Publication: Modelo teórico y validación experimental de una bomba de calor de expansión directa con asistencia solar: eficiencia energética: aplicación a calefacción y ACS
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2013-09
Defense date
2013-09-16
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Abstract
Las bombas de calor son máquinas que transportan el calor desde un ambiente exterior
frío, hasta otro interior caliente. Absorben calor del aire, pero no aprovechan la
radiación solar. Esta tesis propone una bomba de calor que capta la radiación a través de
colectores solares, aumentando la eficiencia energética del sistema. Para conocer el
comportamiento de esta máquina en diferentes condiciones exteriores, se ha
desarrollado un modelo teórico y se ha validado experimentalmente.
En el capítulo 1 se introduce la tesis con sus objetivos, y se justifica el equipo ensayado
desde la sostenibilidad, la escasez de recursos y la eficiencia. Se muestra un análisis del
consumo y la demanda de las fuentes de energía en la UE, del consumo por sectores,
principalmente el residencial y, de forma más concreta, del consumo de calefacción y
del ACS en la Comunidad de Madrid y en España.
En el capítulo 2 se hace una introducción a la tecnología actual de bombas de calor, y se
muestran diferentes configuraciones con esta tecnología que se realizan con el objetivo
de mejorar su eficiencia. Finalmente, se revisan las publicaciones relacionadas con la
máquina que en esta tesis se estudia.
En el capítulo 3 se propone un modelo teórico que determina las características de
funcionamiento de una DXSAHP. A partir de la temperatura exterior, del viento y de la
radiación solar, y haciendo un balance de energía con los mecanismos de transferencia
de calor en el campo de colectores, se obtiene la ecuación en forma diferencial con la
que se determinará el calor que absorberá la máquina para ser transportado y finalmente
consumido. Para conocer el calor transportado entre los colectores y el sistema de
consumo, se emplean las ecuaciones del ciclo de compresión mecánica de refrigeración.
No todo el calor que captan los colectores-evaporadores es absorbido por el refrigerante del circuito frigorífico; se aplica por ello un rendimiento que tiene en cuenta sólo la
superficie del colector en la que la transferencia de calor es relevante.
En el capítulo 4 se valida experimentalmente el modelo teórico que determina los
parámetros de funcionamiento de una DXSAHP aplicada a calefacción. Previamente, se
describe el proceso seguido desde el montaje del primer prototipo, su estudio
experimental, las propuestas de mejora y las modificaciones realizadas, hasta que el
equipo funciona de acuerdo con las especificaciones de diseño.
En el capítulo 5 se estudia el comportamiento del sistema cuando trabaja aplicado a
ACS. Se analizan experimentalmente los parámetros de operación, se determinan los
límites mecánicos de funcionamiento y se valida el modelo teórico con los resultados
experimentales. --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Heat pumps carry energy from a cold outside environment to a hot indoor one. They absorb heat from the air, but do not use solar radiation. This thesis proposes a heat pump that captures radiation through solar collectors and energy efficiency of the system increasing. To understand the behavior of the equipment in different external conditions, a theoretical model has been experimentally developed and validated. Chapter 1 introduces the thesis objectives. The tested equipment is justified from the point of view of sustainability, scarcity of resources and efficiency. An analysis of consumption and demand for energy sources in the EU is also shown. A part of that, consumption in different sectors is dealt with. This research has been focused on the residential sector, and more specifically on heating and DHW consumption in the Community of Madrid and in Spain. In chapter 2 current heat pump technology is introduced. Different configurations are shown in order to improve heat pump efficiency. Finally, the different publications related to this topic are reviewed. Chapter 3 proposes a theoretical model that determines the characteristics of operation of a DXSAHP. Taking into account the outside temperature, wind and solar radiation, and doing an energy balance with the mechanisms of heat transfer in the collector, a differential equation is obtained. This equation determines the amount of heat absorbed by the machine to be transported and finally consumed. To discover the amount of heat transported between the collectors and the consumption subsystem, equations of cooling mechanical compression cycle are employed. Not all the heat captured by the collectorevaporators is absorbed by the refrigerant of the cooling circuit. Thereby a performance is applied that takes into account only the surface of the collector in which the heat transfer is relevant. In chapter 4 the theoretical model that determines the operating parameters of a DXSAHP applied to heating is validated. Previously, the installation process is described: from the first prototype, the experimental study, the proposed improvements and modifications, to how the equipment is operated in accordance with design specifications. In Chapter 5 the behavior of the system applied to DHW is studied. Experimental operating parameters are analyzed, mechanical limits are determined and the theoretical model is validated by means of experimental results.
Heat pumps carry energy from a cold outside environment to a hot indoor one. They absorb heat from the air, but do not use solar radiation. This thesis proposes a heat pump that captures radiation through solar collectors and energy efficiency of the system increasing. To understand the behavior of the equipment in different external conditions, a theoretical model has been experimentally developed and validated. Chapter 1 introduces the thesis objectives. The tested equipment is justified from the point of view of sustainability, scarcity of resources and efficiency. An analysis of consumption and demand for energy sources in the EU is also shown. A part of that, consumption in different sectors is dealt with. This research has been focused on the residential sector, and more specifically on heating and DHW consumption in the Community of Madrid and in Spain. In chapter 2 current heat pump technology is introduced. Different configurations are shown in order to improve heat pump efficiency. Finally, the different publications related to this topic are reviewed. Chapter 3 proposes a theoretical model that determines the characteristics of operation of a DXSAHP. Taking into account the outside temperature, wind and solar radiation, and doing an energy balance with the mechanisms of heat transfer in the collector, a differential equation is obtained. This equation determines the amount of heat absorbed by the machine to be transported and finally consumed. To discover the amount of heat transported between the collectors and the consumption subsystem, equations of cooling mechanical compression cycle are employed. Not all the heat captured by the collectorevaporators is absorbed by the refrigerant of the cooling circuit. Thereby a performance is applied that takes into account only the surface of the collector in which the heat transfer is relevant. In chapter 4 the theoretical model that determines the operating parameters of a DXSAHP applied to heating is validated. Previously, the installation process is described: from the first prototype, the experimental study, the proposed improvements and modifications, to how the equipment is operated in accordance with design specifications. In Chapter 5 the behavior of the system applied to DHW is studied. Experimental operating parameters are analyzed, mechanical limits are determined and the theoretical model is validated by means of experimental results.
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Keywords
Bombas de calor, Eficiencia energética, Energía solar, Agua caliente sanitaria, ACS, Calefacción