Análisis experimentales y teóricos sobre almacenamiento de calor mediante pozos de agua en Dronninglund, Dinamarca

Abstract

[EN] In this project, the pit thermal energy storage (PTES) of the Dronninglund solar district heating plant has been investigated. The use of this technology is raising in Denmark given that it improves the reliability of solar energy and allows for a higher solar fraction and overall plant efficiency. Within the scope of this project, temperatures inside the storage, outlet temperatures from the charging/discharging openings, as well as heat losses will be assessed for the year 2015, by using TRNSYS as a simulation software. The model selected to do so will be Type 342. The procedure of the experiment was comparing measurement data taken from the Dronninglund plant during the year 2015 to the output data obtained as a result of the simulations, to determine how well the simulated results adjust to real conditions. The obtained results show that, in the case of thermal losses, and provided an insulation of 0,24 m in the top of the storage, top losses account for a 12,16%, side losses account for 12,33% and side losses represent the 75,5% of the total losses. The results show a deviation of a 42,18% compared to the measurement data, which is a quite large underestimation of losses. When it comes to temperatures inside the storage, maximum, minimum and average temperature were simulated and compared to measurements, showing a good correlation in the three cases. The only relevant deviation observed was given for the first days of simulation, and was attributed to initialization conditions of the PTES model. When it comes to top, middle and bottom outlet temperatures, the model also performs well. Based on this set of comparisons, Type 342 model was validated, even though it may not give precise results in terms of thermal losses, tending to underestimation. In a last section of the report, some parametrical investigations were conducted. The storage size and geometry was changed in order to asses how this changes affect the thermal losses and how the model tackles this modifications. It was concluded that bigger storage sizes lead to higher efficiency values overall.

[ES] El almacenamiento de energía estacional tiene cada vez más relevancia en los sistemas de producción energética actual dado que permiten incrementar considerablemente el aprovechamiento de la energía proveniente de fuentes variables, como la solar o la eólica. En particular, el presente proyecto pretende investigar los pozos de agua para almacenamiento de energía térmica destinada a calefacción urbana de forma teórica (mediante una revisión de la literatura existente sobre la materia) y experimental, mediante la validación de un modelo de pozo de agua con el programa TRNSYS. El sistema a estudiar es el pozo de Dronningland, Dinamarca, país donde este tipo de tecnología se está comenzando a instalar de forma cada vez más frecuente.