Browsing by Author "Barraza, Rodrigo"

Now showing 1 - 4 of 4
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    "An enhanced and optimized Monte Carlo method to calculate view factors in packed beds"
    (2023) Cortes, Eduardo; Gavino, David; Calderon-Vasquez, Ignacio; Garcia, Jesus; Estay, Danilo; Cardemil Iglesias, Jose Miguel; Barraza, Rodrigo
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    Application of layer view factor method in high temperature thermal storage packed bed
    (2024) Cortes, Eduardo; Gavino, David; Calderon-Vasquez, Ignacio; Garcia, Jesus; Estay, Danilo; Cardemil, Jose M.; Barraza, Rodrigo
    This study provides a comprehensive evaluation of radiation effects on the thermal behavior of a packed bed using a discrete model for heat transfers integrating a novel method called Layer View Factor for view factors estimation, which significantly decreases computational time by less than 9000 times compared to the parallel ray tracing method. The model is validated and strongly aligned with experimental data at 823 K, with a maximum mean bias and root mean square errors of +/- 4.5 K and 10 K, respectively. Analyses of temperature profiles and thermocline lengths for charging, discharging, and stand-by processes at a charge temperature of 1473 K were performed, finding a thermal flattening effect with radiation, leading to lower peak temperatures and quicker thermocline length evolutions. Notably, the stand-by process exhibited the largest impact, with a maximum temperature difference of up to 100 K compared to the non-radiation case. Moreover, analysis of the temperature and energy of discharge found that the maximum discharge temperature drops below 90% of the charge temperature when radiation is included. Finally, efficiency analysis of the processes showed differences of up to 2% between having or not the radiation effect, aiming its role as a redistribution mechanism in the packed bed's temperature.
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    Review on modeling approaches for packed-bed thermal storage systems
    (2021) Calderon-Vasquez, Ignacio; Cortes, Eduardo; Garcia, Jesus; Segovia, Valentina; Caroca, Alejandro; Sarmiento, Cristobal; Barraza, Rodrigo; Cardemil Iglesias, Jose Miguel
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    Transient modeling of stratified thermal storage tanks: Comparison of 1D models and the Advanced Flowrate Distribution method
    (2024) Riebel, Adrian; Wolde, Ian; Escobar, Rodrigo; Barraza, Rodrigo; Cardemil, Jose M.
    Thermal energy storage (TES) is one of the key technologies for enabling a higher deployment of renewable energy. In this context, the present study analyzes the modeling strategies of one of the most common TES systems: stratified thermal storage tanks. These systems are essential to many solar thermal installations and heat pumps, among other clean energy technologies. Three different one-dimensional tank models are compared by their computing speed and resilience to long time steps. Two of the models analyzed are numerical, one being explicit and the other one implicit, and the other is analytical. The models are validated against data from experiments carried out considering small-scale stratified tanks, showing that their performance can be improved by using the Advanced Flowrate Distribution (AFD) method. The results show that the analytical model maintains its accuracy with longer time steps and is robust against divergence. Conversely, the numerical models show equivalent performance for short time steps, while the computation time is reduced. Although the AFD method shows promising results by achieving an improvement of 43% in terms of Dynamic Time Warping, its parameter optimization must be generalized for different tank designs, flow rates, and temperatures.