Grupo de Investigación 'Ingeniería de Sistemas Energéticos' (ISE)http://hdl.handle.net/10016/9622015-02-26T23:01:16Z2015-02-26T23:01:16ZExperimental studies of phase change materials in a bubbling fluidized bedIzquierdo-Barrientos, María AsunciónSobrino, CeliaAlmendros-Ibañez, José AntonioEllis, N.Bi, X.T.Epstein, N.http://hdl.handle.net/10016/200832015-02-24T09:06:13Z2013-01-01T00:00:00ZExperimental studies of phase change materials in a bubbling fluidized bed
Izquierdo-Barrientos, María Asunción; Sobrino, Celia; Almendros-Ibañez, José Antonio; Ellis, N.; Bi, X.T.; Epstein, N.
The aim of this work is to experimentally study the behaviour of three microencapsulated PCM in a bubbling fluidized bed for thermal energy storage. Different experiments, heating and cooling the granular PCM with fluidizing air, are carried out with different superficial gas velocities. When achieving their phase change temperature two of the three materials present agglomeration. For this reason, the material flowability and wear resistance are studied by measuring the angle of repose and attrition, respectively. Nevertheless, the angle of repose does not seem to be influenced by the temperature of the material and the particle size distributions after the attrition tests indicate that the bed particles are just slightly smaller than the original ones.
Proceedings of: 14th International Conference on Fluidization: From Fundamentals to Products. Noordwijkerhout, Netherlands, 26-31 may 2013.
2013-01-01T00:00:00ZConvective heat transfer coefficient in a bubbling fluidized bed with PCMIzquierdo-Barrientos, María AsunciónSobrino, CeliaAlmendros-Ibañez, José Antoniohttp://hdl.handle.net/10016/200792015-02-24T09:01:50Z2013-01-01T00:00:00ZConvective heat transfer coefficient in a bubbling fluidized bed with PCM
Izquierdo-Barrientos, María Asunción; Sobrino, Celia; Almendros-Ibañez, José Antonio
This work presents an experimental study to determine the capacity of a Phase Change Material (PCM) in granular form to be used in a bubbling fluidized bed for thermal energy storage. The experimental measurements are focused on the determination of the heat transfer coefficient between a heated surface and the granular PCM in fluidized state. The results obtained indicates that the heat transfer coefficient notably increases (up to values three times higher) when the granular PCM is in solid form because it changes its phase when touches the heated surface
Proceedings of: 14th International Conference on Fluidization: From Fundamentals to Products. Noordwijkerhout, Netherlands, 26-31 may 2013.
2013-01-01T00:00:00ZA novel methodology for simulating vibrated fluidized beds using two-fluid modelsAcosta-Iborra, AntonioHernández-Jiménez, FernandoVega, Mercedes deVilla Briongos, Javierhttp://hdl.handle.net/10016/187662014-08-01T22:00:05Z2012-08-01T00:00:00ZA novel methodology for simulating vibrated fluidized beds using two-fluid models
Acosta-Iborra, Antonio; Hernández-Jiménez, Fernando; Vega, Mercedes de; Villa Briongos, Javier
The present work considers the use of the two-fluid (Euler-Euler) CFD approach for the continuum description of vibrated fluidized beds as a less computationally demanding alternative to the discrete description given by Lagrangian-Eulerian methods such as DEM. In particular, a novel simulation strategy consisting on solving the two-fluid model equations in a coordinate reference system that moves with the vibrating walls of a gas-solid fluidized bed is proposed. By this way, vibration is transformed into simple alternating acceleration terms that are introduced through body forces in both the gas and the particle phase equations. The results of a series of two-fluid model simulations compare well with discrete particle simulations as well as with experimental data reported for beds containing Geldart group B particles. In general, the results of a series of two-fluid model simulations show similar trends to those seen in discrete particle simulations as well as in experimental data reported for beds containing Geldart group B particles. Exception of that is the velocity of bubbles, for which the two-fluid simulations compare less satisfactorily with the available experimental data. The two-fluid model simulations are also able to reproduce expected phenomena like the bubble growth with the vibration amplitude and the dependence of the pressure drop fluctuation on the vibration strength. In view of these promising results, the proposed two-fluid model formulation opens the possibility of increasing the scale of the vibrated fluidized beds currently simulated.
2012-08-01T00:00:00ZSolid conduction effects and design criteria in moving bed heat exchangersAlmendros-Ibáñez, José AntonioSoria-Verdugo, AntonioRuiz-Rivas, UlpianoSantana, D.http://hdl.handle.net/10016/139212014-12-03T09:50:08Z2011-05-01T00:00:00ZSolid conduction effects and design criteria in moving bed heat exchangers
Almendros-Ibáñez, José Antonio; Soria-Verdugo, Antonio; Ruiz-Rivas, Ulpiano; Santana, D.
This work presents a theoretical study of the energetic performance of a moving bed heat exchanger (MBHE), which consists of a flow of solid particles moving down that recovers heat from a gas flow percolating the solids in cross-flow. In order to define the solid conduction effects, two solutions for the MBHE energy equations have been studied: an analytical solution considering only convection heat transfer (and neglecting solid conduction) and a numerical solution with the solid conductivity retained in the equations. In a second part, the power requirements of a MBHE (to pump the gas and to raise the down-flowing particles) are confronted with the heat transferred considering the variation of design parameters, such as gas and solids’ velocities, solids particle diameter or MBHE dimensions. The numerical results show that solid conductivity reduces the global efficiency of the heat exchanger. Therefore, a selection criterion for the solids can be established, in which their thermal conductivity should be minimized to avoid conduction through the solid phase, but to a limit in order to ensure that temperature differences inside an individual solid particle remain small. Regarding the other energy interactions involved in the system, these are at least one order of magnitude lower than the heat exchanged. Nevertheless, for a proper analysis of the system the efficiency of the devices used to pump the gas and to raise the particles and the relative costs of the different energy forms present in the system should be taken into account.
2011-05-01T00:00:00Z