Mathematical analysis of the influence of the chimney height and collector area on the performance of a roof top solar chimney

• Published in: Energy and buildings 2014-01, Vol.68, p.305-311
• Main Authors: Al-Kayiem, Hussain H., K.V., Sreejaya, Gilani, Syed Ihtsham Ul-Haq
• Format: Article
• Language: English
• Subjects: Applied sciences; Building technical equipments; Buildings; Buildings. Public works; Chimney. Smokestack; Computation methods. Tables. Charts; Environmental engineering; Exact sciences and technology; Mathematical modelling; Renewable energy; Roof top solar chimney; Solar chimney; Solar updraft; Structural analysis. Stresses; Thermal solar system
• ISSN: 0378-7788
• DOI: 10.1016/j.enbuild.2013.09.021

•A mathematical model of roof top solar chimney (RTSC) was developed.•Influences of absorber area and chimney height on the performance were studied.•The model was validated by comparing with experimental measurements.•Results are presented in form of air velocity and mass flow rate in the RTSC.•The performance is evaluated as the product of mass and temperature rise of air. Determination of the roof top solar chimney behaviour during the day time is essential for the proper designing and sizing. This paper presents a mathematical model and analysis of an inclined type roof top solar chimney. The thermal energy and fluid flow processes were simulated mathematically based on the energy and mass balances. The model was converted to a MATLAB computer program and solved by iteration method. The analysis was carried out at various collector areas (15, 150, and 600m2) and various chimney heights (5, 10, and 15m). The model was validated by comparing the results with the experimental measurements. The developed mathematical model was able to predict the dynamic behaviour of the system. The results demonstrated that the performance of the system is highly influenced by the solar intensity. The system becomes functional for space ventilation when the solar intensity is higher than 400W/m2 with a 15m2 collector area and 5m chimney height, under Malaysia and similar weather conditions. As the wind speed increases from 1.5 to 6m/s, it contributes to reduce the system performance by 25% at solar intensity of 900W/m2.