Computational modelling and simulation of the feasibility of a novel dual purpose solar chimney for power generation and passive ventilation in buildings

Abstract

This paper presents numerical study and analysis of a novel application of a proposed solar chimney system to help solve the problem of ventilation (thermal comfort) and energy management (inadequate power supply) of buildings in the tropics. The main objective of the study is to determine the feasibility of the proposed system vis-à-vis the airflow rate within the room for adequate ventilation and within the solar chimney for required velocity to power a small size wind turbine. The commercial Computational Fluid Dynamics package FLUENT (ANSYS WORKBENCH 14.5) was used for the simulation. The computational domain consist of a 2-D 4 × 4 m2 room and solar chimney with varying heights between 5 and 9 m and gap between 0.5 and 1 m. The solar radiation condition with solar heat flux (SHF) of between 200 and 1,000 W/m2 and ambient wind conditions of no wind and wind speed of 1.0 to 8.0 m/s were simulated. The validation of simulated results with experimental data from previous studies showed conformity with a deviation not more than 2.5%. Results showed that the room mass flow rate increased from 1.0 kg/s with no wind effect to about 30.1 kg/s with induced wind of 1.0 to 8.0 m/s. The air mass flow rate increased from about 0.57 to 0.91 kg/s at chimney height of 5 and 9 m respectively for no wind condition and SHF of 400 W/m2. The power outputs obtained from the SC with SHF of 400 W/m2 for chimney height of 5 and 9 m were 32.8 and 85.2 W/m2 respectively. The results presented helps layout and establish the fundamentals and system response to temperature and airflow of a solar chimney system used for the combined purpose of passive ventilation and power generation in a building.

Keywords

• Building
• Solar chimney
• Stack effect
• CFD
• ANSYS