be implemented in one EFGT cycle.Artigo de evento 0 Citação(ões) na Scopus Heat transfer and pressure drop correlations for finned plate ceramic heat exchangers(2014-06-15) VILLANUEVA, H. H. S.; Paulo de MelloThe use of ceramic materials is a good option to build heat exchangers for high temperature applications when cost is a concern. This work presents heat transfer and pressure drop correlations for one finned plate heat exchanger evaluated using CFD simulations. One adequate turbulence model was used to include transitional Reynolds number range. The influence of geometrical parameters is included into the correlations, following the same approach commonly used for offset strip fins heat exchangers. For validation purposes, the CFD results are compared to experiments for one particular geometrical configuration. The resultant correlations for the high temperature heat exchanger could be used for optimization purposes, considering possible applications. Analysis of simulation results revealed significant heat transfer enhancement produced by a horseshoe vortex formed in the frontal part of the fins.Artigo de evento 1 Citação(ões) na Scopus A novel scroll expander for flank leakage investigation: preliminary tests(2016-07-19) FANTI, G. R.; Gustavo Donato; Paulo de Mello© 2016 University of Ljubljana.The isentropic efficiency of the expander is a concern for organic Rankine cycle (ORC) and compressed air energy storage (CAES) implementation. In these applications, the expander alone has a great influence over the whole system efficiency. Scroll expanders are particularly interesting for the low power range comprehended between 1 and 10 kW. Many previous works have attributed to internal leakages a great importance to obtain high isentropic efficiency in these machines. We present herein experimental results obtained with a novel scroll expander constructed to investigate the effect of internal leakages. We discuss the geometry definition and design of the prototype in detail. The maximum mechanical power produced by the prototype was 923 W at 2690 rpm but its isentropic efficiency was only 30.6%. Filling factor as high as 4.9 reveals that internal leakage must be reduced to obtain a more efficient expander.Artigo de evento 0 Citação(ões) na Scopus CFD simulation of scroll expanders: Influence of pressure ratio and flank clearance over the performance(2019-06-23) OLIVEIRA, F. V.; SILVA, F. M. F.; Paulo de Mello© ECOS 2019 - Proceedings of the 32nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. All rights reserved.Scroll expanders are considered ideal for low power applications, in particular in small scale ORC (organic Rankine cycle). Internal leakages decrease considerably the isentropic efficiency of scroll expanders and consist the main source of inefficiency. In this paper, the performance of one scroll expander working with air for which experimental data is available is simulated. The influence of pressure ratio and tangential clearance over the results is investigated. Transient 2D CFD (computational fluid dynamics) simulations of the compressible flow capable of quantifying the internal leakages present in this machine were performed. The filling factor, generated power and isentropic efficiency were obtained and compared with experimental results from our research group. The results obtained reveal that the pressure ratio variation does not change the filling factor, thereby the internal leakages remain practically constants with the inlet pressure increase. The pressure ratio value for which the highest isentropic efficiency is obtained tends to reduce when increasing the internal leakages. The CFD simulations have shown generated power 11% higher if compared with experimental results. This difference can be attributed to uncertainty in tangential clearance measurements, radial leakage and pressure drop at expander inlet not considered in the 2D simulations.