Ηλιακή θερμική αποθήκευση και αντλίες θερμότητας με υλικά αλλαγής φάσης

The purpose of this thesis is the thermal storage in Phase Change Materials (PCM) by integration a) in the envelope of the building b) in BAPVs and by studying c) the capability of dissipation of accumulated heat of PCMs cyclic charges from heat pumps. The thesis is developed in two parts, the theoretical and the experimental. Chapter 1 contains the review of the key processes associated with PCMs. Chapter 2 analyzes the classification and properties of PCMs, and the latest developments in various techniques of increasing heat transfer are presented. Chapter 3 contains a review of innovative applications systems of Solar Thermal Storage with PCMs which directly or indirectly affect the energy consumption of heat pumps. Chapter 4 follows the analysis of the data from these applications and summarizes the key efficiency factors and the modeling with PCMs. Chapter 5 completes the theoretical part of the thesis with the findings. The experimental part presents the analytical methodology and the developed experiments. Chapter 6 describes the mathematical formulation of transient transfer phenomena. Here analyzed, the method of lumped capacitance, the Boussinesq approach and underlying assumptions of solving the system of differential equations of energy, momentum and continuity used in later experiments. There is an overview of the solutions to the problems of moving boundary conditions and presents the TRNSYS software used in the experiments to model and to validate the results. Chapter 7 describes the experiments performed in the thesis. a) The incorporation of PCMs to BAPV made in TRNSYS, after consideration of the boundary surfaces around and under the PV, environmental factors that affect the temperature of the cell and the relationship to the exergetic efficiency of PV. After modeling and validation of measurements of BAPV, different amounts of PCM is placed in the back of the PV and examines the behavior of the curves I-V into varying load with and without PCM. b) Integration of the PCM to the envelope of the building is simulated with TRNSYS and is based on optimizing the PCM melting temperature over the internal temperature. Three PCMs are used with respective melting temperatures of 20 ° C, 25 ° C, and 32 ° C. The experiment examines the behavior of PCMs at different exposure temperatures of the heat transfer fluid through the integration of internal and external wall surface and analyzes the differences. c) The above measuring devices provide evidence for charge and discharge cycles of the PCM and the flow temperature during the experiments. The dissipation of accumulated heat from the heat pump can improve overall system performance PV-PCM-HP when done in a controlled manner. Chapter 8 summarizes the thesis conclusions which are also suggestions for further research.