Use of CFD Modelling for Transpired Solar Collectors and Associated Characterization of Multi-scale Airflow and Heat Transfer Mechanisms

Abstract

Transpired Solar Collectors (TSCs) are façade-integrated solar air-heating systems which comprise perforated wall-mounted cladding or over-cladding panels. The thermal performance of TSCs can be modeled, however current approaches tend to rely on non-realistic assumptions and simplifications, casting doubts over the resulting accuracy. The aim of this research has been to provide a comprehensive numerical model for TSCs using Computational Fluid Dynamics (CFD) able to take full account of factors such as: solar radiation, wind direction, non-uniform flows (particularly around the perforated plate), and the various types of heat transfer that occur. Many of these are not easily modeled using conventional CFD based approaches used for smaller or more easily predictable technologies.The model comprises a full size section of a typical TSC that can be easily morphed. A multi-block meshing approach was used to reduce grid size and to capture jet flows taking place in the plenum region through the perforations. When compared to experimental data over a wide range of climatic conditions, the modeled values of outlet temperatures at the absorber plate and plenum demonstrated a high level of accuracy, giving assurance regarding the validity of the approach. To the authors’ best knowledge, the model represents the most comprehensive TSC simulation tool so far developed.