Publication: Análisis bidimensional de la influencia de la separación entre los tubos del receptor de una central termosolar tipo torre
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2019-06
Defense date
2019-07-05
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Abstract
Las centrales termosolares de tipo torre basan su funcionamiento en la concentración
mediante el uso de espejos de los rayos solares sobre un receptor, calentando un fluido
que es utilizado posteriormente para generar energía. Los receptores de estas centrales
están lejos de su punto óptimo pues tienden a romperse debido a las tensiones térmicas y
a la corrosión. Algunas de las soluciones ante esta ruptura del receptor incluyen las
estrategias de apuntamiento, el cambio de fluido de trabajo o la reducción de las
temperaturas.
El presente trabajo propone una posible solución para disminuir las temperaturas
aumentando la separación entre tubos dentro del receptor para que más flujo de calor pase
entre ellos, aumentando la temperatura de la parte trasera y reduciendo las tensiones
térmicas. Para ello, se ha estudiado la geometría de un receptor basada en la de la central
de Gemasolar en Sevilla y posteriormente se han variado las separaciones entre tubos para
analizar su comportamiento.
El análisis térmico de las geometrías se ha llevado a cabo mediante el método de la
simulación fluidocomputacional, que resuelve las ecuaciones asociadas al problema
térmico establecido. Además de diferentes geometrías, se han estudiado diferentes
condiciones térmicas de actuación para un mejor conocimiento del desempeño de los
receptores de las centrales tipo torre.
Los resultados de las simulaciones indican que las separaciones óptimas entre los tubos
son del 8% del diámetro exterior, reduciendo así las tensiones térmicas y aumentando el
tiempo de vida útil del receptor. Además, se establecen los materiales óptimos para la
fabricación de los tubos (Incoloy, Inconel y Haynes) y el gasto másico de fluido
recorriendo el receptor adecuado para este tipo de centrales (290 kg/s).
Solar Power Towers (SPT) concentrate by means of mirrors the sun’s radiation onto a receiver, heating a fluid that flows within to generate energy. The receivers in this kind of solar plants are far from perfect because they tend to fail due to high thermal levels and corrosion. Some solutions to avoid failure are: the aiming strategies, change of working fluid or temperature reduction. In this project, a solution for temperature reduction is stablished by means of tubes separation. This way, more heat flux would be able to flow between the tubes, raising the temperature in the points located in the back of the tubes, decreasing thermal tensions. To do so, the geometry of a receiver based on Gemasolar (Sevilla) power plant was studied, and the separation between tubes was varied to study its thermal behaviour. The thermal analysis was carried on via the computational fluid mechanics metho d that solves the different equations related to the thermal situation that is present in the study case. Besides different geometries, different thermal operational conditions were studied in order to fully understand the performance of solar power tower’s receivers. The results of the simulations show that the optimal separation between tubes is 8% of the diameter, decreasing this way the thermal tensions and raising the life expectancy of the receiver. Fuerthermore, optimal materials for the fabrication of the tubes are stablished (Incoloy, Inconel and Haynes) and so is the mass flow of the fluid inside the tubes (290 kg/s).
Solar Power Towers (SPT) concentrate by means of mirrors the sun’s radiation onto a receiver, heating a fluid that flows within to generate energy. The receivers in this kind of solar plants are far from perfect because they tend to fail due to high thermal levels and corrosion. Some solutions to avoid failure are: the aiming strategies, change of working fluid or temperature reduction. In this project, a solution for temperature reduction is stablished by means of tubes separation. This way, more heat flux would be able to flow between the tubes, raising the temperature in the points located in the back of the tubes, decreasing thermal tensions. To do so, the geometry of a receiver based on Gemasolar (Sevilla) power plant was studied, and the separation between tubes was varied to study its thermal behaviour. The thermal analysis was carried on via the computational fluid mechanics metho d that solves the different equations related to the thermal situation that is present in the study case. Besides different geometries, different thermal operational conditions were studied in order to fully understand the performance of solar power tower’s receivers. The results of the simulations show that the optimal separation between tubes is 8% of the diameter, decreasing this way the thermal tensions and raising the life expectancy of the receiver. Fuerthermore, optimal materials for the fabrication of the tubes are stablished (Incoloy, Inconel and Haynes) and so is the mass flow of the fluid inside the tubes (290 kg/s).
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Keywords
Energías renovables, Energía solar, Centrales termosolares, Sistemas térmicos, Flujo de calor, Simulación numérica CFD, Separación entre tubos, Receptor central, Temperatura