APPLIED THERMAL ENGINEERING, cilt.164, 2020 (SCI-Expanded)
Due to the intermittent nature of the solar energy and the mismatch between the instantaneous demand and supply, solar energy could not be used effectively, or continuously, in solar-assisted applications such as heating of a building. As a common approach, it is possible to store the available solar energy when it is abundant and use it later to operate solar-assisted applications sustainably. Thermal energy storage (TES) applications provide critical solutions for ensuring the sustainability of solar energy. A proper TES tank should be designed in such a way to possess a high heat transfer rate, energy efficiency, and exergy efficiency during the charging and discharging processes. In the current work, a sensible heat TES tank that is integrated with a flat plate solar collector is considered. An in-house transient code is developed to evaluate spatial and temporal temperature variations within the storage tank and the solar collector throughout a day under variable weather conditions. The variation in working fluid temperature along the tank height is compared against the experimental and numerical results from the literature to ensure the validity of the code. The influences of the mass flow rate of heat transfer fluid, the diameter of the storage material and height of the TES tank on dimensionless performance measures, such as stratification number, energy, and exergy efficiencies, are numerically evaluated under real weather data for four months as November, December, January and February. In the proposed system, the storage medium temperatures vary in the range of 40-60 degrees C. The stored thermal energy can be used in a building in various aspects such as supplying warm water, underfloor space heating, or indirect heating with a heat pump system.