الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Thermal energy storage is a crucial component in solar thermal systems. It can solve the mismatch issue between the supply and demand loads by storing excess energy during off-peak times to be used later when needed. Energy can be stored in latent form using phase change materials (PCMs). Such latent thermal energy storages have intricate heat transfer process and fluid dynamics developing inside them. It is important to study the heat transfer characteristics of the thermal energy storages and try to develop a model that precisely predicts their behavior.
The investigated thermal energy storage mainly consists of a square container, a spiral coil heat exchanger, and phase change material modules. The container has a square cross-section and dimensions of 0.527 m length, 0.533 m width, and 0.860 m height. When It is filled with 200 L of water, the water height becomes 0.72 m. The heat exchanger used for charging is a square spiral coil made from copper with 19.5 mm inner diameter, 22.2 mm outer diameter, and 7.5 m length. Lauric acid was used as Summary PCM material. It is contained in rectangular high-density polyethylene containers; each is 0.515 m in height, 0.205 m in length, and 0.03 m in width.
In the current thesis, the previously mentioned storage was numerically investigated by constructing a two-dimensional computational fluid dynamics (CFD) model. The model was validated against experimental data to prove its accuracy in predicting the thermal behavior of the studied tank. The effect of changing some of the parameters was also studied including the effect of changing the mass flow rate of the charging fluid entering the spiral coil, the effect of changing the temperature of the charging fluid entering the spiral coil, and the volume fraction of the phase change material. Finally, a correlation of Nusselt Number for the outer surface of the charging spiral coil was deduced to help monitor the nature of the coil heat transfer process.
And to cover the previous main topics, the dissertation was divided into many chapters:
Chapter 1 is an introduction that illustrates the importance of thermal storage systems, their components, how it functions and some ways to classify such systems.
Chapter 2 introduces the literature review of the researchers’ previous studies on the thermal storage systems especially latent storage that uses phase change materials. The chapter also discusses the gab in the previous studies and the aim of the current research.
Chapter 3 presents the Computational Fluid Dynamics (CFD) model used in the study of the storage system as well as the governing equations. It also illustrates how the simulations were performed and what parameters were studied.
Chapter 4 presents validation for the numerical CFD model by comparing the results of the current simulations to experimental results to show that the model constructed is able to precisely predict the thermal behavior of the studied tank.
Chapter 5 presents a correlation that describes the thermal behavior of the charging coil.
Chapter 6 the results were discussed starting from discussing the effect of changing some parameters like (the inlet temperature of the fluid entering the charging coil- the mass flow rate of the fluid entering the charging coil and number of PCM modules). The chapter also dives into the results of the correlation deduced in chapter 5 and comparing them with correlations of previous studies.
Chapter 7 provides the conclusion and the recommendation for more development for those who will build on the current study.
Keywords: thermal storage, water heating using solar energy, phase change materials, numerical modeling