A numerical analysis on a solar chimney with an integrated latent heat thermal energy storage

Abstract

Solar chimney is a solar system which is employed in several applications such as ventilation for thermal comfort, passive solar heating and cooling of buildings, solar energy drying, and electric power generation. It employs solar radiation to raise the temperature of the air and the buoyancy of warm air to accelerate the air stream flowing through the system. It is very important to evaluate the thermal and fluid dynamic behaviors to realize a correct design of the solar chimney also for the case with an integrated thermal energy storage system. It includes height, width and depth of cavity, type of glazing, type of absorber, and inclusion of insulation or thermal mass. Besides these system parameters, other factors such as the location, climate, and orientation can also affect its performance. In this paper, a two-dimensional numerical investigation on a prototypal solar chimney system integrated with an absorbing capacity wall in a south facade of a building is presented. The capacity wall is composed of a high absorbing plate and an assigned thickness of phase change material. The chimney consists of a converging channel with one vertical absorbing wall and the glass plate inclined of 2° with respect to the vertical. The chimney is 5.0 m high, with the channel height equal to 4.0 m, whereas the channel gap is at the inlet equal to 0.34 m and at the outlet it is 0.20 m. The thermal energy storage system is 4.0 high. The transient analysis is carried out on a two-dimensional model in airflow and the governing equations are given in terms of k-e turbulence model. The problem is solved by means of the commercial code Ansys-Fluent. The numerical analysis was intended to evaluate the thermal and fluid dynamic behavior of the solar chimney integrated with a latent thermal energy storage system. Results are given in terms of wall temperature distributions, air velocity and temperature fields and transversal profiles. Thermal and fluid dynamics behaviors are evaluated in order to have some indications to improve the energy conversion system.