Numerical Investigation of Convective-Radiative Heat Transfer in a Building-integrated Solar Chimney

Solar chimney is a new method to produce electrical power. 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. By converting thermal energy into the kinetic energy of air movement, solar chimneys have a number of different applications such as ventilation, passive solar heating and cooling of buildings, solar-energy drying, and power generation. Moreover, it can be employed as an energy conversion system from solar to mechanical. A component, such as a turbine or piezoelectric component, set in the path of the air current, converts the kinetic energy of the flowing air into electricity. In this paper, a numerical investigation on a prototypal solar chimney system integrated in a south facade of a building is presented. The chimney is 50.0 m high, 10 m wide whereas the thickness is 2.00 m for the vertical parallel walls at the outlet section. The chimney consists of a converging channel with one vertical wall and one inclined. The analysis is carried out on a three-dimensional model in airflow and the governing equations are given in terms of k-ε turbulence model. The problem is solved by means of the commercial code Ansys-Fluent. The numerical analysis was intended to examine the effect of the glass wall inclination. Results are given in terms of wall temperature distributions, air velocity and temperature fields and transversal profiles for a uniform wall heat flux on the vertical wall equal to 300 W/m2. These simulations are compared with a case considering real solar radiation in Napoli.Thermal and fluid dynamics behaviours are evaluated in order to have some indications to improve the energy efficiency of the system.