J. Arce

Thermal Performance of a Natural Ventilation System

Natural ventilation in buildings using solar passive systems, such as solar chimneys, has emerged in the last years. Several theoretical and experimental studies in the literature show that their design parameters strongly depend on the ambient conditions, in which they are installed. In order to increase the knowledge of this kind of systems, this work presents the thermal behavior of a stand alone experimental solar chimney during one year. The dimensions of the solar chimney are 5.60 m high, 1.0 m width, and 0.52 m depth. The absorber plate is made of a common reinforced concrete wall of 4.5 m high, 1.0 m wide and 0.15 m depth. This system was designed by Marti J., and Heras M.R. in 2003 [1,2] and it is located in the L aboratorio de E nsayos Energeticos para C omponentes de la E dificacion (LECE ) in the P lataforma S olar of A lmeria (PSA ) in Spain. The entrance of this solar chimney was redesigned in 2007 by Arce et al. [3] and also the instrumentation of the system was increased and improved. During one year, the solar chimney was monitored and several experimental variables were measured. The results present the temperature profiles of the different measured elements of the solar chimney as well as the air mass flow rate through the solar chimney channel. It was observed that the effect of the outdoor wind added to the thermal effects plays an important role affecting the performance of the solar chimney studied.Copyright

A Simulation of the Thermal Performance of a Small Solar Chimney Already Installed in a Building

In this paper we present the theoretical and experimental study of a small solar chimney. The dimensions of the solar Chimney channel are 1.95 m high, 1.70 m width and 0.24 m depth. The channel of the solar chimney has in its backside a metallic plate as a solar heat absorber, and it is attached to a concrete wall, which acts as a storage and thermal isolation. On the front part of the chimney there is a glass plate used to decrease the heat losses to the exterior. Because the metallic plate is heated, air circulates from the lower side to the top side of the chimney channel. For the theoretical study, the steady state energy balance equations were solved for each element of the solar chimney following the methodology proposed by Ong in 2003 [8]. A numerical code was developed and reduced to cases of literature in order to validate it (Ong and Chow in 2003 [12]). The results showed the temperature distributions of the glass, the air inside the channel and the metallic plate. Also, the air mass flow rate was determined. For an hourly Irradiance of 400 W/m2 , the efficiency of the solar chimney decreased from 38 to 15% as the height of the chimney increased from 0.25 to 1.95 m.Copyright