Parallel triangular channel system for sensible heat thermal energy storages with external heat losses

Solar energy is an important renewable energy source that is increasingly used. One of the main drawbacks in the solar energy application is its working periodic time. Thermal Energy Storage (TES) can improve the efficient use and provision of thermal energy whenever there is a mismatch between energy generation and use. Various subsets of TES processes have been investigated and developed for heating and cooling of buildings, industrial applications, and utility and space power systems. The amount of energy input to TES by a sensible heat device is proportional to the difference between the storage final and initial temperatures, the mass of storage medium and its heat capacity. In this paper a high temperature TES is numerically investigated, and a parametric analysis is accomplished. In the formulation of the model it is assumed that the system geometry is cylindrical, the fluid thermophysical properties are dependent on temperature, the effect of gravity is neglected. Air is employed as the heat-carrying fluid and the solid elements, which are minichannels, are made of Cordierite. The system is a honeycomb structure made of parallel triangular channels. The Fluent code is used to solve the governing equations in transient regime. Numerical simulations are carried out with storage medium at different mass flow rates of the heat-carrying fluid and different number of channels for unit of length. Results show the effects of storage medium, mass flow rate on stored thermal energy and storage time. Results in terms of temperature as function of time are presented.