Análisis y modelado de una instalación geotérmica para climatización de un conjunto de oficinas

Abstract

[EN] The use of ground source heat pump systems has spread during the last years. When designing, studying and optimizing this kind of systems, models are used, more or less detailed, which allow predicting the behavior of the system within the application minimum requirements. The installation studied in this thesis is located at Universitat Politecnica de Valencia. In this report, the development of a global detailed model of this installation is presented, along with its validation using experimental data. The main objective is to obtain a model able to correctly predict the dynamic and static behavior of the system, both on a short- and a long-term basis. Prior to the model development, it is necessary to study the performance of the experimental system. Besides the system description, also an analysis of the performance of the installation during five years (from 2008 to 2012) is carried out. For this analysis, some characteristic parameters of the system behavior have been taken into account which are obtained from the experimental measurements corresponding to the typical operation of the installation, such as the average water temperatures, the building's thermal load, the partial load ratio, or the daily and seasonal performance factors. Since the study and analysis of these parameters is one of the aims of the present work, the calculation procedure and the formulas used for their determination are detailed, in some cases involving a highly complex raw data processing. From the short-term evolution study of the variables that represent the performance of the installation, the main characteristics of the system dynamic behavior are identified. The model will intend to reproduce these characteristics. On the other hand, the long-term performance parameters are studied as monthly averages. In this analysis, the characteristic trends of the system long-term performance are identified. The model should be able to also reproduce these trends. The global model has been developed using the TRNSYS software. A progressive incorporation strategy has been followed. At each step, the correct adjustment of the model is ensured by validating it with experimental data, allowing the identification of the influence that each component has on the final results. When including the ground source heat exchanger to the global model, it is evident the need for a new model for this component that can correctly reproduce both the dynamic and static response of the water temperature at the end of the pipes of the heat exchanger. Therefore, as a final step, a new ground source heat exchanger model has been developed, based on combining two different models: the g-function model in order to account for the long-term behavior of the ground temperature, and the B2G model, specifically developed for this application. The ground source heat exchanger model has been validated against experimental data from two different installations and, finally, it has been included into the global model of the system. The system global model…