Papers by Rafaela Reinaldo
Experimental Thermal and Fluid Science, 2000
This work presents experimental data for R-113 pool boiling, at atmospheric pressure and moderate... more This work presents experimental data for R-113 pool boiling, at atmospheric pressure and moderate heat flux, inside vertical and horizontal aluminum open-ended tubes, whose internal surfaces are either smooth or grooved. The tube length is 40 mm and the internal diameters of the smooth and the grooved tubes are 16.64 and 15.88 mm, respectively. The results are presented and discussed in relation to the heat transfer coefficients and compared with the Cooper and the Forster and Zuber empirical correlations. For all the tests, the heat transfer coefficient of the grooved tube is higher than that of the smooth tube. For horizontal tubes, an elongated bubble at the top region promotes a better local heat transfer coefficient as is indicated by the lower temperature than that of the bottom region, where the bubbles are isolated.
The Impact of Ash Deposition on Coal Fired Plants
The ash deposition on heat transfer surfaces of utility boilers is one of the main problems assoc... more The ash deposition on heat transfer surfaces of utility boilers is one of the main problems associated to the use of coal. The ash deposits reduce the heat transfer in the boiler, causing a decrease of the boiler efficiency. The prediction of ash deposition gives important information to boilers' designers and operators. This work presents numerical simulation of the flow, heat transfer and combustion in a pulverized coal furnace in order to predict the ash deposition in the furnace walls and superheater tubes. The ash deposition model is based on the concepts of impact efficiency and sticking probability of the particles. This calculation procedure is an extension of the Computational Fluid Dynamics based model for pulverized coal combustion already extensively used at Instituto Superior Tecnico. Further works concerning ash deposition measurements will be carried out for chemical characterization of the ash deposits and comparison with the predicted results.
Most unplanned outages in the Jorge Lacerda Power Plant, situated in Capivari de Baixo-SC, are du... more Most unplanned outages in the Jorge Lacerda Power Plant, situated in Capivari de Baixo-SC, are due to tube failures in the boiler. Historical records and metallographic analysis indicate that the working metal temperature of the tubes of the final superheater and reheaters of the utility boiler is higher than the recommended value. The high temperature level of the tubes is the main cause of the tube failures by creep and is an important factor determining the remaining life-time of the tube bundles. This work presents the simulation of the combustion, flow and heat transfer of the utility boiler furnace to determine the metal temperature of the final superheater and reheater. The tube metal temperature is calculated taking into account local convective and radiative heat transfer. This calculation procedure is an extension of the Computational Fluid Dynamics based model for pulverized coal combustion already extensively used at Instituto Superior Tecnico. Comparisons are made betwe...
International Journal of Hydrogen Energy
Journal of Renewable and Sustainable Energy
Journal of Renewable and Sustainable Energy
Proceedings of the 23rd ABCM International Congress of Mechanical Engineering, 2015
Esta tese foi julgada adequada para a obtenção do título de DOUTOR EM ENGENHARIA ESPECIALIDADE EN... more Esta tese foi julgada adequada para a obtenção do título de DOUTOR EM ENGENHARIA ESPECIALIDADE ENGENHARIA MECÂNICA sendo aprovada em sua forma final.
Experimental Thermal and Fluid Science, 2000
... The experimental uncertainty of the value of the heat transfer coefficient was computed follo... more ... The experimental uncertainty of the value of the heat transfer coefficient was computed following the procedure presented by Kline [17] and Holman [15]. The relative uncertainty values for q are equal to ±3.5% and ±2% for a heat flux of 5 and 45 kW/m 2 , respectively. ...
Experimental thermal and fluid science, 2000
... The experimental uncertainty of the value of the heat transfer coefficient was computed follo... more ... The experimental uncertainty of the value of the heat transfer coefficient was computed following the procedure presented by Kline [17] and Holman [15]. The relative uncertainty values for q are equal to ±3.5% and ±2% for a heat flux of 5 and 45 kW/m 2 , respectively. ...
Clean Air: International Journal on Energy for a Clean Environment, 2005
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Papers by Rafaela Reinaldo