Computational fluid dynamics using finite volume method: A numerical model for Double Skin Façades with renewable energy source in cold climates

Abstract

Double-skin façades often rely on proper cavity design, which unleashes a significant potential for inhabitation and renewable energy integration in cold climates. A co-model between Matlab and Ansys Fluent was developed to investigate the performance of a new typology for such façades. The steady-state energy balance equations for heat transfer were introduced with governing non-isothermal turbulent flow such that energy was conserved at each element of the assembly. Internal and mixed-mode ventilation schemes were utilized with multiple cavity widths and boundary conditions. The numerical model was validated against experimental measurements where the average temperature deviation was 1.9 °C. For the renewable energy source, the system utilized photovoltaics and microalgae modules which were brought in contact with the occupied space in order to counter the heat loss to the cold ambient. Results showed that double-skin façades were more energy efficient than an insulated double-glazed assembly regardless of the cavity ventilation scheme. The flow of heat transfer was reversed from 82.1 W/m2 loss to the surrounding to 35.7 W/m2 gain into the occupied space. Microalgae photobioreactors were found to have higher heating potential by generating 8.1% more than that of photovoltaics. Introducing ventilation into the cavity led to enhanced photovoltaics efficiency by 7.5% associated with a minimum drop in the cavity's temperature from 16.3 °C to −6.8 °C. Photobioreactors' functionability was enhanced by feeding water at a mean flow of 0.26 kg/s. The study recommended utilizing adjustable external air vents that can be regulated depending on the ambient temperature and the personal occupancy level in the cavity whenever its size fits.