Induced flow for ventilation and cooling by a solar chimney

Abstract

a b s t r a c tAn experimental and numerical model of a solar chimney was proposed in order to predict its performance under varying geometrical features in Iraqi environmental conditions. Steady, two dimensional, turbulent flow was developed by natural convection inside an inclined solar chimney. This flow was investigated numerically at inclination angles 15 to 60 , solar heat flux 150e750 W/m 2 and chimney thickness (50, 100 and 150) mm. The experimental study was conducted using a single solar chimney installed on the roof of a single room with a volume of 12 m 3 . The chimney was 2 m long; 2 m wide has three gap thicknesses namely: 50, 100 and 150 mm. The performance of the solar chimney was evaluated by measuring the temperature of its glass cover, the absorbing wall and the temperature and velocity of induced air. The results of numerical model showed that; the optimum chimney inclination angle was 60 to obtain the maximum rate of ventilation. At this inclination angle, the rate of ventilation was about 20% higher than 45 . Highest rate of ventilation induced with the help of solar energy was found to be 30 air changes per hour in a room of 12 m 3 volumes, at a solar radiation of 750 W/m 2 , inclined surface angle of 60 , aspect ratio of 13.3 and chimney length of 2 m. The maximum air velocity was 0.8 m/s for a radiation intensity of 750 W/m 2 at an air gap of 50 mm thickness. No reverse air flow circulation was observed even at the largest gap of 150 mm. The induced air stream by solar chimney can be used for ventilation and cooling in a natural way (passive), without any mechanical assistance.

Comparison of the Energy Conversion Efficiency of a Solar Chimney and a Solar PV-Powered Fan for Ventilation Applications

“…A numerical model of an inclined solar chimney was presented by Imran et al [4]. The model solved two-dimensional (2D) steady-state turbulent flow induced by natural convection, and its functionality was validated with experimental data.…”

A review on solar chimney systems

“…In 2015, an experimental and numerical model of a solar chimney was carried out by Imran et al [197] in Iraq for ventilation and cooling a single room. They measured the temperature of the chimney's glass cover, the absorbing wall, and the induced air and analyzed them considering the induced air velocity.…”

Thermal-Fluids Analysis of a Hybrid Solar/Compost Waste Heat Updraft Tower

“…In [13], the geometrical shape of the solar chimney is studied where it is concluded that after a comprehensive analysis of system output power and efficiency, that the cylindrical chimney would be the best choice among the three basic configurations, whose optimum height to diameter aspect ratio. The work of [14] presents an experimental and numerical model of a solar whereby the maximum air velocity was 0.8 m/s for a radiation intensity of 750 W/m 2 at an air gap of 50 mm thickness. In [15] a novel small scale model of solar chimney was investigated experimentally and numerically where the experimental results show that utilization of intensifiers lead to a maximum velocity of 5.12 m/s.…”