Kapsüller içerisindeki faz değişim malzemelerinin katılaşma ve erime periyotlarının incelenmesi

The current thesis consists of two parts as experimental and numerical. In the experimental part, the storage performance of spherical encapsulated phase change material (PCM) under various external boundary conditions was obtained experimentally. As the charging performance of spherical encapsulated PCM is achieved, the entry velocity of the heat transfer fluid (HTF) into the test zone is kept constant and the entry temperature is changed. The effect of changing HTF temperatures on the change in temperature of the capsule and the heat transfer rate were investigated. In the numerical part, the influences of inlet temperature and velocity of the HTF and the capsule material on the performance of a latent heat thermal energy storage unit is numerically investigated. The enhanced thermal conductivity approach is implemented into the ANSYS-FLUENT software to consider the natural-convection-dominated melting process within the capsules. Results of the parametric analyses are evaluated by using the first and second laws of the thermodynamics. The time-wise variations of the melting front, the temperature of the PCM and the rate of entropy generation are evaluated. Increasing the inlet temperature and velocity of air significantly reduces the time required for complete melting. The total time for melting is reduced when the inlet temperature of air increase and the entropy generation rate enhances more than four times. Besides, increasing the air inlet velocity enhances the entropy generation.