Publicación: Células termoradiativas con banda intermedia: Estudio de la eficiencia teórica por medio del método de balance detallado
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2019-03-13
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Universidad Nacional de Educación a Distancia (España). Facultad de Ciencias. Departamento de Física Fundamental
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En este trabajo se presenta una nueva tecnología para la conversión de calor en electricidad, capaz de aprovechar la energía de fuentes de calor a baja temperatura. Resulta interesante su estudio dado que este tipo de fuentes se pueden encontrar, por ejemplo, como residuo en multitud de procesos industriales. Se implementa por medio de las llamadas células termoradiativas (TRC) cuyo funcionamiento se basa en los mismos principios que las células fotovoltaicas (FV), aunque trabajan en sentido inverso: producen una corriente y una tensión eléctricas emitiendo fotones al entorno, en lugar de absorberlos. Actualmente se posee un conocimiento detallado de su funcionamiento teórico y empiezan a aparecer los primeros prototipos. Aun así, las densidades de potencia (POD) y eficiencia calculadas son inferiores a las de las células FV. Con la idea de mejorar las prestaciones, se presenta un nuevo modelo de célula TRC basado en una unión semiconductora, en donde se incluye una banda intermedia en el gap de energía entre las BC y BV: son las llamadas células termoradiativas con banda intermedia (IBTRC). Se analiza en detalle los principios físicos en los que se basa y, aplicando el método del balance detallado, se derivan expresiones para la densidad de corriente, la densidad de potencia y la eficiencia del nuevo dispositivo. En una IBTRC con Egap=0.2eV y operando a una temperatura de 1000K en un ambiente de 300K, se obtiene que la POD es 1.94 y el rendimiento 1.31 veces mayores, respectivamente, que los proporcionados por una célula TRC de gap simple operando en las mismas condiciones. Esto demuestra que la inclusión de la banda intermedia mejora sensiblemente las prestaciones de la TRC. Se presentan también ciertos criterios de selección de parámetros clave que permiten la configuración de la IBTRC, determinando las condiciones óptimas de operación.
We present in this work a new technology of heat conversion into electricity, able to take advantage of heat sources at low temperature. This technology is interesting because heat sources usually appear in many industrial processes. It is implemented by means of the so-called thermoradiative cells (TRC), whose operation is based on the same principles as photovoltaic cells (PV). TRC’s work in the opposite direction than PV cells: they provide electrical current and voltage emitting photons to the environment instead of absorbing them. At the moment, one owns a detailed knowledge of his theoretical operation and begin to appear the first prototypes. Even so, the calculated power (POD) and efficiency densities are lower than those of the PV. To improve their performance, a new TRC model based on a semiconductor junction is presented. This new device includes an intermediate narrow band in the bandgap: they are called intermediate band thermoradiative cells (IBTRC). Applying the detailed balance method, expressions are derived for the current density, the power density and the efficiency. In an IBTRC with bandgap = 0.2eV and operating at 1000K in an environment at 300K, it is obtained that the máximum POD and efficiency are 1.94 1.31 times higher respectively than those provided by a basic TRC operating under the same conditions. This shows that the inclusion of the intermediate band significantly improves the performance of the TRC. There are also certain criteria for the selection of key parameters that allow the configuration of the IBTRC, determining the optimal operating conditions.
We present in this work a new technology of heat conversion into electricity, able to take advantage of heat sources at low temperature. This technology is interesting because heat sources usually appear in many industrial processes. It is implemented by means of the so-called thermoradiative cells (TRC), whose operation is based on the same principles as photovoltaic cells (PV). TRC’s work in the opposite direction than PV cells: they provide electrical current and voltage emitting photons to the environment instead of absorbing them. At the moment, one owns a detailed knowledge of his theoretical operation and begin to appear the first prototypes. Even so, the calculated power (POD) and efficiency densities are lower than those of the PV. To improve their performance, a new TRC model based on a semiconductor junction is presented. This new device includes an intermediate narrow band in the bandgap: they are called intermediate band thermoradiative cells (IBTRC). Applying the detailed balance method, expressions are derived for the current density, the power density and the efficiency. In an IBTRC with bandgap = 0.2eV and operating at 1000K in an environment at 300K, it is obtained that the máximum POD and efficiency are 1.94 1.31 times higher respectively than those provided by a basic TRC operating under the same conditions. This shows that the inclusion of the intermediate band significantly improves the performance of the TRC. There are also certain criteria for the selection of key parameters that allow the configuration of the IBTRC, determining the optimal operating conditions.
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Facultades y escuelas::Facultad de Ciencias
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Física Fundamental